Fig. 1.

Schematic representation of the plasmid segregation mechanism involving actin-like bacterial proteins. (A) Overview of the key macromolecular complexes involved in the plasmid segregation process. Bundling and growth of the filaments toward opposite directions push the plasmids toward different ends of the cell. The filaments are coupled to the plasmid with an adaptor protein that binds the filament end and the centromere-like sequence. For the ParMRC system a structure is available for each key step. This includes the complex between the centromere-like sequence (ParC) and the adaptor (ParR) (14), the complex between ParM and ParR (15), filament with AMP-PNP (10), and filament bundles (10). (B) Polymerization is connected to nucleotide hydrolysis. For ParM, hydrolysis destabilizes the filament, which ends in depolymerization in the absence of ParR/ParC. In contrast, AlfA filaments are stable in their ADP form.