Interactions of Helicobacter pylori CagA with Host Factors

描述（由申请方提供）：幽门螺杆菌是一种革兰氏阴性、微需氧性胃病原体，感染近50%的人群。它是唯一能够在胃中定植的病原体，并且与十二指肠溃疡和胃溃疡以及腺癌密切相关。该细菌已被世界卫生组织列为1组致癌物。CagA细胞毒素H.幽门螺杆菌通过IV型分泌系统转移到宿主细胞中，与许多细胞蛋白相互作用，增加毒力，并与癌症风险增加有关。CagA已显示操纵许多宿主细胞功能，包括细胞骨架功能、细胞间粘附和细胞内信号转导。然而，近二十年来，CagA的功能仍然是一个谜。我们实验室的初步数据正在改变这种情况。我们已经确定了与宿主靶点结合的CagA的高分辨率晶体结构，鉴定了这种大细胞毒素的稳定可溶性亚结构域，并鉴定了与这些亚结构域相互作用的新型宿主因子。 子域。本申请提出对这些鉴定的亚结构域及其与宿主因子的相互作用进行生物化学、结构和感染生物学研究。具体目的是（1）鉴定、生化和结构表征CagA功能亚结构域，和（2）鉴定、生化和结构表征CagA-宿主因子相互作用。预期的结果包括获得CagA宿主因子相互作用的详细晶体结构，这些相互作用的性质的生化表征，以及CagA宿主因子相互作用的作用。 调节宿主细胞生物学的相互作用。这些数据将极大地增强我们对毒力的理解，以及螺杆菌驱动的致癌作用。 公共卫生相关性：世界上每两个人中就有一个人感染幽门螺杆菌，并且与胃癌有关。幽门螺杆菌将CagA蛋白注入胃细胞，从而使受感染细胞的许多功能失调。我们建议分离CagA与人类蛋白质的相互作用，并在分子水平上对其进行成像，以了解CagA的功能。这样的理解将是解开CagA介导的毒力和对人类癌症的贡献的第一步。

DESCRIPTION (provided by applicant): Helicobacter pylori is a Gram negative, microaerophilic gastric pathogen that infects nearly 50% of the human population. It is the sole pathogen able to colonize the stomach, and has been closely linked to duodenal and gastric ulcers and adenocarcinomas. The bacterium has been listed as a Group 1 carcinogen by the World Health Organization. The CagA cytotoxin of H. pylori is translocated into host cells by a Type IV Secretion System, interacts with many cellular proteins, increases virulence, and is associated with an increased risk of cancer. CagA has been shown to manipulate many host cellular functions, including cytoskeletal function, cell- to-cell adhesion, and intracellular signl transduction. However, how CagA functions has remained mostly a mystery for nearly two decades. Preliminary data from our laboratory is changing this situation. We have determined high-resolution crystal structures of CagA bound to host targets, have identified stable, soluble subdomains of this large cytotoxin, and have identified novel host factors that interact with these subdomains. This application proposes to perform biochemical, structural, and infection biological studies of these identified subdomains and their interactions with host factors. The specific aims are (1) to identify, biochemically and structurally characterize the CagA functional subdomains, and (2) to identify, biochemically and structurally characterize the CagA-host factor interactions. Expected outcomes include obtaining detailed crystal structures of CagA host factor interactions, biochemical characterization of the nature of these interactions, and the role of the interactions in modulating host cell biology. Such data will greatly enhance our understanding of virulence, as well as Helicobacter driven carcinogenesis. PUBLIC HEALTH RELEVANCE: The bacterium Helicobacter pylori infects one out of every two people in the world, and is linked to stomach cancer. Helicobacter pylori injects the CagA protein into stomach cells, which deregulates many functions of the infected cell. We propose to isolate the interactions CagA makes with human proteins, and image them at the molecular level to understand how CagA functions. Such an understanding will be the first step in unraveling CagA mediated-virulence and contributions to human cancers.