Zhou Xiaotian, Roujeinikova Anna
Infection and Immunity Program, Monash Biomedicine Discovery Institute, Monash University, Clayton, VIC, Australia.
Department of Microbiology, Monash University, Clayton, VIC, Australia.
Front Microbiol. 2021 Mar 11;12:639490. doi: 10.3389/fmicb.2021.639490. eCollection 2021.
In the bacterial flagellar motor, the cell-wall-anchored stator uses an electrochemical gradient across the cytoplasmic membrane to generate a turning force that is applied to the rotor connected to the flagellar filament. Existing theoretical concepts for the stator function are based on the assumption that it anchors around the rotor perimeter by binding to peptidoglycan (P). The existence of another anchoring region on the motor itself has been speculated upon, but is yet to be supported by binding studies. Due to the recent advances in electron cryotomography, evidence has emerged that polar flagellar motors contain substantial proteinaceous periplasmic structures next to the stator, without which the stator does not assemble and the motor does not function. These structures have a morphology of disks, as is the case with spp., or a round cage, as is the case with . It is now recognized that such additional periplasmic components are a common feature of polar flagellar motors, which sustain higher torque and greater swimming speeds compared to peritrichous bacteria such as and . This review summarizes the data available on the structure, composition, and role of the periplasmic scaffold in polar bacterial flagellar motors and discusses the new paradigm for how such motors assemble and function.
在细菌鞭毛马达中，细胞壁锚定的定子利用跨细胞质膜的电化学梯度产生一个转向力，该力施加于与鞭毛丝相连的转子上。现有的关于定子功能的理论概念基于这样的假设，即它通过与肽聚糖（P）结合而围绕转子周边锚定。人们推测马达自身上存在另一个锚定区域，但尚未得到结合研究的支持。由于电子冷冻断层扫描技术的最新进展，有证据表明，极性鞭毛马达在定子旁边含有大量蛋白质性周质结构，没有这些结构，定子就无法组装，马达也无法发挥功能。这些结构具有圆盘形态，如 属的情况，或者是圆形笼状，如 属的情况。现在人们认识到，这种额外的周质成分是极性鞭毛马达的一个共同特征，与诸如 和 等周生鞭毛细菌相比，极性鞭毛马达能维持更高的扭矩和更快的游动速度。本综述总结了关于极性细菌鞭毛马达中周质支架的结构、组成和作用的现有数据，并讨论了此类马达组装和发挥功能的新范式。
