Nakamura Shuichi, Minamino Tohru
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. 2024 Nov 22;14(12):1488. doi: 10.3390/biom14121488.
Many bacteria swim in liquids and move over solid surfaces by rotating flagella. The bacterial flagellum is a supramolecular protein complex that is composed of about 30 different flagellar proteins ranging from a few to tens of thousands. Despite structural and functional diversities of the flagella among motile bacteria, the flagellum commonly consists of a membrane-embedded rotary motor fueled by an ion motive force across the cytoplasmic membrane, a universal joint, and a helical propeller that extends several micrometers beyond the cell surface. The flagellar motor consists of a rotor and several stator units, each of which acts as a transmembrane ion channel complex that converts the ion flux through the channel into the mechanical work required for force generation. The rotor ring complex is equipped with a reversible gear that is regulated by chemotactic signal transduction pathways. As a result, bacteria can move to more desirable locations in response to environmental changes. Recent high-resolution structural analyses of flagella using cryo-electron microscopy have provided deep insights into the assembly, rotation, and directional switching mechanisms of the flagellar motor complex. In this review article, we describe the current understanding of the structure and dynamics of the bacterial flagellum.
许多细菌通过旋转鞭毛在液体中游泳并在固体表面移动。细菌鞭毛是一种超分子蛋白质复合体，由大约30种不同的鞭毛蛋白组成，数量从几个到数万不等。尽管运动细菌的鞭毛在结构和功能上存在差异，但鞭毛通常由一个由跨细胞质膜的离子动力驱动的膜嵌入旋转马达、一个万向节和一个延伸到细胞表面几微米之外的螺旋推进器组成。鞭毛马达由一个转子和几个定子单元组成，每个定子单元都作为一个跨膜离子通道复合体，将通过通道的离子通量转化为产生力所需的机械功。转子环复合体配备有一个由趋化信号转导途径调节的可逆齿轮。因此，细菌可以根据环境变化移动到更适宜的位置。最近使用冷冻电子显微镜对鞭毛进行的高分辨率结构分析，为鞭毛马达复合体的组装、旋转和方向切换机制提供了深入见解。在这篇综述文章中，我们描述了目前对细菌鞭毛结构和动力学的理解。
