Load-dependent adaptation near zero load in the bacterial flagellar motor
Load-dependent adaptation near zero load in the bacterial flagellar motor
复制标题
DOI：
10.1098/rsif.2019.0300
复制
发表时间：
2019-10-01
影响因子：
3.9
通讯作者：
Berry, Richard M.
中科院分区：
文献类型：
--
作者：
Nirody, Jasmine A.;Nord, Ashley L.;Berry, Richard M.
细菌鞭毛马达是一种离子驱动的跨膜蛋白复合物，它驱动许多细菌物种的游泳。马达由一个细胞质“转子”环和许多“定子”单元组成，它们与细菌的细胞壁结合。最近，它已被证明，在电机中的功能扭矩产生定子单元的数量取决于外部负载，并建议，在鞭毛电机中的mechanosensing是通过一个'捕捉债券'机制驱动电机的定子单元。我们提出了一种方法，使我们能够在一个单一的电机定子单元动态测量在很大范围的外部负载，包括接近零转矩限制。通过将超顺磁珠附着在鞭毛钩上，我们可以通过旋转磁场控制马达的速度。我们在两种不同的离子动力（IMF）条件下操纵电机到四个不同的速度水平。该框架允许通过分离出影响电机扭矩的电机特性（例如转速和IMF形式的能量可用性）来更深入地探索负载相关重构背后的机制。
The bacterial flagellar motor is an ion-powered transmembrane protein complex which drives swimming in many bacterial species. The motor consists of a cytoplasmic 'rotor' ring and a number of 'stator' units, which are bound to the cell wall of the bacterium. Recently, it has been shown that the number of functional torque-generating stator units in the motor depends on the external load, and suggested that mechanosensing in the flagellar motor is driven via a 'catch bond' mechanism in the motor's stator units. We present a method that allows us to measure-on a single motor-stator unit dynamics across a large range of external loads, including near the zero-torque limit. By attaching superparamagnetic beads to the flagellar hook, we can control the motor's speed via a rotating magnetic field. We manipulate the motor to four different speed levels in two different ion-motive force (IMF) conditions. This framework allows for a deeper exploration into the mechanism behind load-dependent remodelling by separating out motor properties, such as rotation speed and energy availability in the form of IMF, that affect the motor torque.