Investigating Stator Dynamics of the Escherichia Coli Flagellar Motor

Abstract

The bacterial flagellar motor (BFM) of the Escherichia Coli is an elegant molecular nano-machine that regulates bacterial motility. Powered by the proton-motive force, each motor generates mechanical torque via proton flux through numerous associated stator units that surround the rotor complex. These stator units freely diffuse in the cytoplasmic membrane and temporally engage with the BFM to rotate helical flagellar filaments and propel the bacterium to favorable environments. However, a fundamental understanding of stator dynamics of the BFM is still needed. We are employing a tweezer set-up that is capable of applying external torque to individual tethered E. Coli cells and therefore allows us to investigate mechanisms of the BFM. By adjusting the external load torque on the motor, we can physically control motor rotation, such as inducing forward rotation, backward rotation, and moments of stall to observe the behavior of the BFM with a temporal resolution of a few milliseconds. These results will further elucidate the dynamic role of stators in the BFM and in bacterial motility.