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Curatable
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PMID:22279046
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One of the long-standing questions in eukaryotic DNA replication is the mechanisms that determine where and when a particular segment of the genome is replicated. Cdc7/Hsk1 is a conserved kinase required for initiation of DNA replication and may affect the site selection and timing of origin firing. We identified rif1Δ, a null mutant of rif1(+), a conserved telomere-binding factor, as an efficient bypass mutant of fission yeast hsk1. Extensive deregulation of dormant origins over a wide range of the chromosomes occurs in rif1Δ in the presence or absence of hydroxyurea (HU). At the same time, many early-firing, efficient origins are suppressed or delayed in firing timing in rif1Δ. Rif1 binds not only to telomeres, but also to many specific locations on the arm segments that only partially overlap with the prereplicative complex assembly sites, although Rif1 tends to bind in the vicinity of the late/dormant origins activated in rif1Δ. The binding to the arm segments occurs through M to G1 phase in a manner independent of Taz1 and appears to be essential for the replication timing program during the normal cell cycle. Our data demonstrate that Rif1 is a critical determinant of the origin activation program on the fission yeast chromosomes.
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Genes Dev 2012 Jan 15;26(2):137-50
| 287 | 1 |
Wrong organism
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PMID:10531356
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To expand our understanding of the role of Jak2 in cellular signaling, we used the yeast two-hybrid system to identify Jak2-interacting proteins. One of the clones identified represents a human homologue of the Schizosaccaromyces pombe Shk1 kinase-binding protein 1, Skb1, and the protein encoded by the Saccharomyces cerevisiae HSL7 (histone synthetic lethal 7) gene. Since no functional motifs or biochemical activities for this protein or its homologues had been reported, we sought to determine a biochemical function for this human protein. We demonstrate that this protein is a protein methyltransferase. This protein, designated JBP1 (Jak-binding protein 1), and its homologues contain motifs conserved among protein methyltransferases. JBP1 can be cross-linked to radiolabeled S-adenosylmethionine (AdoMet) and methylates histones (H2A and H4) and myelin basic protein. Mutants containing substitutions within a conserved region likely to be involved in AdoMet binding exhibit little or no activity. We mapped the JBP1 gene to chromosome 14q11.2-21. In addition, JBP1 co-immunoprecipitates with several other proteins, which serve as methyl group acceptors and which may represent physiological targets of this methyltransferase. Messenger RNA for JBP1 is widely expressed in human tissues. We have also identified and sequenced a homologue of JBP1 in Drosophila melanogaster. This report provides a clue to the biochemical function for this conserved protein and suggests that protein methyltransferases may have a role in cellular signaling.
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J Biol Chem 1999 Oct 29;274(44):31531-42
| 361 | 0 |
Curatable
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PMID:25473118
|
Rho GTPases, activated by guanine nucleotide exchange factors (GEFs), are essential regulators of polarized cell growth, cytokinesis, and many other cellular processes. However, the regulation of Rho-GEFs themselves is not well understood. Rgf3 is an essential GEF for Rho1 GTPase in fission yeast. We show that Rgf3 protein levels and localization are regulated by arrestin-related protein Art1. art1∆ cells lyse during cell separation with a thinner and defective septum. As does Rgf3, Art1 concentrates to the contractile ring starting at early anaphase and spreads to the septum during and after ring constriction. Art1 localization depends on its C-terminus, and Art1 is important for maintaining Rgf3 protein levels. Biochemical experiments reveal that the Rgf3 C-terminus binds to Art1. Using an Rgf3 conditional mutant and mislocalization experiments, we found that Art1 and Rgf3 are interdependent for localization to the division site. As expected, active Rho1 levels at the division site are reduced in art1∆ and rgf3 mutant cells. Taken together, these data reveal that the arrestin family protein Art1 regulates the protein levels and localization of the Rho-GEF Rgf3, which in turn modulates active Rho1 levels during fission yeast cytokinesis.
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Mol Biol Cell 2015 Feb 01;26(3):453-66
| 308 | 1 |
Wrong organism
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PMID:27496102
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Chilo iridescent virus (CIV) is the type member of the genus Iridovirus within the family Iridoviridae. The virions of CIV contain a single linear dsDNA molecule that is circularly permuted and terminally redundant. The genome of CIV contains an open reading frame (ORF 012L) encoding a protein homologous to exonuclease II of Schizosaccharomyces pombe. In this study, we focused on the characterization of CIV ORF 012L. The target ORF was cloned into the pET28a vector, expressed in E. coli strain BL21 (DE3) pLysS with an N-terminal His tag and purified to homogeneity by using Ni-NTA affinity chromatography. Biochemical characterization of the purified CIV 012L confirmed that this viral protein is a functional 5'-3' exonuclease that digests 3'-biotin-labelled oligonucleotides and linear double-stranded DNA (dsDNA) molecules from their 5' termini in a highly processive manner. CIV 012L also has a potent endonuclease activity on dsDNA in vitro. In addition, CIV 012L converted supercoiled plasmid DNA (replicative form I, RFI) into the open circular form (RFII) and then open circular form into linear form (RFIII). Endonuclease activity of CIV 012L was optimal in the presence of 10 mM Mg(2+) or 30 mM Mn(2+) ions and at 150 mM NaCl or KCl salt concentrations. The highest endonuclease activity was obtained at pH 8, and it reached a maximum at 55 °C. The CIV 012L protein showed deficiencies for both double- and single-stranded RNAs.
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Arch Virol 2016 Nov;161(11):3029-37
| 399 | 0 |
Wrong organism
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PMID:3293803
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In the fission yeast S. pombe, the Mr = 34 kd product of the cdc2+ gene (p34cdc2) is a protein kinase that controls entry into mitosis. In Xenopus oocytes and other cells, maturation-promoting factor (MPF) appears in late G2 phase and is able to cause entry into mitosis. Purified MPF consists of two major proteins of Mr approximately equal to 32 kd and 45 kd and expresses protein kinase activity. We report here that antibodies to S. pombe p34cdc2 are able to immunoblot and immunoprecipitate the approximately equal to 32 kd component of MPF from Xenopus eggs. The Mr approximately equal to 32 kd and 45 kd proteins exist as a complex that expresses protein kinase activity. These findings indicate that a Xenopus p34cdc2 homolog is present in purified MPF and suggest that p34cdc2 is a component of the control mechanism initiating mitosis generally in eukaryotic cells.
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Cell 1988 Jul 29;54(3):433-9
| 223 | 0 |
Review or comment
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PMID:11102318
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Increasing evidence suggests that HIV-1 viral protein R (Vpr) plays an important role in viral pathogenesis, as its functions are being linked to viral activation, suppression of human immune functions and depletion of human CD4 lymphocytes, which are the major clinical manifestation of AIDS. In vitro, Vpr shows multiple activities both in mammalian and yeast cells, which include nuclear transport, induction of cell cycle G2 arrest, morphological changes and cell death. The occurrence of these activities in yeast indicates that Vpr interacts with highly conserved cellular processes to cause these effects and allows Vpr activities to be studied in these genetically well characterized organisms. Studies of Vpr in fission yeast (Schizosaccharomyces pombe) and budding yeast (Saccharomyces cerevisiae) have helped to establish these major conclusions. 1) Vpr induces G2 arrest through inhibitory phosphorylation of the cyclin-dependent kinase by a pathway in which protein phosphatase 2A plays an important role. 2) Vpr fulfills its essential role in the nuclear transport of the viral pre-integration complex by binding to a novel site on importin ?. 3) Vpr induces apoptosis by directly permeabilizing the mitochondrial membrane. 4) Vpr also appears to kill cells by mitochondrial-independent mechanisms. 5) G2 arrest and cell death induced by Vpr are two independent functions, and 6) amino acid residues of Vpr at position 29, 33 and 71 are important sites for maintaining the overall structure of Vpr. Future studies of Vpr in yeast are expected to make additional contributions to understanding the mechanisms of Vpr activities and may also help address the importance of these activities during the course of a HIV-1 infection.
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Front Biosci 2000 Dec 01;5:D905-16
| 358 | 0 |
Review or comment
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PMID:29694899
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In fission yeast, the nuclear envelope (NE) remains intact during mitosis and meiosis I but is compromised during meiosis II. In this issue of Cell Reports, Flor-Parra et al. (2018) demonstrate that this NE alteration regulates meiosis II spindle disassembly and the ploidy of meiotic products.
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Cell Rep 2018 04 24;23(4):931-932
| 71 | 0 |
Wrong organism
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PMID:15120066
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While double-strand break (DSB) repair is vital to the survival of cells during both meiosis and mitosis, the preferred mechanism of repair differs drastically between the two types of cell cycle. Thus, during meiosis, it is the homologous chromosome rather than the sister chromatid that is used as a repair template. Cells attempting to undergo meiosis in the absence of Mnd1 arrest in prophase I due to the activation of the Mec1 DNA-damage checkpoint accumulating hyperresected DSBs and aberrant synapsis. Sporulation of mnd1Delta strains can be restored by deleting RED1 or HOP1, which permits repair of DSBs by using the sister chromatid as a repair template. Mnd1 localizes to chromatin as foci independently of DSB formation, axial element (AE) formation, and synaptonemal complex (SC) formation and does not colocalize with Rad51. Mnd1 does not preferentially associate with hotspots of recombination. Our results suggest that Mnd1 acts specifically to promote DSB repair by using the homologous chromosome as a repair template. The presence of Rec8, Red1, or Hop1 renders Mnd1 indispensable for DNA repair, presumably through the establishment of interhomolog (IH) bias. Localization studies suggest that Mnd1 carries out this function without being specifically recruited to the sites of DNA repair. We propose a model in which Mnd1 facilitates chromatin accessibility, which is required to allow strand invasion in meiotic chromatin.
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Curr Biol 2004 May 04;14(9):752-62
| 330 | 0 |
Other
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PMID:2298254
|
An antifungal antibiotic, leptomycin B (LMB), which induced cell elongation of fission yeast, Schizosaccharomyces pombe, was found to be a unique inhibitor of the cell cycle of mammalian and fission yeast cells. Proliferation of rat 3Y1 fibroblasts was reversibly blocked by LMB in both the G1 and G2 phases and the treated cells were presumably introduced into the resting state (GO). After removal of LMB, proliferative tetraploid cells were produced from the cells which had been arrested by LMB at the G2 phase, as a result of DNA replication without passage through the M phase. LMB also inhibited the proliferation of S. pombe in both the G1 and G2 phases. These results suggest that the molecular target of LMB is one of the components necessary for progression of both G1 and G2 in the eukaryotic cell cycle.
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Exp Cell Res 1990 Mar;187(1):150-6
| 199 | 0 |
Curatable
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PMID:23732911
|
Broadly conserved, mitogen-activated/stress-activated protein kinases (MAPK/SAPK) of the p38 family regulate multiple cellular processes. They transduce signals via dimeric, basic leucine zipper (bZIP) transcription factors of the ATF/CREB family (such as Atf2, Fos, and Jun) to regulate the transcription of target genes. We report additional mechanisms for gene regulation by such pathways exerted through RNA stability controls. The Spc1 (Sty1/Phh1) kinase-regulated Atf1-Pcr1 (Mts1-Mts2) heterodimer of the fission yeast Schizosaccharomyces pombe controls the stress-induced, posttranscriptional stability and decay of sets of target RNAs. Whole transcriptome RNA sequencing data revealed that decay is associated nonrandomly with transcripts that contain an M26 sequence motif. Moreover, the ablation of an M26 sequence motif in a target mRNA is sufficient to block its stress-induced loss. Conversely, engineered M26 motifs can render a stable mRNA into one that is targeted for decay. This stress-activated RNA decay (SARD) provides a mechanism for reducing the expression of target genes without shutting off transcription itself. Thus, a single p38-ATF/CREB signal transduction pathway can coordinately induce (promote transcription and RNA stability) and repress (promote RNA decay) transcript levels for distinct sets of genes, as is required for developmental decisions in response to stress and other stimuli.
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Mol Cell Biol 2013 Aug;33(15):3026-35
| 326 | 1 |
Curatable
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PMID:12186947
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Fission yeast cells with a temperature-sensitive Orp1 protein, a component of the origin recognition complex, cannot perform DNA replication at the restrictive temperature. Seventy percent of orp1-4 cells arrest with a 1C DNA content, whereas 30% proceed to mitosis ('cut'). The arrest depends upon the checkpoint Rad proteins and, surprisingly, the Chk1 protein, which is thought to act only from late S phase. The arrested cells maintain a 1C DNA content, as judged by flow cytometry, and the early origin ars3001 has not been initiated, as judged by 2D gel analysis. We show that in G1-arrested orp1-4 cells, Wee1 phosphorylates and inactivates Cdc2. Activation of Chk1 occurs earlier than Cdc2 phosphorylation, indicating a novel role for Chk1, namely to induce and/or maintain Cdc2 phosphorylation upon checkpoint activation in G1. We also show that commitment to cutting occurs already in early G1 phase.
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J Cell Sci 2002 Sep 15;115(Pt 18):3609-18
| 219 | 1 |
Wrong organism
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PMID:11426862
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The differentiation and metabolism in the soil-borne saprophytic deuteromycete Trichoderma viride are subject to control by light. We have investigated the effect of illumination of mycelia on the activities of cell-wall synthesizing enzymes beta-1,3-glucan synthase and chitin synthase and on the composition of cell alls. After 10 min illumination of dark-grown mycelia with white fluorescent light at 600 1x, a gradual rise in specific activity of membrane-bound enzymes beta-1,3-glucan synthase by about 130% and a decrease in specific activity of chitin synthase by about 50% in relation to the dark control were observed. The changes in enzyme activities were caused by de novo synthesis of corresponding polysaccharide synthases(s) and/or their regulatory components since they were not observed when protein synthesis was blocked with 50 microg/ml cycloheximide. The content of beta-1,3-glucan in the cell walls of illuminated mycelia has increased by 35-50% in comparison to the dark control while the content of chitin remained practically unchanged.
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Acta Biol Hung 2001;52(2-3):281-8
| 247 | 0 |
Curatable
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PMID:17299416
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The fission yeast Schizosaccharomyces pombe is a widely used model organism to study basic mechanisms of eukaryotic biology, but unlike other model organisms, its proteome remains largely uncharacterized. Using a shotgun proteomics approach based on multidimensional prefractionation and tandem mass spectrometry, we have detected approximately 30% of the theoretical fission yeast proteome. Applying statistical modelling to normalize spectral counts to the number of predicted tryptic peptides, we have performed label-free quantification of 1465 proteins. The fission yeast protein data showed considerable correlations with mRNA levels and with the abundance of orthologous proteins in budding yeast. Functional pathway analysis indicated that the mRNA-protein correlation is strong for proteins involved in signalling and metabolic processes, but increasingly discordant for components of protein complexes, which clustered in groups with similar mRNA-protein ratios. Self-organizing map clustering of large-scale protein and mRNA data from fission and budding yeast revealed coordinate but not always concordant expression of components of functional pathways and protein complexes. This finding reaffirms at the protein level the considerable divergence in gene expression patterns of the two model organisms that was noticed in previous transcriptomic studies.
