Do the divisome and elongasome share a common evolutionary past?

• Proposal that divisome and elongasome have descended from common ancestor.
• Divisome and elongasome have similar functions, features and subunits.
• Similar subunits are Mur/Mra, PBPs, FtsW/RodA and actin-like proteins FtsA and MreB.
• Actin-like FtsA and MreB guide the divisome and elongasome, respectively.
• FtsZ is a unique component of the divisome.

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.