<p>This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.</p> <p>Using a hierarchical approach, 620 non-essential single-gene yeast deletants generated by
EUROFAN I were systematically screened for cell-wall-related phenotypes. By analyzing
for altered sensitivity to the presence of Calcofluor white or SDS in the growth medium,
altered sensitivity to sonication, or abnormal morphology, 145 (23%) mutants showing at
least one cell wall-related phenotype were selected. These were screened further to identify
genes potentially involved in either the biosynthesis, remodeling or coupling of cell wall
macromolecules or genes involved in the overall regulation of cell wall construction and to
eliminate those genes with a more general, pleiotropic effect. Ninety percent of the mutants
selected from the primary tests showed additional cell wall-related phenotypes. When
extrapolated to the entire yeast genome, these data indicate that over 1200 genes may
directly or indirectly affect cell wall formation and its regulation. Twenty-one mutants with
altered levels of <italic>β</italic>1,3-glucan synthase activity and five Calcofluor white-resistant mutants
with altered levels of chitin synthase activities were found, indicating that the
corresponding genes affect <italic>β</italic>1,3-glucan or chitin synthesis. By selecting for increased
levels of specific cell wall components in the growth medium, we identified 13 genes that
are possibly implicated in different steps of cell wall assembly. Furthermore, 14 mutants
showed a constitutive activation of the cell wall integrity pathway, suggesting that they
participate in the modulation of the pathway either directly acting as signaling components
or by triggering the Slt2-dependent compensatory mechanism. In conclusion, our screening
approach represents a comprehensive functional analysis on a genomic scale of gene
products involved in various aspects of fungal cell wall formation.</p>
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Comp Funct Genomics. 2001 Jun; 2(3):124-142