Environmental adaptation by Vibrio cholerae

项目总结/摘要 霍乱是一种急性肠道疾病，每年影响300万至500万人。霍乱是一种 由革兰氏阴性细菌霍乱弧菌引起，经常与流行病有关 疾病霍乱弧菌是水生生态系统的原生菌，也是一种兼性人类病原体， 人们通过食用受污染的水或食物。一旦摄入，霍乱弧菌定殖于 小肠，在那里它产生毒素，导致脱水分泌性腹泻，可以迅速 致命的霍乱的毁灭性后果，加上它传播的速度， 它在水生生态系统中持续存在的能力，强调了开发新方法的必要性 来对抗这种流行病我们最近对霍乱弧菌的研究证明， 属于抗性-增殖-分裂（RND）超家族的系统具有外排细胞的功能， 细胞的代谢物。我们进一步表明，受损的外排导致代谢物积累 在细胞内，它们与周质传感器蛋白相互作用以启动适应性反应。这 包括ToxR的激活导致leuO转录的增加和 毒力基因表达然而，负责毒力抑制的代谢物 仍然未知。在这个提议中，我们将测试这样一个假设，即自诱导物的功能是启动 导致毒力抑制的适应性反应的表达。两个具体目标是 提出了第一个目的是研究细胞密度依赖基因ToxR和LeuO的功能 调控第二个目标是研究RND介导的外排对适应性反应的贡献 和殖民化。确定调节V的调节机制和环境线索。 霍乱适应性反应将阐明霍乱弧菌发病机制的重要方面， 更好地了解有助于疾病和流行病传播的因素，并突出新的 为抗击霍乱采取措施。

PROJECT SUMMARY/ABSTRACT Cholera is an acute diarrheal disease that affects 3-5 million people each year. Cholera is an is caused by the Gram negative bacterium Vibrio cholerae and is frequently associated with epidemic disease. V. cholerae is a native to aquatic ecosystems and a facultative human pathogen that infects people through the consumption of contaminated water or food. Once ingested, V. cholerae colonizes the small intestine where it produces a toxin that causes a dehydrating secretory diarrhea that can be rapidly fatal. The devastating consequences of cholera, combined with the rapidity with which it can spread and its ability to persist in aquatic ecosystems, underscore the need for the development of novel approaches to combat this epidemic disease. Our recent studies in V. cholerae documented that multiple drug efflux systems belonging to the resistance-nodulation-division (RND) superfamily function to efflux cellular metabolites from the cell. We further showed that impaired efflux resulted in the metabolites accumulating intracellularly where they interacted with periplasmic sensor proteins to initiate adaptive responses. This included the activation of ToxR which resulted in increased leuO transcription and the downregulation of virulence gene expression. However, the metabolites that were responsible for virulence repression remain unknown. In this proposal we will test the hypothesis that auto-inducers function to initiate the expression of the adaptive responses that resulted in virulence repression. Two specific aims are proposed. The first aim will investigate the function of ToxR and LeuO in cell density-dependent gene regulation. The second aim will investigate the contribution of RND-mediated efflux to adaptive responses and colonization. Determining the regulatory mechanisms and environmental cues that modulate V. cholerae adaptive responses will illuminate important aspects of V. cholerae pathogenesis, provide a better understanding of the factors that contribute to disease and epidemic spread, and highlight novel approaches to combat cholera.