Flagellar Motor Biogenesis in Polarly-Flagellated Bacterial Pathogens

 描述(申请人提供)：鞭毛是天然的旋转马达，促进游泳运动，许多细菌病原体需要在环境中导航，感染宿主促进疾病，并促进生物膜的形成。与大肠杆菌和沙门氏菌等富含细菌的病原体相比，许多重要的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只在细菌细胞的极点产生非常有限的鞭毛马达。此外，与富含周围菌的鞭毛马达相比，这些极地鞭毛马达促进了更高的扭矩和更快的运动速度。因此，必须存在替代范式来解释极鞭毛马达如何在细菌病原体中形成和发挥作用。我们探索了空肠弯曲菌中鞭毛的生物发生，以发现新的范式来研究极化鞭毛细菌如何调控鞭毛基因的转录，空间和数字上调控鞭毛生物发生，以及改变鞭毛运动结构来推动鞭毛旋转的动力。我们还发现了在一系列极化鞭毛病原体中这些机制普遍保守的证据。在这个计划中，我们将继续使用空肠弯曲菌作为一个模式系统来了解鞭毛马达是如何在广泛的有鞭毛的细菌病原体中形成和功能的，鞭毛马达是一个普遍的毒力和定植决定因素。我们的工作还将继续揭示细菌鞭毛如何超越运动影响信号转导途径、细菌细胞的空间组织和空肠弯曲杆菌的细胞分裂。在目标1中，我们将研究多鞭毛病原体保守的鞭毛双组分调节系统(TCS)如何检测鞭毛III型分泌系统(T3SS)的形成及其周围的环结构，以启动鞭毛基因转录所需的信号转导。我们还将利用T3SS形成的自然工程来激活空肠弯曲菌鞭毛TCS，以确定细菌病原体中形成T3SS的蛋白质的分子需求。在目标2中，我们将探索极鞭毛虫保守的FlhG ATPase和可能不寻常的鞭毛C环组成如何共同发挥作用，在数字上调节空肠弯曲杆菌鞭毛的生物发生，并在空间上控制细胞分裂。在目标3中，我们将利用诱变和电子冷冻断层扫描技术来破译鞭毛盘附属物形成的有序生物合成途径，这是鞭毛旋转和创造功能性极鞭毛马达所必需的。这些目标的实现将促进对以下方面的新见解：1)TCS检测和感知启动鞭毛基因表达所需的信号转导的刺激；2)保守的蛋白质在细菌病原体中启动T3SS的形成；3)细菌以数字方式调节极鞭毛电机的生物发生；4)鞭毛蛋白用于交替的生物活动，如信号转导、细胞分裂和细胞的空间组织；5)极鞭毛病原体 利用磁盘附属物使鞭毛结构多样化，并推动鞭毛旋转以产生扭矩，从而产生高运动速度。

 DESCRIPTION (provided by applicant): Flagella are natural rotary motors that promote swimming motility required by many bacterial pathogens to navigate environments, infect hosts to promote disease, and promote biofilm formation. Compared to peritrichous bacterial pathogens such as E. coli and Salmonella species, many significant pathogens including Campylobacter jejuni, Vibrio cholerae, Helicobacter pylori, and Pseudomonas aeruginosa produce only a very limited number of flagellar motors specifically at poles of a bacterial cell. Furthermore, these polar flagellar motors promote higher torque and greater velocity of motility compared to flagellar motors of peritrichous bacteria. Thus, alternative paradigms must exist to account for how polar flagellar motors form and function in bacterial pathogens. We have explored flagellar biogenesis in C. jejuni to discover new paradigms for how polarly-flagellated bacterial pathogens regulate flagellar gene transcription, spatially and numerically regulate flagellar biogenesis, and alter flagellar motor structure to power flagellar rotation for motility.We also found evidence for general conservation of these mechanisms in a range of polarly-flagellated pathogens. In this proposal, we will continue to use C. jejuni as a model system to understand how the flagellar motor, which is a universal virulence and colonization determinant, forms and functions in a wide range of polarly-flagellated bacterial pathogens. Our work will also continue to reveal how the bacterial flagellum functions beyond motility to influence signal transduction pathways, spatial organization of the bacterial cell, and cell division in C. jejuni. n Aim 1, we will examine how conserved flagellar two-component regulatory systems (TCSs) of polarly-flagellated pathogens detect formation of the flagellar type III secretion system (T3SS) and surrounding ring structures to initiate signal transduction required for flagellar gene transcription. We will also exploit the natural engineering of T3SS formation to activation of the C. jejuni flagellar TCS to determine molecular requirements of proteins to form T3SSs in bacterial pathogens. In Aim 2, we will explore how the conserved FlhG ATPase of polar flagellates and a possible unusual flagellar C ring composition function together to numerically regulate flagellar biogenesis and spatially control cell division in C. jejuni. In Aim 3, we will exploit mutagenesis and electron cryotomography technologies to decipher the ordered biosynthetic pathway for formation of flagellar disk appendages, which are required for powering flagellar rotation and creation of a functional polar flagellar motor. Accomplishment of these aims will promote new insights for how: 1) TCSs detect and perceive stimuli for initiation of signal transduction required for flagellar gene expression; 2) conserved proteins initiate T3SS formation in bacterial pathogens; 3) bacteria numerically regulate polar flagellar motor biogenesis; 4) flagellar proteins are used in alternate biological activities such as signal transduction, cell division, and spatial organization of the cell; 5) polarly-flagellated pathogens employ disk appendages to diversify flagellar structure and power flagellar rotation to generate torque resulting in high velocities of motility.