Better explicating the strengths and shortcomings of these models will help refine projections and improve transparency in the years ahead.
Image credit: Witsawat.S.
Edited by Caroline S. Harwood, University of Washington, Seattle, WA, and approved September 17, 2020 (received for review May 20, 2020)
Significance
Form follows function is true of living organisms, including bacteria, as the shapes and morphology they adopt contribute to their biological characteristics. But whether bacteria can actively change their shape to adapt to their environment is less understood. Vibrio cholerae, the pathogenic bacterium responsible for the diarrheal disease cholera, adopts a characteristic “comma”-shaped cell morphology. Here we show that the intracellular signaling molecule, cyclic di-GMP, drives curved V. cholerae to adopt a straight cell morphology that is advantageous to a sessile biofilm lifestyle, while curved V. cholerae are better adapted for swimming. Our research provides a clear example of how bacteria can actively alter their form to impact function.
Abstract
The cell morphology of rod-shaped bacteria is determined by the rigid net of peptidoglycan forming the cell wall. Alterations to the rod shape, such as the curved rod, occur through manipulating the process of cell wall synthesis. The human pathogen Vibrio cholerae typically exists as a curved rod, but straight rods have been observed under certain conditions. While this appears to be a regulated process, the 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 posttranscriptionally 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. During microcolony formation, wild-type V. cholerae cells tended to exist as straight rods, while genetically engineering cells to maintain high curvature reduced microcolony formation and biofilm density. Conversely, straight V. cholerae mutants have reduced swimming speed when using flagellar motility in liquid. Our results demonstrate regulation of cell shape in bacteria is a mechanism to increase fitness in planktonic and biofilm lifestyles.
Footnotes
↵1Present address: Department of Molecular, Cellular, and Developmental Biology, University of Michigan, Ann Arbor, MI 48103.
- ↵2To whom correspondence may be addressed. Email: watersc3{at}msu.edu.
Author contributions: N.L.F., B.Y.H., N.T.Q.N., J.L.F., Y.S.D., and C.M.W. designed research; N.L.F., B.Y.H., and N.T.Q.N. performed research; N.L.F., B.Y.H., N.T.Q.N., J.L.F., Y.S.D., and C.M.W. analyzed data; and N.L.F., Y.S.D., and C.M.W. wrote the paper.
The authors declare no competing interest.
This article is a PNAS Direct Submission.
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This article contains supporting information online at https://www.pnas.org/lookup/suppl/doi:10.1073/pnas.2010199117/-/DCSupplemental.
Data Availability.
All study data are included in the article and supporting information.
Published under the PNAS license.
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Vibrio cholerae adapts to sessile and motile lifestyles by cyclic di-GMP regulation of cell shape
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- Microbiology
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