RAPID ROTATION OF FLAGELLAR BUNDLES IN SWIMMING BACTERIA
RAPID ROTATION OF FLAGELLAR BUNDLES IN SWIMMING BACTERIA
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DOI：
10.1038/325637a0
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发表时间：
1987-02-12
期刊：
影响因子：
64.8
通讯作者：
BERG, HC
中科院分区：
文献类型：
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作者：
LOWE, G;MEISTER, M;BERG, HC
细菌鞭毛由可逆旋转马达1 -3驱动。功率输入由质子动力和质子通量决定，功率输出由转矩和速度决定：这些参数之间的相互关系为电动机机制提供了重要线索。在这里，我们描述在恒定质子动力下的转矩和速度之间的关系。这些测量类似于将电动机插入恒压插座，改变外部负载，并确定在不同速度下传递的扭矩。我们使用的motileStreptococcus代谢细胞的悬浮液，通过改变介质的粘度来改变外部负荷，确定电机速度从细胞体的振动频率，并推断电机转矩从身体旋转的速率。鞭毛束的旋转速度比以前设想的要快，其速率随温度线性增加。鞭毛马达传递的扭矩随速度线性下降。在高速下，与一个质子的转移相关的扭矩产生循环似乎以一系列小步耗散自由能。
A bacterial flagellum is driven by a reversible rotary motor1–3. The power input is determined by protonmotive force and proton flux, the power output by torque and speed: interrelationships between these parameters provide important clues to motor mechanisms. Here we describe the relationship between torque and speed at constant protonmotive force. The measurements are analogous to those that could be made by plugging an electric motor into a constant-voltage outlet, varying the external load, and determining the torque delivered at different speeds. We used suspensions of metabolizing cells of a motileStreptococcus, varied the external load by changing the viscosity of the medium, determined motor speed from the frequency of vibration of the cell body, and inferred motor torque from the rate of body rotation. The flagellar bundles rotate more rapidly than formerly supposed, at rates that increase linearly with temperature. The torque delivered by the flagellar motor drops linearly with speed. At high speed, the torque-generating cycle associated with the transfer of one proton appears to dissipate free energy in a series of small steps.