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.

革兰氏阴性细菌霍乱弧菌是沿海水生和河口环境中的天然居民，是胃肠道疾病霍乱的病原体。霍乱弧菌的毒力基因调控非常复杂，主要调控因子ToxR/ToxS位于调控级联的顶端，负责控制毒力以及管家/适应性基因。尽管其重要性，信号输入，特别是在这个主调节系统中的ToxS的功能仍然是未知的。在这个项目中，我们将研究这个系统的激活的新模式，因为我们发现膜结合转录调节因子ToxR的活性受到蛋白酶（DegS）的影响，这也是sigmaE膜应激反应途径的一部分。此外，ToxR反应受到另一个信号转导系统的影响，我们将其鉴定为双组分调节系统，称为OsmRK。我们还观察到，ToxR调节的孔蛋白ompU和ompT的表达变化显着，这取决于环境胁迫条件和toxS，osmRK和degS的等位基因状态。首先分析表明，这些调节作用是ToxR介导的，并且ToxR可以被DegS引起的蛋白水解修饰激活，然后可以被未知的蛋白酶进一步降解。此外，ToxS似乎负责稳定ToxR，从而维持其在膜中的活性。因此，我们的数据表明，ToxR活性是由一种新的和更复杂的变异的调节膜内蛋白水解（RIP）。拟议的项目将为这一刚刚出现的新调控途径提供额外的实验证据，并将解决进一步的问题，如：（i）在接收激活信号时，ToxR内发生了什么变化或修饰？(ii)ToxR是DegS的直接靶点吗？(iii)ToxR活性如何受到OsmRK系统的影响？最后，（iv）DegS和OsmRK识别的信号的性质是什么，这些系统是否在单一途径中合作？预期的结果将大大有助于我们理解ToxR介导的调控，这不仅对霍乱弧菌的毒力基因调控和弧菌属的其他关键细胞功能至关重要，但也可能揭示RIP途径的新的调节潜力。