Investigation of gliding motility in Bacteroidetes

拟杆菌门滑动运动的研究

• 批准号: 2605539
• 金额: --
• 依托单位: University of Oxford
• 依托单位国家: 英国
• 项目类别: Studentship
• 财政年份: 2021
• 资助国家: 英国
• 起止时间: 2021 至 无数据
• 项目状态: 未结题
• 来源: https://gtr.ukri.org/projects?ref=studentship-2605539
• 关键词: Investigation; gliding; motility; Bacteroidetes

Disease-causing bacteria invade and colonise the host organism using protein molecules on their cell surface or secreted into their environment. Specific transport mechanisms are needed to transport these protein molecules from their site of synthesis inside the cell to the cell exterior. These protein transporters are, thus, important pathogenicity factors in bacterial diseases. The Type 9 Secretion System (T9SS) is a recently-discovered bacterial protein export system that is essential for the pathogenesis of Porphyromonas gingivalis and related dental pathogens that cause severe periodontal disease. These bacteria have also been implicated in the etiology of rheumatoid arthritis and alzheimers disease. The evolutionary origin of the T9SS lies in the machinery used by gliding bacteria to move rapidly over solid surfaces. In these bacteria the proto-T9SS exports proteins that bind to the solid surface and then moves these `adhesins' along the cell body on helical tracks located in the outer membrane. It has recently been shown that the T9SS requires an energetic input to extract substrate proteins from the outer membrane transporter. Similarity between T9SS and gliding motility components suggests that this is accomplished using a cut-down version of the gliding track. The mechanism of this crucial step in T9SS transport will be elucidated using the movement of adhesins on tracks in gliding bacteria as our experimental model. Our rationale for using the gliding motility model organism, Flavobacterium johnsoniae, is that the mechanical process of movement on tracks needs to be studied in intact cells. It has previously been shown that the movements of fluorescently-labelled adhesins along the cell body on gliding tracks can be followed by single molecule imaging methods in actively gliding cells. By contrast, the cut-down gliding tracks of the P. gingivalis T9SS are too small for movement on the tracks to be optically resolved for study. The organisation and mechanism of gliding tracks will be probed using in-cell imaging complemented by biochemical, structural, and computational characterisation of track components. The insights obtained from this work will then be used to guide experiments to directly test T9SS function. These studies will substantially increase our understanding of the mechanism of the T9SS.

致病细菌利用其细胞表面的蛋白质分子或分泌到其环境中的蛋白质分子侵入并定殖宿主生物体。需要特定的转运机制将这些蛋白质分子从细胞内的合成位点转运到细胞外。因此，这些蛋白质转运蛋白是细菌性疾病中重要的致病因子。 9型分泌系统（T9SS）是最近发现的细菌蛋白输出系统，其对于引起严重牙周病的牙龈卟啉单胞菌和相关牙科病原体的发病机理是必需的。这些细菌也与类风湿性关节炎和阿尔茨海默病的病因有关。 T9SS的进化起源在于滑行细菌在固体表面上快速移动所使用的机器。在这些细菌中，原T9 SS输出与固体表面结合的蛋白质，然后沿着位于外膜中的螺旋轨道沿着细胞体移动这些“粘附素”。 最近已经表明，T9SS需要能量输入以从外膜转运蛋白提取底物蛋白。T9 SS和滑行运动成分之间的相似性表明，这是使用滑动轨迹的简化版本来实现的。T9SS运输中的这一关键步骤的机制将使用在滑行细菌中的轨道上的粘附素的运动作为我们的实验模型来阐明。 我们使用滑行运动模式生物，黄杆菌johnsoniae的理由是，轨道上的运动的机械过程需要在完整的细胞中进行研究。先前已经表明，荧光标记的粘附素沿着细胞体在滑动轨道上的运动可以通过在主动滑动细胞中的单分子成像方法来跟踪。相比之下，牙龈卟啉单胞菌T9SS的切割滑动轨迹太小，无法在轨迹上运动，从而无法光学分辨以用于研究。滑动轨道的组织和机制将使用细胞内成像，辅以轨道组件的生物化学，结构和计算表征来探索。从这项工作中获得的见解将用于指导实验，直接测试T9SS功能。这些研究将大大增加我们对T9 SS机制的理解。