Feb 7, 2015

GC-Content evolution in bacterial genomes: the biased gene conversion hypothesis expands

PLoS Genetics
Florent LassalleVincent Daubin

Abstract

The characterization of functional elements in genomes relies on the identification of the footprints of natural selection. In this quest, taking into account neutral evolutionary processes such as mutation and genetic drift is crucial because these forces can generate patterns that may obscure or mimic signatures of selection. In mammals, and probably in many eukaryotes, another such confounding factor called GC-Biased Gene Conversion (gBGC) has been documented. This mechanism generates patterns identical to what is expected under selection for higher GC-content, specifically in highly recombining genomic regions. Recent results have suggested that a mysterious selective force favouring higher GC-content exists in Bacteria but the possibility that it could be gBGC has been excluded. Here, we show that gBGC is probably at work in most if not all bacterial species. First we find a consistent positive relationship between the GC-content of a gene and evidence of intra-genic recombination throughout a broad spectrum of bacterial clades. Second, we show that the evolutionary force responsible for this pattern is acting independently from selection on codon usage, and could potentially interfere with selection in favor of optimal AU...Continue Reading

Mentioned in this Paper

Genetic Drift
Biochemical Pathway
Patterns
Ribosomal Proteins
Genome
Genes
Tract
Pathogenic Organism
Helicobacter pylori
Sulfolobus

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