Fine‐tuning protein self‐organization by orthogonal chemo‐optogenetic tools

A universal gain-of-function approach for the spatiotemporal control of protein activity is highly desirable when reconstituting biological modules in vitro . Here we used orthogonal translation with a photocaged amino acid as an optogenetic tool to map and elucidate molecular mechanisms in the self-organization of the prokaryotic filamentous cell division protein (FtsZ). This protein is highly relevant for the assembly of the division ring in bacteria, and displays intriguing circular treadmilling dynamics when reconstituted on membranes in vitro. We masked a tyrosine residue of FtsZ by site-specific incorporation of a photocaged tyrosine analog. While the mutant still shows self-assembly into filaments, dynamic self-organization into ring patterns can no longer be observed. UV-mediated uncaging revealed that tyrosine 222 is essential for the regulation of the protein's GTPase activity, self-organization and treadmilling dynamics. Thus, the light-mediated assembly of functional protein modules appears to be a promising minimal regulation strategy for building up molecular complexity towards a minimal cell.