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Mol Syst Biol 2007;3:79
| 251 | 1 |
Wrong organism
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PMID:21852534
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A major role of the RNAi pathway in Schizosaccharomyces pombe is to nucleate heterochromatin, but it remains unclear whether this mechanism is conserved. To address this question in Drosophila, we performed genome-wide localization of Argonaute2 (AGO2) by chromatin immunoprecipitation (ChIP)-seq in two different embryonic cell lines and found that AGO2 localizes to euchromatin but not heterochromatin. This localization pattern is further supported by immunofluorescence staining of polytene chromosomes and cell lines, and these studies also indicate that a substantial fraction of AGO2 resides in the nucleus. Intriguingly, AGO2 colocalizes extensively with CTCF/CP190 chromatin insulators but not with genomic regions corresponding to endogenous siRNA production. Moreover, AGO2, but not its catalytic activity or Dicer-2, is required for CTCF/CP190-dependent Fab-8 insulator function. AGO2 interacts physically with CTCF and CP190, and depletion of either CTCF or CP190 results in genome-wide loss of AGO2 chromatin association. Finally, mutation of CTCF, CP190, or AGO2 leads to reduction of chromosomal looping interactions, thereby altering gene expression. We propose that RNAi-independent recruitment of AGO2 to chromatin by insulator proteins promotes the definition of transcriptional domains throughout the genome.
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Genes Dev 2011 Aug 15;25(16):1686-701
| 314 | 0 |
Curatable
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PMID:16585273
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During meiotic prophase I of the fission yeast Schizosaccharomyces pombe, oscillatory nuclear movement occurs. This promotes homologous chromosome pairing and recombination and involves cortical dynein, which plays a pivotal role by generating a pulling force with the help of an unknown dynein anchor. We show that Mcp5, the homologue of the budding yeast dynein anchor Num1, may be this putative dynein anchor. mcp5+ is predominantly expressed during meiotic prophase, and GFP-Mcp5 localizes at the cell cortex. Moreover, the mcp5Delta strain lacks the oscillatory nuclear movement. Accordingly, homologous pairing and recombination rates of the mcp5Delta strain are significantly reduced. Furthermore, the cortical localization of dynein heavy chain 1 appears to be reduced in mcp5Delta cells. Finally, the full function of Mcp5 requires its coiled-coil and pleckstrin homology (PH) domains. Our results suggest that Mcp5 localizes at the cell cortex through its PH domain and functions as a dynein anchor, thereby facilitating nuclear oscillation.
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J Cell Biol 2006 Apr 10;173(1):27-33
| 245 | 1 |
Curatable
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PMID:12589433
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Mkp1 ( MAPKAP kinase Schizosaccharomyces pombe 1) and Mkp2 are two members from fission yeast of the sub-class of putative MAPK-activated protein kinases in yeasts, the other known members being Rck1 and Rck2 from Saccharomyces cerevisiae. The Mkp1 protein is readily co-immunoprecipitated with Sty1 from S. pombe extracts; Mkp2 shows a weaker interaction with Sty1. In mkp1 mutants, conjugation and meiosis proceed more readily and rapidly than in wild-type cells, in analogy to what was previously found for S. cerevisiae rck1 mutants. Conversely, overexpression of mkp1(+) delays meiosis. Mkp1 is phosphorylated in vivo in a sty1(+)-dependent manner; this modification is removed when cells are starved for nitrogen, a condition that is conducive to entry into stationary phase and meiosis. Overexpression of mkp1(+), like a sty1 mutation, also causes vegetative cells to elongate. The level of Mkp1 phosphorylation drops as cells enter mitosis. We have localised Mkp1 to the cytoplasm, excluded from the nucleus, in vegetative cells. The Mkp1 protein accumulates in zygotic asci and is concentrated within spores. The mkp2(+) gene has no noticeable impact on meiosis. Mkp2 is excluded from the nucleus in vegetative cells, and is concentrated at the septa of dividing cells. Mkp2 does not accumulate in meiotic cells.
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Mol Genet Genomics 2003 Feb;268(5):585-97
| 348 | 1 |
Review or comment
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PMID:11385632
|
Homologous chromosome pairing is required for proper chromosome segregation and recombination during meiosis. The mechanism by which a pair of homologous chromosomes contact each other to establish pairing is not fully understood. When pairing occurs during meiotic prophase in the fission yeast, Schizosaccharomyces pombe, the nucleus oscillates between the cell poles and telomeres remain clustered at the leading edge of the moving nucleus. These meiosis-specific activities produce movements of telomere-bundled chromosomes. Several lines of evidence suggest that these movements facilitate homologous chromosome pairing by aligning homologous chromosomes and promoting contact between homologous regions. Since telomere clustering and nuclear or chromosome movements in meiotic prophase have been observed in a wide range of eukaryotic organisms, it is suggested that telomere-mediated chromosome movements are general activities that facilitate homologous chromosome pairing.
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Bioessays 2001 Jun;23(6):526-33
| 190 | 0 |
Wrong organism
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PMID:12788039
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Walker-Warburg syndrome (WWS) is an autosomal recessive disorder characterized by the combined involvement of the central nervous and skeletal muscle systems. Although the molecular basis of WWS remains unknown, defects in the muscle fibre basal lamina are characteristic of other forms of congenital muscular dystrophy (CMD). In agreement with this, some forms of CMD, due to glycosyltransferase defects, display a reduction in the immunolabelling of alpha-dystroglycan, whilst beta-dystroglycan labelling appears normal. Here we describe an almost complete absence of alpha-dystroglycan using both immunohistochemistry and immunoblotting in two patients with WWS. In addition, there was a mild reduction of laminin-alpha 2. In contrast, immunohistochemical labelling of perlecan and collagen VI was normal. Linkage analysis excluded the recently identified POMT1 locus, responsible for a proportion of WWS cases. These results confirm that WWS is a genetically heterogeneous condition and suggest that disruption of the alpha-dystroglycan/laminin-alpha 2 axis in the basal lamina may play a role in the degeneration of muscle fibres in WWS-also in cases not due to POMT1 defects.
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Eur J Paediatr Neurol 2003;7(3):129-37
| 274 | 0 |
Curatable
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PMID:23271606
|
TOR (target of rapamycin) signaling regulates cell growth and division in response to environmental stimuli such as the availability of nutrients and various forms of stress. The vegetative growth of fission yeast cells, unlike other eukaryotic cells, is not inhibited by treatment with rapamycin. We found that certain mutations including pmc1Δ (Ca(2+)-ATPase), cps9-193 (small GTPase, Ryh1) and cps1-12 (1,3-β-D-glucan synthase, Bgs1) confer a rapamycin-sensitive phenotype to cells under salt stress with potassium chloride (>0.5 M). Cytometric analysis revealed that the mutant cells were unable to enter the mitotic cell cycle when treated with the drug under salt stress. Gene cloning and overexpression experiments revealed that the sensitivity to rapamycin was suppressed by the ectopic expression of tyrosine phosphatases, Pyp1 and Pyp2, which are negative regulators of Spc1/Sty1 mitogen-activated protein kinase (MAPK). The level of tyrosine phosphorylation on Spc1 was higher and sustained substantially longer in these mutants than in the wild type under salt stress. The hyperphosphorylation was significantly suppressed by overexpression of pyp1 (+) with concomitant resumption of the mutant cells' growth. In fission yeast, TOR signaling has been thought to stimulate the stress-response pathway, because mutations of TORC2 components such as Tor1, Sin1 and Ste20 result in similar sensitive phenotypes to environmental stress. The present study, however, strongly suggests that TOR signaling is required for the down-regulation of a hyperactivated Spc1 for reentry into the mitotic cell cycle. This finding may shed light on our understanding of a new stress-responsive mechanism in TOR signaling in higher organisms.
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Mol Genet Genomics 2013 Feb;288(1-2):63-75
| 396 | 1 |
Review or comment
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PMID:28684607
|
One of the major challenges of modern cell biology is to understand how cells are assembled from nanoscale components into micrometer-scale entities with a specific size and shape. Here I describe how our quest to understand the morphogenesis of the fission yeast Schizosaccharomyces pombe drove us to investigate cellular mechanics. These studies build on the view that cell shape arises from the physical properties of an elastic cell wall inflated by internal turgor pressure. Consideration of cellular mechanics provides new insights into not only mechanisms responsible for cell-shape determination and growth, but also cellular processes such as cytokinesis and endocytosis. Studies in yeast can help to illuminate approaches and mechanisms to study the mechanobiology of the cell surface in other cell types, including animal cells.
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Mol Biol Cell 2017 Jul 07;28(14):1819-1824
| 164 | 0 |
Not physically mapped
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PMID:8381667
|
An enzyme that catalyzes the asymmetric hydrolysis of Ap4A has been partially purified from the fission yeast, Schizosaccharomyces pombe. The crude supernatant fraction from log-phase cells was fractionated by (NH4)2SO4 precipitation followed by chromatography on DEAE-cellulose, Red A dye-ligand and QAE-Sepharose resins. Two peaks of Ap4A hydrolase activity, designated major and minor, were separated on the Red A dye-ligand resin. Both the major and minor Ap4A hydrolase have an apparent molecular mass of 49 kDa based on gel filtration chromatography. On a SDS polyacrylamide gel, a protein of 22 kDa exhibited Ap4A hydrolase activity. Both forms of the enzyme have a Km value in the range of 22 to 36 microM for Ap4A. Both forms of the enzyme asymmetrically hydrolyze Ap4A to AMP and ATP as determined by HPLC. Ap4A is the optimal substrate among several nucleotides and dinucleoside polyphosphates tested at 10 microM. A divalent metal cation is required for activity. Concentrations of Pi below 30 mM stimulate Ap4A hydrolase while higher concentrations inhibit the activity. Pi is not a substrate for this Ap4A-degradative enzyme. Fluoride, from 50 microM to 20 mM, has no significant effect on Ap4A hydrolase activity.
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Biochim Biophys Acta 1993 Feb 13;1161(2-3):139-48
| 321 | 0 |
Curatable
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PMID:16085489
|
Schizosaccharomyces pombe cells divide through the use of an actomyosin-based contractile ring. In response to perturbation of the actomyosin ring, S. pombe cells delay in a "cytokinesis-competent" state characterized by continuous repair and maintenance of the actomyosin ring and a G2 delay. This checkpoint mechanism requires the function of the Cdc14p-family phosphatase Clp1p/Flp1p and the septation initiation network (SIN). In response to cytokinetic defects, Clp1p, normally nucleolar in interphase, is retained in the cytoplasm until completion of cell division in a SIN-dependent manner. Here, we show that a phosphorylated form of Clp1p binds the 14-3-3 protein Rad24p and is retained in the cytoplasm in a Rad24p-dependent manner in response to cytokinesis defects. This physical interaction depends on the function of the SIN component, Sid2p. In the absence of Rad24p, cells are unable to maintain SIN signaling and lose viability upon mild cytokinetic stress. The requirement of Rad24p in this checkpoint is bypassed by ectopic activation of the SIN. Furthermore, SIN-dependent nuclear exclusion of Clp1p is dependent on Rad24p function. We conclude that Rad24p-mediated cytoplasmic retention of Clp1p/Flp1p is important for cell viability upon stress to the division apparatus.
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Curr Biol 2005 Aug 09;15(15):1376-83
| 333 | 1 |
Biotech
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PMID:33648190
|
The microbiota in traditional solid-state fermentation is a complex microbiota that plays a key role in the production of feed, fuel, food and pharmaceutical products. The function of microbiota is an important factor dictating the quantity and quality of products. Core functional species play key metabolic roles in the microbiota, and their disappearance could result in the abnormal fermentation process. In this work, we combined Baijiu production and laboratory experiments to explore the keystone microbes and their metabolites. We found the deletion of core functional microbe resulted in the loss of multiple metabolites involved many alcohols and acids. In the traditional Baijiu production, the absence or appearance of Schizosaccharomyces pombe caused the content divergence in 227 flavor-related metabolites, especially in ethanol, butanol and pentanoic acid between abnormal and normal group (each content > 1 mg/kg and the content ratio of normal/abnormal group > 2). Schi. pombe increased the expression level of related genes involving alcohol dehydrogenase (ADH), acyl-CoA oxidase (ACOX) and trans-2-enoyl-CoA reductase (TER). Moreover, in the verification experiment of laboratory, the absence or appearance of Schizosaccharomyces pombe C-11 caused the content divergence in 136 flavor-related metabolites, especially in ethanol, butanol and pentanoic acid between Sp- and Sp+ group (each content > 1 mg/kg and the content ratio of Sp+/Sp- group > 2). Our results identified specific member that were essential for the function of fermentation microbiota. This study also suggests species deletions from fermentation microbiota and synthetic consortium could be a useful approach to illustrate relevant microbe-metabolites association and defining metabolic roles in the traditional solid-state fermentation.
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Food Res Int 2021 02;140:109872
| 381 | 0 |
Review or comment
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PMID:22746336
|
RNA interference (RNAi) is a conserved eukaryotic gene regulatory mechanism that uses small noncoding RNAs to mediate posttranscriptional/transcriptional gene silencing. The fission yeast Schizosaccharomyces pombe and the filamentous fungus Neurospora crassa have served as important model systems for RNAi research. Studies on these two organisms and other fungi have contributed significantly to our understanding of the mechanisms and functions of RNAi in eukaryotes. In addition, surprisingly diverse RNAi-mediated processes and small RNA biogenesis pathways have been discovered in fungi. In this review, we give an overview of different fungal RNAi pathways with a focus on their mechanisms and functions.
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Annu Rev Microbiol 2012;66:305-23
| 152 | 0 |
Curatable
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PMID:33159083
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Nuclear Pore complexes (NPCs) act as docking sites to anchor particular DNA lesions facilitating DNA repair by elusive mechanisms. Using replication fork barriers in fission yeast, we report that relocation of arrested forks to NPCs occurred after Rad51 loading and its enzymatic activity. The E3 SUMO ligase Pli1 acts at arrested forks to safeguard integrity of nascent strands and generates poly-SUMOylation which promote relocation to NPCs but impede the resumption of DNA synthesis by homologous recombination (HR). Anchorage to NPCs allows SUMO removal by the SENP SUMO protease Ulp1 and the proteasome, promoting timely resumption of DNA synthesis. Preventing Pli1-mediated SUMO chains was sufficient to bypass the need for anchorage to NPCs and the inhibitory effect of poly-SUMOylation on HR-mediated DNA synthesis. Our work establishes a novel spatial control of Recombination-Dependent Replication (RDR) at a unique sequence that is distinct from mechanisms engaged at collapsed-forks and breaks within repeated sequences.
