On Type-4 Pilus Genetics and the Motor ATPase PilB

被称为菌毛的蛋白丝从细菌细胞中伸出并延伸到细胞外。菌毛的一端固定在细菌上，另一端可以自由地附着在有生命或无生命的表面上。这种附着物对于细菌在环境中的生存和增殖是重要的，它们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和物理化学性质。一种类型的细菌菌毛，即4型菌毛，一旦其远端附着在固体表面上的合适粘附点上，就能够在其基部收缩。许多细菌利用4型菌毛收缩作为动力来移动自己，到达新的资源并在新的表面上定居。本研究将研究4型毛状马达，包括其将化学能转化为机械能的分子机制，并可为纳米级马达的设计提供新的原理。该项目将为研究生和本科生（包括科学领域代表性不足的群体成员）提供生物学、物理学和工程学交叉领域的跨学科研究和教育培训。革兰氏阴性菌中可伸缩的4型菌毛是目前已知的最强生物马达，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是一个谜。本项目采用多学科方法研究4型毛囊马达及其马达atp酶PilB。利用黄粘球菌明确定义的突变，研究4型菌毛组装和拆卸的遗传学；PilB的结构将在原子分辨率下确定（通过x射线晶体学）。本项目的完成将阐明T4P伸展和收缩的遗传学，阐明由PilB atp酶催化的4型菌毛组装机制。

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.