Small host GTPases: Direct targets of Vibrio vulnificus MARTX toxin effectors

项目摘要/摘要 由革兰氏阴性杆菌创伤弧菌(VV)引起的胃肠道和伤口感染可 在约50%的病例中，有极大的生命危险导致死亡。这些感染在体内进展 而且必须迅速确定和治疗，以减少死亡率和发病率。在使用抗生素的同时 对于VV感染的治疗，随着疾病的迅速发展，它们往往无效，特别是在 免疫功能受损的个体。这种疾病现在特别令人担忧，因为这种疾病的发病率 由于气候变化而增加。多功能自动处理重复序列毒素(MARTX)毒素是一种大型的 VV分泌的一种蛋白质毒素，对引起感染是必不可少的。MARTX毒素的功能是将 将五种不同的毒性效应物作为单一推注直接进入真核宿主细胞质。已知的有十个 独特的效应器，每个效应器都能引起细胞毒效应。确定通过什么机制 编码在MARTX毒素功能中的效应器将揭示与细菌毒素相关的新机制 这一功能可能会影响我们对许多不同系统中宿主-微生物相互作用的理解。这个 毛毛虫类软盘(MCF)毒素是最常见的VV MARTX效应器。麦克夫与高尔基有关 弥散，抑制细胞增殖，促进细胞凋亡。在初步研究中，观察到MCF被刺激 通过与ADP-核糖化因子结合进行自动处理，从而使其作为单独的效应物绝对释放 宿主细胞内的结构域和激活。然而，一旦MCF在真核宿主中发挥作用 单独释放和激活导致其毒性的原因尚不清楚。这项提案的目标是调查 一种假设是，一旦被激活，MCF就会继续结合并靶向另一类小GTP酶，RABS， 导致正常细胞功能的中断。为了检验这一假设，我们将确定：1)哪个子集 RAB是MCF的目标；2)MCF如何访问这些RAB；3)这种交互如何改变适当的RAB 功能和定位；4)这两种蛋白质相互作用的方式；以及5) 不同的MCF结构域。此外，这些研究将涉及使用新技术和概念的培训。 这项工作的结果有可能发展成几个独立的研究项目。这个 拟议的研究金将涉及合作，这在新闻部得到了促进和鼓励 西北大学微生物学-免疫学。

Project Summary/Abstract Gastrointestinal and wound infections caused by the Gram-negative bacterium Vibrio vulnificus (Vv) can be exceptionally life-threatening resulting in death in approximately 50% of cases. These infections progress within days and must be identified and treated quickly to decrease mortality and morbidity. While antibiotics are used to treat Vv infections, they are often ineffective as the disease progresses rapidly, especially in immunocompromised individuals. This disease is of particular concern now as the incidence of the disease is increasing due to climate change. The Multifunctional Autoprocessing Repeats in Toxin (MARTX) toxin is a large protein toxin that is secreted by Vv and is essential to cause infections. The MARTX toxin functions to deliver up to five different toxic effectors as a single bolus directly into the eukaryotic host cytoplasm. There are ten known unique effectors, and each is capable of causing cytotoxic effects. Determining the mechanism by which the effectors encoded within the MARTX toxin function will reveal a novel mechanisms related to bacterial toxin function that could impact our understanding of host-microbe interactions across many diverse systems. The Makes Caterpillars Floppy-like (MCF) toxin is the most common Vv MARTX effector. MCF is linked to Golgi dispersion, inhibition of cell proliferation, and apoptosis. In preliminary studies, MCF is observed to be stimulated to autoprocess via binding to ADP-ribosylation factors resulting in its absolute release as an individual effector domain within the host cell and activation. However, how MCF functions within the eukaryotic host once individually released and activated that results in its toxicity is unclear. The goal of this proposal is to investigate the hypothesis that, once activated, MCF moves on to bind and target another class of small GTPases, Rabs, resulting in a disruption of proper cell functions. To test this hypothesis, we will determine: 1) Which subset of Rabs are the target of MCF; 2) How MCF gains access to these Rabs; 3) How this interaction alters proper Rab functioning and localization; 4) The manner in which these two proteins interact; and 5) The function of the different domains of MCF. In addition, these studies will involve training to utilize novel techniques and concepts. The results from this work have the potential to develop into several independent research projects. The proposed fellowship will involve collaborations, which are facilitated and encouraged in the Department of Microbiology-Immunology at Northwestern.