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Nat Commun 2020 11 06;11(1):5643
| 223 | 1 |
Curatable
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PMID:15932060
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In fission yeast (Schizosaccharomyces pombe) the homologue of the mammalian SUMO-1 ubiquitin-like modifier is encoded by the pmt3 gene. A two-hybrid screen using the telomere-binding protein Taz1p as bait identified Pmt3p as an interacting factor. In vitro experiments using purified components of the fission yeast Pmt3p modification system demonstrated that Taz1p could be modified directly by Pmt3p. The amino acid sequence of Taz1p contains a close match to the consensus modification site for SUMO-1, and a PEST sequence similar to those found in established SUMO-1 targets. Although previous experiments have identified an increase in telomere length as one consequence of the pmt3--genotype, we could not detect Pmt3p modification of Taz1p in protein extracts made from exponentially growing haploid cells or any effect of Pmt3p on the localization of GFP-Taz1p at discrete foci in the haploid cell nucleus.
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Biochem Genet 2005 Apr;43(3-4):103-17
| 225 | 1 |
Curatable
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PMID:29866182
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Heat-shock molecular chaperone proteins (Hsps) promote the loading of small interfering RNA (siRNA) onto RNA interference (RNAi) effector complexes. While the RNAi process is coupled with heterochromatin assembly in several model organisms, it remains unclear whether the Hsps contribute to epigenetic gene regulation. In this study, we used the fission yeast Schizosaccharomyces pombe as a model organism and investigated the roles of Hsp90 and Mas5 (a nucleocytoplasmic type-I Hsp40 protein) in RNAi-dependent heterochromatin assembly. Using a genetic screen and biochemical analyses, we identified Hsp90 and Mas5 as novel silencing factors. Mutations in the genes encoding these factors caused derepression of silencing at the pericentromere, where heterochromatin is assembled in an RNAi-dependent manner, but not at the subtelomere, where RNAi is dispensable. The mutations also caused a substantial reduction in the level of dimethylation of histone H3 at Lys9 at the pericentromere, where association of the Argonaute protein Ago1 was also abrogated. Consistently, siRNA corresponding to the pericentromeric repeats was undetectable in these mutant cells. In addition, levels of Tas3, which is a protein in the RNA-induced transcriptional silencing complex along with Ago1, were reduced in the absence of Mas5. Our results suggest that the Hsps Hsp90 and Mas5 contribute to RNAi-dependent heterochromatin assembly. In particular, Mas5 appears to be required to stabilize Tas3 in vivo. We infer that impairment of Hsp90 and Hsp40 also may affect the integrity of the epigenome in other organisms.
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Epigenetics Chromatin 2018 06 04;11(1):26
| 378 | 1 |
Phylogeny and evolutionary studies
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PMID:14676319
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Fungal type I polyketides (PKs) are synthesized by PK synthases (PKSs) and include well known secondary metabolites such as the anticholesterol drug lovastatin and the potent natural carcinogen aflatoxin. Other type I PKs are known to be virulence factors for some plant pathogens and pigments such as melanin. In this study, a phylogenomic approach was used to investigate the origin and diversity of fungal genes encoding putative PKSs that are predicted to synthesize type I PKs. The resulting genealogy, constructed by using the highly conserved PKS ketosynthase (KS) domain, indicated that: (i). Species within subphylum Pezizomycotina (phylum Ascomycota) but not early diverging ascomycetes, like Saccharomyces cerevisiae (Saccharomycotina) or Schizosaccharomyces pombe (Taphrinomycotina), had large numbers (7-25) of PKS genes. (ii). Bacteria and fungi had separate groups of PKS genes; the few exceptions are the likely result of horizontal gene transfer from bacteria to various sublineages of fungi. (iii). The bulk of genes encoding fungal PKSs fell into eight groups. Four groups were predicted to synthesize variously reduced PKs, and four groups were predicted to make unreduced PKs. (iv). Species within different classes of Pezizomycotina shared the same groups of PKS genes. (v). Different fungal genomes shared few putative orthologous PKS genes, even between closely related genomes in the same class or genus. (vi) The discontinuous distributions of orthologous PKSs among fungal species can be explained by gene duplication, divergence, and gene loss; horizontal gene transfer among fungi does not need to be invoked.
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Proc Natl Acad Sci U S A 2003 Dec 23;100(26):15670-5
| 398 | 0 |
Wrong organism
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PMID:19466602
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In Saccharomyces cerevisiae, ribosomal protein L7, one of the approximately 46 ribosomal proteins of the 60S subunit, is encoded by paralogous RPL7A and RPL7B genes. The amino acid sequence identity between Rpl7a and Rpl7b is 97 percent; they differ by only 5 amino acid residues. Interestingly, despite the high sequence homology, Rpl7b is detected in both the cytoplasm and the nucleolus, whereas Rpl7a is detected exclusively in the cytoplasm. A site-directed mutagenesis experiment revealed that the change in the amino acid sequence of Rpl7b does not influence its sub-cellular localization. In addition, introns of RPL7A and RPL7B did not affect the subcellular localization of Rpl7a and Rpl7b. Remarkably, Rpl7b was detected exclusively in the cytoplasm in rpl7a knockout mutant, and overexpression of Rpl7a resulted in its accumulation in the nucleolus, indicating that the subcellular localization of Rpl7a and Rpl7b is influenced by the intracellular level of Rpl7a. Rpl7b showed a wide range of localization patterns, from exclusively cytoplasmic to exclusively nucleolar, in knock-out mutants for some rRNA-processing factors, nuclear pore proteins, and large ribosomal subunit assembly factors. Rpl7a, however, was detected exclusively in the cytoplasm in these mutants. Taken together, these results suggest that although Rpl7a and Rpl7b are paralogous and functionally replaceable with each other, their precise physiological roles may not be identical.
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Mol Cells 2009 May 31;27(5):539-46
| 373 | 0 |
Curatable
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PMID:10679013
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Eukaryotic cells coordinate cell size with cell division by regulating the length of the G1 and G2 phases of the cell cycle. In fission yeast, the length of the G1 phase depends on a precise balance between levels of positive (cig1, cig2, puc1, and cdc13 cyclins) and negative (rum1 and ste9-APC) regulators of cdc2. Early in G1, cyclin proteolysis and rum1 inhibition keep the cdc2/cyclin complexes inactive. At the end of G1, the balance is reversed and cdc2/cyclin activity down-regulates both rum1 and the cyclin-degrading activity of the APC. Here we present data showing that the puc1 cyclin, a close relative of the Cln cyclins in budding yeast, plays an important role in regulating the length of G1. Fission yeast cells lacking cig1 and cig2 have a cell cycle distribution similar to that of wild-type cells, with a short G1 and a long G2. However, when the puc1(+) gene is deleted in this genetic background, the length of G1 is extended and these cells undergo S phase with a greater cell size than wild-type cells. This G1 delay is completely abolished in cells lacking rum1. Cdc2/puc1 function may be important to down-regulate the rum1 Cdk inhibitor at the end of G1.
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Mol Biol Cell 2000 Feb;11(2):543-54
| 308 | 1 |
Wrong organism
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PMID:16922681
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Neurospora crassa has been the model filamentous fungus for the study of many fundamental cellular mechanisms of transport and metabolism. The recently completed genome sequence of N. crassa has over 10,000 genes without significant matches for a large number of genes (41%) in the sequence databases, indeed presents many challenges for new discoveries. Using transporter database and BLAST searches a total of 65 open reading frames for putative cation transporter genes have been identified in N. crassa. These were further confirmed by characteristic features of the family like transmembrane domains (TOPPRED 2), conserved motifs (Clustal W) and phylogenetic analysis (TREETOP). In Neurospora cation transporter genes constitute nearly 18.3% of the total membrane transport systems, which is higher than E. coli (8.8%), S. cerevisiae (13.7%), S. pombe (17.2%), A. fumigatus (10.1%), A. thaliana (16.8%) and H. sapiens (15.6%). We refer to the complete complement of metal ion transporter genes as "Metal Transportome". There are a total of 33 putative transporters for alkali and alkaline earth metals constituting 18 for calcium (P-ATPase, VIC, CaCA, Mid1), 7 for sodium (P-ATPase, CPA1, CPA2), 4 for potassium (Trk, VIC, KUP), and 4 for magnesium (MIT). Transition metal ion transporters account for 32 transporters including 7 for zinc (ZIP), 6 for copper (Ctr2, Ctr1), 2 each for manganese (Nramp), iron (OFeT), arsenite (ArsAB, ACR3) and other metal ions (ABC and P-ATPase) and 1 each for nickel (NiCoT) and chromate (CHR). N. crassa has 7 linkage groups of which LGI harbors 21 of metal ion transporters and in contrast LGVII has only 2. Studies on metal transportomes of different organisms will help to unravel the role of metal ion transporters in homeostasis.
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In Silico Biol 2006;6(3):169-80
| 468 | 0 |
Curatable
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PMID:14762117
|
We have cloned a fission yeast (Schizosaccharomyces pombe) homologue of Ini, a novel RING-finger-like protein recently identified in rat that interacts with the connexin43 (cx43) promoter and might be important for the response of the cx43 gene to estrogen. S. pombe cells deleted for ini1(+) fail to form colonies and arrest with an elongated cell phenotype, indicating a cell cycle block. Cell cycle arrest is dependent on expression of Wee1, but not Rad3, suggesting that it occurs independently of the DNA damage checkpoint control. Analysis of mRNA intermediates in cells depleted for Ini1 demonstrates that Ini1 is required for pre-mRNA splicing. We observe an accumulation of pre-mRNA for six of seven genes analysed, suggesting that Ini1 is required for general splicing activity. Interestingly, loss of Ini1 results in cell death that is partially suppressed by elimination of the Wee1 kinase. Therefore, Wee1 might promote cell death in the absence of Ini1.
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J Cell Sci 2004 Feb 29;117(Pt 6):967-74
| 226 | 1 |
Curatable
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PMID:9693378
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Eukaryotic proteins containing a C-terminal CAAX motif undergo a series of posttranslational CAAX-processing events that include isoprenylation, C-terminal proteolytic cleavage, and carboxyl methylation. We demonstrated previously that the STE14 gene product of Saccharomyces cerevisiae mediates the carboxyl methylation step of CAAX processing in yeast. In this study, we have investigated the subcellular localization of Ste14p, a predicted membrane-spanning protein, using a polyclonal antibody generated against the C terminus of Ste14p and an in vitro methyltransferase assay. We demonstrate by immunofluorescence and subcellular fractionation that Ste14p and its associated activity are localized to the endoplasmic reticulum (ER) membrane of yeast. In addition, other studies from our laboratory have shown that the CAAX proteases are also ER membrane proteins. Together these results indicate that the intracellular site of CAAX protein processing is the ER membrane, presumably on its cytosolic face. Interestingly, the insertion of a hemagglutinin epitope tag at the N terminus, at the C terminus, or at an internal site disrupts the ER localization of Ste14p and results in its mislocalization, apparently to the Golgi. We have also expressed the Ste14p homologue from Schizosaccharomyces pombe, mam4p, in S. cerevisiae and have shown that mam4p complements a Deltaste14 mutant. This finding, plus additional recent examples of cross-species complementation, indicates that the CAAX methyltransferase family consists of functional homologues.
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Mol Biol Cell 1998 Aug;9(8):2231-47
| 367 | 1 |
Wrong organism
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PMID:28305960
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Recently we cloned tms1 (a putative dehydrogenase) by complementation of a human tumour-derived mutant p53 induced growth arrest in fission yeast. Microinjection of purified tmsl protein into Xenopus laevis embryos abrogated normal embryo development by causing cleavage retardation or cleavage arrest of injected blastomeres in a concentration dependant manner, whereas injection of specific affinity purified tms1 antiserum showed no significant morphological defects. Microinjection of tms1 protein together with affinity purified tms1 antibody resulted in a significantly reduced number of cleavage arrested embryos.
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Rouxs Arch Dev Biol 1995 Jan;204(3):198-202
| 129 | 0 |
Curatable
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PMID:9161410
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A new gene encoding a heat shock protein 70 family protein of Schizosaccharomyces pombe (Sp), named sks2+, was cloned as a weak suppressor for the K-252a-sensitive mutation, ucm1. The nucleotide sequence of sks2+ revealed an open reading frame of a 613-amino-acid (aa) protein. The deduced aa sequence of sks2+ showed significant homology with Saccharomyces cerevisiae (Sc) Ssb1p and Ssb2p responsible for protein synthesis by non-organelle-localized ribosomes, as well as with other proteins of the HSP70 family. The cells lacking the functional sks2+ gene were viable and showed no increased sensitivity to K-252a but grew slowly with an elongated morphology. These results suggest that the sks2+ gene product plays a role in the cell cycle progression and is able to confer drug resistance in a multicopy state.
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Gene 1997 Apr 11;189(1):43-7
| 209 | 1 |
Curatable
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PMID:11016847
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The Schizosaccharomyces pombe mutant ehs1-1 mutant was isolated on the basis of its hypersensitivity to Echinocandin and Calcofluor White, which inhibit cell wall synthesis. The mutant shows a thermosensitive growth phenotype that is suppressed in the presence of an osmotic stabiliser. The mutant also showed other cell wall-associated phenotypes, such as enhanced sensitivity to enzymatic cell wall degradation and an imbalance in polysaccharide synthesis. The ehs1 + gene encodes a predicted integral membrane protein that is 30% identical to Saccharomyces cerevisiae Mid1p, a protein that has been proposed to form part of a calcium channel. As expected for such a function, we found that ehs1+ is involved in intracellular Ca2+ accumulation. High external Ca2+ concentrations suppressed all phenotypes associated with the ehs1 null mutation, suggesting that the cell integrity defects of ehs1 mutants result from inadequate levels of calcium in the cell. We observed a genetic relationship between ehs1+ and the protein kinase C homologue pck2+. pck2+ suppressed all phenotypes of ehs1-1 mutant cells. Overproduction of pck2p is deleterious to wild-type cells, increasing 1,3-beta-D-glucan synthase activity and promoting accumulation of extremely high levels of Ca2+. The lethality associated with pck2p, the increase in 1,3-beta-D-glucan synthase production and the strong Ca2+ accumulation are all dependent on the presence of ehs1p. Our results suggest that in fission yeast ehs1p forms part of a calcium channel that is involved in the cell wall integrity pathway that includes the kinase pck2p.
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Mol Gen Genet 2000 Sep;264(1-2):173-83
| 378 | 1 |
Biotech
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PMID:33322563
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The synthesis of a molecularly diverse library of tetrasubstituted alkenes containing a barbiturate motif is described. Base-induced condensation of N 1 -substituted pyrimidine-2,4,6(1 H ,3 H ,5 H )-triones with 5-(bis(methylthio)methylene)-2,2-dimethyl-1,3-dioxane-4,6-dione gave 3-substituted 5-(methylthio)-2 H -pyrano[2,3- d ]pyrimidine-2,4,7(1 H ,3 H )-triones ('pyranopyrimidinones'), regioselectively. A sequence of reactions involving ring-opening of the pyran moiety, displacement of the methylthio group with an amine, re-formation of the pyran ring, and after its final cleavage with an amine, gave tetrasubstituted alkenes (3-amino-3-(2,4,6-trioxotetrahydropyrimidin-5(2 H )-ylidene)propanamides) with a diversity of substituents. Cleavage of the pyranopyrimidinones with an aniline was facilitated in 2,2,2-trifluoroethanol under microwave irradiation. Compounds were tested against Escherichia coli , Staphylococcus aureus , the yeast Schizosaccharomyces pombe, and the pathogenic fungus Candida albicans . No compounds exhibited activity against E. coli , whilst one compound was weakly active against S. aureus . Three compounds were strongly active against S. pombe , but none was active against C. albicans .
