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Synonymous Substitution Rates in Enterobacteria

journal contribution
posted on 2023-06-08, 00:42 authored by Adam Eyre-WalkerAdam Eyre-Walker, M Bulmer
It has been shown previously that the synonymous substitution rate between Escherichia coli and Salmonella typhimurium is lower in highly than in weakly expressed genes, and it has been suggested that this is due to stronger selection for translational efficiency in highly expressed genes as reflected in their greater codon usage bias. This hypothesis is tested here by comparing the substitution rate in codon families with different patterns of synonymous codon use. It is shown that the decline in the substitution rate across expression levels is as great for codon families that do not appear to be subject to selection for translational efficiency as for those that are. This implies that selection on translational efficiency is not responsible for the decline in the substitution rate across genes. It is argued that the most likely explanation for this decline is a decrease in the mutation rate. It is also shown that a simple evolutionary model in which synonymous codon use is determined by a balance between mutation, selection for an optimal codon, and genetic drift predicts that selection should have little effect on the substitution rate in the present case.

History

Publication status

  • Published

Journal

Genetics

ISSN

0016-6731

Volume

140

Page range

1407-1412

Pages

6.0

Department affiliated with

  • Evolution, Behaviour and Environment Publications

Full text available

  • No

Peer reviewed?

  • Yes

Legacy Posted Date

2012-02-06

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