Journal
JOURNAL OF BACTERIOLOGY
Volume 200, Issue 18, Pages -Publisher
AMER SOC MICROBIOLOGY
DOI: 10.1128/JB.00230-18
Keywords
Proteus mirabilis; RffG; cell motility; cell surface; outer membrane; swarm development; swarm motility; swarming
Categories
Funding
- Smith Family Graduate Fellowship in Science and Engineering
- Simmons Family Award for the Harvard Center for Biological Imaging
- David and Lucile Packard Foundation
- George W. Merck Fund
- Harvard University
Ask authors/readers for more resources
Individual cells of the bacterium Proteus mirabilis can elongate up to 40-fold on surfaces before engaging in a cooperative surface-based motility termed swarming. How cells regulate this dramatic morphological remodeling remains an open question. In this paper, we move forward the understanding of this regulation by demonstrating that P. mirabilis requires the gene rffG for swarmer cell elongation and subsequent swarm motility. The rffG gene encodes a protein homologous to the dTDPglucose 4,6-dehydratase protein of Escherkhio coil, which contributes to enterobacterial common antigen biosynthesis. Here, we characterize the rffG gene in P. mirabilis, demonstrating that it is required for the production of large lipopolysaccharide-linked moieties necessary for wild-type cell envelope integrity. We show that the absence of the rffG gene induces several stress response pathways, including those controlled by the transcriptional regulators RpoS, CaiF, and RcsB. We further show that in MG-deficient (C) cells, the suppression of the Rcs phosphorelay, via loss of RcsB, is sufficient to induce cell elongation and swarm motility. However, the loss of RcsB does not rescue cell enve- lope integrity defects and instead results in abnormally shaped cells, including cells producing more than two poles. We conclude that an RcsB-mediated response acts to suppress the emergence of shape defects in cell envelope-compromised cells, suggesting an additional role for RcsB in maintaining cell morphology under stress conditions. We further propose that the composition of the cell envelope acts as a checkpoint before cells initiate swarmer cell elongation and motility. IMPORTANCE Proteus mirabilis swarm motility has been implicated in pathogenesis. We have found that cells deploy multiple uncharacterized strategies to handle cell envelope stress beyond the Rcs phosphorelay when attempting to engage in swarm motility. While RcsB is known to directly inhibit the master transcriptional regulator for swarming, we have shown an additional role for RcsB in protecting cell morphology. These data support a growing appreciation that the Rcs phosphorelay is a multifunctional regulator of cell morphology in addition to its role in microbial stress responses. These data also strengthen the paradigm that outer membrane composition is a crucial checkpoint for modulating entry into swarm motility. Furthermore, the rffG-dependent moieties provide a novel attractive target for potential antimicrobials.
Authors
I am an author on this paper
Click your name to claim this paper and add it to your profile.
Reviews
Recommended
No Data Available