Flagellar Motor Biogenesis in Polarly-Flagellated Bacterial Pathogens

项目摘要 细菌鞭毛作为两台机器发挥作用：第三型分泌系统（T3SS）分泌大部分的 鞭毛的细胞质外成分和促进游泳运动的可逆旋转马达 许多细菌病原体感染宿主以促进疾病所需的。周毛鞭毛虫如E. 大肠杆菌和沙门氏菌已作为模型来了解鞭毛生物发生的各种过程 和功能然而，许多重要的细菌病原体，包括空肠弯曲杆菌，霍乱弧菌， 幽门螺杆菌和铜绿假单胞菌是极性鞭毛虫，在有限的条件下产生鞭毛马达。 数字只在极地地区。这些极性鞭毛马达的特点是结构更复杂 而不是它们的周毛型同类。利用C.空肠作为了解极鞭毛运动模型系统 在细菌病原体的生物发生和功能中，我们发现， 鞭毛马达是由于独特的结构和由不同集合形成的保守亚结构造成的 蛋白质。重要的是，这些结构改变增强了C。空肠鞭毛 T3SS和旋转电机。我们发现C.空肠鞭毛T3SS分泌能力增强， 鞭毛蛋白和组装鞭毛，即使缺乏其他T3SS通常所必需的成分， 功能此外，我们还发现了C.空肠鞭毛有助于共同的 许多病原体的极鞭毛马达的特征--产生更高的扭矩以获得高运动速度 在生理粘度范围内。我们还确定了C。空肠鞭毛T3SS和运动组件， 促进其在运动之外的细胞活动中的多任务能力。该提案的主要目的是分析 这些特定的结构和亚结构是如何形成和适应C.空肠鞭毛增强 机械，以增强其作为分泌机器和旋转马达的功能。在目标1中，我们将分析 组成和排列的蛋白质形成的C.空肠鞭毛T3SS，并确定如何燃料 与其他T3SS相比，机械结构发生了改变，使其能够分泌蛋白质并组装鞭毛，即使没有 通常是重要的部分。在目标2中，我们将分析新型盘结构如何形成以及转子组件如何 的电动机已经扩大到影响的数量和安置的定子单位所需的产生高扭矩 用于鞭毛旋转和高速运动。在目标3中，我们将探索两个C。空肠蛋白质， 假设作为独特分子制动器或离合器来控制高扭矩极鞭毛的输出 运动和调节最佳运动速度在不同的粘度。这些目标的实现将为 深入了解许多细菌病原体：1）T3SS如何改变并确保提供能量以增强分泌 活性和细胞器组装; 2）极性鞭毛马达如何自然地被赋予产生高扭矩 推进; 3）极性鞭毛马达的新子结构如何形成;以及4）运动速度如何 由高扭矩极性鞭毛马达促进的高粘度可在具有不同粘度的环境中调节。

Project Summary Bacterial flagella function as two machines: a type III secretion system (T3SS) that secretes most of the extracytoplasmic components of the flagellum and a reversible rotary motor that promotes swimming motility required for many bacteria pathogens to infect hosts to promote disease. Peritrichous flagellates such as E. coli and Salmonella species have served as models to understand various processes for flagellar biogenesis and function. However, many significant bacterial pathogens, including Campylobacter jejuni, Vibrio cholerae, Helicobacter pylori, and Pseudomonas aeruginosa are polar flagellates that produce flagellar motors in limited numbers only at polar regions. These polar flagellar motors are characteristically more structurally complex than their peritrichous counterparts. By using C. jejuni as a model system to understand polar flagellar motor biogenesis and function in bacterial pathogens, we found that the increased structural complexity in polar flagellar motors is due to both unique structures and conserved substructures formed by a different collection of proteins. Importantly, these structural alterations enhance mechanical functions of both the C. jejuni flagellar T3SS and the rotary motor. We discovered that the C. jejuni flagellar T3SS has an enhanced ability to secrete flagellar proteins and assemble flagella even when lacking components usually essential for other T3SSs to function. Furthermore, we discovered the structural alterations in the C. jejuni flagellum contribute to a common feature of polar flagellar motors of many pathogens – the generation of higher torque for high motility velocities in a range of physiological viscosities. We also identified C. jejuni flagellar T3SS and motor components that promote its ability to multitask in cellular activities beyond motility. The major goal of this proposal is to analyze how these specific structures and substructures form and adapt the C. jejuni flagellum with enhanced mechanics to augment its function as a secretory machine and rotary motor. In Aim 1, we will analyze the composition and arrangement of proteins forming the C. jejuni flagellar T3SS and determine how fueling mechanics are altered relative to other T3SSs to allow it to secrete proteins and assemble flagella even without usually essential parts. In Aim 2, we will analyze how novel disk structures form and how the rotor component of the motor has expanded to affect the number and placement of stator units required to generate high torque for flagellar rotation and a high velocity of motility. In Aim 3, we will explore two C. jejuni proteins that we hypothesize function as a unique molecular brake or clutch to control output of a high-torque polar flagellar motor and regulate optimal motility velocities in different viscosities. Completion of these aims will provide new insights into many bacterial pathogens for: 1) how T3SSs can alter and ensure fueling to enhance secretory activity and organelle assembly; 2) how polar flagellar motors are naturally endowed to generate high torque for propulsion; 3) how novel substructures of polar flagellar motors form; and 4) how motility velocities facilitated by high-torque polar flagellar motors can be modulated in environments with different viscosities.