STRUCTURE AND FUNCTION OF BACTERIAL ADHESION PILI

这个子项目是利用由NIH/NCRR资助的中心拨款提供的资源的许多研究子项目之一。子项目和调查员(PI)可能从另一个NIH来源获得了主要资金，因此可能会出现在其他CRISE条目中。列出的机构是针对中心的，而不一定是针对调查员的机构。SAXS溶液散射数据将用于细菌粘连菌毛的电子显微镜数据的图像处理。我实验室目前的研究主要集中在两种细菌粘附菌毛，CFA/I菌毛和P-菌毛。这两种菌毛都是螺旋状细丝，直径约8 nm，长度可变，约为1微米。细菌的粘附毛的作用是结合并保持与人类宿主细胞的结合，从而允许细菌定植和随后的疾病。CFA/I菌毛表达在产肠毒素的大肠杆菌上，当它们在小肠定植时会导致旅行者S腹泻。P-菌毛在大肠杆菌上表达，会导致涉及肾脏的尿路感染。我们的研究阐明了每种菌毛类型的结构如何促进细菌在其专门的宿主环境中生存。例如，我们已经证明P-菌毛可以解开它们的螺旋，延伸到原来长度的5倍。我们认为这可以防止它们在周期性的液体流动中断裂和脱离尿路。我们目前的目标是确定CFA/I菌毛的结构基础S保持与小肠结合的能力，由于酸性条件和蠕动细菌必须在胃中生存而真正恶劣的环境，以及进入小肠时遇到的中性pH和剪刀状收缩。我们目前有CFA/I菌毛和P-菌毛的三维螺旋重建。对P-菌毛的研究进一步深入，从电子冷冻显微镜数据得到了9.8°分辨率的结构。对于CFA/I菌毛，我们即将开始收集低温数据，目前正在从阴性染色的样本中重建14.5%。与此同时，一位合作者正在开发一种基于菌毛的疫苗，以对抗旅行者S腹泻(海军医学研究中心斯蒂芬·萨瓦里诺船长)。

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. SAXS solution scattering data will be used for image processing of electron microscopy data on bacterial adhesion pili. Research in my lab currently focuses on two bacterial adhesion pili, CFA/I pili and P-pili. Both of these pili are helical filaments, approximately 8nm in diameter with variable lengths on the order of 1micron. The role of adhesion pili for bacteria is to bind, and remain bound, to the human host cell, thereby allowing bacterial colonization and subsequent disease. CFA/I pili are expressed on enterotoxigenic E. coli that cause Traveler¿¿s Diarrhea when they colonize the small intestines. P-pili are expressed on E. coli that cause Urinary Tract Infections that involve the kidneys. Our studies elucidate how the structure of each pilus type facilitates survival of the bacteria in their specialized host environment. For example, we have shown that P-pili can unwind their helix, extending to 5 times their original length. We propose this prevents their breaking and detaching from the urinary tract during periodic fluid flow. Our current goal is to determine the structural basis of CFA/I pili¿¿s ability to remain bound to the small intestines, a truly harsh environment due to the acidic conditions and peristalsis the bacteria must survive in the stomach, and the reversal back to neutral pH and scissor-like contractions that are encountered upon entering the small intestine. We currently have three-dimensional helical reconstructions of both CFA/I pili and P-pili. Studies on the P-pili are further advanced, with a 9.8 ¿¿resolution structure from electron cryomicroscopy data. For CFA/I pili, we are just about to begin collecting cryo data, and the current reconstruction is at 14.5 ¿¿from negatively stained samples. Concurrently, a collaborator is working on developing a pili-based vaccine against Traveler¿¿s Diarrhea (Capt. Stephen Savarino; Naval Medical Research Center).