Vibrio Cholerae Adapts to Sessile and Motile Lifestyles by Cyclic Di-GMP Regulation of Cell Shape

Abstract

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. cholerae’s 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.

A Broadly Conserved Deoxycytidine Deaminase Protects Bacteria from Phage Infection

“…The spiral nature of V. cholerae filaments (Fig. 1D) is due to the natural curvature of V. cholerae mediated by crvA [33,34].Taken together, these results indicated that DcdV overexpression severely impacts cell physiology in the absence of VSP-1.…”

“…Cells were imaged as previously described [34]. Briefly, overnight cultures were diluted 1:1000 into LB supplemented with antibiotics and IPTG.…”

“…To normalize in vivo nucleotide samples, an additional cell pellet was collected from 1 mL of culture by centrifugation at 15,000 x g for 1 min, resuspended in 200 μL lysis buffer B (20 mM Tris•HCl, 1% SDS, pH 6.8), and denatured for 10 minutes at 60°C. Denatured lysates were centrifuged at 15,000 x g for 1 min to pellet cellular debris, and the supernatant was used to quantify the total protein concentration in the sample using the DC protein assay (Bio-Rad) a BSA standard curve [34]. The concentrations of deoxynucleotides detected by UPLC-MS/MS were then normalized to total protein in each sample.…”

“…The spiral nature of V. cholerae filaments (Fig. 1D) is due to the natural curvature of V. cholerae mediated by crvA [33,34].…”

Straightening up for life in a biofilm

“…Vibrio cholerae, the pathogen responsible for the diarrheal disease cholera, typically adopts a characteristic comma (curved) shape. In PNAS, Fernandez et al (2) report that cellular curvature in V. cholerae is regulated by the second messenger cyclic dimeric guanosine monophosphate (c-di-GMP), whose levels are known to regulate cell motility (3) and biofilm formation (4). Fernandez et al further suggest that c-di-GMP regulation of cell shape may provide an advantage during environmental transitions in which motility and formation of a sessile biofilm are alternately beneficial (4).…”