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Molecules 2020 Dec 11;25(24)
| 405 | 0 |
Method or reagent
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PMID:25884495
|
Single-molecule super-resolution microscopy allows imaging of fluorescently-tagged proteins in live cells with a precision well below that of the diffraction limit. Here, we demonstrate 3D sectioning with single-molecule super-resolution microscopy by making use of the fitting information that is usually discarded to reject fluorophores that emit from above or below a virtual-'light-sheet', a thin volume centred on the focal plane of the microscope. We describe an easy-to-use routine (implemented as an open-source ImageJ plug-in) to quickly analyse a calibration sample to define and use such a virtual light-sheet. In addition, the plug-in is easily usable on almost any existing 2D super-resolution instrumentation. This optical sectioning of super-resolution images is achieved by applying well-characterised width and amplitude thresholds to diffraction-limited spots that can be used to tune the thickness of the virtual light-sheet. This allows qualitative and quantitative imaging improvements: by rejecting out-of-focus fluorophores, the super-resolution image gains contrast and local features may be revealed; by retaining only fluorophores close to the focal plane, virtual-'light-sheet' single-molecule localisation microscopy improves the probability that all emitting fluorophores will be detected, fitted and quantitatively evaluated.
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PLoS One 2015;10(4):e0125438
| 282 | 0 |
Curatable
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PMID:1868575
|
The complete nucleotide sequence of the ARG7 gene, coding for argininosuccinate lyase (EC 4.3.2.1), in the fission yeast (Schizosaccharomyces pombe) has been determined. It consists of an open reading frame of 461 codons. The deduced protein has a molecular weight of 51,200 Da. The gene is devoid of introns which is confirmed by the fact that it is expressed in Escherichia coli after spontaneous insertion of a bacterial sequence probably bearing a prokaryotic promoter. A perfect "TATA" box is found at -72 and the major transcription initiation site in Saccharomyces cerevisiae is located at -11 as shown by primer extension experiments. Comparison of the S. pombe lyase with related proteins from other organisms reveals an important degree of conservation except in the carboxyterminal part of the polypeptide. Additionally, a deletion removing 66 amino acids of the carboxy terminus yields an enzyme exhibiting some biological activity. A unique 1,500 b transcript was found in S. cerevisiae when the intact gene was present, but the deleted version of the gene gave rise to at least three transcripts of 1,800, 2,800 and 3,900 b.
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Curr Genet 1991 Apr;19(4):255-60
| 269 | 1 |
Curatable
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PMID:16496115
|
In this study, the effects of inositol addition on expression of the MAL gene encoding maltase and phosphatidylinositol (PI) biosynthesis in Schizosaccharomyces pombe (a naturally inositol-requiring strain) were examined. We found that specific maltase activity was at its maximum when the concentration of added inositol reached 6 microg ml(-1) in a synthetic medium containing 2.0% (w/v) glucose. When the concentration of added inositol was 1 microg ml(-1) in the medium, repression of MAL gene expression occurred at glucose concentration higher than 0.2% (w/v). However, when S. pombe was cultured in the synthetic medium containing 6 microg ml(-1), repression of maltase gene expression occurred only at initial glucose concentration above 1.0% (w/v). More mRNA encoding maltase was detected in the cells grown in the medium with 6 microg ml(-1) inositol than in those grown in the same medium with 1 microg ml(-1) inositol. These results demonstrate that higher inositol concentrations in the synthetic medium could derepress MAL gene expression in S. pombe. PI content of the yeast cells grown in the synthetic medium with 6 microg ml(-1) of inositol was higher than that of the yeast cells grown in the same medium with 1 microg ml(-1) of inositol. This means that PI may be involved in the derepression of MAL gene expression in S. pombe.
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J Ind Microbiol Biotechnol 2006 Jun;33(6):417-22
| 335 | 1 |
Wrong organism
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PMID:7979276
|
The lipopeptide antifungal agents, echinocandins, papulacandins, and pneumocandins, kill Candida albicans by inhibiting glucan synthesis. For this fungus, there is a good correlation of in vitro enzyme inhibition with in vitro assays of MICs. Semisynthetic lipopeptides such as cilofungin, LY303366, L-693,989, and L-733,560 have activity in vivo against Aspergillus infections but appear to be inactive in broth dilution in vitro tests (MICs, > 128 micrograms/ml). To understand how compounds which lack activity in vitro can have good in vivo activity, we monitored the effect of pneumocandins on the morphology of Aspergillus fumigatus and A, flavus strains by light microscopy and electron microscopy and related the changes in growth to inhibition of glucan synthesis. Pneumocandin B0 caused profound changes in hyphal growth; light micrographs showed abnormally swollen germ tubes, highly branched hyphal tips, and many cells with distended balloon shapes. Aspergillus electron micrographs confirmed that lipopeptides produce changes in cell walls; drug-treated germlings showed very stubby growth with thick walls and a conspicuous dark outer layer which was much thicker in the subapical regions. The rest of the hyphal tip ultrastructure was unaffected by the drug, indicating considerable specificity for the primary target. The drug-induced growth alteration produced very compact clumps in broth dilution wells, making it possible to score the morphological effect macroscopically. The morphological changes could be assayed quantitatively by using conventional broth microdilution susceptibility assay conditions. We defined the endpoint as the lowest concentration required to produce the morphological effect and called it the minimum effective concentration to distinguish it from the no-growth endpoints used in MIC determinations. The minimum effective concentration assay was related to inhibition of glucan synthase activity in vitro and may provide a starting point for development of susceptibility testing methods for lipopeptides.
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Antimicrob Agents Chemother 1994 Jul;38(7):1480-9
| 443 | 0 |
Wrong organism
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PMID:8065346
|
The rad16 mutant of Saccharomyces cerevisiae was previously shown to be impaired in removal of UV-induced pyrimidine dimers from the silent mating-type loci (D. D. Bang, R. A. Verhage, N. Goosen, J. Brouwer, and P. van de Putte, Nucleic Acids Res. 20:3925-3931, 1992). Here we show that rad7 as well as rad7 rad16 double mutants have the same repair phenotype, indicating that the RAD7 and RAD16 gene products might operate in the same nucleotide excision repair subpathway. Dimer removal from the genome overall is essentially incomplete in these mutants, leaving about 20 to 30% of the DNA unrepaired. Repair analysis of the transcribed RPB2 gene shows that the nontranscribed strand is not repaired at all in rad7 and rad16 mutants, whereas the transcribed strand is repaired in these mutants at a fast rate similar to that in RAD+ cells. When the results obtained with the RPB2 gene can be generalized, the RAD7 and RAD16 proteins not only are essential for repair of silenced regions but also function in repair of nontranscribed strands of active genes in S. cerevisiae. The phenotype of rad7 and rad16 mutants closely resembles that of human xeroderma pigmentosum complementation group C (XP-C) cells, suggesting that RAD7 and RAD16 in S. cerevisiae function in the same pathway as the XPC gene in human cells. RAD4, which on the basis of sequence homology has been proposed to be the yeast XPC counterpart, seems to be involved in repair of both inactive and active yeast DNA, challenging the hypothesis that RAD4 and XPC are functional homologs.
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Mol Cell Biol 1994 Sep;14(9):6135-42
| 374 | 0 |
Curatable
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PMID:34674264
|
The timing of cytokinesis relative to other mitotic events in the fission yeast Schizosaccharomyces pombe is controlled by the septation initiation network (SIN). During a mitotic checkpoint, the SIN is inhibited by the E3 ubiquitin ligase Dma1 to prevent chromosome mis-segregation. Dma1 dynamically localizes to spindle pole bodies (SPBs) and the contractile ring (CR) during mitosis, though its role at the CR is unknown. Here, we examined whether Dma1 phosphorylation affects its localization or function. We found that preventing Dma1 phosphorylation by substituting the six phosphosites with alanines diminished its CR localization but did not affect its mitotic checkpoint function. These studies reinforce the conclusion that Dma1 localization to the SPB is key to its role in the mitotic checkpoint.
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FEBS Lett 2021 11;595(22):2781-2792
| 189 | 1 |
Loaded in error
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PMID:456987
|
Breast carcinoma is the most frequent form of cancer in women. In Switzerland 1265 women died of it in 1975, the mortality rate is rising slowly, the cause of this being unclear. There is no uniformity about the best treatment of breast cancer. We analyzed 454 carcinomas, operated in the years 1961--1971 according to Halsted, Patey and McWhirter. We found similar 5- and 10-year survival rates with the Halsted and the Patey method of operation, however, decidedly worse results with the simple mastectomy. Today we recommend the modified radical excision of the breast after Patey at all stages; in addition we treat all patients with postoperative X-ray therapy or prescribe an adjuvant cytostatic therapy based on the experimental study of the SAKK (Swis Therapy Group for Clincal Cancer Research).
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Fortschr Med 1979 Apr 26;97(16):785-6
| 181 | 0 |
Curatable
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PMID:8188765
|
Mutants of Schizosaccharomyces pombe were used to define genes involved in the cell cycle arrest produced by cisplatin (DDP), an agent that causes both DNA damage and inhibition of DNA synthesis. Previous work has demonstrated that strains with defective or absent wee1+ function fail to arrest in G2 when DNA is damaged, but do arrest when DNA synthesis is inhibited (Rowley et al., 1992a, Nature, 356:353-355). Strains defective in wee1+ function, or in the ability of the wee1+ kinase to regulate cdc2, failed to arrest following DDP exposure, as did a rad1-1 mutant. All strains failing to arrest in G2 were hypersensitive to DDP. Thus, DNA damage rather than inhibition of DNA synthesis is causative of DDP-induced cell cycle arrest. In addition, this work shows that the wee1+ and rad1+ gene products are required for successful DDP-induced arrest, and suggests that the ability of S. pombe to arrest is a major determinant of sensitivity to DDP.
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J Cell Physiol 1994 Jun;159(3):506-14
| 229 | 1 |
Curatable
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PMID:11884590
|
Schizosaccharomyces pombe Cdc5p and its Saccharomyces cerevisiae ortholog, Cef1p, are essential Myb-related proteins implicated in pre-mRNA splicing and contained within large multiprotein complexes. Here we describe the tandem affinity purification (TAP) of Cdc5p- and Cef1p-associated complexes. Using transmission electron microscopy, we show that the purified Cdc5p complex is a discrete structure. The components of the S. pombe Cdc5p/S. cerevisiae Cef1p complexes (termed Cwfs or Cwcs, respectively) were identified using direct analysis of large protein complex (DALPC) mass spectrometry (A. J. Link et al., Nat. Biotechnol. 17:676-682, 1999). At least 26 proteins were detected in the Cdc5p/Cef1p complexes. Comparison of the polypeptides identified by S. pombe Cdc5p purification with those identified by S. cerevisiae Cef1p purification indicates that these two yeast complexes are nearly identical in composition. The majority of S. pombe Cwf proteins and S. cerevisiae Cwc proteins are known pre-mRNA splicing factors including core Sm and U2 and U5 snRNP components. In addition, the complex contains the U2, U5, and U6 snRNAs. Previously uncharacterized proteins were also identified, and we provide evidence that several of these novel factors are involved in pre-mRNA splicing. Our data represent the first comprehensive analysis of CDC5-associated proteins in yeasts, describe a discrete highly conserved complex containing novel pre-mRNA splicing factors, and demonstrate the power of DALPC for identification of components in multiprotein complexes.
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Mol Cell Biol 2002 Apr;22(7):2011-24
| 393 | 1 |
Loaded in error
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PMID:12365478
|
A patient with breast cancer developed severe asthenia, accompanied with progressively increasing transaminases, during adjuvant chemotherapy with CMF (cyclophosphamide, methotrexate and 5-fluorouracil). Additional blood tests and imaging were negative. A liver biopsy revealed a grade II toxic hepatitis. Because methotrexate was suspected to be the cause of the hepatotoxicity, the administration of this drug was stopped and mitoxantrone was given instead. A recovery of clinical symptoms and normalisation of the liver function tests was observed afterwards. In that sense, mitoxantrone appears to be a valuable alternative to methotrexate in cases of hepatotoxicity in patients with breast cancer. An overview of the literature regarding methotrexate hepatotoxicity is presented.
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Neth J Med 2002 Jun;60(5):216-22
| 164 | 0 |
Review or comment
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PMID:25002088
|
The fungal plasma membrane is organized into specialized domains that vary in size, stability, and composition. Membrane compartment of Can1(MCC)/eisosome domains that were recently discovered in the budding yeast Saccharomyces cerevisiae are interesting because they represent a novel type of membrane domain that is important for plasma membrane organization, sphingolipid homeostasis, and cell wall morphogenesis. The MCC portion was identified as stable punctate patches that correspond to furrows in the plasma membrane that are about 300 nm long and 50 nm deep. These domains contain integral membrane proteins, including the tetraspan proteins Sur7 and Nce102. The eisosome portion includes proteins peripherally associated with the cytoplasmic side of the MCC, including the Bin/amphiphysin/Rvs-domain proteins Pil1 and Lsp1, which assemble into filaments that curve the membrane to form the furrows. By comparing MCC/eisosome domains in diverse fungi, researchers are identifying common features that further our understanding of their unique biogenesis, structure, and function.
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Annu Rev Microbiol 2014;68:377-93
| 235 | 0 |
Curatable
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PMID:11115118
|
Many secretory proteins are synthesized as inactive proproteins that undergo proteolytic activation as they travel through the eukaryotic secretory pathway. The best characterized family of processing enzymes are the prohormone convertases or kexins, and these are responsible for the processing of a wide variety of prohormones and other precursors. Recent work has identified other proteases that appear to be involved in proprotein processing, but characterization of these enzymes is at an early stage. Krp1 is the only kexin identified in the fission yeast Schizosaccharomyces pombe, in which it is essential for cell viability. We have used a genetic screen to identify four proteases with specificities that overlap Krp1. Two are serine proteases, one is a zinc metalloprotease (glycoprotease) and one is an aspartyl protease that belongs to the recently described yapsin family of processing enzymes. All four proteases support the growth of a yeast strain lacking Krp1, and each is able to process the P-factor precursor, the only substrate currently known to be processed by Krp1.
