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1 Wuhan Institute of Virology, The Chinese Academy of Sciences, Wuhan 430071, PR China
2 Institute of Infection, Immunity and Inflammation, Centre for Biomolecular Sciences, University of Nottingham, Nottingham NG7 2UH, UK
3 Graduate School of the Chinese Academy of Sciences, Beijing 100049, PR China
Yersinia pseudotuberculosis is an enteric bacterium which must overcome the acidic stress in host organs for successful colonization, but how this bacterium survives in acidic conditions remains largely unknown. In the present study, the importance of OmpR in acid survival of Y. pseudotuberculosis YpIII was confirmed by the fact that mutation of ompR (strain
ompR) greatly reduced cell survival at pH 4.5 or lower. To characterize the regulatory role of OmpR in this acid survival process, proteomic analysis was carried out to compare YpIII at pH 7.0 and pH 4.5 with
ompR at pH 7.0, and urease components were revealed to be the main targets for OmpR regulation. Addition of urea to the culture medium also enhanced acid survival of YpIII but not
ompR and urease activity was significantly induced by acid in YpIII but not in
ompR. Each of the seven components of the YpIII urease gene cluster was fused to a lacZ reporter and their expression was dramatically decreased in a
ompR background; this supports the notion that OmpR positively regulates urease expression. Furthermore, gel shift analysis revealed that OmpR binds to the deduced promoter regions of three polycistronic transcriptional units (ureABC, ureEF and ureGD) in the urease cluster, suggesting that the regulation of OmpR to urease components is direct. Taken together, these data strongly suggest that OmpR activates urease expression to enhance acid survival in Y. pseudotuberculosis.
Correspondence
Shiyun Chen
sychen{at}wh.iov.cn
Two supplementary tables and two supplementary figures are available with the online version of this paper.
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Y. Hu, Y. Wang, L. Ding, P. Lu, S. Atkinson, and S. Chen Positive regulation of flhDC expression by OmpR in Yersinia pseudotuberculosis Microbiology, November 1, 2009; 155(11): 3622 - 3631. [Abstract] [Full Text] [PDF] |
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