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dc.contributor.authorYuan, Junhua
dc.contributor.authorFahrner, Karen Alicia
dc.contributor.authorTurner, Linda
dc.contributor.authorBerg, Howard
dc.date.accessioned2010-07-30T14:12:31Z
dc.date.issued2010
dc.identifier.citationYuan, Junhua, Karen A. Fahrner, Linda Turner, and Howard C. Berg. 2010. Asymmetry in the clockwise and counter-clockwise rotation of the bacterial flagellar motor. Proceedings of the National Academy of Science 107(29): 12846-12849.en_US
dc.identifier.issn0027-8424en_US
dc.identifier.urihttp://nrs.harvard.edu/urn-3:HUL.InstRepos:4322129
dc.description.abstractCells of Escherichia coli are able to swim up gradients of chemical attractants by modulating the direction of rotation of their flagellar motors, which spin alternately clockwise (CW) and counterclockwise (CCW). Rotation in either direction has been thought to be symmetric and exhibit the same torques and speeds. The relationship between torque and speed is one of the most important measurable characteristics of the motor, used to distinguish specific mechanisms of motor rotation. Previous measurements of the torque–speed relationship have been made with cells lacking the response regulator CheY that spin their motors exclusively CCW. In this case, the torque declines slightly up to an intermediate speed called the “knee speed” after which it falls rapidly to zero. This result is consistent with a “power-stroke” mechanism for torque generation. Here, we measure the torque–speed relationship for cells that express large amounts of CheY and only spin their motors CW. We find that the torque decreases linearly with speed, a result remarkably different from that for CCW rotation. We obtain similar results for wild-type cells by reexamining data collected in previous work. We speculate that CCW rotation might be optimized for runs, with higher speeds increasing the ability of cells to sense spatial gradients, whereas CW rotation might be optimized for tumbles, where the object is to change cell trajectories. But why a linear torque–speed relationship might be optimum for the latter purpose we do not know.en_US
dc.description.sponsorshipMolecular and Cellular Biologyen_US
dc.language.isoen_USen_US
dc.publisherNational Academy of Sciencesen_US
dc.relation.isversionofdoi:10.1073/pnas.1007333107en_US
dash.licenseLAA
dc.subjectmolecular motoren_US
dc.subjectmotilityen_US
dc.subjectnanogolden_US
dc.subjectswitchen_US
dc.titleAsymmetry in the Clockwise and Counter-Clockwise Rotation of the Bacterial Flagellar Motoren_US
dc.typeJournal Articleen_US
dc.description.versionAccepted Manuscripten_US
dc.relation.journalProceedings of the National Academy of Sciences of the United States of Americaen_US
dash.depositing.authorBerg, Howard
dash.waiver2010-06-17
dc.date.available2010-07-30T14:12:31Z
dc.identifier.doi10.1073/pnas.1007333107*
dash.contributor.affiliatedFahrner, Karen
dash.contributor.affiliatedYuan, Junhua
dash.contributor.affiliatedBerg, Howard


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