Selection, Mutations and Codon Usage in Bacterial Model

TL;DR

This paper introduces a statistical model of bacterial evolution that links codon usage and tRNA abundance, highlighting the balance between mutation-driven homogenization and natural selection-driven translation efficiency improvements.

Contribution

It develops a thermodynamical framework to describe the asymptotic state of codon bias influenced by mutation and natural selection in bacteria.

Findings

Natural selection affects codon bias in genes active during rapid growth.

The model explains how mutation and selection shape codon usage patterns.

Analysis of sequences supports the balance between mutation and natural selection.

Abstract

We present a statistical model of bacterial evolution based on the coupling between codon usage and tRNA abundance. Such a model interprets this aspect of the evolutionary process as a balance between the codon homogenization effect due to mutation process and the improvement of the translation phase due to natural selection. We develop a thermodynamical description of the asymptotic state of the model. The analysis of naturally occurring sequences shows that the effect of natural selection on codon bias not only affects genes whose products are largely required at maximal growth rate conditions but also gene products that undergo rapid transient increases.