Effect of switching time scale of receptor activity on chemotactic performance of Escherichia coli

TL;DR

This study investigates how the switching rate of chemoreceptor activity in E. coli influences chemotactic efficiency, revealing that higher switching rates enhance drift velocity up to a saturation point and alter run durations.

Contribution

It provides a detailed numerical analysis of how receptor activity switching time-scale affects chemotactic performance, a novel insight into bacterial navigation mechanisms.

Findings

Drift velocity increases with switching rate and saturates.

Downhill run duration decreases strongly with switching rate.

Uphill run duration decreases slowly with switching rate.

Abstract

In the chemotactic motion of Escherichia coli, the switching of transmembrane chemoreceptors between active and inactive states is one of the most important steps of the signaling pathway. We study the effect of this switching time-scale on the chemotactic performance of the cell. We quantify performance by the chemotactic drift velocity of the cell. Our extensive numerical simulations on a detailed theoretical model show that as the activity switching rate increases, the drift velocity increases and then saturates. Our data also show the mean duration of a downhill run decreases strongly with the switching rate, while that of an uphill run decreases relatively slowly. We explain this effect from temporal variation of activity along uphill and downhill trajectories. We show that for large and small switching rates the nature of activity variation show qualitatively different behaviors along a downhill run but similar behavior along an uphill run. This results in a stronger dependence of downhill run duration on the switching rate and relatively milder dependence for uphill run duration.