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 rooted to the cell wall of the bacterium. Recently, it has been shown that the number of engaged torque-generating 'stator ' units in the motor varies depending on the external load the motor experiences , and suggested that mechanosensing in the flagellar motor is driven via a 'catch bond' mechanism in the motor's stator units. Here, we present a method that allows us to measure stator 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. Here, we manipulate the motor to three different speed levels in two different ion-motive force (IMF) conditions. Our results suggest that stator dynamics are affected by the torque that each stator unit experiences, manifested as a function of the energy available to it in the form of IMF and the speed at which the rotor is driven .
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 .
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Our results suggest that stator dynamics are affected by the torque that each stator unit experiences, manifested as a function of the energy available to it
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
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and the speed at which the rotor is driven
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