STRUCTURE AND MECHANISM OF CS1 PILUS ASSEMBLY

这个子项目是许多研究子项目中利用 资源由NIH/NCRR资助的中心拨款提供。子项目和 调查员(PI)可能从NIH的另一个来源获得了主要资金， 并因此可以在其他清晰的条目中表示。列出的机构是 该中心不一定是调查人员的机构。 菌毛是毛发状的表面纤维，介导病原菌与宿主组织的附着和定植。产肠毒素大肠埃希菌(ETEC)的CS1菌毛系统是ETEC建立和在人体肠道定植所必需的，导致腹泻疾病，这是第三世界国家婴儿和儿童发病率的重要原因。CS1编码在CooBACD操纵子上，由多个CooA亚基组成，这些CooA亚基的末端有一个CooD亚基，这是黏附肠道细胞所必需的。此外，菌毛组装还需要95 kDa的外膜蛋白CooC和周质伴侣蛋白CooB。具体的假设是，CS1菌毛的组装是由CooB单独与CooD或CooA结合时外膜蛋白CooC的构象变化启动的。这一假说基于以下数据：1)CooC是一个完整的外膜蛋白，2)CooC的表达是将菌毛输出到细胞表面所必需的，3)CooB与CooC共同纯化并稳定CooC以防止蛋白质降解。因此，CooB本身或作为CooA或CooD的复合体，启动CooC的构象变化，从而允许亚基运输到表面。本研究的具体目的是：1.表征CooB的天然结构和齐聚状态。2.定义CooC中的结构性变化。3.确定CooC在CooA聚合机理中的作用。从这些研究中获得的信息可能有助于设计新的疗法，提供对ETEC感染的保护。

This subproject is one of many research subprojects utilizing the resources provided by a Center grant funded by NIH/NCRR. The subproject and investigator (PI) may have received primary funding from another NIH source, and thus could be represented in other CRISP entries. The institution listed is for the Center, which is not necessarily the institution for the investigator. Pili are hair-like surface fibers that mediate attachment and colonization of pathogenic bacteria to host tissues. The CS1 pilus system from enterotoxigenic Escherichia coli (ETEC) is required for the establishment and colonization of ETEC to the human intestine, resulting in diarrheal disease that is a significant cause of morbidity in infants and children in third-world countries. CS1 is encoded on the cooBACD operon, and is composed of multiple CooA subunits that have at the distal tip the single subunit of CooD that is required for adherence to intestinal cells. Additionally, CooC, a 95-kDa outer membrane protein, and CooB, a periplasmic chaperone, are required for pilus assembly. The specific hypothesis is that the assembly of CS1 pili is initiated by a conformational change in the outer membrane protein CooC upon binding of CooB alone are as a complex with CooD or CooA. The hypothesis is based on data that indicate that 1) CooC is an integral outer membrane protein, 2) expression of CooC is required for export of pili to the cell surface and 3) CooB co-purifies with CooC and stabilizes CooC against proteolytic degradation. Therefore CooB, either by itself or as a complex with CooA or CooD, initiates a conformational change in CooC that allows transport of subunits to the surface. The specific aims of our research are: 1. Characterize the native structure and oligomerization state of CooB. 2. Define structural changes in CooC. 3. Determine the role of CooC in the mechanism of polymerization of CooA. Information obtained from these studies may be useful in the design of novel therapies that provide protection against ETEC infection.