Sowa Yoshiyuki, Hotta Hiroyuki, Homma Michio, Ishijima Akihiko
Department of Biophysical Engineering, Osaka University, 1-3, Machikaneyama, Toyonaka, 560-8531, Osaka, Japan.
J Mol Biol. 2003 Apr 11;327(5):1043-51. doi: 10.1016/s0022-2836(03)00176-1.
The torque-speed relationship of the Na(+)-driven flagellar motor of Vibrio alginolyticus was investigated. The rotation rate of the motor was measured by following the position of a bead, attached to a flagellar filament, using optical nanometry. In the presence of 50mM NaCl, the generated torque was relatively constant ( approximately 3800pNnm) at lower speeds (speeds up to approximately 300Hz) and then decreased steeply, similar to the H(+)-driven flagellar motor of Escherichia coli. When the external NaCl concentration was varied, the generated torque of the flagellar motor was changed over a wide range of speeds. This result could be reproduced using a simple kinetic model, which takes into consideration the association and dissociation of Na(+) onto the motor. These results imply that for a complete understanding of the mechanism of flagellar rotation it is essential to consider both the electrochemical gradient and the absolute concentration of the coupling ion.
研究了溶藻弧菌钠驱动鞭毛马达的扭矩-速度关系。通过使用光学纳米测量法跟踪附着在鞭毛丝上的珠子的位置来测量马达的转速。在存在50mM氯化钠的情况下，在较低速度（高达约300Hz的速度）下产生的扭矩相对恒定（约3800pNnm），然后急剧下降，这与大肠杆菌的氢驱动鞭毛马达相似。当外部氯化钠浓度变化时，鞭毛马达产生的扭矩在很宽的速度范围内发生变化。使用一个简单的动力学模型可以重现这一结果，该模型考虑了钠与马达的结合和解离。这些结果表明，为了全面理解鞭毛旋转的机制，必须同时考虑电化学梯度和耦合离子的绝对浓度。
