Understanding Unique Aspects of Motility and Chemotaxis in Borrelia burgdorferi

了解伯氏疏螺旋体的运动性和趋化性的独特方面

• 批准号: 10446214
• 负责人: Chunhao Chris Li
• 金额: $ 48.7万
• 依托单位: VIRGINIA COMMONWEALTH UNIVERSITY
• 依托单位国家: 美国
• 财政年份: 2008
• 资助国家: 美国
• 起止时间: 2008-09-19 至 2027-01-31
• 项目状态: 未结题
• 来源: https://reporter.nih.gov/project-details/10446214
• 关键词: Achievement; Address; Agar; Animal Model; Anterior; Arthropods; Bacillus subtilis; Bacteria; Bacteria sigma factor KatF protein; Basement membrane; Biochemistry; Biology; Borrelia burgdorferi; Cell Shape; Cells; Cellular Morphology; Chemotaxis; Complex; Cryo-electron tomography; Crystallography; Data; Dermis; Disease; Environment; Flagella; Funding; Gel; Genetic; Genome; Geometry; Goals; Hematogenous; Homologous Gene; Human; Immune Evasion; Infection; Interdisciplinary Study; Invaded; Journals; Knowledge; Laboratories; Lead; Leptospirosis; Lyme Disease; Molecular; Molecular Analysis; Motor; Movement; Mus; Order Spirochaetales; Organ; OspC protein; Paper; Pathogenesis; Pathogenicity; Peer Review; Play; Process; Proteins; Publishing; Role; Rotation; Running; Site; Solid; Structure; Surface; Swimming; Syphilis; Systemic infection; Ticks; Tissues; Virulence; Virulence Factors; cell motility; disorder prevention; enzootic; genetic approach; in vivo; insight; interdisciplinary approach; intravital imaging; lyme pathogenesis; mutant; periplasm; protein-histidine kinase; structural biology; success; tick transmission; tissue tropism; transcriptome sequencing; transmission process; vector

SUMMARY Lyme disease bacterium Borrelia burgdorferi (Bb) is highly motile and can traverse complex environments inside mammalian and arthropod hosts during its infectious cycle. The central hypothesis of this application is that the motility and chemotaxis of Bb constitute a distinct paradigm and play a pivotal role in the host-vector cycle as well as in the disease process, including invasion, dissemination, tissue tropism, and immune evasion. During the last two funding cycles, we revealed several unique aspects of Bb motility and chemotaxis; however, their underlying molecular mechanisms and precise roles in the disease process remain largely unknown. Building upon our previous findings, this renewal aims to fill this knowledge gap by addressing three key questions: (1) How does Bb control asymmetrical flagellar rotation? Due to its unique cell shape and geometry, Bb must rotate its bipolar periplasmic flagella (PF) asymmetrically in order to run: the anterior PF rotates counterclockwise, and the posterior PF rotates clockwise. Without asymmetrical rotation, the cells become distorted. This is a hallmark feature of spirochete motility; however, its underlying molecular mechanism remains elusive. Aim 1 seeks to unravel this longstanding conundrum by determining the function and structure of FliG1, a noncanonical flagellar motor switch protein, using an integrative approach of genetics, biochemistry, cryo-electron tomography, and crystallography. (2) Has Bb evolved swarming motility to facilitate its invasiveness and virulence? During the enzootic cycle, on several occasions, Bb swims in highly viscous gel-like environments, such as mammalian dermis tissue and the tick-gut basement membrane, which are reminiscent of the environments in which bacteria swarm, a form of movement that allows bacteria to crawl over solid and semi-solid surfaces. It has been speculated that Bb has evolved swarming motility to empower its invasiveness. Aim 2 plans to delineate the underlying mechanism of swarming motility and its role in the pathogenicity of Bb, using a comprehensive approach of genetics, biochemistry, structural biology, and in vivo animal models along with intravital imaging. (3) Does CheA1 control Bb virulence and, if so, how? Bb has evolved unique chemotaxis to accommodate its distinct motility and enzootic cycle, e.g., its genome encodes multiple chemotaxis proteins such as two CheA histidine kinases (HK): CheA1 and CheA2. A longstanding question is why Bb needs multiple chemotaxis proteins. CheA2, but not CheA1, is essential for Bb chemotaxis. The role of CheA1 remains unknown. Interestingly, we recently found that CheA1 is required for Bb hematogenous dissemination in mice and expression of several key virulence factors of Bb. Building upon these results, Aim 3 proposes to elucidate the role and underlying molecular mechanism of CheA1 in Bb pathogenicity, using a multidisciplinary approach of genetics, biochemistry, RNA-seq, and animal models. Achievement of these aims will lead to a better understanding of Bb motility and chemotaxis as well as their precise roles in the pathogenesis of Lyme disease. Moreover, the fundamental knowledge to be gained is highly impactful and likely to aid understanding of these processes in other pathogenic spirochetes as well.

