Do the divisome and elongasome share a common evolutionary past?

The divisome and elongasome are bacterial protein complexes responsible for peptidoglycan (PG) synthesis during cell division and elongation, respectively. We review several lines of evidence, arguing for a shared evolutionary past of the divisome and elongasome. Both integrate closely related penicillin-binding proteins (PBPs) for PG synthesis, use proteins of the RodA/FtsW (SEDS, shape, elongation, division and sporulation) family for Lipid II export and interact with MraY/Mur proteins for Lipid II synthesis. It was recently shown that the actin-like protein FtsA of the divisome polymerises on membranes, adding another parallel, since membrane-associated filaments of the bacterial actin MreB guide the elongasome. Given these similarities, it seems plausible to conclude that the elongasome is a modified version of the divisome, without the membrane-constricting FtsZ-ring and its associated machinery on the inside.