Rönnebäumer Karin, Sander Gunnar, Shutinoski Bojan, Schmidt M Alexander, Heusipp Gerhard
Institut für Infektiologie, Zentrum für Molekularbiologie der Entzündung, Westfälische Wilhelms-Universität Münster, Münster, Germany.
FEMS Microbiol Lett. 2009 Jun;296(2):274-81. doi: 10.1111/j.1574-6968.2009.01649.x. Epub 2009 May 9.
The Cpx two-component signal transduction system regulates the expression of genes in response to stimuli associated with the maintenance of the bacterial cell envelope. Additionally, the Cpx system is important for virulence in several bacterial pathogens. In this study, we analyzed the Cpx system of the human enteropathogen Yersinia enterocolitica. We provide evidence that transcription of cpxR is autoregulated and that the response regulator CpxR negatively affects transcription of rpoE, coding for the extracytoplasmic function sigma factor sigma(E), thereby linking at the transcriptional level two systems involved in envelope maintenance. A mutated form of CpxR that cannot be phosphorylated, CpxRD51A, affects transcription of cpxR and rpoE similar to the wild-type CpxR. In contrast, CpxR and CpxRD51A differentially regulate transcription of htrA, indicating phosphorylation-dependent and -independent mechanisms of transcriptional regulation. Moreover, overproduction of CpxR, CpxRD51A and CpxA result in a growth defect. Interestingly, a cpxA mutant strain could not be obtained. We conclude that the phosphorylation status of CpxR needs to be tightly controlled by CpxA, and that the Cpx system has a central role in regulating basic cellular functions. In addition, we show that cpxR and cpxP mutant strains have no defect in Y. enterocolitica invasion of host cells.
Cpx双组分信号转导系统可响应与细菌细胞膜维持相关的刺激来调节基因表达。此外，Cpx系统对几种细菌病原体的毒力很重要。在本研究中，我们分析了人类肠道病原体小肠结肠炎耶尔森菌的Cpx系统。我们提供的证据表明，cpxR的转录是自我调节的，并且反应调节因子CpxR对编码胞质外功能σ因子σ(E)的rpoE的转录产生负面影响，从而在转录水平上连接了参与细胞膜维持的两个系统。一种不能被磷酸化的CpxR突变形式CpxRD51A，对cpxR和rpoE转录的影响与野生型CpxR相似。相比之下，CpxR和CpxRD51A对htrA转录的调节存在差异，表明转录调节存在磷酸化依赖性和非依赖性机制。此外，CpxR、CpxRD51A和CpxA的过量表达会导致生长缺陷。有趣的是，无法获得cpxA突变株。我们得出结论，CpxR的磷酸化状态需要由CpxA严格控制，并且Cpx系统在调节基本细胞功能中起核心作用。此外，我们表明cpxR和cpxP突变株在小肠结肠炎耶尔森菌侵袭宿主细胞方面没有缺陷。
