Metal-dependent regulation of the H. pylori Cag type IV secretion system

描述(申请人提供)：幽门螺杆菌是人类胃壁龛中主要的原核生物。幽门螺杆菌感染导致持续的慢性炎症，是消化性溃疡和胃腺癌发生的重要危险因素。腺癌的发展依赖于多种因素，包括宿主遗传、饮食和细菌因素。导致细菌发病的一个特殊功能是幽门螺杆菌CAG致病岛(CAG PAI)，它编码一个IV型分泌系统(T4SS)，负责将致癌蛋白CagA运送到胃上皮细胞。T4SS装置跨越两个细菌膜，并包括一个被称为T4SS菌毛的细胞外细胞器。这种细胞器被认为对真核膜的破坏和CagA的转位负责。尽管T4SS在幽门螺杆菌的致病和最终致癌过程中发挥了重要作用，但调节这一复杂分子机器组装的机制在很大程度上尚不清楚。本申请提出了一些实验，以阐明CAG T4SS被调控的机制。具体地说，我们假设T4SS菌毛的组装受到铁和锌等金属可用性的调节。我们将利用电子显微镜、定量RT-PCR和分子生物学技术的组合来阐明管理这一重要细胞器的生物发生的复杂调控网络。 公共卫生相关性：幽门螺杆菌是一种定植于人胃的细菌，导致胃癌和消化性溃疡疾病。这项研究试图了解这种细菌如何调节CAG IV型分泌系统，该系统将致癌效应物转移到宿主细胞中。这一知识可能会为预防和治疗胃癌和消化性溃疡疾病带来新的方法。

DESCRIPTION (provided by applicant): Helicobacter pylori is the predominant colonizing prokaryote in the human gastric niche. H. pylori infection results in persistent chronic inflammation, and is a strong risk factor for the development of peptic ulceration and gastric adenocarcinoma. The development of adenocarcinoma is dependent upon a variety of factors, including host genetics, diet, and bacterial factors. One specific feature that contributes to bacterial pathogenesis is the H. pylori cag pathogenicity island (cag PAI), which encodes a type IV secretion system (T4SS) responsible for the delivery of the oncogenic protein CagA into gastric epithelial cells. The T4SS apparatus spans two bacterial membranes and includes an extracellular organelle referred to as the T4SS pilus. This organelle is proposed to be responsible for compromising the eukaryotic membrane and translocation of CagA. Although the T4SS has an important role in H. pylori pathogenesis and ultimately carcinogenesis, the mechanisms that regulate assembly of this complex molecular machine are largely obscure. This application proposes experiments that will elucidate the mechanisms by which the cag T4SS is regulated. Specifically, we hypothesize that assembly of the T4SS pilus is regulated by the availability of metals such as iron and zinc. We will utilize a combination of electron microscopy, quantitative RT-PCR, and molecular biology techniques to shed light upon the complex regulatory networks that govern the biogenesis of this important organelle. PUBLIC HEALTH RELEVANCE: Helicobacter pylori is a bacterium that colonizes the human stomach and contributes to gastric cancer and peptic ulcer disease. This research seeks to understand how this bacterium regulates the cag type IV secretion system, which translocates carcinogenic effectors into host cells. This knowledge may lead to new approaches for the prevention and treatment of stomach cancer and peptic ulcer disease.