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Mol Microbiol 2000 Nov;38(4):839-53
| 245 | 1 |
Curatable
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PMID:9136929
|
The fission yeast Sty1 MAP kinase is required for cell cycle control, initiation of sexual differentiation, and protection against cellular stress. Like the mammalian JNK/SAPK and p38/CSBP1 MAP kinases, Sty1 is activated by a range of environmental insults including osmotic stress, hydrogen peroxide, menadione, heat shock, and the protein synthesis inhibitor anisomycin. We have identified an upstream regulator that mediates activation of the Sty1 MAP kinase by multiple environmental stresses as the product of the mitotic catastrophe suppressor, mcs4. Mcs4 is structurally and functionally homologous to the budding yeast SSK1 response regulator, suggesting that the eukaryotic stress-activated MAP kinase pathway is controlled by a conserved two-component system. Mcs4 acts upstream of Wak1, a homolog of the SSK2 and SSK22 MEK kinases, which transmits the stress signal to the Wis1 MEK. We show that the Wis1 MEK is controlled by an additional pathway that is independent of both Mcs4 and the Wak1 MEK kinase. Furthermore, we demonstrate that Mcs4 is required for the correct timing of mitotic initiation by mechanisms both dependent and independent on Sty1, indicating that Mcs4 coordinately controls cell cycle progression with the cellular response to environmental stress.
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Genes Dev 1997 Apr 15;11(8):1008-22
| 285 | 1 |
Curatable
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PMID:12620220
|
One fundamental function of telomeres is to prevent the ends of chromosomes from being sensed and treated as DNA damage. Here we present evidence for additional roles of telomeres in promoting proper chromosome segregation and DNA repair. We find that the fission yeast telomere protein Taz1p is required for cell cycle progression at 20 degrees C, a temperature at which taz1Delta cells exhibit a G(2)/M DNA damage checkpoint delay, chromosome missegregation, and DNA double-strand breaks (DSBs). Spindle assembly checkpoint components and a checkpoint-independent function of Rad3p are required for taz1Delta cells to survive at 20 degrees C. Disruption of topoisomerase II activity suppresses the cold sensitivity of taz1Delta cells, suggesting a scenario in which telomeric entanglement is the primary defect. Furthermore, hypersensitivity to treatments that induce DSBs suggests that Taz1p is involved in DSB repair. Our observations imply roles for Taz1p-containing telomeres in preventing and repairing DNA breaks throughout the genome.
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Mol Cell 2003 Feb;11(2):303-13
| 223 | 1 |
Curatable
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PMID:16421926
|
Cytokinesis in fission yeast involves the coordination of septum deposition with the contraction of a cytokinetic actomyosin ring. We have examined the role of the type V myosin Myo52 in the coupling of these two events by the construction of a series of deletion mutants of the Myo52 tail and a further mutant within the ATP binding domain of the head. Each mutant protein was ectopically expressed in fission yeast cells. Each truncation was assayed for the ability to localize to the cell poles and septum (the normal cellular locations of Myo52) and to rescue the morphology defects and temperature sensitivity of a myo52Delta strain. A region within the Myo52 tail (amino acids 1320-1503), with a high degree of similarity to the vesicle-binding domain of the budding yeast type V myosin Myo2p, was essential for Myo52's role in the maintenance of growth polarity and cell division. A separate region (amino acids 1180-1320) was required for Myo52 foci to move throughout the cytoplasm; however, constructs lacking this region, but which retained the ability to dimerize still associated with actin at sites of cell growth. Not all of the Myo52 truncations which localized rescued the morphological defects of myo52Delta, demonstrating that loss of function was not simply brought about by an inability of mutant proteins to target the correct cellular location. By contrast, Myo52 motor activity was required for both localization and cellular function. myo52Delta cells were unable to efficiently localize the beta-1,3-glucan synthase, Bgs1, either at the cell poles or at the division septum, regions of cell wall deposition. Bgs1 and Myo52 localized to vesicle-like dots at the poles in interphase and these moved together to the septum at division. These data have led to the formulation of a model in which Myo52 is responsible for the delivery of Bgs1 and associated molecules to polar cell growth regions during interphase. On the commencement of septum formation, Myo52 transports Bgs1 to the cell equator, thus ensuring the accurate deposition of beta-1,3-glucan at the leading edge of the primary septum.
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Cell Motil Cytoskeleton 2006 Mar;63(3):149-61
| 492 | 1 |
Wrong organism
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PMID:17493829
|
The least understood components of the DNA damage checkpoint are the DNA damage sensors. Genetic studies of Schizosaccharomyces pombe identified six yeast genes, Rad3, Rad17, Rad9, Rad1, Hus1, and Rad26, which encode proteins thought to sense DNA damage and activate the checkpoint-signaling cascade. It has been suggested that Rad9, Rad1 and Hus1 make a heterotrimeric complex forming a PCNA-like structure. In order to carry out structural and biophysical studies of the complex and its associated proteins, the cDNAs encoding full length human Rad9, Rad1 and Hus1 were cloned together into the pET28a vector using a one-step ligation procedure. Here we report successful tri-cistronic cloning, overexpression and purification of this three-protein complex using a single hexa-histidine tag. The trimeric protein complex of Rad9, Rad1 and Hus1 was purified to near homogeneity, yielding approximately 10mg of protein from one liter of Escherichia coli culture.
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Protein Expr Purif 2007 Aug;54(2):204-11
| 224 | 0 |
Curatable
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PMID:27189367
|
Peroxisomes are ubiquitous organelles found in most eukaryotic cells. In yeasts, peroxisomes play important roles in cell metabolism, especially in different catabolic processes including fatty acid β-oxidation, the glyoxylic shunt and methanol metabolism, as well as some biosynthetic processes. In addition, peroxisomes are the compartment in which oxidases and catalase are localized. New peroxisomes mainly arise by fission of pre-existing ones, although they can also be formed from the endoplasmic reticulum (ER). Peroxisomes consist of matrix-soluble proteins and membrane proteins known as peroxins. A total of 34 PEX peroxin genes and proteins have been identified to date. and their functions have been elucidated. Protein import into peroxisomes depends on peroxins and requires specific signals in the structure of transported proteins: PTS1, PTS2 and mPTS. The mechanisms of metabolite penetration into peroxisomes are still poorly understood. Peroxisome number and the volume occupied by these organelles are tightly regulated. Methanol, fatty acids and methylamine act as efficient peroxisome proliferators, whereas glucose and ethanol induce peroxisome autophagic degradation (pexophagy). To date, 42 Atg proteins involved in pexophagy are known. Catabolism and alcoholic fermentation of the major pentose sugar, xylose, depend on peroxisomal enzymes. Overexpression of peroxisomal transketolase and transaldolase activates xylose fermentation. Peroxisomes could be useful as target organelles for overexpression of foreign toxic proteins.
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FEMS Yeast Res 2016 06;16(4)
| 361 | 1 |
Review or comment
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PMID:23466674
|
Many cells are able to orient themselves in a non-uniform environment by responding to localized cues. This leads to a polarized cellular response, where the cell can either grow or move towards the cue source. Fungal haploid cells secrete pheromones to signal mating, and respond by growing a mating projection towards a potential mate. Upon contact of the two partner cells, these fuse to form a diploid zygote. In this review, we present our current knowledge on the processes of mating signalling, pheromone-dependent polarized growth and cell fusion in Saccharomyces cerevisiae and Schizosaccharomyces pombe, two highly divergent ascomycete yeast models. While the global architecture of the mating response is very similar between these two species, they differ significantly both in their mating physiologies and in the molecular connections between pheromone perception and downstream responses. The use of both yeast models helps enlighten both conserved solutions and species-specific adaptations to a general biological problem.
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Open Biol 2013 Mar 06;3(3):130008
| 214 | 0 |
Wrong organism
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PMID:11694351
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Pombe and human Cdc5 have been implicated in G2/M progression, but recently Cdc5 was identified as a component of a multiprotein complex essential for pre-mRNA splicing. We have previously isolated a prolactin (PRL)-inducible partial cDNA (1907 bp) encoding rat Cdc5. In the present study, the full length rCdc5 sequence (2847 bp) was obtained by 5'-RACE and cytokine regulation of Cdc5 expression was examined. PRL and interleukin-2 (IL2) act as mitogens in Nb2 T-lymphoma cells. Fibroblast growth factor (FGF-2) is not mitogenic in Nb2 cells but inhibits apoptosis of PRL-deprived cells. This study showed that PRL, IL-2 and FGF-2 rapidly increased Nb2 Cdc5 expression (3.4 kb mRNA) to reach 2-3-fold above controls at 4 h, and Cdc5 mRNA levels remained elevated at 24 h. There was a corresponding 2-3-fold increase in Cdc5 protein (105 kDa) levels at 24 h. Immunoblotting and fluorescent confocal microscopy showed predominant nuclear/perinuclear Cdc5 in quiescent Nb2 cells. PRL or FGF-2 treatment transiently increased nuclear Cdc5-specific immunofluorescence at 4 h but IL-2 gave maximal nuclear accumulation of Cdc5 at 24 h. The deduced rCdc5 protein has approximately 98% amino acid identity with human Cdc5. Like other Cdc5 family members, the N-terminus of rCdc5 contains two repeats of a DNA-binding domain found in a-, b- and c-Myb. Gel shift assays using (32)P-labeled Myb consensus oligonucleotides revealed two Myb-specific DNA-protein complexes in Nb2 nuclear extracts. Formation of both complexes was increased by PRL or FGF-2 at 1-5 and at 20 h and was partially inhibited by anti-Myb or anti-Cdc5 antibodies. In summary, rapid activation of Cdc5 in response to mitogenic and non-mitogenic stimuli suggests a complex role for Cdc5 in cellular regulation and this may not be restricted to mitotic entry or G2/M progression as previously supposed.
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Mol Cell Endocrinol 2001 Nov 26;184(1-2):151-61
| 509 | 0 |
Mutagenicity or toxicity study
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PMID:16912194
|
Trabectedin (Yondelis) is a potent antitumor drug that has the unique characteristic of killing cells by poisoning the DNA nucleotide excision repair (NER) machinery. The basis for the NER-dependent toxicity has not yet been elucidated but it has been proposed as the major determinant for the drug's cytotoxicity. To study the in vivo mode of action of trabectedin and to explore the role of NER in its cytotoxicity, we used the fission yeast Schizosaccharomyces pombe as a model system. Treatment of S. pombe wild-type cells with trabectedin led to cell cycle delay and activation of the DNA damage checkpoint, indicating that the drug causes DNA damage in vivo. DNA damage induced by the drug is mostly caused by the NER protein, Rad13 (the fission yeast orthologue to human XPG), and is mainly repaired by homologous recombination. By constructing different rad13 mutants, we show that the DNA damage induced by trabectedin depends on a 46-amino acid region of Rad13 that is homologous to a DNA-binding region of human nuclease FEN-1. More specifically, an arginine residue in Rad13 (Arg961), conserved in FEN1 (Arg314), was found to be crucial for the drug's cytotoxicity. These results lead us to propose a model for the action of trabectedin in eukaryotic cells in which the formation of a Rad13/DNA-trabectedin ternary complex, stabilized by Arg961, results in cell death.
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Cancer Res 2006 Aug 15;66(16):8155-62
| 345 | 0 |
Wrong organism
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PMID:19074629
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The synthesis of phytochelatins (PCs) is essential for the detoxification of nonessential metals and metalloids such as cadmium and arsenic in plants and a variety of other organisms. To our knowledge, no direct evidence for a role of PCs in essential metal homeostasis has been reported to date. Prompted by observations in Schizosaccharomyces pombe and Saccharomyces cerevisiae indicating a contribution of PC synthase expression to Zn2+ sequestration, we investigated a known PC-deficient Arabidopsis (Arabidopsis thaliana) mutant, cad1-3, and a newly isolated second strong allele, cad1-6, with respect to zinc (Zn) homeostasis. We found that in a medium with low cation content PC-deficient mutants show pronounced Zn2+ hypersensitivity. This phenotype is of comparable strength to the well-documented Cd2+ hypersensitivity of cad1 mutants. PC deficiency also results in significant reduction in root Zn accumulation. To be able to sensitively measure PC accumulation, we established an assay using capillary liquid chromatography coupled to electrospray ionization quadrupole time-of-flight mass spectrometry of derivatized extracts. Plants grown under control conditions consistently showed PC2 accumulation. Analysis of plants treated with same-effect concentrations revealed that Zn2+-elicited PC2 accumulation in roots reached about 30% of the level of Cd2+-elicited PC2 accumulation. We conclude from these data that PC formation is essential for Zn2+ tolerance and provides driving force for the accumulation of Zn. This function might also help explain the mysterious occurrence of PC synthase genes throughout the plant kingdom and in a wide range of other organisms.
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Plant Physiol 2009 Feb;149(2):938-48
| 374 | 0 |
Other
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PMID:2703462
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Although sexual reproduction is widespread, its adaptive advantage over asexual reproduction is unclear. One major advantage of sex may be its promotion of recombinational repair of DNA damage during meiosis. This idea predicts that treatment of the asexual form of a facultatively sexual-asexual eucaryote with a DNA-damaging agent may cause it to enter the sexual cycle more frequently. Endogenous hydrogen peroxide is a major natural source of DNA damage. Thus, we treated vegetative cells of Schizosaccharomyces pombe with hydrogen peroxide to test if sexual reproduction increases. Among untreated stationary-phase S. pombe populations the sexual spores produced by meiosis represented about 1% of the total cells. However, treatment of late-exponential-phase vegetative cells with hydrogen peroxide increased the percentage of meiotic spores in the stationary phase by 4- to 18-fold. Oxidative damage therefore induces sexual reproduction in a facultatively sexual organism, a result expected by the hypothesis that sex promotes DNA repair.
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J Bacteriol 1989 Apr;171(4):1893-7
| 211 | 0 |
Curatable
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PMID:10198041
|
In the fission yeast Schizosaccharomyces pombe, the protein kinase Cds1 is activated by the S-M replication checkpoint that prevents mitosis when DNA is incompletely replicated. Cds1 is proposed to regulate Wee1 and Mik1, two tyrosine kinases that inhibit the mitotic kinase Cdc2. Here, we present evidence from in vivo and in vitro studies, which indicates that Cds1 also inhibits Cdc25, the phosphatase that activates Cdc2. In an in vivo assay that measures the rate at which Cdc25 catalyzes mitosis, Cds1 contributed to a mitotic delay imposed by the S-M replication checkpoint. Cds1 also inhibited Cdc25-dependent activation of Cdc2 in vitro. Chk1, a protein kinase that is required for the G2-M damage checkpoint that prevents mitosis while DNA is being repaired, also inhibited Cdc25 in the in vitro assay. In vitro, Cds1 and Chk1 phosphorylated Cdc25 predominantly on serine-99. The Cdc25 alanine-99 mutation partially impaired the S-M replication and G2-M damage checkpoints in vivo. Thus, Cds1 and Chk1 seem to act in different checkpoint responses to regulate Cdc25 by similar mechanisms.
