OmpR positively regulates urease expression to enhance acid survival of Yersinia pseudotuberculosis
OmpR positively regulates urease expression to enhance acid survival of Yersinia pseudotuberculosis
复制标题
DOI：
10.1099/mic.0.028381-0
复制
发表时间：
2009-08-01
期刊：
影响因子：
2.8
通讯作者：
Chen, Shiyun
中科院分区：
文献类型：
--
作者：
Hu, Yangbo;Lu, Pei;Chen, Shiyun
假结核耶尔森氏菌是一种肠道细菌，它必须克服宿主器官中的酸性胁迫才能成功定植，但这种细菌如何在酸性条件下生存仍不得而知。在本研究中，在pH为4.5或更低的环境下，OmpR（菌株Delta OmpR）的突变大大降低了细胞的存活率，证实了OmpR在假结核杆菌YpIII酸性存活中的重要性。为了描述OmpR在这种酸存活过程中的调节作用，我们进行了蛋白质组学分析，比较了pH 7.0和pH 4.5下的YpIII和pH 7.0下的Delta OmpR，发现脲酶组分是OmpR调节的主要靶点。在培养基中添加尿素也能提高YpIII的酸存活率，但对Delta ompR没有作用，而且酸能显著诱导YpIII的脲酶活性，而对Delta ompR没有作用。YpIII脲酶基因簇的七个组成部分中的每一个都被融合到lacZ报告基因中，它们在Delta ompR背景下的表达显著降低；这支持了OmpR正调控脲酶表达的观点。此外，凝胶位移分析显示，OmpR结合到脲酶簇中三个多顺反电子转录单元（ureABC， ureEF和ureGD）的推断启动子区域，这表明OmpR对脲酶组分的调节是直接的。综上所述，这些数据强烈表明OmpR激活脲酶表达，提高假结核杆菌的酸存活。
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. pseudo tuberculosis YpIII was confirmed by the fact that mutation of ompR (strain Delta 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 Delta 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 Delta ompR and urease activity was significantly induced by acid in YpIII but not in Delta 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 Delta 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.