Structure-Function Relationships in the Spirochetal Flagellar Motor

 描述（由申请人提供）：伯氏疏螺旋体是一种高度运动和侵入性的螺旋体病原体，引起莱姆病，这是美国最常见的媒介传播感染。周质鞭毛是运动的主要细胞器，对B的独特形态、运动和感染生活史至关重要。burgdorferi。周质鞭毛与模型系统大肠杆菌和肠道沙门氏菌中的外部鞭毛不同，因为它们被封闭在外膜内，并且它们的鞭毛马达相当大且更复杂。重要的是，由于其小的细胞直径和高度有序的鞭毛马达在细胞尖端，B。burgdorferi是一种独特的范例，通过采用突破性的冷冻电子断层扫描（cryo-ET）方法，用于周质鞭毛的原位结构分析。在上一个融资期，我们已经产生了一个大的B。超过40种不同鞭毛和趋化性突变体的burgdorferi文库 Steven Norris博士、Md Motaleb博士、Chunhao Li博士和Nyles Charon博士。在了解螺旋体独特的周质鞭毛及其对螺旋体运动和形态的巨大影响方面取得了重大进展。本申请的目的是理解周质鞭毛的三个基本方面：1）鞭毛旋转的结构基础; 2）鞭毛转换机制;和3）鞭毛III型分泌器的结构和机制。结合遗传学和生物化学方法，冷冻ET将被用于确定天然细胞环境中螺旋体鞭毛马达的结构/功能关系。

 DESCRIPTION (provided by applicant): Borrelia burgdorferi is a highly motile and invasive spirochete pathogen causing Lyme disease, the most common vector-borne infection in the United States. Periplasmic flagella, the main organelles for motility, are essential for the distint morphology, motility and infectious life cycle of B. burgdorferi. The periplasmic flagella are distinct from the external flagella in the model systems Escherichia coli and Salmonella enterica, as they are enclosed within the outer membrane and their flagellar motors are considerably larger and more complex. Importantly, owing to its small cell diameter and highly ordered flagellar motors at the cell tip, B. burgdorferi is emerging as a unique paradigm for in situ structural analysis of the periplasmic flagella by employing the ground-breaking methodology of cryo-electron tomography (cryo-ET). During the previous funding period, we have generated a large B. burgdorferi library of over 40 different flagellar and chemotaxis mutants in collaboration with Drs. Steven Norris, Md Motaleb, Chunhao Li and Nyles Charon. Significant progress has been made in understanding the unique periplasmic flagella and their dramatic impacts in the unique spirochetal motility and morphology. The objective of this application is to understand three fundamental aspects of the periplasmic flagella: 1) the structural basis of the flagellar rotation; 2) the flagellar switching mechanism; and 3) the structure and mechanism of the flagellar type III secretion apparatus. Together with genetic and biochemical approaches, cryo-ET will be utilized to determine the structure/function relationship of the spirochetal flagellar motor in native cellular environment.