Department of Applied Physics, Graduate School of Engineering, Tohoku University, 6-6-05 Aoba, Aoba-ku, Sendai 980-8579, Japan.
Graduate School of Frontier Biosciences, Osaka University, 1-3 Yamadaoka, Suita, Osaka 565-0871, Japan.
Biomolecules. 2019 Jul 14;9(7):279. doi: 10.3390/biom9070279.
The bacterial flagellum is a helical filamentous organelle responsible for motility. In bacterial species possessing flagella at the cell exterior, the long helical flagellar filament acts as a molecular screw to generate thrust. Meanwhile, the flagella of spirochetes reside within the periplasmic space and not only act as a cytoskeleton to determine the helicity of the cell body, but also rotate or undulate the helical cell body for propulsion. Despite structural diversity of the flagella among bacterial species, flagellated bacteria share a common rotary nanomachine, namely the flagellar motor, which is located at the base of the filament. The flagellar motor is composed of a rotor ring complex and multiple transmembrane stator units and converts the ion flux through an ion channel of each stator unit into the mechanical work required for motor rotation. Intracellular chemotactic signaling pathways regulate the direction of flagella-driven motility in response to changes in the environments, allowing bacteria to migrate towards more desirable environments for their survival. Recent experimental and theoretical studies have been deepening our understanding of the molecular mechanisms of the flagellar motor. In this review article, we describe the current understanding of the structure and dynamics of the bacterial flagellum.
细菌鞭毛是一种负责运动的螺旋丝状细胞器。在具有细胞外鞭毛的细菌物种中，长螺旋鞭毛丝充当分子螺旋，产生推力。同时，螺旋体的鞭毛位于周质空间内，不仅作为细胞骨架决定细胞体的螺旋度，而且还旋转或波动螺旋状细胞体以进行推进。尽管细菌物种之间的鞭毛结构存在多样性，但鞭毛细菌共享一种共同的旋转纳米机器，即鞭毛马达，它位于丝体的底部。鞭毛马达由转子环复合物和多个跨膜定子单元组成，将每个定子单元的离子通道中的离子通量转化为马达旋转所需的机械功。细胞内趋化信号通路调节鞭毛驱动运动的方向，以响应环境的变化，使细菌能够向更有利于其生存的环境迁移。最近的实验和理论研究加深了我们对鞭毛马达分子机制的理解。在这篇综述文章中，我们描述了对细菌鞭毛的结构和动力学的现有理解。
