Structural Components of the Campylobacter jejuni Polar Flagellar Motor

描述（由申请方提供）：鞭毛运动对于许多病原菌促进宿主感染从而导致疾病至关重要。此外，鞭毛的能动性 许多环境细菌到达特定的生态位和营养素的最佳生长。原型鞭毛纳米机器的结构和功能主要来自沙门氏菌和大肠杆菌的围毛鞭毛的累积研究。一个典型的鞭毛是由一个鞭毛马达，从内外膜延伸，表面定位的钩，和细胞外丝旋转。鞭毛马达由内膜中的定子复合物和鞭毛基部的转子和开关组件以及穿透肽聚糖和外膜的杆组成。定子产生离子梯度，为转子提供动力，使棒和灯丝转动， 在游泳运动中。极鞭毛细菌的鞭毛马达包含这些核心成分，但也具有对马达功能至关重要的额外结构成分。通过使用电子冷冻断层扫描，我们已经确定了三个磁盘结构与空肠弯曲菌，在美国和世界各地的其他国家，这是人类胃肠炎的主要原因，这是必不可少的促进运动的极鞭毛电机。我们已经确定了两种蛋白质，FlgP和Cjj 0413，其中两个组成这些马达盘结构。任何一种蛋白质的缺失都会使C. 空肠。由于这些蛋白质的同系物中发现的其他极性鞭毛虫，也产生盘状结构与各自的鞭毛电机，我们相信，我们已经确定了组件普遍需要的极性鞭毛电机的功能。本提案的目标是使用C。空肠作为模型系统来理解鞭毛马达的结构和功能，因为它们涉及医学上重要的极鞭毛细菌病原体，如弧菌属、假单胞菌属和螺杆菌属。在目标1中，我们将进行实验以鉴定C.空肠形成马达盘结构和鞭毛马达功能特别需要的蛋白质。在目标2中，我们将分析 FlgP所需的基础马达盘的形成和其他马达盘的成核。此外，我们将分析Cjj 0413的细胞质和周质结构域及其对近端盘聚合和运动性的要求。这些目标的实现将有助于理解：1）功能性极鞭毛马达所需的独特组件; 2） 极性鞭毛马达的结构和功能的替代机制， 周毛型马达;以及3）运动细菌之间关于鞭毛纳米机器如何起作用以促进跨细菌物种的游泳运动性的多样性，这对于许多细菌在宿主和环境中的最佳生长是必需的。

DESCRIPTION (provided by applicant): Flagellar motility is essential for many pathogenic bacteria to promote infection of hosts to result in disease. In addition, flagellar motility allows many environmental bacteria to reach specific niches and nutrients for optimal growth. The structure and function of a prototypic flagellar nanomachine is largely derived from cumulative studies of peritrichous flagella from Salmonella species and Escherichia coli. A typical flagellum is composed of a flagellar motor that extends from the inner and outer membranes, a surface-localized hook, and an extracellular filament that rotates. The flagellar motor is composed of stator complexes in the inner membrane that associate with rotor and switch components at the base of the flagellum and a rod that penetrates the peptidoglycan and the outer membrane. The stators generate an ion gradient to power the rotor to turn the rod and the filament, which results in swimming motility. The flagellar motors of polarly-flagellated bacteria contain these core components, but also possess additional structural components that are essential for motor function. By using electron cryo-tomography, we have identified three disk structures associated with the polar flagellar motor of Campylobacter jejuni, a leading cause of gastroenteritis in humans in the United States and in other countries throughout the world, which are essential for promoting motility. We have identified two proteins, FlgP and Cjj0413, which compose two of these motor disk structures. Deletion of either protein abolishes motor function and motility in C. jejuni. Because homologues of these proteins are found in other polar flagellates that also produce disk-like structures associated with their respective flagellar motors, we believe that we have identified components universally required for function of polar flagellar motors. The objectives of this proposal are to use C. jejuni as a model system to understand construction and function of flagellar motors as they relate to medically-important polar-flagellated bacterial pathogens such as Vibrio, Pseudomonas, and Helicobacter species. In Aim 1, we will perform experiments to identify other proteins of C. jejuni forming motor disk structures and proteins specifically required for flagellar motor function. In Aim 2, we will analyze essential residues of FlgP required for formation of the basal motor disk and nucleation of the other motor disks. In addition, we will analyze cytoplasmic and periplasmic domains of Cjj0413 and their requirements for polymerization of the proximal disk and motility. Accomplishment of these aims will aid in understanding: 1) unique components required for a functional polar flagellar motor; 2) alternative mechanisms for the construction and function of polar flagellar motors that differ from peritrichous motors; and 3) diversity amongst motile bacteria for how flagellar nanomachines function to promote swimming motility across bacterial species, which is essential for optimal growth of many bacteria in hosts and in environments.