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Mol Biol Cell 1999 Apr;10(4):833-45
| 280 | 1 |
Curatable
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PMID:3536917
|
We have identified a genetic locus, pho4, in Schizosaccharomyces pombe which encodes a minor expressed cell surface acid phosphatase that is repressed by low concentrations (0.5 microM) of thiamin. The enzyme was purified from a strain that overproduces the enzyme. It is an Asn-linked glycoprotein. Removal of the carbohydrates by endoglycosidase H does not abolish enzymatic activity. The molecular mass of deglycosylated and unglycosylated enzyme that accumulates in membranes when cells are grown in the presence of tunicamycin is 56 kDa as determined by sodium dodecyl sulfate-gel electrophoresis. Thiamin regulation, at least in part, operates by reducing the level of pho4-mRNA. Pho4 is not genetically linked to the phosphate repressible acid phosphatase gene pho1. Phosphate and thiamin repressible acid phosphatase differ in their substrate specificity. Their protein moieties are immunologically related. Pho4 and pho1 are the only genes in S. pombe that express cell surface acid phosphatases being enzymatically active with nitrophenyl phosphate as substrate. S. pombe is not unique in having a thiamin repressible acid phosphatase. In Saccharomyces cerevisiae this enzyme is encoded by PHO3.
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J Biol Chem 1986 Dec 05;261(34):15877-82
| 305 | 1 |
Wrong organism
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PMID:12920300
|
Plants attacked by pathogens rapidly deposit callose, a beta-1,3-glucan, at wound sites. Traditionally, this deposition is thought to reinforce the cell wall and is regarded as a defense response. Surprisingly, here we found that powdery mildew resistant 4 (pmr4), a mutant lacking pathogen-induced callose, became resistant to pathogens, rather than more susceptible. This resistance was due to mutation of a callose synthase, resulting in a loss of the induced callose response. Double-mutant analysis indicated that blocking the salicylic acid (SA) defense signaling pathway was sufficient to restore susceptibility to pmr4 mutants. Thus, callose or callose synthase negatively regulates the SA pathway.
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Science 2003 Aug 15;301(5635):969-72
| 153 | 0 |
Method or reagent
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PMID:11790253
|
Sequestration of transcription factors in the membrane is emerging as an important mechanism for the regulation of gene expression. A handful of membrane-spanning transcription factors has been previously identified whose access to the nucleus is regulated by proteolytic cleavage from the membrane. To investigate the existence of other transmembrane transcription factors, we analyzed computationally all proteins in SWISS-PROT/TrEMBL for the combined presence of a DNA-binding domain and a transmembrane segment. Using Pfam hidden Markov models and four transmembrane-prediction programs, we identified with high confidence 76 membrane-spanning transcription factors in SWISS-PROT/TrEMBL. Analysis of the distribution of two proteins predicted by our method, MTJ1 and DMRT2, confirmed their localization to intracellular membrane compartments. Furthermore, elimination of the predicted transmembrane segment led to nuclear localization for each of these proteins. Our analysis uncovered a wealth of predicted membrane-spanning transcription factors that are structurally and taxonomically diverse, 56 of which lack experimental annotation. Seventy-five of the proteins are modular in structure, suggesting that a single proteolysis may be sufficient to liberate a DNA-binding domain from the membrane. This study provides grounds for investigations into the stimuli and mechanisms that release this intriguing class of transcription factors from membranes.
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Genome Biol 2001;2(12):RESEARCH0050
| 280 | 0 |
Wrong organism
|
PMID:17437319
|
Nuclear receptor-binding SET-domain-containing protein 1 (NSD1), a culprit gene for Sotos syndrome, contains a su(var)3-9, enhancer-of-zeste, trithorax (SET) domain that is responsible for histone methyltransferase activity and other domains such as plant homeodomain (PHD) and proline-tryptophan-tryptophan-proline (PWWP) involved in protein-protein interactions in the C-terminal half of NSD1. To elucidate the function of NSD1 on cell growth, we overexpressed NSD1 in NIH3T3 cells. Cells overexpressing NSD1 grew in the presence of 2% serum, whereas vector transfected cells did not. Overexpression of the C-terminal half of NSD1 but not the N-terminal half of NSD1 also produced cell growth under low serum concentration. Furthermore, overexpression in NIH3T3 of Schizosaccharomyces pombe SET2 which has a SET domain but not PHD or PWWP domains conferred the reduced serum dependence. Thus, the SET domain of NSD1 is involved in cell growth by modulating serum dependence.
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Cell Biochem Funct 2008 Mar;26(2):146-50
| 268 | 0 |
Method or reagent
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PMID:32651564
|
RNA-protein interactions play a pivotal role in cell homeostasis and disease, but current approaches to study them require a considerable amount of starting material, favor the recovery of only a subset of RNA species or are complex and time-consuming. We recently developed orthogonal organic phase separation (OOPS): a quick, efficient and reproducible method to purify cross-linked RNA-protein adducts in an unbiased way. OOPS avoids molecular tagging or the capture of polyadenylated RNA. Instead, it is based on sampling the interface of a standard TRIzol extraction to enrich RNA-binding proteins (RBPs) and their cognate bound RNA. OOPS specificity is achieved by digesting the enriched interfaces with RNases or proteases to release the RBPs or protein-bound RNA, respectively. Here we present a step-by-step protocol to purify protein-RNA adducts, free protein and free RNA from the same sample. We further describe how OOPS can be applied in human cell lines, Arabidopsis thaliana, Schizosaccharomyces pombe and Escherichia coli and how it can be used to study RBP dynamics.
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Nat Protoc 2020 08;15(8):2568-2588
| 245 | 0 |
Wrong organism
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PMID:1339336
|
This paper reports the nucleotide and predicted amino acid sequences of the goldfish cdk2, a cognate variant of the cell cycle regulator cdc2. The predicted protein sequence shows strong homology to the other known cdk2 (88% for Xenopus and 90% for human). A monoclonal antibody against the C-terminal sequence of goldfish cdk2 recognized a 34-kDa protein in extracts from various goldfish tissues. The protein level was high in such tissues as testis and ovary containing actively dividing cells. Protein cdk2 binds to p13sucl, the fission yeast suc1+ gene product, but not to cyclin B, with which cdc2 forms a complex. The kinase activity of cdk2 increased 30-fold when oocytes matured, although its protein level did not remarkably change. Anti-cdk2 immunoprecipitates from 32P-labeled mature oocyte extracts contained a 47-kDa protein, which was not recognized by either anti-cyclin A or anti-cyclin B antibody, indicating complex formation of cdk2 with a protein other than cyclins A or B.
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Dev Biol 1992 Jul;152(1):113-20
| 242 | 0 |
Review or comment
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PMID:12194845
|
Heterotrimeric G proteins mediate signal transduction pathways to control development in fungal, plant, and animal cells. A recent study in the July issue of Molecular Cell identifies three proteins that, while not displaying sequence similarity to G protein subunits, appear to act as structural mimics of a Gbetagamma dimer to negatively regulate pseudohyphal growth in budding yeast.
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Dev Cell 2002 Aug;3(2):154-5
| 82 | 0 |
Wrong organism
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PMID:14697358
|
In the newly fertilized Caenorhabditis elegans zygote, cytoplasmic determinants become localized asymmetrically along the anterior-posterior (A-P) axis of the embryo. The mitotic apparatus then orients so as to cleave the embryo into anterior and posterior blastomeres that differ in both size and developmental potential. Here we describe a role for MBK-2, a member of the Dyrk family of protein kinases, in asymmetric cell division in C. elegans. In mbk-2 mutants, the initial mitotic spindle is misplaced and cytoplasmic factors, including the germline-specific protein PIE-1, are mislocalized. Our findings support a model in which MBK-2 down-regulates the katanin-related protein MEI-1 to control spindle positioning and acts through distinct, as yet unknown factors, to control the localization of cytoplasmic determinants. These findings in conjunction with work from Schizosaccharomyces pombe indicate a possible conserved role for Dyrk family kinases in the regulation of spindle placement during cell division.
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Dev Biol 2004 Jan 01;265(1):127-39
| 249 | 0 |
Curatable
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PMID:16371130
|
RCC1, a conserved chromosomal protein with a seven-bladed propeller is a GDP/GTP nucleotide exchange factor for RanGTPase that mediates various cellular events. We isolated 16 temperature-sensitive (ts) mutants of S. pombeRCC1-homolog, pim1+, by error-prone PCR. Five pim1(ts) mutants had a single mutation. The obtained pim1(ts) mutations and previously reported mutations were localized on similar sites in seven RCC1 repeats. Those mutations resulted in a reduced binding of Pim1 with Spi1. All pim1(ts) mutants showed a defect in nucleocytoplasmic protein transports, whereas the majority of them showed a normal mRNA export. In all pim1(ts) examined, chromosomal DNA replication was completed. However, mitotic spindle formation was abrogated, the septum was formed being uncoupled with nuclear division and abnormally widened, thus resulting in chromosomal DNA mis-segregation and the accumulation of enucleated cells. As a result, a defect of RanGEF/Pim1 abolished the orchestration of sequential mitotic events, spindle formation, septation and cytokinesis that are essential to produce two identical daughter cells.
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Genes Cells 2006 Jan;11(1):29-46
| 267 | 1 |
Method or reagent
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PMID:17189857
|
Studies in th Saccharomyces cerevisiae have provided a framework for understanding how eukaryotic cells replicate their chromosomal DNA to ensure faithful transmission of genetic information to their daughter cells. In particular, S. cerevisiae is the first eukaryote to have its origins of replication mapped on a genomic scale, by three independent groups using three different microarray-based approaches. Here we describe a new technique of origin mapping via detection of single-stranded DNA in yeast. This method not only identified the majority of previously discovered origins, but also detected new ones. We have also shown that this technique can identify origins in Schizosaccharomyces pombe, illustrating the utility of this method for origin mapping in other eukaryotes.
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Methods 2007 Feb;41(2):151-7
| 157 | 0 |
Curatable
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PMID:28264193
|
The target of rapamycin (TOR) protein kinase forms multi-subunit TOR complex 1 (TORC1) and TOR complex 2 (TORC2), which exhibit distinct substrate specificities. Sin1 is one of the TORC2-specific subunit essential for phosphorylation and activation of certain AGC-family kinases. Here, we show that Sin1 is dispensable for the catalytic activity of TORC2, but its conserved region in the middle (Sin1CRIM) forms a discrete domain that specifically binds the TORC2 substrate kinases. Sin1CRIM fused to a different TORC2 subunit can recruit the TORC2 substrate Gad8 for phosphorylation even in the sin1 null mutant of fission yeast. The solution structure of Sin1CRIM shows a ubiquitin-like fold with a characteristic acidic loop, which is essential for interaction with the TORC2 substrates. The specific substrate-recognition function is conserved in human Sin1CRIM, which may represent a potential target for novel anticancer drugs that prevent activation of the mTORC2 substrates such as AKT.
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Elife 2017 03 07;6
| 240 | 1 |
Curatable
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PMID:15157890
|
The nuclear envelope is essential for compartmentalizing the nucleus from the cytoplasm in all eukaryotic cells. There is a tremendous flux of both RNA and proteins across the nuclear envelope, which is intact throughout the entire cell cycle of yeasts but breaks down during mitosis of animal cells. Transport across the nuclear envelope requires the recognition of cargo molecules by receptors, docking at the nuclear pore, transit through the nuclear pore, and then dissociation of the cargo from the receptor. This process depends on the RanGTPase system, transport receptors, and the nuclear pore complex. We provide an overview of the nuclear transport process, with particular emphasis on the fission yeast Schizosaccharomyces pombe, including strategies for predicting and experimentally verifying the signals that determine the sub-cellular localization of a protein of interest. We also describe a variety of reagents and experimental strategies, including the use of mutants and chemical inhibitors, to study nuclear protein import, nuclear protein export, nucleocytoplasmic protein shuttling, and mRNA export in fission yeast. The RanGTPase and its regulators also play an essential transport independent role in nuclear envelope re-assembly after mitosis in animal cells and in the maintenance of nuclear envelope integrity at mitosis in S. pombe. Several experimental strategies and reagents for studying nuclear size, nuclear shape, the localization of nuclear pores, and the integrity of the nuclear envelope in living fission yeast cells are described.
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Methods 2004 Jul;33(3):226-38
| 307 | 1 |
Curatable
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PMID:20537132
|
A genome-wide deletion library is a powerful tool for probing gene functions and one has recently become available for the fission yeast Schizosaccharomyces pombe. Here we use deep sequencing to accurately characterize the barcode sequences in the deletion library, thus enabling the quantitative measurement of the fitness of fission yeast deletion strains by barcode sequencing.
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Genome Biol 2010;11(6):R60
| 74 | 1 |
Method or reagent
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PMID:26900659
|
A series of novel morpholinoquinoline based conjugates with pyrazoline moiety were synthesized under microwave irradiation. The newly synthesized compounds were screened for their preliminary in vitro antibacterial activity against a panel of pathogenic strains of bacteria and fungi, antituberculosis activity against Mycobacterium tuberculosis H37Rv and antimalarial activity against Plasmodium falciparum. Most of them exhibited significant antibacterial activity as compared to the first line drugs. Compounds 6a and 9d were found to possess excellent antibacterial activity potency as compared to ampicillin (286 μM), chloramphenicol (154 μM) and ciprofloxacin (150 μM). In antifungal screening, against Candida albicans, compounds 6c, 7c, 8a, 8b, 8c and 9b showed significant activity as compared to griseofulvin (1147 μM). Compounds 8b, 6b, 9d, 6a, 9b, 7b and 8a displayed brilliant activity against P. falciparum strain as compared to chloroquine (IC50 0.062 μM) as well as quinine (IC50 0.826 μM). Compounds 6d, 7b, 8b, 9c and 9d exhibited superior antitubercular activity. Among them 8b was found to be equipotent to rifampicin with 95% inhibition. The cytotoxicity of the synthesized compounds was tested using bioassay of Schizosaccharomyces pombe cells at cellular level.
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Eur J Med Chem 2016 Apr 13;112:270-279
| 342 | 0 |
Wrong organism
|
PMID:10199953
|
The Cdc7 kinase is required for the G1/S-phase transition during the cell cycle and plays a direct role in the activation of individual origins of replication in Saccharomyces cerevisiae. Here, we report the identification of a mouse cDNA, MmCdc7, whose product is closely related in sequence to Saccharomyces cerevisiae Cdc7 as well as their human, Xenopus and Schizosaccharomyces pombe homologues. The MmCdc7p contains the conserved subdomains common to all protein-serine/threonine kinases and three kinase inserts that are characteristic of members of the Cdc7 protein family. We have mapped the locus of the MmCdc7 gene to chromosome 5, band 5E. Conservation of structures among members of the Cdc7-related proteins suggests that these proteins play a key role in the regulation of DNA replication during the cell cycle in all eukaryotes.
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Chromosoma 1999 Apr;108(1):26-31
| 209 | 0 |
Review or comment
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PMID:24354645
|
Polarization is a fundamental cellular property, which is essential for the function of numerous cell types. Over the past three to four decades, research using the best-established yeast systems in cell biological research, Saccharomyces cerevisiae (or budding yeast) and Schizosaccharomyces pombe (or fission yeast), has brought to light fundamental principles governing the establishment and maintenance of a polarized, asymmetric state. These two organisms, though both ascomycetes, are evolutionarily very distant and exhibit distinct shapes and modes of growth. In this review, we compare and contrast the two systems. We first highlight common cell polarization pathways, detailing the contribution of Rho GTPases, the cytoskeleton, membrane trafficking, lipids, and protein scaffolds. We then contrast the major differences between the two organisms, describing their distinct strategies in growth site selection and growth zone dimensions and compartmentalization, which may be the basis for their distinct shapes.
