title: The Limiting Speed of the Bacterial Flagellar Motor.
abstract: Recent experiments on the bacterial flagellar motor have shown that the structure of this nanomachine, which drives locomotion in a wide range of bacterial species, is more dynamic than previously believed. Specifically, the number of active torque-generating complexes (stators) was shown to vary across applied loads. This finding brings under scrutiny the experimental evidence reporting that limiting (zero-torque) speed is independent of the number of active stators. In this study, we propose that, contrary to previous assumptions, the maximum speed of the motor increases as additional stators are recruited. This result arises from our assumption that stators disengage from the motor for a significant portion of their mechanochemical cycles at low loads. We show that this assumption is consistent with current experimental evidence in chimeric motors, as well as with the requirement that a processive motor driving a large load via an elastic linkage must have a high duty ratio.
authors: Biophysics Graduate Group, University of California, Berkeley, Berkeley, California. Electronic address: jnirody@berkeley.edu.
authors: Jasmine A
authors: JA
authors: Nirody
authors: Department of Physics, Clarendon Laboratory, University of Oxford, United Kingdom.
authors: Richard M
authors: RM
authors: Berry
authors: Department of Molecular and Cell Biology, University of California, Berkeley, Berkeley, California.
authors: George
authors: G
authors: Oster
mesh_terms: D001426:Bacterial Proteins / Q000378:metabolism*; D005407:Flagella / Q000378:metabolism*; D007700:Kinetics; D008954:Models, Biological; D020409:Molecular Motor Proteins / Q000378:metabolism*
chemical_list: D001426:Bacterial Proteins; D020409:Molecular Motor Proteins