Study on the Vibro flagellar motor as the mechanosensor

某些海洋弧菌在海水中游动，由极地鞭毛推动，并利用许多侧鞭毛在海面上群集。极性鞭毛马达和横向鞭毛马达分别由钠动力和质子动力驱动。侧鞭毛是在高粘度的介质中产生的，相关的粘度传感器是极性鞭毛。细胞可以监测鞭毛马达的旋转速率或施加在鞭毛上的机械力。为了测试这些可能性，我们研究了amiloride及其衍生物对副溶血性弧菌侧鞭毛基因（laf）表达的影响，这些衍生物抑制了钠驱动马达的旋转。非那米是一种抑制微摩尔浓度游泳的阿米洛利类似物，在没有黏稠剂的介质中以剂量依赖的方式诱导laf转录。在不同浓度的苯胺存在下，平均游泳速度与lafinduction之间的关系与粘度变化时观察到的关系非常相似。这些结果表明，海洋弧菌感觉极性鞭毛马达的旋转速率（或钠流入）降低，作为laf感应的触发因素。

Certain marine Vibrio species swim in seawater propelled by a polar flagellum and swarm over surfaces using numerous lateral flagella. The polar and the lateral flagellar motors are powered by sodium-and proton-motive forces, respectively. The lateral flagella are produced in media of high viscosity, and the relevant viscosity sensor is the polar flagellum. The cell might monitor either the rotation rate of the flagellar motor or mechanical force applied against the flagellum. To test these possibilities, we examined the effects of amiloride and its derivatives, which inhibit the rotation of the dodium-driven motor, on lateral flagella gene (laf) expression in Vibrio parahaemolyticus. Phenamil, an amiloride analogue that inhibits swimming at micromolar concentrations, induced laf transcription in media devoid of viscous agents in a dose-dependent manner. The relationship between the average swimming speed and laf induction in the presence of various concentrations of phenamil was very similar to that observed when viscosity was changed. These results indicate that marine Vibrio senses decrease in the rotation rate of (or the sodium influx through) the polar flagellar motor as a trigger for laf induction.