Heroven Ann Kathrin, Böhme Katja, Rohde Manfred, Dersch Petra
Institut für Mikrobiologie, Technische Universität Braunschweig, 38106 Braunschweig, Germany.
Mol Microbiol. 2008 Jun;68(5):1179-95. doi: 10.1111/j.1365-2958.2008.06218.x. Epub 2008 Apr 22.
The MarR-type regulator RovA controls expression of virulence genes of Yersinia pseudotuberculosis in response to environmental signals. Using a genetic strategy to discover components that influence rovA expression, we identified new regulatory factors with homology to components of the carbon storage regulator system (Csr). We showed that overexpression of a CsrB- or a CsrC-type RNA activates rovA, whereas a CsrA-like protein represses RovA synthesis. We further demonstrate that influence of the Csr system on rovA is indirect and occurs through control of the LysR regulator RovM, which inhibits rovA transcription. The CsrA protein had also a major influence on the motility of Yersinia, which was independent of RovM. The CsrB and CsrC RNAs are differentially expressed in Yersinia. CsrC is highly induced in complex but not in minimal media, indicating that medium-dependent rovM expression is mediated through CsrC. CsrB synthesis is generally very low. However, overexpression of the response regulator UvrY was found to activate CsrB production, which in turn represses CsrC synthesis independent of the growth medium. In summary, the post-transcriptional Csr-type components were shown to be key regulators in the co-ordinated environmental control of physiological processes and virulence factors, which are crucial for the initiation of Yersinia infections.
MarR 型调节因子 RovA 可根据环境信号控制鼠疫耶尔森菌毒力基因的表达。我们采用遗传学策略来发现影响 rovA 表达的成分，从而鉴定出了与碳储存调节系统（Csr）成分具有同源性的新调节因子。我们发现，过表达 CsrB 型或 CsrC 型 RNA 可激活 rovA，而一种类似 CsrA 的蛋白则会抑制 RovA 的合成。我们进一步证明，Csr 系统对 rovA 的影响是间接的，是通过控制 LysR 调节因子 RovM 来实现的，RovM 会抑制 rovA 的转录。CsrA 蛋白对鼠疫耶尔森菌的运动性也有重大影响，且这种影响独立于 RovM。CsrB 和 CsrC RNA 在鼠疫耶尔森菌中的表达存在差异。CsrC 在复杂培养基中高度诱导表达，但在基本培养基中则不然，这表明培养基依赖性的 rovM 表达是通过 CsrC 介导的。CsrB 的合成通常非常低。然而，我们发现应答调节因子 UvrY 的过表达可激活 CsrB 的产生，进而抑制 CsrC 的合成，且这一过程与生长培养基无关。总之，转录后水平的 Csr 型成分被证明是生理过程和毒力因子协同环境控制中的关键调节因子，而这些生理过程和毒力因子对于鼠疫耶尔森菌感染的起始至关重要。