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FEMS Microbiol Rev 2014 Mar;38(2):228-53
| 203 | 0 |
Curatable
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PMID:1464318
|
The p34cdc2 M-phase kinase is regulated by inhibitory phosphorylation of Tyr15, largely through the actions of the p107wee1 tyrosine kinase and p80cdc25 protein tyrosine phosphatase (PTPase). In this study we demonstrate that a second PTPase, encoded by pyp3, also contributes to tyrosyl dephosphorylation of p34cdc2. Pyp3 was identified as a high copy suppressor of a cdc25- mutation. The pyp3 gene encodes a 33 kDa PTPase that is more closely related to human PTP1B and fission yeast pyp1 and pyp2 PTPases than to cdc25. Pyp3 does not share an essential overlapping function with pyp1 or pyp2. We demonstrate that disruption of pyp3 causes a mitotic delay that is greatly exacerbated in cells that are partially defective for cdc25 function and that pyp3 function is essential in cdc25-disruption wee1- strains. Pyp3 PTPase effectively dephosphorylates and activates the p34cdc2 kinase in vitro. We conclude that the pyp3 PTPase acts cooperatively with p80cdc25 to dephosphorylate Tyr15 of p34cdc2.
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EMBO J 1992 Dec;11(13):4933-41
| 287 | 1 |
Review or comment
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PMID:34680098
|
Target of rapamycin (TOR) kinases form two distinct complexes, TORC1 and TORC2, which are evolutionarily conserved among eukaryotes. These complexes control intracellular biochemical processes in response to changes in extracellular nutrient conditions. Previous studies using the fission yeast, Schizosaccharomyces pombe , showed that the TORC2 signaling pathway, which is essential for cell proliferation under glucose-limited conditions, ensures cell-surface localization of a high-affinity hexose transporter, Ght5, by downregulating its endocytosis. The TORC2 signaling pathway retains Ght5 on the cell surface, depending on the presence of nitrogen sources in medium. Ght5 is transported to vacuoles upon nitrogen starvation. In this review, we discuss the molecular mechanisms underlying this regulation to cope with nutritional stress, a response which may be conserved from yeasts to mammals.
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Biomolecules 2021 10 06;11(10)
| 195 | 0 |
Curatable
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PMID:16252005
|
Cullin-4 forms a scaffold for multiple ubiquitin ligases. In Schizosaccharomyces pombe, the Cullin-4 homologue (Pcu4) physically associates with Ddb1 and the COP9 signalosome (CSN). One target of this complex is Spd1. Spd1 regulates ribonucleotide reductase (RNR) activity. Spd1 degradation during S phase, or following DNA damage of G2 cells, results in the nuclear export of the small RNR subunit. We demonstrate that Cdt2, an unstable WD40 protein, is a regulatory subunit of Pcu4-Ddb1-CSN ubiquitin ligase. cdt2 deletion stabilises Spd1 and prevents relocalisation of the small RNR subunit from the nucleus to the cytoplasm. cdt2+ is periodically transcribed by the Cdc10/DSC1 transcription factor during S phase and transiently transcribed following DNA damage of G2 cells, corresponding to Spd1 degradation profiles. Cdt2 co-precipitates with Spd1, and Cdt2 overexpression results in constitutive Spd1 degradation. We propose that Cdt2 incorporation into the Pcu4-Ddb1-CSN complex prompts Spd1 targeting and subsequent degradation and that Cdt2 is a WD40 repeat adaptor protein for Cullin-4-based ubiquitin ligase.
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EMBO J 2005 Nov 16;24(22):3940-51
| 310 | 1 |
Wrong organism
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PMID:8037772
|
We isolated a novel human cDNA, termed hCDC10, whose predicted product showed a high degree of homology to the CDC10 protein of Saccharomyces cerevisiae. This cDNA contained an open reading frame of 1254 nucleotides encoding 418 amino acids, which included a GTP-binding motif, GX4GKS--DX2G--KXD. The predicted peptide sequence also revealed partial amino-acid identity (40-50%) with Diff 6 in Drosophila and with H5 in mouse. Each of these sequence homologues, including Saccharomyces cerevisiae CDC10, contains the GTP-binding motif. Northern blot analyses indicated that the hCDC10 gene is expressed ubiquitously in normal tissues.
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Biochem Biophys Res Commun 1994 Jul 15;202(1):82-7
| 159 | 0 |
Curatable
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PMID:20547592
|
Multiple KH-domain proteins, collectively known as vigilins, are evolutionarily highly conserved proteins that are present in eukaryotic organisms from yeast to metazoa. Proposed roles for vigilins include chromosome segregation, messenger RNA (mRNA) metabolism, translation and tRNA transport. As a step toward understanding its biological function, we have identified the fission yeast vigilin, designated Vgl1, and have investigated its role in cellular response to environmental stress. Unlike its counterpart in Saccharomyces cerevisiae, we found no indication that Vgl1 is required for the maintenance of cell ploidy in Schizosaccharomyces pombe. Instead, Vgl1 is required for cell survival under thermal stress, and vgl1Δ mutants lose their viability more rapidly than wild-type cells when incubated at high temperature. As for Scp160 in S. cerevisiae, Vgl1 bound polysomes accumulated at endoplasmic reticulum (ER) but in a microtubule-independent manner. Under thermal stress, Vgl1 is rapidly relocalized from the ER to cytoplasmic foci that are distinct from P-bodies but contain stress granule markers such as poly(A)-binding protein and components of the translation initiation factor eIF3. Together, these observations demonstrated in S. pombe the presence of RNA granules with similar composition as mammalian stress granules and identified Vgl1 as a novel component that required for cell survival under thermal stress.
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Nucleic Acids Res 2010 Oct;38(19):6555-66
| 317 | 1 |
Wrong organism
|
PMID:12743046
|
Fission yeast Cut5/Rad4 and its budding yeast homolog Dpb11 are required for both DNA replication and the S-phase checkpoint. Here, we have investigated the role of the Xenopus homolog of Cut5 in the initiation of DNA replication using Xenopus egg extracts. Xenopus Cut5, which shows sequence similarity to DmMus101 and HsTopBP1, is essential for DNA replication in the egg extracts. It is required for the chromatin binding of Cdc45 and DNA polymerases, but not for the formation of pre-replicative complexes or the elongation stage of DNA replication. The chromatin binding of Cut5 consists of two distinct modes. S-phase cyclin-dependent kinase (S-CDK)-independent binding is sufficient for DNA replication while S-CDK-dependent binding is dispensable. Further, S-CDK acts after the chromatin binding of Cut5 and before the binding of Cdc45. These results demonstrate that the chromatin binding of Cut5 is required for the action of S-CDK, which in turn triggers the formation of pre-initiation complexes of DNA replication.
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EMBO J 2003 May 15;22(10):2526-35
| 237 | 0 |
Sequence feature or region
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PMID:9658023
|
We describe the presence of a minisatellite sequence that displays length polymorphisms in the fission yeast Schizosaccharomyces pombe. The minisatellite sequence was found to reside within the propeptide region of the vacuolar carboxypeptidase Y gene. The minisatellite sequence, which was found only at a single locus, was mitotically stable and displayed length polymorphisms between the two varieties of S. pombe (S. pombe var. pombe and S. pombe var. malidevorans). The minisatellite sequence, however, appeared to be species specific and was absent in other members of the Schizosaccharomyces genus. This report constitutes the first experimental demonstration of the presence of such sequences in yeasts.
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J Bacteriol 1998 Jul;180(14):3727-9
| 169 | 0 |
Curatable
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PMID:12951513
|
The ste12+ gene of Schizosaccharomyces pombe codes for a phosphatidylinositol (PI) 3-phosphate 5'-kinase, which is required for efficient mating. Suppressor mutants for sterility of ste12Delta cells were screened for. Most of the mutant genes turned out to be recessive. Six genes were cloned and the open reading frames responsible for the suppressor activity were identified. They included genes coding for proteins with domains homologous to calcium transporters, casein kinase II, UBC13, AMSH, Vps23p, and Vps27p of Saccharomyces cerevisiae. Disruption of these genes resulted in suppression of the defects of the ste12Delta cells, including low mating efficiency and formation of large vacuoles. Since many of these gene products are homologous to the proteins involved in vesicle transport, sterility caused by inactivation of ste12 may be due to a disordered vesicle transport system.
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Biosci Biotechnol Biochem 2003 Aug;67(8):1772-9
| 215 | 1 |
Curatable
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PMID:9190794
|
The cDNA of a previously uncharacterized gene fet5 (factor of eukaryotic transcription, clone no. 5) of the fission yeast Schizosaccharomyces pombe was cloned by the heterospecific complementation of a conditional mutant of Saccharomyces cerevisiae defective in the function of the RNA polymerases I-III common subunit ABC10 beta. The gene encodes a new factor of eukaryotic transcription, Fet5, the first member of a superfamily of proteins for which the area of functioning is determined. The Fet5-superfamily consists of three distinct families of proteins highly evolutionarily conserved and widely spread among eukaryotes. Features of the Fet5 amino acid sequence suggest that it belongs to ATP/GTP-binding proteins.
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Bioorg Khim 1997 Mar;23(3):234-7
| 168 | 1 |
Curatable
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PMID:23503588
|
The final step of cytoplasmic mRNA degradation proceeds in either a 5'-3' direction catalysed by Xrn1 or in a 3'-5' direction catalysed by the exosome. Dis3/Rrp44, an RNase II family protein, is the catalytic subunit of the exosome. In humans, there are three paralogues of this enzyme: DIS3, DIS3L, and DIS3L2. In this work, we identified a novel Schizosaccharomyces pombe exonuclease belonging to the conserved family of human DIS3L2 and plant SOV. Dis3L2 does not interact with the exosome components and localizes in the cytoplasm and in cytoplasmic foci, which are docked to P-bodies. Deletion of dis3l2(+) is synthetically lethal with xrn1Δ, while deletion of dis3l2(+) in an lsm1Δ background results in the accumulation of transcripts and slower mRNA degradation rates. Accumulated transcripts show enhanced uridylation and in vitro Dis3L2 displays a preference for uridylated substrates. Altogether, our results suggest that in S. pombe, and possibly in most other eukaryotes, Dis3L2 is an important factor in mRNA degradation. Therefore, this novel 3'-5' RNA decay pathway represents an alternative to degradation by Xrn1 and the exosome.
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EMBO J 2013 Jul 03;32(13):1842-54
| 319 | 1 |
Curatable
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PMID:8769419
|
Two fission yeast temperature-sensitive mutants, cut6 and lsd1, show a defect in nuclear division. The daughter nuclei differ dramatically in size (the phenotype designated lsd, large and small daughter). Fluorescence in situ hybridization (FISH) revealed that sister chromatids were separated in the lsd cells, but appeared highly compact in one of the two daughter nuclei. EM showed asymmetric nuclear elongation followed by unequal separation of nonchromosomal nuclear structures in these mutant nuclei. The small nuclei lacked electron-dense nuclear materials and contained highly compacted chromatin. The cut6+ and lsd1+ genes are essential for viability and encode, respectively, acetyl CoA carboxylase and fatty acid synthetase, the key enzymes for fatty acid synthesis. Gene disruption of lsd1+ led to the lsd phenotype. Palmitate in medium fully suppressed the phenotypes of lsd1. Cerulenin, an inhibitor for fatty acid synthesis, produced the lsd phenotype in wild type. The drug caused cell inviability during mitosis but not during the G2-arrest induced by the cdc25 mutation. A reduced level of fatty acid thus led to impaired separation of non-chromosomal nuclear components. We propose that fatty acid is directly or indirectly required for separating the mother nucleus into two equal daughters.
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J Cell Biol 1996 Aug;134(4):949-61
| 283 | 1 |
Review or comment
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PMID:28470426
|
Cells contain signal transduction pathways that mediate communication between the extracellular environment and the cell interior. These pathways control transcriptional programs and posttranscriptional processes that modify cell metabolism in order to maintain homeostasis. One type of these signal transduction systems are the so-called Two Component Systems (TCS), which conduct the transfer of phosphate groups between specific and conserved histidine and aspartate residues present in at least two proteins; the first protein is a sensor kinase which autophosphorylates a histidine residue in response to a stimulus, this phosphate is then transferred to an aspartic residue located in a response regulator protein. There are classical and hybrid TCS, whose difference consists in the number of proteins and functional domains involved in the phosphorelay. The TCS are widespread in bacteria where the sensor and its response regulator are mostly specific for a given stimulus. In eukaryotic organisms such as fungi, slime molds, and plants, TCS are present as hybrid multistep phosphorelays, with a variety of arrangements (Stock et al. in Annu Rev Biochem 69:183-215, 2000; Wuichet et al. in Curr Opin Microbiol 292:1039-1050, 2010). In these multistep phosphorelay systems, several phosphotransfer events take place between different histidine and aspartate residues localized in specific domains present in more than two proteins (Thomason and Kay, in J Cell Sci 113:3141-3150, 2000; Robinson et al. in Nat Struct Biol 7:626-633, 2000). This review presents a brief and succinct description of the Two-component systems of model yeasts, Saccharomyces cerevisiae, Schizosaccharomyces pombe, Candida albicans, Cryptococcus neoformans and Kluyveromyces lactis. We have focused on the comparison of domain organization and functions of each component present in these phosphorelay systems.
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World J Microbiol Biotechnol 2017 Jun;33(6):111
| 419 | 0 |
Curatable
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PMID:9461438
|
Mad2 is a component of the spindle checkpoint, which delays the onset of anaphase until all chromosomes are attached to the spindle. Mad2 formed a complex with Slp1, a WD (tryptophan-aspartic acid)-repeat protein essential for the onset of anaphase. When the physical interaction between the two proteins was disrupted, the spindle checkpoint was no longer functional. Post-anaphase events such as chromosome decondensation and the next round of DNA replication were not delayed even when the spindle assembly was incomplete. This relief of dependence appears to be a result of deregulation of ubiquitin-dependent proteolysis mediated by the anaphase-promoting complex.
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Science 1998 Feb 13;279(5353):1045-7
| 147 | 1 |
Curatable
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PMID:1319571
|
The RAD3 gene of Saccharomyces cerevisiae encodes an ATP-dependent 5'-3' DNA helicase, which is involved in excision repair of ultraviolet radiation damage. By hybridisation of a Schizosaccharomyces pombe genomic library with a RAD3 gene probe we have isolated the S. pombe homologue of RAD3. We have also cloned the rad15 gene of S. pombe by complementation of radiation-sensitive phenotype of the rad15 mutant. Comparison of the restriction map and DNA sequence, shows that the S. pombe rad15 gene is identical to the gene homologous to S. cerevisiae RAD3, identified by hybridisation. The S. pombe rad15.P mutant is highly sensitive to UV radiation, but only slightly sensitive to ionising radiation, as expected for a mutant defective in excision repair. DNA sequence analysis of the rad15 gene indicates an open reading frame of 772 amino acids, and this is consistent with a transcript size of 2.6 kb as detected by Northern analysis. The predicted rad15 protein has 65% identity to RAD3 and 55% identity to the human homologue ERCC2. This homology is particularly striking in the regions identified as being conserved in a group of DNA helicases. Gene deletion experiments indicate that, like the S. cerevisiae RAD3 gene, the S. pombe rad15 gene is essential for viability, suggesting that the protein product has a role in cell proliferation and not solely in DNA repair.
