Optogenetic Navigation of Routes Leading to Protein Amyloidogenesis in Bacteria.
Modulation of liquid liquid and liquid hydrogel phase transitions is central to avoid the cytotoxic aggregation of proteins in eukaryotic cells, but knowledge on its relevance in bacteria is limited. Here the power of optogenetics to engineer proteins as light responsive switches has been used to control the balance between solubility and aggregation for LOV2 WH1, a chimera between the plant blue light responsive domain LOV2 and the bacterial prion like protein RepA WH1. These proteins were first linked by fusing, as a continuous a helix, the C terminal photo transducer Ja helix in LOV2 with the N terminal domain closure a1 helix in RepA WH1, and then improved for light responsiveness by including mutations in the Ja moiety. In the darkness and in a crowded solution in vitro, LOV2 WH1 nucleates the irreversible assembly of amyloid fibers into a hydrogel. However, under blue light illumination, LOV2 WH1 assembles as soluble oligomers. When expressed in Escherichia coli, LOV2 WH1 forms in the darkness large intracellular amyloid inclusions compatible with bacterial proliferation. Strikingly, under blue light, LOV2 WH1 aggregates decrease in size, while they become detrimental for bacterial growth. LOV2 WH1 optogenetics governs the assembly of mutually exclusive inert amyloid fibers or cytotoxic oligomers, thus enabling the navigation of the conformational landscape of protein amyloidogenesis to generate potential photo activated anti bacterial devices (optobiotics)
Journal of molecular biology