Modeling torque versus speed, shot noise, and rotational diffusion of the bacterial flagellar motor.
We present a minimal physical model for the flagellar motor that enables bacteria to swim. Our model explains the experimentally measured torque-speed relationship of the proton-driven E. coli motor at various pH and temperature conditions. In particular, the dramatic drop of torque at high rotation speeds (the "knee") is shown to arise from saturation of the proton flux. Moreover, we show that shot noise in the proton current dominates the diffusion of motor rotation at low loads. This suggests a new way to probe the discreteness of the energy source, analogous to measurements of charge quantization in superconducting tunnel junctions.
Mora
Thierry
T
Lewis-Sigler Institute for Integrative Genomics, Princeton University, Princeton, New Jersey, USA.
Yu
Howard
H
Wingreen
Ned S
NS
D004058:Diffusion; D004926:Escherichia coli / Q000378:metabolism*; D029968:Escherichia coli Proteins / Q000378:metabolism*; D005407:Flagella / Q000378:metabolism*; D008954:Models, Biological; D020409:Molecular Motor Proteins / Q000378:metabolism*; D012399:Rotation; D019415:Torque
D029968:Escherichia coli Proteins; D020409:Molecular Motor Proteins