Molecular Mechanisms of the Type I Secretion System from Bacterial Pathogens

细菌病原体I型分泌系统的分子机制

基本信息

批准号：
10795448
负责人：
Wei Mi
金额：
$ 6.35万
依托单位：
YALE UNIVERSITY
依托单位国家：
美国
项目类别：
财政年份：
2021
资助国家：
美国
起止时间：
2021-08-01 至 2026-07-31
项目状态：
未结题

项目摘要

ABSTRACT Protein secretion is an essential component of the arsenal used by many bacterial pathogens to invade hosts, damage tissues, and suppress immune responses. Gram-negative bacteria have evolved sophisticated machines to secrete proteins across two membranes: the inner membrane and outer membrane. Since discovered in 1979, the type I secretion system (T1SS) has been identified in more than 800 bacterial genomes, and many of its substrates contribute to the virulence of pathogens, examples being hemolysin HlyA in uropathogenic Escherichia coli, adhesin SiiE in Salmonella enterica, and adenylate cyclase CyaA in Bordetella pertussis. The T1SS secretes unfolded substrates from the cytoplasm to the extracellular milieu. It includes three components: an ATP-binding cassette transporter (ABC transporter), associated periplasmic adapter proteins located in the inner membrane, and a porin in the outer membrane. The canonical “alternating access” model cannot explain how the large protein substrates are transported by the T1SS ABC transporter across the inner membrane. Therefore, the mechanisms of substrate secretion at the molecular level is still obscure. The proposed research leverages single particle cryo-electron microscopy (cryoEM), bioinformatics, in vivo and in vitro assays to answer key questions in the field, including the structural basis of substrate recognition, the nature of the translocation pathway, the energetics for substrate translocation, and the regulation of the T1SS ABC transporter's activity. The studies will substantially increase the fundamental scientific knowledge about the mechanisms of the T1SS and provide a new basis for developing future therapeutic interventions against a broad range of bacterial infections.

抽象的蛋白质分泌是许多细菌病原体使用的阿森纳的重要组成部分入侵宿主，损害组织和抑制免疫反应。革兰氏阴性细菌具有将复杂的机器进化为跨两个膜的秘密蛋白质：内膜和外膜。自1979年发现以来，I型分泌系统（T1SS）一直是在800多个细菌基因组中鉴定出来，其许多底物有助于病原体的病毒，例子是肝病大肠杆菌中的hlya hlya，沙门氏菌中的粘合素siie，以及百日草的Bordetella cyaa。 T1SS分泌从细胞质到细胞外环境中展开的底物。它包括三个组件：ATP结合盒转运蛋白（ABC转运蛋白），相关的周质衔接蛋白位于内膜，外膜中的孔蛋白。这规范的“交替访问”模型无法解释大蛋白质底物的方式由T1SS ABC转运蛋白运输于内膜。因此，分子水平的底物分泌的机理仍然晦涩。拟议的研究利用单粒子冷冻电子显微镜（冷冻），生物信息学，体内和体外测定回答现场关键问题的测定，包括底物识别的结构基础，易位途径的性质，底物易位的能量学和 T1SS ABC转运蛋白活性的调节。研究将大大增加关于T1SS机制的基本科学知识，并提供了新的基础用于开发针对广泛的细菌感染的未来治疗干预措施。