Bacterial Flagellar Rotation

细菌鞭毛的基部由一个旋转马达驱动 包括嵌入细胞壁中的杆和一组环， 细胞质膜 旋转所需的能量是由 电化学质子梯度 马达交替地顺时针旋转 逆时针方向，偏置取决于感觉转导， 例如，细胞对化学刺激的反应（趋化性）。 对该系统的生物化学和生理学的研究正在进行中 大肠杆菌和能动的链球菌E.大肠杆菌中， 因为它的发动机结构可以被遗传性地扰乱。 链球菌正在被使用，因为它的马达可以被激励， 人为地 已经进行了测量，无论是游泳细胞， 或者细胞通过鞭毛或质子动力固定在玻璃上， 质子通量扭矩和速度 瘫痪的变种人已经被修复， 合成由质粒上携带的基因编码的野生型蛋白。 这项工作导致了一个模型的电机符合现有的 实验数据正在接受进一步的测试。 目的是了解鞭毛在分子水平上的旋转， 生物如何利用化学能 机械工作。

A bacterial flagellum is driven at its base by a rotary motor comprising a rod and set of rings embedded in the cell wall and cytoplasmic membrane. The energy for rotation is supplied by an electrochemical proton gradient. The motor spins alternately clockwise and counterclockwise, with a bias depending on sensory transduction, for example, on the cell's response to chemical stimuli (chemotaxis). Studies of the biochemistry and physiology of this system are being made with Escherichia coli and a motile streptococcus. E. coli is being used, because the structure of its motors can be perturbed genetically. Streptococcus is being used, because its motors can be energized artificially. Measurements have been made, either with swimming cells or with cells tethered to glass by a flagellum, or protonmotive force, proton flux, torque and speed. Paralyzed mutants have been repaired by synthesis of wild-type protein encoded by genes carried on plasmids. This work had led to a model for the motor consistent with existing experimental data that is being subjected to further test. The goal is an understanding of flagellar rotation at the molecular level, or more broadly, of how living things use chemical energy to do mechanical work.