Late assembly of the Vibrio cholerae cell division machinery postpones septation to the last 10% of the cell cycle

Abstract

Bacterial cell division is a highly regulated process, which involves the formation of a complex apparatus, the divisome, by over a dozen proteins. In the few model bacteria in which the division process was detailed, divisome assembly occurs in two distinct steps: A few proteins, including the FtsZ tubulin-like protein, form a membrane associated contractile ring, the Z-ring, at ∼30% of the cell cycle. The Z-ring serves as a scaffold for the recruitment of a second series of proteins, including integral membrane and periplasmic cell wall remodelling enzymes, at ∼50% of the cell cycle. Actual septation occupies most of the remaining half of the cell cycle. In contrast, we present evidence suggesting that early pre-divisional Z-rings form between 40 and 50% of the cell cycle and mature into fully assembled divisome at about 80% of the cell cycle in Vibrio cholerae. Thus, actual septation is restricted to a very short amount of time. Our results further suggest that late assembly of the divisome probably helps maintain the asymmetric polar organisation of V. cholerae cells by limiting the accumulation of a cell pole marker, HubP, at the nascent cell poles.