Flagellar Motor Biogenesis in Polarly-Flagellated Bacterial Pathogens

项目摘要 细菌鞭毛起两种作用：一种III型分泌系统(T3SS)，它分泌大部分 鞭毛的胞质外组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。富铁鞭毛虫，如E。 大肠杆菌和沙门氏菌是理解鞭毛生物发生的各种过程的模型 和功能。然而，许多重要的细菌病原体，包括空肠弯曲菌，霍乱弧菌， 幽门螺杆菌和铜绿假单胞菌是极地鞭毛虫，在有限的时间内产生鞭毛马达 数字仅限于极地地区。这些极地鞭毛马达的结构特征更为复杂。 而不是那些富足的同类。以空肠弯曲菌为模型系统来理解极鞭毛运动 在细菌的生物发生和功能方面，我们发现极地结构的复杂性增加 鞭毛马达是由于独特的结构和由不同的集合形成的保守亚结构所致 蛋白质的含量。重要的是，这些结构变化增强了空肠弯曲菌鞭毛的机械功能。 T3SS和旋转电机。我们发现空肠弯曲菌鞭毛T3SS具有增强的分泌能力 鞭毛蛋白和组装鞭毛，即使缺少通常是其他T3SS所必需的成分 功能。此外，我们发现空肠弯曲菌鞭毛的结构变化有助于共同的 许多病原体的极鞭毛马达的特征--为高运动速度产生更大的扭矩 在一定的生理粘度范围内。我们还鉴定了空肠弯曲菌鞭毛T3SS和运动成分 提升其在细胞活动中多任务处理的能力，而不是运动。这项提案的主要目标是分析 这些特定的结构和亚结构如何形成和适应增强的空肠弯曲菌鞭毛 机械以增强其作为分泌机和旋转马达的功能。在目标1中，我们将分析 空肠弯曲菌鞭毛T3SS形成蛋白的组成和排列及其补给方式的确定 与其他T3SS相比，机制发生了改变，使其即使在没有T3SS的情况下也能够分泌蛋白质和组装鞭毛 通常是必不可少的部件。在目标2中，我们将分析新的圆盘结构是如何形成的，以及转子部件是如何形成的 已扩展到影响产生高扭矩所需的定子单元的数量和位置 用于鞭毛的旋转和高速运动。在目标3中，我们将探索两种空肠弯曲菌蛋白质，我们 假想作为一个独特的分子刹车或离合器来控制高扭矩极鞭毛的输出 驱动并调节不同粘度下的最佳运动速度。完成这些目标将提供新的 对许多细菌病原体的洞察：1)T3SS如何改变和确保补充燃料以增强分泌 活动和细胞器组装；2)极性鞭毛马达是如何被赋予产生高扭矩的 用于推进；3)极鞭毛马达的新亚结构是如何形成的；以及4)运动速度如何 由高扭矩极鞭毛马达推动，可以在不同粘度的环境中进行调制。

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.