Load-dependent assembly of the bacterial flagellar motor.
Load-dependent assembly of the bacterial flagellar motor.
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DOI：
10.1128/mbio.00551-13
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发表时间：
2013-08-20
期刊：
影响因子：
6.4
通讯作者：
Armitage JP
中科院分区：
文献类型：
--
作者：
Tipping MJ;Delalez NJ;Lim R;Berry RM;Armitage JP
越来越清楚的是，细菌鞭毛马达的输出不仅对细菌的运动很重要，而且对介导从液体到表面生命的转变也是重要的。鞭毛马达的输出会随着外部环境施加在它身上的机械负载而变化：负载越高，马达运行越慢，产生的扭矩就越大。在这里，我们表明，连接到鞭毛电机的扭矩产生单元的数量也取决于外部机械负载，在较低负载时定子较少。停滞电机包含的定子数量至少与旋转电机在高负载下的数量相同，这表明定子捆绑不需要旋转。无法在电机周围检测到无法产生扭矩的突变定子。我们推测，细菌鞭毛马达的一个组件感知外部负载，并调节定子与马达其余部分的结合强度。在许多细菌的生命周期中，液体生命和表面生命之间的过渡是重要的。在这篇文章中，我们描述了鞭毛马达，细菌用来在液体介质和固体表面上移动，如何能够调整结合的定子单元的数量，以更好地适应外部负载条件。通过使用外部磁场使电机失速，我们还表明，维护电机周围的定子不需要旋转；相反，扭矩产生是电机稳定性的关键因素。这些新的结果，加上以前的数据，让我们假设电机定子的功能既是机械传感器，也是扭矩产生单元。
It is becoming clear that the bacterial flagellar motor output is important not only for bacterial locomotion but also for mediating the transition from liquid to surface living. The output of the flagellar motor changes with the mechanical load placed on it by the external environment: at a higher load, the motor runs more slowly and produces higher torque. Here we show that the number of torque-generating units bound to the flagellar motor also depends on the external mechanical load, with fewer stators at lower loads. Stalled motors contained at least as many stators as rotating motors at high load, indicating that rotation is unnecessary for stator binding. Mutant stators incapable of generating torque could not be detected around the motor. We speculate that a component of the bacterial flagellar motor senses external load and mediates the strength of stator binding to the rest of the motor. The transition between liquid living and surface living is important in the life cycles of many bacteria. In this paper, we describe how the flagellar motor, used by bacteria for locomotion through liquid media and across solid surfaces, is capable of adjusting the number of bound stator units to better suit the external load conditions. By stalling motors using external magnetic fields, we also show that rotation is not required for maintenance of stators around the motor; instead, torque production is the essential factor for motor stability. These new results, in addition to previous data, lead us to hypothesize that the motor stators function as mechanosensors as well as functioning as torque-generating units.