SaureusDivisomeDynamics
Bacterial cell division requires recruitment of peptidoglycan (PG) synthesis enzymes to the division site by the tubulin homologue FtsZ. Septal PG synthases promote inward growth of the septum. FtsZ treadmilling is proposed to drive the processive movement of PG synthases and septal constriction in some bacteria, however the precise mechanisms spatiotemporally regulating PG synthase movement, activity and FtsZ treadmilling are poorly understood. Using single-molecule imaging of division proteins of the Gram-positive pathogen Staphylococcus aureus, we showed that the septal PG synthesis enzyme complex FtsW/PBP1, and its putative activator protein, DivIB, move with similar velocity around the division site. Impairing FtsZ treadmilling did not affect FtsW or DivIB velocities or septum constriction rates. Contrarily, inhibition of PG synthesis decelerated or stopped the directional movement of FtsW and DivIB, and septum constriction. Our findings suggest that a single population of processively moving FtsW/PBP1 associated with DivIB drives cell constriction independently of FtsZ filament treadmilling in S. aureus.