Motility is important for the survival and dispersal of many bacteria, and it often plays a role during infections. Regulation of bacterial motility by chemical stimuli is well studied, but recent work has added a new dimension to the problem of motility control. The bidirectional flagellar motor of the bacterium Escherichia coli recruits or releases torque-generating units (stator units) in response to changes in load. Here, we show that this mechanosensitive remodeling of the flagellar motor is independent of direction of rotation. Remodeling rate constants in clockwise rotating motors and in counterclockwise rotating motors, measured previously, fall on the same curve if plotted against torque. Increased torque decreases the off rate of stator units from the motor, thereby increasing the number of active stator units at steady state. A simple mathematical model based on observed dynamics provides quantitative insight into the underlying molecular interactions. The torque-dependent remodeling mechanism represents a robust strategy to quickly regulate output (torque) in response to changes in demand (load).

运动性对于许多细菌的生存和传播很重要，并且通常在感染过程中发挥作用。通过化学刺激对细菌运动的调节进行了很好的研究，但是最近的工作为运动控制的问题增加了新的维度。大肠杆菌的双向鞭毛马达响应于负载的变化，募集或释放扭矩产生单元（定子单元）。在这里，我们表明鞭毛马达的这种机械敏感性重塑与旋转方向无关。如果相对于转矩作图，则先前测量的顺时针旋转电动机和逆时针旋转电动机的重塑速率常数落在同一条曲线上。增大的转矩会降低定子单元从电动机的断开率，从而增加稳态下活动定子单元的数量。基于观察到的动力学的简单数学模型可提供对潜在分子相互作用的定量了解。依赖于扭矩的重塑机制代表了一种鲁棒的策略，可以根据需求（负载）的变化快速调节输出（扭矩）。