Phenotypic and transcriptional analysis of the osmotic regulator OmpR in <it>Yersinia pestis</it>

• Main Authors: Guo Zhaobiao, Liu Xia, Yang Lin, Han Yanping, Zhang Yiquan, Gao He, Tan Yafang, Huang Xinxiang, Zhou Dongsheng, Yang Ruifu
• Format: Article
• Language: English
• Published: BMC 2011-02-01
• Series: BMC Microbiology
• Online Access: http://www.biomedcentral.com/1471-2180/11/39

<p>Abstract</p> <p>Background</p> <p>The osmotic regulator OmpR in <it>Escherichia coli </it>regulates differentially the expression of major porin proteins OmpF and OmpC. In <it>Yersinia enterocolitica </it>and <it>Y. pseudotuberculosis</it>, OmpR is required for both virulence and survival within macrophages. However, the phenotypic and regulatory roles of OmpR in <it>Y. pestis </it>are not yet fully understood.</p> <p>Results</p> <p><it>Y. pestis </it>OmpR is involved in building resistance against phagocytosis and controls the adaptation to various stressful conditions met in macrophages. The <it>ompR </it>mutation likely did not affect the virulence of <it>Y. pestis </it>strain 201 that was a human-avirulent enzootic strain. The microarray-based comparative transcriptome analysis disclosed a set of 224 genes whose expressions were affected by the <it>ompR </it>mutation, indicating the global regulatory role of OmpR in <it>Y. pestis</it>. Real-time RT-PCR or <it>lacZ </it>fusion reporter assay further validated 16 OmpR-dependent genes, for which OmpR consensus-like sequences were found within their upstream DNA regions. <it>ompC</it>, <it>F</it>, <it>X</it>, and <it>R </it>were up-regulated dramatically with the increase of medium osmolarity, which was mediated by OmpR occupying the target promoter regions in a tandem manner.</p> <p>Conclusion</p> <p>OmpR contributes to the resistance against phagocytosis or survival within macrophages, which is conserved in the pathogenic yersiniae. <it>Y. pestis </it>OmpR regulates <it>ompC</it>, <it>F</it>, <it>X</it>, and <it>R </it>directly through OmpR-promoter DNA association. There is an inducible expressions of the pore-forming proteins OmpF, C, and × at high osmolarity in <it>Y. pestis</it>, in contrast to the reciprocal regulation of them in <it>E. coli</it>. The main difference is that <it>ompF </it>expression is not repressed at high osmolarity in <it>Y. pestis</it>, which is likely due to the absence of a promoter-distal OmpR-binding site for <it>ompF</it>.</p>