Mechanism of the Usher in Assembly and Secretion of Pili

霹雳虫的组装与分泌机制

• 批准号: 6878097
• 负责人: David G Thanassi
• 金额: $ 23.33万
• 依托单位: STATE UNIVERSITY NEW YORK STONY BROOK
• 依托单位国家: 美国
• 财政年份: 2001
• 资助国家: 美国
• 起止时间: 2001-04-01 至 2007-03-31
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/6878097
• 关键词: Escherichia coli; bacteria infection mechanism; bacterial proteins; cell free system; epitope mapping; liposomes; membrane biogenesis; membrane model; membrane permeability; membrane proteins; molecular assembly /self assembly; molecular chaperones; pilus; urinary tract infection; virulence

DESCRIPTION (provided by the applicant): Pathogenic bacteria must assemble and secrete virulence factors in order to interact with their hosts and cause disease. Gram-negative bacteria have an outer membrane in addition to a cytoplasmic membrane and must secrete virulence factors across both these barriers. The mechanisms by which this occurs can be quite complex and are not well understood. The chaperone/usher pathway is a virulence protein secretion pathway that requires two components for secretion across the outer membrane: a periplasmic chaperone and an outer membrane protein termed an usher. The chaperone directs proper folding of the secreted proteins and prevents their engagement in non-productive interactions. The usher serves as an assembly platform at the outer membrane and provides a secretion channel to the cell surface. The chaperone/usher pathway is required for assembly and secretion of a superfamily of adhesive structures in a broad range of Gram-negative pathogens. The prototypical organelles assembled by this pathway are the P and type 1 pili expressed by uropathogenic Escherichia coli, the primary causative agent of urinary tract infections. P and type 1 pili are critical virulence factors, allowing binding and colonization of the kidney and bladder, respectively. The long-term goal of this proposal is to use pilus biogenesis by uropathogenic E. coli as a model system with which to understand virulence factor secretion in Gram-negative bacteria. More specifically, the structure and function of the usher will be investigated to elucidate the molecular mechanisms governing secretion across the outer membrane. The first specific aim is to create a detailed model of the structural arrangement of the usher in the outer membrane using computer analysis and epitope mapping techniques. The second specific aim is to probe function of the usher through generation and analysis of mutants. The third specific aim is to establish a cell-free system for pilus biogenesis based on reconstitution of the usher into liposomes. Such a system will provide an invaluable tool for studying the chaperone/usher pathway and analyzing mutants. The work described in this proposal will elucidate mechanisms of virulence factor secretion and create opportunities for the development of novel antimicrobial agents to treat not only urinary tract infections, but also a broad range of infectious diseases.

描述（由申请人提供）：致病菌必须聚集并 分泌毒力因子以与宿主相互作用并引起 疾病。革兰氏阴性菌除具有外膜外，还具有外膜。 细胞质膜并且必须在这两个膜上分泌毒力因子 障碍。发生这种情况的机制可能相当复杂，并且不 很好理解。伴侣/引座途径是毒力蛋白分泌 需要两个成分才能穿过外膜分泌的途径： 周质伴侣和称为引座员的外膜蛋白。这 伴侣指导分泌蛋白的正确折叠并防止其 参与非生产性互动。引座员担任集会人员 外膜平台，为细胞提供分泌通道 表面。分子伴侣/引座子途径是组装和分泌所必需的 广泛的革兰氏阴性胶粘剂结构超家族 病原体。通过该途径组装的原型细胞器是 P 和 尿路致病性大肠杆菌表达的 1 型菌毛，是主要致病菌 尿路感染剂。 P 型菌毛和 1 型菌毛具有临界毒力 因素，允许肾脏和膀胱的结合和定植， 分别。该提案的长期目标是通过菌毛生物发生 尿路致病性大肠杆菌作为了解毒力的模型系统 革兰氏阴性菌的分泌因子。更具体地说，结构 将研究引座员的功能和功能，以阐明分子 控制跨外膜分泌的机制。第一个具体 目的是创建一个详细的引入结构安排模型 使用计算机分析和表位作图技术确定外膜。这 第二个具体目标是通过生成和探索引座员的功能 突变体分析。第三个具体目标是建立无细胞系统 用于基于脂质体重建的菌毛生物发生。这样的 系统将为研究陪伴/引座员提供宝贵的工具 途径和分析突变体。本提案中描述的工作将 阐明毒力因子分泌机制并为 新型抗菌药物的开发不仅可以治疗泌尿道疾病 感染，而且还包括广泛的传染病。