Membrane stress and ToxR-mediated virulence of Vibrio cholerae

霍乱弧菌的膜应激和 ToxR 介导的毒力

• 批准号: 39788588
• 负责人: Professor Dr. Joachim Reidl
• 金额: --
• 依托单位: Institut für Molekulare Biowissenschaften
• 依托单位国家: 德国
• 项目类别: Research Grants
• 财政年份: 2007
• 资助国家: 德国
• 起止时间: 2006-12-31 至 2009-12-31
• 项目状态: 已结题
• 来源: https://gepris.dfg.de/gepris/projekt/39788588?language=en
• 关键词: Membrane; stress; ToxR; mediated; virulence

The Gram-negative bacterium Vibrio cholerae, which is a natural inhabitant of the coastal aquatic and estuarine environment, is the causative agent of the gastrointestinal disease cholera. Virulence gene regulation in V. cholerae is highly complex with the master regulator components ToxR/ToxS acting at the top of a regulation cascade, which is responsible for the control of virulence as well as housekeeping/fitness genes. Despite its importance, signal input and in particular the function of ToxS in this master regulatory system have remained unknown. In this project we will investigate a new mode of activation of this system, as we found that the activity of the membran-bound transcriptional regulator ToxR is influenced by a protease (DegS), which is also part of the sigmaE membrane-stress response pathway. In addition, the ToxR response is influenced by another signal transduction system, which we identified as a two-component regulatory system, termed OsmRK. We also observed, that the expression of the ToxR-regulated porins ompU and ompT varies significantly, depending on environmental stress conditions and the allelic status of toxS, osmRK and degS. First analyses indicate, that these regulatory effects are ToxR-mediated, and that ToxR may be activated by proteolytic modification caused by DegS, and may then be further degraded by yet unknown proteases. In addition, ToxS seems responsible for stabilizing ToxR and thereby maintaining its activity in the membrane. Thus, our data indicate that ToxR activity is conrtolled by a novel and more complex variant of regulated intramembrane proteolysis (RIP). The proposed project will provide additional experimental evidence for this just emerging new regulatory pathway and will address further questions such as: (i) what is changed or modified within ToxR while receiving activating signals? (ii) Is ToxR a direct target for DegS? (iii) How is ToxR activity influenced by the OsmRK system? And finally, (iv) what is the nature of the signals recognized by DegS and OsmRK and do these systems cooperate in a single pathway? The expected results will significantly contribute to our understanding of ToxR-mediated regulation, which is not only crucial for virulence gene regulation in V. cholerae and other pivotal cell functions in Vibrio spp., but may also reveal a novel regulatory potential of the RIP pathway.

革兰氏阴性细菌弧菌霍乱是沿海水生和河口环境的自然居民，是胃肠道疾病霍乱的病因。 V.霍乱中的毒力基因调节与作用在调节级联的顶部的主调节剂ToxR/Toxs高度复杂，该级联级联反应控制毒力以及管家/适应性基因。尽管它的重要性，但信号输入，尤其是TOX在此主调控系统中的功能尚不清楚。在这个项目中，我们将研究该系统的一种新的激活方式，因为我们发现膜结合的转录调节剂TOXR的活性受蛋白酶（DEGS）的影响，蛋白酶也是Sigmae膜压力响应途径的一部分。此外，TOXR响应受另一个信号转导系统的影响，我们将其确定为一个称为OSMRK的两个组件调节系统。我们还观察到，根据环境应力条件和TOXS，OSMRK和DEGS的等位基因状态，TOXR调节的Porins Ompu和OMPT的表达差异很大。首先分析表明，这些调节作用是TOXR介导的，并且可能会因DEG引起的蛋白水解修饰而激活TOXR，然后可能会被未知的蛋白酶进一步降解。此外，Toxs似乎是负责稳定Toxr的原因，从而维持其在膜中的活性。因此，我们的数据表明，TOXR活性是由一种新型且更复杂的膜内蛋白水解（RIP）的变体汇总的。拟议的项目将为这一新出现的新监管途径提供其他实验证据，并将解决以下问题：（i）在接收激活信号时TOXR中发生了什么变化或修改的问题？ （ii）TOXR是DEG的直接目标吗？ （iii）如何受OSMRK系统影响TOXR活动？最后，（iv）DEGS和OSMRK认可的信号的性质是什么，并且这些系统是否在单个途径中合作？预期的结果将显着有助于我们对TOXR介导的调节的理解，这不仅对V. Cholerae和Vibrio spp中的V. Cholerae和其他关键细胞功能至关重要，而且还可能揭示RIP途径的新调节潜力。