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 to map and elucidate molecular mechanisms in the self-organization of the prokaryotic filamentous cell-division protein (FtsZ) that is highly relevant for the assembly of the division ring in bacteria. We masked a tyrosine residue of FtsZ by site-specific incorporation of a photocaged tyrosine analogue. 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.