An Element of Determinism in a Stochastic Flagellar Motor Switch

Peer reviewed: 
Yes, item is peer reviewed.
Scholarly level: 
Faculty/Staff
Final version published as: 

Xie L, Altindal T, Wu X-L (2015) An Element of Determinism in a Stochastic Flagellar Motor Switch. PLoS ONE 10(11): e0141654. doi:10.1371/journal.pone.0141654

Date created: 
2015
Keywords: 
Swimming
Marine bacteria
Motor proteins
Flagellar rotation
Phenols
Dwell time
Flagella
Cell polarity
Abstract: 

Marine bacterium Vibrio alginolyticus uses a single polar flagellum to navigate in an aqueous environment. Similar to Escherichia coli cells, the polar flagellar motor has two states; when the motor is counter-clockwise, the cell swims forward and when the motor is clockwise, the cell swims backward. V. alginolyticus also incorporates a direction randomization step at the start of the forward swimming interval by flicking its flagellum. To gain an understanding on how the polar flagellar motor switch is regulated, distributions of the forward Δf and backward Δb intervals are investigated herein. We found that the steady-state probability density functions, Pf) and Pb), of freely swimming bacteria are strongly peaked at a finite time, suggesting that the motor switch is not Poissonian. The short-time inhibition is sufficiently strong and long lasting, i.e., several hundred milliseconds for both intervals, which is readily observed and characterized. Treating motor reversal dynamics as a first-passage problem, which results from conformation fluctuations of the motor switch, we calculated Pf) and Pb) and found good agreement with the measurements.

Language: 
English
Document type: 
Article
File(s): 
Sponsor(s): 
National Science Foundation
Andrew Mellon Predoctoral Fellowship, University of Pittsburgh
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