VIBRIO CHOLERAE ADAPTS TO SESSILE AND MOTILE LIFESTYLES BY CYCLIC DI-GMP REGULATION OF CELL SHAPE

The cell morphology of rod-shaped bacteria is determined by the rigid net of peptidoglycan forming the cell wall. While V. cholerae grows into a curved shape under most conditions, straight rods have been observed. However, the signals and regulatory pathways controlling cell shape transitions in V. cholerae and the benefits of switching between rod and curved shape have not been determined. We demonstrate that cell shape in V. cholerae is regulated by the bacterial second messenger cyclic dimeric guanosine monophosphate (c-di-GMP) by repressing expression of crvA, a gene encoding an intermediate filament-like protein necessary for curvature formation in V. cholerae. This regulation is mediated by the transcriptional cascade that also induces production of biofilm matrix components, indicating that cell shape is coregulated with V. choleraes induction of sessility. Wild-type V. cholerae cells adhering to a surface lose their characteristic curved shape to become as straight as cells lacking crvA while genetically engineering cells to maintain high curvature reduced microcolony formation and biofilm density. Conversely, straight V. cholerae mutants have reduced speed when swimming using flagellar motility in liquid. Our results demonstrate regulation of cell shape in bacteria is a mechanism to increase fitness in planktonic or biofilm lifestyles.