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

描述（由申请人提供）：幽门螺杆菌是人类胃生态位中主要的定殖原核生物。幽门螺杆菌感染可导致持续性慢性炎症，是发生消化性溃疡和胃腺癌的重要危险因素。腺癌的发展取决于多种因素，包括宿主遗传、饮食和细菌因素。促成细菌发病的一个特定特征是幽门螺杆菌cag致病性岛（cag PAI），它编码一种IV型分泌系统（T4SS），负责将致癌蛋白CagA传递到胃上皮细胞。T4SS装置跨越两个细菌膜，并包括称为T4SS菌毛的细胞外细胞器。这种细胞器被认为是破坏真核生物膜和CagA易位的原因。尽管T4SS在幽门螺杆菌的发病和最终的癌变中起着重要作用，但调控这一复杂分子机器组装的机制在很大程度上尚不清楚。该应用程序提出了将阐明cag T4SS被调节的机制的实验。具体来说，我们假设T4SS菌毛的组装是由铁和锌等金属的可用性调节的。我们将利用电子显微镜、定量RT-PCR和分子生物学技术的结合来阐明控制这一重要细胞器生物发生的复杂调控网络。

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.