Minamino Tohru, Kinoshita Miki, Namba Keiichi
Graduate School of Frontier Biosciences, Osaka University, 1-3 Yamadoaka, Suita, Osaka 565-0871, Japan.
RIKEN Center for Biosystems Dynamic Research & Spring-8 Center, 1-3 Yamadaoka, Suita, Osaka 565-0871, Japan.
Comput Struct Biotechnol J. 2019 Jul 31;17:1075-1081. doi: 10.1016/j.csbj.2019.07.020. eCollection 2019.
Bacteria sense temporal changes in extracellular stimuli via sensory signal transducers and move by rotating flagella towards into a favorable environment for their survival. Each flagellum is a supramolecular motility machine consisting of a bi-directional rotary motor, a universal joint and a helical propeller. The signal transducers transmit environmental signals to the flagellar motor through a cytoplasmic chemotactic signaling pathway. The flagellar motor is composed of a rotor and multiple stator units, each of which acts as a transmembrane proton channel to conduct protons and exert force on the rotor. FliG, FliM and FliN form the C ring on the cytoplasmic face of the basal body MS ring made of the transmembrane protein FliF and act as the rotor. The C ring also serves as a switching device that enables the motor to spin in both counterclockwise (CCW) and clockwise (CW) directions. The phosphorylated form of the chemotactic signaling protein CheY binds to FliM and FliN to induce conformational changes of the C ring responsible for switching the direction of flagellar motor rotation from CCW to CW. In this mini-review, we will describe current understanding of the switching mechanism of the bacterial flagellar motor.
细菌通过感官信号转导器感知细胞外刺激的时间变化，并通过旋转鞭毛向有利于其生存的环境移动。每根鞭毛都是一个超分子运动机器，由双向旋转马达、万向节和螺旋推进器组成。信号转导器通过细胞质趋化信号通路将环境信号传递给鞭毛马达。鞭毛马达由一个转子和多个定子单元组成，每个定子单元充当跨膜质子通道，传导质子并对转子施加力。FliG、FliM和FliN在由跨膜蛋白FliF构成的基体MS环的细胞质面上形成C环，并充当转子。C环还作为一个切换装置，使马达能够逆时针（CCW）和顺时针（CW）两个方向旋转。趋化信号蛋白CheY的磷酸化形式与FliM和FliN结合，诱导C环的构象变化，从而负责将鞭毛马达的旋转方向从逆时针切换为顺时针。在这篇小型综述中，我们将描述目前对细菌鞭毛马达切换机制的理解。
