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Proc Natl Acad Sci U S A. 2012 Sep 4;109(36):14504-7. doi: 10.1073/pnas.1205683109. Epub 2012 Aug 20.

A selective force favoring increased G+C content in bacterial genes.

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  • 1Department of Ecology and Evolutionary Biology, Yale University, New Haven, CT 06520, USA.

Abstract

Bacteria display considerable variation in their overall base compositions, which range from 13% to over 75% G+C. This variation in genomic base compositions has long been considered to be a strictly neutral character, due solely to differences in the mutational process; however, recent sequence comparisons indicate that mutational input alone cannot produce the observed base compositions, implying a role for natural selection. Because bacterial genomes have high gene content, forces that operate on the base composition of individual genes could help shape the overall genomic base composition. To explore this possibility, we tested whether genes that encode the same protein but vary only in their base compositions at synonymous sites have effects on bacterial fitness. Escherichia coli strains harboring G+C-rich versions of genes display higher growth rates, indicating that despite a pervasive mutational bias toward A+T, a selective force, independent of adaptive codon use, is driving genes toward higher G+C contents.

PMID:
22908296
[PubMed - indexed for MEDLINE]
PMCID:
PMC3437849
Free PMC Article
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