STRUCTURE AND FUNCTION OF BACTERIAL ADHESION PILI

本子项目是利用由NIH/NCRR资助的中心赠款提供的资源的众多研究子项目之一。子项目和研究者（PI）可能已经从另一个NIH来源获得了主要资金，因此可以在其他CRISP条目中表示。列出的机构是中心的，不一定是研究者的机构。SAXS溶液散射数据将用于细菌黏附毛的电子显微镜数据的图像处理。我的实验室目前主要研究两种细菌黏附菌毛，CFA/I毛和p -毛。这两种毛都是螺旋状的细丝，直径约8nm，长度在1微米左右。细菌黏附菌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菌毛在产肠毒素的大肠杆菌上表达，当它们定植在小肠时，会引起旅行者腹泻。p -毛菌在大肠杆菌上表达，引起尿路感染，包括肾脏。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特定宿主环境中的生存。例如，我们已经证明P-pili可以展开它们的螺旋，延伸到它们原始长度的5倍。我们建议这样做可以防止它们在周期性液体流动期间从尿道中断裂和分离。我们目前的目标是确定CFA/I菌毛保持与小肠结合能力的结构基础，由于酸性条件和蠕动，细菌必须在胃中生存的真正恶劣的环境，以及在进入小肠时遇到的中性pH值和剪刀状收缩的逆转。我们目前有CFA/I和P-pili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中获得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，目前对阴性染色样品的重建为14.5¿¿。与此同时，一位合作者正在开发一种针对旅行者腹泻的基于阴茎的疫苗（海军医学研究中心的Stephen Savarino上尉）。

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).