Skip to main page content
U.S. flag

An official website of the United States government

Dot gov

The VSports app下载. gov means it’s official. Federal government websites often end in . gov or . mil. Before sharing sensitive information, make sure you’re on a federal government site. .

Https

The site is secure. The https:// ensures that you are connecting to the official website and that any information you provide is encrypted and transmitted securely. V体育官网.

Review
. 2014 Sep 9:6:38.
doi: 10.1186/s13099-014-0038-9. eCollection 2014.

Fine tuning of virulence regulatory pathways in enteric bacteria in response to varying bile and oxygen concentrations in the gastrointestinal tract

Chirantana Sengupta  1 , Sreejana Ray  1 , Rukhsana Chowdhury  2
Affiliations
Review

Fine tuning of virulence regulatory pathways in enteric bacteria in response to varying bile and oxygen concentrations in the gastrointestinal tract

Chirantana Sengupta et al. Gut Pathog. .

Abstract

After entering the gastrointestinal (GI) tract on the way to their physiological site of infection, enteric bacteria encounter a remarkable diversity in environmental conditions VSports手机版. There are gross differences in the physico-chemical parameters in different sections of the GI tract e. g. between the stomach, small intestine and large intestine. Furthermore, even within a certain anatomical site, there are subtle differences in the microenvironment e. g. between the lumen, mucous layer and epithelial surface. Enteric pathogens must not only survive passage through the rapidly changing environments encountered at different niches of the GI tract but must also appropriately coordinate expression of virulence determinants in response to environmental cues at different stages of infection. There are some common themes in the responses of enteric pathogens to environmental cues, there are also distinct differences that may reflect differences in basic pathogenesis mechanisms. The role of bile and oxygen concentration in spatiotemporal regulation of virulence genes in selected enteric pathogens has been reviewed. .

Keywords: Bile; Oxygen concentration; Salmonella; Shigella; V. cholerae; Virulence. V体育安卓版.

PubMed Disclaimer

Figures

Figure 1
Figure 1
Effect of bile onV. choleraevirulence regulation. A. When V. cholerae is grown in vitro under permissive conditions without bile the ToxR regulon is activated and the major virulence factors CT and TCP are produced. B. In the intestinal lumen where bile concentration is high, UFA present in bile prevents dimerization of ToxT and thus expression of the virulence genes ctxAB and tcpA is reduced. As the bacteria move away from the lumen through the mucus layer to the underlying epithelium, concentration of bile gradually decreases, consequently ctxAB and tcpA expression increases.
Figure 2
Figure 2
Spatio-temporal regulation of virulence by oxygen. The concentration of oxygen is low in the intestinal lumen but increases adjacent to the mucosal surface. A. In S. flexneri microaerobic condition of the lumen activates FNR [FNR(a)] which in turn represses Ipa secretion. Extended T3SS needles are formed. As the bacteria moves to the zone of higher oxygen concentration adjacent to the epithelial layer, FNR is inactivated [FNR(ia)] and T3SS effector genes are induced. B. In V. cholerae, the tcpA gene, but not ctxAB, is induced under the microaerobic condition of the lumen, when the bacteria reach the epithelial layer, the relatively higher oxygen concentration allows expression of both tcpA and ctxAB.
See this image and copyright information in PMC

References

    1. Kolling G, Wu M, Guerrant RL. Enteric pathogens through life stages. Frontiers Cell Infect Microbiol. 2012;2:114. doi: 10.3389/fcimb.2012.00114. - DOI - PMC - PubMed
    1. Mekalanos JJ. Environmental signals controlling expression of virulence determinants in bacteria. J Bacteriol. 1992;174:1–7. - PMC - PubMed
    1. Krukonis ES, DiRita VJ. From motility to virulence: Sensing and responding to environmental signals in Vibrio cholerae. Curr Opin Microbiol. 2003;6:186–190. doi: 10.1016/S1369-5274(03)00032-8. - "V体育官网入口" DOI - PubMed
    1. Ferreyra JA, Ng KM, Sonnenburg JL. The Enteric Two-Step: nutritional strategies of bacterial pathogens within the gut. Cell Microbiol. 2014;16:993–1003. doi: 10.1111/cmi.12300. - VSports手机版 - DOI - PMC - PubMed
    1. Castellani F, Ghidini V, Tafi MC, Boaretti M, Lleo MM. Fate of pathogenic bacteria in microcosms mimicking human body sites. Microb Ecol. 2013;66:224–231. doi: 10.1007/s00248-013-0239-7. - DOI - PubMed

LinkOut - more resources