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Limiting (zero-load) speed of the rotary motor of Escherichia coli is independent of the number of torque-generating units.

ABSTRACT: Rotation of the bacterial flagellar motor is driven by multiple torque-generating units (stator elements). The torque-generating dynamics can be understood in terms of the "duty ratio" of the stator elements, that is, the fraction of time a stator element engages with the rotor during its mechanochemical cycle. The dependence of the limiting speed (zero-load speed) of the motor on the number of stator elements is the determining test of the duty ratio, which has been controversial experimentally and theoretically over the past decade. Here, we developed a method combining laser dark-field microscopy and optical trapping to resolve this controversy. We found that the zero-load speed is independent of the number of stator elements for the bacterial flagellar motor in Escherichia coli, demonstrating that these elements have a duty ratio close to 1.

SUBMITTER: Wang B

PROVIDER: S-EPMC5703321 | biostudies-other | 2017 Nov

REPOSITORIES: biostudies-other

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Limiting (zero-load) speed of the rotary motor of <i>Escherichia coli</i> is independent of the number of torque-generating units.

Wang Bin B Zhang Rongjing R Yuan Junhua J

Proceedings of the National Academy of Sciences of the United States of America 20171106 47

Rotation of the bacterial flagellar motor is driven by multiple torque-generating units (stator elements). The torque-generating dynamics can be understood in terms of the "duty ratio" of the stator elements, that is, the fraction of time a stator element engages with the rotor during its mechanochemical cycle. The dependence of the limiting speed (zero-load speed) of the motor on the number of stator elements is the determining test of the duty ratio, which has been controversial experimentally ...[more]

PMID: 29109285

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