概括 莱姆病细菌伯氏疏螺旋体 (Bb) 具有高度活动性，可以穿越内部复杂的环境 哺乳动物和节肢动物宿主在其感染周期中。该应用的中心假设是 Bb 的运动性和趋化性构成了独特的范式，并在宿主-载体循环中发挥着关键作用 在疾病过程中，包括侵袭、传播、组织向性和免疫逃避。最后期间 两个资助周期，我们揭示了 Bb 运动性和趋化性的几个独特方面；然而，他们的底层 疾病过程中的分子机制和精确作用仍然很大程度上未知。建立在我们的 与先前的发现相比，本次更新旨在通过解决三个关键问题来填补这一知识空白：(1) Bb 如何 控制不对称鞭毛旋转？由于其独特的细胞形状和几何形状，Bb 必须旋转其双极 周质鞭毛（PF）为了奔跑而不对称：前部 PF 逆时针旋转，后部 PF 逆时针旋转 PF 顺时针旋转。如果没有不对称旋转，细胞就会扭曲。这是一个标志性特征 螺旋体运动；然而，其潜在的分子机制仍然难以捉摸。目标 1 试图解决这个问题 通过确定 FliG1（一种非规范鞭毛运动开关）的功能和结构，解决了长期存在的难题 蛋白质，采用遗传学、生物化学、冷冻电子断层扫描和晶体学的综合方法。 (2) Bb 是否进化出集群运动以促进其侵袭性和毒力？在地方性动物流行周期中， 有几次，Bb 在高粘性凝胶状环境中游泳，例如哺乳动物真皮组织和皮肤组织。 蜱虫肠道基底膜，让人想起细菌聚集的环境，细菌聚集的环境 允许细菌在固体和半固体表面爬行的运动。据推测，Bb 进化出集群运动能力以增强其侵略性。目标 2 计划描绘潜在机制 采用遗传学、生物化学、 结构生物学、体内动物模型以及活体成像。 (3) CheA1是否控制Bb毒力 如果是这样，怎么办？ Bb 已进化出独特的趋化性，以适应其独特的运动性和地方性循环，例如， 其基因组编码多种趋化蛋白，例如两种 CheA 组氨酸激酶 (HK)：CheA1 和 CheA2。一个 长期存在的问题是为什么 Bb 需要多种趋化蛋白。 CheA2 对 Bb 至关重要，但 CheA1 则不然 趋化性。 CheA1 的作用仍不清楚。有趣的是，我们最近发现 CheA1 是 Bb 所必需的 Bb 在小鼠体内的血行传播和几个关键毒力因子的表达。在此基础上 结果，目标 3 提出阐明 CheA1 在 Bb 致病性中的作用和潜在分子机制， 使用遗传学、生物化学、RNA-seq 和动物模型的多学科方法。取得这些成果 目标将有助于更好地了解 Bb 运动性和趋化性以及它们在 莱姆病的发病机制。此外，要获得的基础知识具有很强的影响力并且可能 也有助于理解其他致病性螺旋体的这些过程。