Biased gene conversion and the evolution of mammalian genomic landscapes

Recombination is typically thought of as a symmetrical process resulting in large-scale reciprocal genetic exchanges between homologous chromosomes. Recombination events, however, are also accompanied by short-scale, unidirectional exchanges known as gene conversion in the neighborhood of the initia...

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Bibliographic Details
Published in:Annual review of genomics and human genetics 2009-01, Vol.10 (1), p.285-311
Main Authors: Duret, Laurent, Galtier, Nicolas
Format: Article
Language:English
Subjects:
Animals
Base Composition
Evolution, Molecular
Gene Conversion
Genome
Humans
Life Sciences
Mammals - genetics
Other
Selection, Genetic
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Summary:Recombination is typically thought of as a symmetrical process resulting in large-scale reciprocal genetic exchanges between homologous chromosomes. Recombination events, however, are also accompanied by short-scale, unidirectional exchanges known as gene conversion in the neighborhood of the initiating double-strand break. A large body of evidence suggests that gene conversion is GC-biased in many eukaryotes, including mammals and human. AT/GC heterozygotes produce more GC- than AT-gametes, thus conferring a population advantage to GC-alleles in high-recombining regions. This apparently unimportant feature of our molecular machinery has major evolutionary consequences. Structurally, GC-biased gene conversion explains the spatial distribution of GC-content in mammalian genomes-the so-called isochore structure. Functionally, GC-biased gene conversion promotes the segregation and fixation of deleterious AT --> GC mutations, thus increasing our genomic mutation load. Here we review the recent evidence for a GC-biased gene conversion process in mammals, and its consequences for genomic landscapes, molecular evolution, and human functional genomics.
ISSN:1527-8204
1545-293X
1527-8204
DOI:10.1146/annurev-genom-082908-150001