On Type-4 Pilus Genetics and the Motor ATPase PilB

被称为菌毛的蛋白质细丝从细菌细胞伸出并延伸到细菌细胞之外。菌毛的一端固定在细菌上，另一端自由附着在有生命或无生命的表面上。这种附着对细菌在环境中的生存和繁殖非常重要，在这种环境中，细菌经常形成微生物组合或生物膜。细菌生物膜的存在和生物活性极大地(以有利或有害的方式)改变了其周围环境的生物以及物理和化学性质。细菌菌毛的一种类型是4型菌毛，一旦其远端连接到固体表面上合适的粘附点，它就能够在其底部收缩。许多细菌使用4型菌毛回缩作为自己移动的马达，以达到新的资源并在新的表面定居。这项研究将研究4型毛细电机，包括它将化学能转化为机械功的分子机制，并可能导致新的纳米级电机的设计原则。该项目将在生物学、物理学和工程学的交叉点为研究生和本科生提供跨学科研究和教育培训(包括在科学方面代表性不足的群体成员)。革兰氏阴性细菌中可伸缩的4型菌毛是目前已知的最强大的生物马达，能够产生150皮牛顿的失速力。然而，4型菌毛的内部工作原理在很大程度上仍然是一个谜。本项目采用多学科方法对4型毛毛电机及其电机ATPase PilB进行研究。将使用黄色粘球菌中明确定义的突变来研究4型菌毛组装和拆解的遗传学；将在原子分辨率下确定PilB的结构(通过X射线结晶学)。该项目的完成将阐明T4P延伸和收缩的遗传学，并阐明PilB ATPase催化的4型菌毛组装的机制。

The protein filament known as a pilus protrudes from and extends beyond a bacterial cell. One end of the pilus is anchored to the bacterium and the other end is free to attach to living or inanimate surfaces. Such attachments are important for the survival and proliferation of bacteria in the environment where they frequently form microbial assemblages or biofilms. The presence and the biological activities of bacterial biofilms drastically alter (in advantageous or deleterious ways) the biological as well as the physical and chemical properties of their surroundings. One type of bacterial pilus, the type-4 pilus, is able to retract at its base once its distal end is attached to a suitable adhesion point on a solid surface. Many bacteria use type-4 pilus retraction as a motor to move themselves and to reach new resources and colonize new surfaces. This research will investigate the type-4 pilus motor including the molecular mechanisms of its conversion of chemical energy to mechanical work and can lead to new design principles for nanoscale motors. This project will provide interdisciplinary research and educational training at the intersection of biology, physics, and engineering to students (including members of groups underrepresented in science) at both the graduate and undergraduate levels. The retractable type-4 pilus in gram-negative bacteria is the strongest biological motor currently known, capable of generating a stall force of 150 piconewtons. Yet the inner workings of the type-4 pilus remain largely an enigma. This project employs a multidisciplinary approach to study the type-4 pilus motor and its motor ATPase PilB. The genetics of type-4 pilus assembly and disassembly will be investigated using well-defined mutations in Myxococcus xanthus; the structure of PilB will be determined (by X-ray crystallography) at an atomic resolution. Completion of this project will clarify the genetics of T4P extension and retraction and elucidate the mechanism of type-4 pilus assembly catalyzed by the PilB ATPase.