The nonequilibrium mechanism for ultrasensitivity in a biological switch: sensing by Maxwell's demons.

ABSTRACT: The Escherichia coli flagellar motor senses the intracellular concentration of the response regulator CheY-P and responds by varying the bias between its counterclockwise (CCW) and clockwise (CW) rotational states. The response is ultrasensitive with a large Hill coefficient (approximately 10). Recently, the detailed distribution functions of the CW and the CCW dwell times have been measured for different CW biases. Based on a general result on the properties of the dwell-time statistics for all equilibrium models, we show that the observed dwell-time statistics imply that the flagellar motor switch operates out of equilibrium, with energy dissipation. We propose a dissipative allosteric model that generates dwell-time statistics consistent with the experimental results. Our model reveals

SUBMITTER: Tu Y 

PROVIDER: S-EPMC2575293 | biostudies-literature | 2008 Aug

REPOSITORIES: biostudies-literature