Constriction Rate Modulation Can Drive Cell Size Control and Homeostasis in C. crescentus

Abstract

Rod-shaped bacteria typically grow first via sporadic and dispersed elongation along their lateral wallsand then via a combination of zonal elongation and constriction at the division site to form the poles ofdaughter cells. Although constriction comprises up to half of the cell cycle, its impact on cell size con-trol and homeostasis has rarely been considered. To reveal the roles of cell elongation and constrictionin bacterial size regulation during cell division, we captured the shape dynamics ofCaulobactercres-centuswith time-lapse structured illumination microscopy and used molecular markers as cell-cyclelandmarks. We perturbed the constriction rate using a hyperconstriction mutant or fosfomycin([(2R,3S)-3-methyloxiran-2-yl]phosphonic acid) inhibition. We report that the constriction rate contrib-utes to both size control and homeostasis, by determining elongation during constriction and bycompensating for variation in pre-constriction elongation on a single-cell basis.