Apparent Selection Pressure for Dynamic Range and Channel Capacity in Bacterial Chemotactic Sensors

TL;DR

This study investigates how bacterial chemotactic sensors optimize information transmission and dynamic range, revealing that E. coli receptor clusters are likely selected for their capacity to sample diverse chemical concentrations.

Contribution

It provides a comprehensive analysis of sensing limits in E. coli chemotactic receptors using a heterogeneous MWC model, highlighting selection for channel capacity and dynamic range.

Findings

Maxima of channel capacity and dynamic range observed across parameter regimes.

Bimodal input distribution maximizes information sampling.

Channel capacity and dynamic range may be evolutionarily selected in E. coli.

Abstract

Bacterial chemotactic sensing converts noisy chemical signals into running and tumbling. We analyze the static sensing limits of mixed Tar/Tsr chemoreceptor clusters in individual Escherichia coli cells using a heterogeneous Monod-Wyman-Changeux (MWC) model. By sweeping a seven-dimensional parameter space, we compute three sensing performance metrics-channel capacity, dynamic range, and effective Hill coefficient. Across E. coli-like parameter regimes, we consistently observe pronounced global maxima of channel capacity and global maxima of the related dynamic range, whereas the effective Hill coefficient does not exhibit comparable optimization. The capacity-achieving input distribution is bimodal, which implies that individual cells maximize information by sampling both low- and high-concentration regimes. Together, these results suggest that, at the individual-cell level, channel capacity and dynamic range may be selected for in E. coli receptor clusters.