Mechanism of Caulobacter adhesion

描述（由申请人提供）：细菌对表面的粘附在疾病中起着重要作用，为表面的生物污垢和生物膜形成提供了关键的第一步。本研究的总体目标是详细了解细菌粘附的机制，从粘附的生物物理学到参与该过程的细胞表面结构的生物合成的协调。该项目利用了细菌Caulobacter crescentus，其中粘附结构在细胞的同一极以有序的方式合成，使得粘附的研究比大多数细菌更容易进行。粘附的初始阶段涉及鞭毛运动和皮利，并且粘附通过多糖固着物的合成而得以巩固。致病细菌也使用这些粘附结构，但它们在粘附中的作用机制知之甚少。此外，单个柄杆菌属细胞的粘附力是生物粘合剂有史以来测量的最强的。该项目有三个主要目标。第一个目标将使用高度同步的文化耦合到原子力显微镜，荧光显微镜，和生物物理建模，以制定一个详细的了解粘附的各个阶段。特别是，这一目标将调查一个新发现的表面接触依赖性触发的粘附多糖出口，这种机制也可能被病原体使用。第二个目的是确定固着多糖合成和附着蛋白的功能。实验描述，以确定这些蛋白质的生化功能和它们的贡献粘附。第三个目的是阐明控制holdfast合成的时间和极性定位的机制。将确定在细胞周期中组成型表达固着合成蛋白对固着合成和粘附时间的影响。将研究固着合成和附着蛋白的定位及其相互依赖性，并确定其定位所需的因素。细菌粘附、多糖生物合成、蛋白质和毒力因子的亚细胞定位是细菌致病的基本组成部分。从这个简单的模型系统的研究中获得的见解将适用于更复杂的细菌病原体，并将提高我们抑制它们的能力。

DESCRIPTION (provided by applicant): The adhesion of bacteria to surfaces plays an important role in disease, providing the critical first step in the biofouling of a surface and in biofilm formation. The general goal of this research is to reach a detailed understanding of the mechanisms of bacterial adhesion, from the biophysics of adhesion to the coordination of the biosynthesis of cell surface structures that participate in this process. This project takes advantage of the bacterium Caulobacter crescentus, in which adhesive structures are synthesized in an ordered fashion at the same pole of the cell, making the study of adhesion more amenable than in most bacteria. Initial stages of adhesion involve flagellar motility and pili, and adhesion is cemented by synthesis of a polysaccharide holdfast. Pathogenic bacteria also use these adhesive structures, but their mechanism of action in adhesion is poorly understood. In addition, the adhesive force of individual Caulobacter cells is the strongest ever measured for a biological adhesive. This project has three major aims. The first aim will use highly synchronized cultures coupled to atomic force microscopy, fluorescence microscopy, and biophysical modeling to develop a detailed understanding of the various stages of adhesion. In particular, this aim will investigate a newly discovered surface contact-dependent trigger of adhesive polysaccharide export; this mechanism may also be used by pathogens. The second aim is to determine the function of holdfast polysaccharide synthesis and attachment proteins. Experiments are described to determine the biochemical function of these proteins and their contribution to adhesion. The third aim is to elucidate the mechanisms that control the timing and polar localization of holdfast synthesis. The effect of constitutively expressing holdfast synthesis proteins during the cell cycle on the timing of holdfast synthesis and adhesion will be determined. The localization of holdfast synthesis and attachment proteins and their interdependence for localization will be studied, and factors required for their localization will be identified. Bacterial adhesion, polysaccharide biosynthesis, and subcellular localization of proteins and virulence factors are essential components of bacterial pathogenesis. Insight gained from the study of this simple model system will be applicable to more complex bacterial pathogens and will enhance our ability to inhibit them.