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Nucleic Acids Res 1992 Jun 11;20(11):2673-8
| 321 | 1 |
Curatable
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PMID:18062930
|
Translin is a conserved protein which associates with the breakpoint junctions of chromosomal translocations linked with the development of some human cancers. It binds to both DNA and RNA and has been implicated in mRNA metabolism and regulation of genome stability. It has a binding partner, translin-associated protein X (TRAX), levels of which are regulated by the translin protein in higher eukaryotes. In this study we find that this regulatory function is conserved in the lower eukaryotes, suggesting that translin and TRAX have important functions which provide a selective advantage to both unicellular and multi-cellular eukaryotes, indicating that this function may not be tissue-specific in nature. However, to date, the biological importance of translin and TRAX remains unclear. Here we systematically investigate proposals that suggest translin and TRAX play roles in controlling mitotic cell proliferation, DNA damage responses, genome stability, meiotic/mitotic recombination and stability of GT-rich repeat sequences. We find no evidence for translin and/or TRAX primary function in these pathways, indicating that the conserved biochemical function of translin is not implicated in primary pathways for regulating genome stability and/or segregation.
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Biochim Biophys Acta 2008 Feb;1783(2):203-13
| 252 | 1 |
Wrong organism
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PMID:20691182
|
The differentiation processes of excystation and encystation of Entamoeba are essential for infection and completion of their life-cycle, and the processes need cell motility and its control by actin cytoskeletal reorganization. This study investigated actin depolymerizing factor (ADF)/cofilin (Cfl) family proteins, which are important molecules in actin cytoskeletal reorganization, in Entamoeba invadens in relation to the encystation and excystation. Axenic culture systems were used to induce encystation and excystation. A homology search of the E. invadens genome database and molecular cloning identified three ADF/Cfl family proteins of the parasite (named for short as EiCfl-1, EiCfl-2, and EiCfl-3). This is different from other Entamoeba species, i.e. Entamoeba histolytica and Entamoeba dispar, each of which has only one ADF/Cfl family protein. These ADF/Cfl of E. invadens do not have Ser3 (serine locates third from first methionine), similar to E. histolytica, E. dispar, Saccharomyces cerevisiae and Schizosaccharomyces pombe, although the activity of ADF/Cfl is negatively regulated by phosphorylation of the Ser3 in metazoans. Phylogenetic analysis revealed that Entamoeba Cfl formed a distinctive clade that is separate from other organisms, and the branches of the tree were separated in two consistent with the presence and absence of Ser3. Rabbit anti-EiCfl-2 serum reacted with all recombinant EiCfls and EiCfl in lysates of cysts, trophozoites and metacystic amoebae. Immunofluorescence staining with this antiserum showed co-localization of EiCfl with actin beneath the cell membrane through the life stages. Both proteins proved to be rich in pseudopodia of trophozoites and metacystic amoebae. Real-time RT-PCR showed that mRNAs of EiCfl-2 and actins were highly expressed, but there were few mRNA of EiCfl-1 and EiCfl-3. Remarkably decreased mRNA levels were observed in EiCfl-2 and actins during encystation. All three EiCfls and actins became transcribed after the induction of excystation. The mRNAs of only EiCfl-1 and EiCfl-3 increased remarkably when the excystation was induced in the presence of cytochalasin D. These findings demonstrate that EiCfl-2 and actins co-localize beneath the cell membrane in trophozoites and cysts as well as metacystic amoebae being rich in pseudopodia, that EiCfl-1 and EiCfl-3 are expressed only after the induction of excystation, and that enhanced excystation by cytochalasin D is associated with high expression of EiCfl-1 and EiCfl-3.
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Exp Parasitol 2011 Jan;127(1):195-201
| 690 | 0 |
Wrong organism
|
PMID:9506902
|
The A. nidulans cysD gene encoding homocysteine synthase (O-acetyl-L-homoserine sulphydrylase) has been isolated by functional complementation of a cysD11 mutation. The gene contains five short introns and codes for a protein of 437 amino acids. The protein shows homology with bacterial and yeast O-acetyl- and O-succinyl-homoserine sulphydrylases, particularly from Schizosaccharomyces pombe, Saccharomyces cerevisiae and Kluyveromyces lactis. The cysD cDNA is able to complement a S. cerevisiae mutation impairing homocysteine synthase. Synthesis of the cysD mRNA is down-regulated by a high concentration of methionine in growth medium without sulphate and up-regulated under sulphur limitation. A comparison of cysD genomic and cDNA copies, derived from different A. nidulans strains, revealed a marked DNA-sequence polymorphism manifested mostly by silent point mutations. There was, however, much less polymorphism in the protein sequence.
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Curr Genet 1998 Feb;33(2):136-44
| 242 | 0 |
Review or comment
|
PMID:29222069
|
Ribonucleotide modifications perform a wide variety of roles in synthesis, turnover and functionality of tRNA molecules. The presence of particular chemical moieties can refine the internal interaction network within a tRNA molecule, influence its thermodynamic stability, contribute novel chemical properties and affect its decoding behavior during mRNA translation. As the lack of specific modifications in the anticodon stem and loop causes disrupted proteome homeostasis, diminished response to stress conditions, and the onset of human diseases, the underlying modification cascades have recently gained particular scientific and clinical interest. Nowadays, a complicated but conclusive image of the interconnectivity between different enzymatic modification cascades and their resulting tRNA modifications emerges. Here we summarize the current knowledge in the field, focusing on the known instances of cross talk among the enzymatic tRNA modification pathways and the consequences on the dynamic regulation of the tRNA modificome by various factors. This article is part of a Special Issue entitled: SI: Regulation of tRNA synthesis and modification in physiological conditions and disease edited by Dr. Boguta Magdalena.
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Biochim Biophys Acta Gene Regul Mech 2018 Apr;1861(4):409-418
| 219 | 0 |
Wrong organism
|
PMID:30726152
|
Evolutionarily conserved polo-like kinase, Cdc5 (Plk1 in humans), associates with kinetochores during mitosis; however, the role of cell cycle-dependent centromeric ( CEN) association of Cdc5 and its substrates that exclusively localize to the kinetochore have not been characterized. Here we report that evolutionarily conserved CEN histone H3 variant, Cse4 (CENP-A in humans), is a substrate of Cdc5, and that the cell cycle-regulated association of Cse4 with Cdc5 is required for cell growth. Cdc5 contributes to Cse4 phosphorylation in vivo and interacts with Cse4 in mitotic cells. Mass spectrometry analysis of in vitro kinase assays showed that Cdc5 phosphorylates nine serine residues clustered within the N-terminus of Cse4. Strains with cse4-9SA exhibit increased errors in chromosome segregation, reduced levels of CEN-associated Mif2 and Mcd1/Scc1 when combined with a deletion of MCM21. Moreover, the loss of Cdc5 from the CEN chromatin contributes to defects in kinetochore integrity and reduction in CEN-associated Cse4. The cell cycle-regulated association of Cdc5 with Cse4 is essential for cell viability as constitutive association of Cdc5 with Cse4 at the kinetochore leads to growth defects. In summary, our results have defined a role for Cdc5-mediated Cse4 phosphorylation in faithful chromosome segregation.
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Mol Biol Cell 2019 04 01;30(8):1020-1036
| 339 | 0 |
Curatable
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PMID:28986587
|
Chlorination of drinking water protects humans from water-born pathogens, but it also produces low concentrations of dibromoacetonitrile (DBAN), a common disinfectant by-product found in many water supply systems. DBAN is not mutagenic but causes DNA breaks and elevates sister chromatid exchange in mammalian cells. The WHO issued guidelines for DBAN after it was linked with cancer of the liver and stomach in rodents. How this haloacetonitrile promotes malignant cell transformation is unknown. Using fission yeast as a model, we report here that DBAN delays G1-S transition. DBAN does not hinder ongoing DNA replication, but specifically blocks the serine 345 phosphorylation of the DNA damage checkpoint kinase Chk1 by Rad3 (ATR) at broken replication forks. DBAN is particularly damaging for cells with defects in the lagging-strand DNA polymerase delta. This sensitivity can be explained by the dependency of pol delta mutants on Chk1 activation for survival. We conclude that DBAN targets a process or protein that acts at the start of S phase and is required for Chk1 phosphorylation. Taken together, DBAN may precipitate cancer by perturbing S phase and by blocking the Chk1-dependent response to replication fork damage.
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Sci Rep 2017 10 06;7(1):12730
| 271 | 1 |
Curatable
|
PMID:20152181
|
RNaseIII ribonucleases act at the heart of RNA silencing pathways by processing precursor RNAs into mature microRNAs and siRNAs. In the fission yeast Schizosaccharomyces pombe, siRNAs are generated by the RNaseIII enzyme Dcr1 and are required for heterochromatin formation at centromeres. In this study, we have analyzed the subcellular localization of Dcr1 and found that it accumulates in the nucleus and is enriched at the nuclear periphery. Nuclear accumulation of Dcr1 depends on a short motif that impedes nuclear export promoted by the double-stranded RNA binding domain of Dcr1. Absence of this motif renders Dcr1 mainly cytoplasmic and is accompanied by remarkable changes in gene expression and failure to assemble heterochromatin. Our findings suggest that Dicer proteins are shuttling proteins and that the steady-state subcellular levels can be shifted toward either compartment.
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Dev Cell 2010 Jan 19;18(1):102-13
| 203 | 1 |
Wrong organism
|
PMID:34589096
|
Pyricularia oryzae is an important plant pathogenic fungus that can severely damage rice and wheat crops, leading to significant reductions in crop productivity. To penetrate into and invade tissues of its plant host, this fungus relies on an invasive structure known as an appressorium. Appressorium formation is rigorously regulated by the cAMP-PKA and Pmk1 MAPK pathways. Here, we identified PoRal2, a homologous protein of Schizosaccharomyces pombe Ral2, and characterized its roles in fungal development and virulence in P. oryzae . PoRal2 contains N-terminal kelch repeats and C-terminal BTB domains. PoRal2 is involved in sporulation, aerial hypha and conidiophore differentiation, appressorium formation, plant penetration, and virulence. During appressorium formation, ∆ Poral2 mutants generate appressoria with long germ tubes on hydrophobic surfaces. ∆ Poral2 mutants exhibited a defective response to exogenous cAMP and the activated RAS2 G18V on a hydrophilic surface, indicating impairment in the cAMP-PKA or Pmk1 MAPK signaling pathways. Deletion of PoRAL2 leads to lowered Pmk1 phosphorylation level in the mutant. Moreover, PoRal2 is found to interact with Scd1, Smo1, and Mst50, which are involved in activation of Pmk1. In addition, the expression levels of MPG1 , WISH , and PDEH in the cAMP-PKA pathway, RAS2 in both the cAMP-PKA and Pmk1 MAPK pathways, and melanin biosynthesis genes ( ALB1 , BUF1 , and RSY1 ) were significantly down-regulated in the ∆ Poral2 . Therefore, PoRal2 is involved in fungal development and virulence by its crosstalk in the cAMP-PKA and Pmk1 MAPK signaling pathways.
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Front Plant Sci 2021;12:702368
| 446 | 0 |
Curatable
|
PMID:12557275
|
The fission yeast Schizosaccharomyces pombe is auxotrophic for biotin (vitamin H) and growth depends on biotin uptake over the plasma membrane. Here a biotin transport mutant of Saccharomyces cerevisiae is used to identify the vht1(+) gene encoding the Schizosaccharomyces pombe plasma membrane transport protein for biotin. SpVht1p belongs to the family of allantoate transporters and has only little sequence homology to the S. cerevisiae biotin transporter. Although having dissimilar primary structures, the biotin transporters in Sz. pombe and S. cerevisiae share similar biochemical properties and regulation. Like in S. cerevisiae, biotin uptake in Sz. pombe is a high-affinity process, is optimal at acidic pH values and inhibited by protonophores, indicating that SpVht1p acts as a proton-biotin symporter. Desthiobiotin, the metabolic precursor of biotin, is also imported by SpVht1p. Deletion of vht1(+) abolishes growth on low external concentrations of the vitamin, showing that vht1(+) encodes the only protein that mediates biotin uptake in Sz. pombe. Expression of vht1(+) is maximal at low external biotin concentrations, indicating that Sz. pombe can adjust the rate of biotin uptake to meet the requirement for the vitamin.
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Yeast 2003 Feb;20(3):221-31
| 316 | 1 |
Curatable
|
PMID:29852001
|
Mating-type switching in Schizosaccharomyces pombe entails programmed gene conversion events regulated by DNA replication, heterochromatin, and the HP1-like chromodomain protein Swi6. The whole mechanism remains to be fully understood. Using a gene deletion library, we screened ~ 3400 mutants for defects in the donor selection step where a heterochromatic locus, mat2-P or mat3-M, is chosen to convert the expressed mat1 locus. By measuring the biases in mat1 content that result from faulty directionality, we identified in total 20 factors required for donor selection. Unexpectedly, these included the histone H3 lysine 4 (H3K4) methyltransferase complex subunits Set1, Swd1, Swd2, Swd3, Spf1 and Ash2, the BRE1-like ubiquitin ligase Brl2 and the Elongator complex subunit Elp6. The mutant defects were investigated in strains with reversed donor loci (mat2-M mat3-P) or when the SRE2 and SRE3 recombination enhancers, adjacent to the donors, were deleted or transposed. Mutants in Set1C, Brl2 or Elp6 altered balanced donor usage away from mat2 and the SRE2 enhancer, towards mat3 and the SRE3 enhancer. The defects in these mutants were qualitatively similar to heterochromatin mutants lacking Swi6, the NAD+-dependent histone deacetylase Sir2, or the Clr4, Raf1 or Rik1 subunits of the histone H3 lysine 9 (H3K9) methyltransferase complex, albeit not as extreme. Other mutants showed clonal biases in switching. This was the case for mutants in the NAD+-independent deacetylase complex subunits Clr1, Clr2 and Clr3, the casein kinase CK2 subunit Ckb1, the ubiquitin ligase component Pof3, and the CENP-B homologue Cbp1, as well as for double mutants lacking Swi6 and Brl2, Pof3, or Cbp1. Thus, we propose that Set1C cooperates with Swi6 and heterochromatin to direct donor choice to mat2-P in M cells, perhaps by inhibiting the SRE3 recombination enhancer, and that in the absence of Swi6 other factors are still capable of imposing biases to donor choice.
|
PLoS Genet 2018 05;14(5):e1007424
| 535 | 1 |
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