title: Flagellar Motor Switching in Caulobacter Crescentus Obeys First Passage Time Statistics.
abstract: A Caulobacter crescentus swarmer cell is propelled by a helical flagellum, which is rotated by a motor at its base. The motor alternates between rotating in clockwise and counterclockwise directions and spends variable intervals of time in each state. We measure the distributions of these intervals for cells either free swimming or tethered to a glass slide. A peak time of around one second is observed in the distributions for both motor directions with counterclockwise intervals more sharply peaked and clockwise intervals displaying a larger tail at long times. We show that distributions of rotation intervals fit first passage time statistics for a biased random walker and the dynamic binding of CheY-P to FliM motor subunits accounts for this behavior. Our results also suggest that the presence of multiple CheY proteins in C. crescentus may be responsible for differences between its switching behavior and that of the extensively studied E. coli.
authors.affiliation: Physics Department, Brown University, Providence, Rhode Island 02912, USA.
authors.forename: Michael
authors.initials: M
authors.lastname: Morse
authors.affiliation: Physics Department, Brown University, Providence, Rhode Island 02912, USA.
authors.forename: Jordan
authors.initials: J
authors.lastname: Bell
authors.affiliation: Physics Department, Brown University, Providence, Rhode Island 02912, USA.
authors.forename: Guanglai
authors.initials: G
authors.lastname: Li
authors.affiliation: Physics Department, Brown University, Providence, Rhode Island 02912, USA.
authors.forename: Jay X
authors.initials: JX
authors.lastname: Tang
mesh_terms: D001426:Bacterial Proteins / Q000502:physiology; D016935:Caulobacter crescentus / Q000502:physiology*; D029968:Escherichia coli Proteins; D005407:Flagella / Q000502:physiology*; D008565:Membrane Proteins / Q000502:physiology; D000072236:Methyl-Accepting Chemotaxis Proteins; D008954:Models, Biological; D015233:Models, Statistical; D020409:Molecular Motor Proteins / Q000502:physiology
chemical_list: D001426:Bacterial Proteins; D029968:Escherichia coli Proteins; D008565:Membrane Proteins; D000072236:Methyl-Accepting Chemotaxis Proteins; D020409:Molecular Motor Proteins; C000607606:cheY protein, E coli