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Published on: August 18, 2023
The rate of adaptive evolution in enteric bacteria
Jane Charlesworth1, Adam Eyre-Walker
1Centre for Study of Evolution, School of Life Sciences, University of Sussex, Brighton, United Kingdom.
Molecular Biology and Evolution
|April 20, 2006
Summary
More than half of amino acid substitutions between Escherichia coli and Salmonella enterica are due to positive selection. Adaptive substitution rates are not linked to gene function but may correlate with codon usage bias.
Area of Science:
- Evolutionary biology
- Genomics
- Molecular evolution
Background:
- Understanding the evolutionary forces driving genetic change is crucial for deciphering species divergence.
- Adaptive substitutions, driven by positive selection, play a key role in shaping protein evolution and organismal adaptation.
Purpose of the Study:
- To estimate the rate of adaptive substitution in genes shared between Escherichia coli and Salmonella enterica.
- To investigate the relationship between adaptive substitution rates, gene function, and codon usage bias.
Main Methods:
- Comparative genomic analysis of 410 orthologous genes from 6 Escherichia coli and 6 Salmonella enterica genomes.
- Estimation of amino acid substitution rates and identification of positively selected sites.
- Analysis of correlations between the proportion of adaptive substitutions and gene function or synonymous codon usage bias.
Main Results:
- Over 50% of amino acid substitutions between E. coli and S. enterica lineages are estimated to be adaptive.
- The proportion of adaptive substitutions shows no correlation with the overall rate of amino acid substitution or gene function.
- A potential correlation exists between the proportion of adaptive substitutions and synonymous codon usage bias.
Conclusions:
- Positive selection is a major driver of protein evolution in the divergence of E. coli and S. enterica.
- Synonymous codon usage bias may be linked to the prevalence of adaptive amino acid changes.
- These findings contribute to understanding the mechanisms of bacterial adaptation and genome evolution.
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