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

项目概要/摘要 由革兰氏阴性细菌创伤弧菌（Vibrio vulnificus，Vv）引起的胃肠道和伤口感染可以是 特别危及生命，导致约50%的病例死亡。这些感染是在 必须迅速发现和治疗，以降低死亡率和发病率。在使用抗生素的同时， 治疗Vv感染，它们通常是无效的，因为疾病进展迅速，特别是在 免疫力低下的人。这种疾病现在特别令人关注，因为这种疾病的发病率是 由于气候变化而增加。多功能自动处理重复序列毒素（MARTX）是一种大的 由VV分泌的蛋白质毒素，是引起感染所必需的。MARTX毒素的作用是 五种不同的毒性效应物作为一个单一的弹丸直接进入真核宿主细胞质。已知有10个 独特的效应物，并且每一种都能够引起细胞毒性作用。确定了一种机制， MARTX毒素功能中编码的效应子将揭示与细菌毒素相关的新机制 这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。的 使毛虫Floppy样（MCF）毒素是最常见的Vv MARTX效应。MCF与高尔基体相连 分散、抑制细胞增殖和凋亡。在初步研究中，观察到MCF被刺激， 通过与ADP-核糖基化因子结合进行自动加工，导致其作为单个效应物的绝对释放 宿主细胞内的结构域和激活。然而，MCF如何在真核宿主中发挥作用， 单独释放和激活，导致其毒性尚不清楚。这项提案的目的是调查 假设一旦被激活，MCF继续结合并靶向另一类小GTP酶，Rabs， 导致正常细胞功能的破坏。为了检验这个假设，我们将确定：1）哪个子集 Rab是MCF的目标; 2）MCF如何接触这些Rab; 3）这种相互作用如何改变正确的Rab 功能和定位; 4）这两种蛋白质相互作用的方式;以及5）蛋白质的功能。 MCF的不同领域。此外，这些研究将涉及培训，以利用新的技术和概念。 这项工作的结果有可能发展成几个独立的研究项目。的 拟议的研究金将涉及合作，这是促进和鼓励在该部 微生物学-免疫学在西北。

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.