Gene Conversion

Abstract

Gene conversion is the nonreciprocal transfer of information between homologous sequences and is closely associated with meiotic recombination and the mismatch repair of DNA heteroduplex.

Keywords: heteroduplex; tetrad analysis; concerted evolution; homologous recombination

Figure 1.

Alternative resolutions of a Holliday junction. Following the formation of a Holliday junction, resolution can result in gene conversion with or without associated crossover. Under Holliday's original model, all gene conversion results from mismatch repair of heteroduplex.

Figure 2.

The double‐strand break model of meiotic recombination. Following a double‐strand break, 5′ ends are digested, allowing single‐stranded 3′ tails to invade homologous sequences. Resynthesis of the gap generated by the exonucleolytic activity results in the formation of an intermediate containing two Holliday junctions. This structure is capable of generating a heteroduplex via branch migration through homologous sequences. Resolution of this intermediate can result in gene conversion with or without associated crossover. Gene conversion results from gap resynthesis and mismatch repair of heteroduplexes.

Figure 3.

Gene conversion between paralogous sequences can appear to have occurred as a result of a double crossover between misaligned chromatids (or chromosomes). This process generates two reciprocal products; however, after segregation, only one product may be observed. Two independent instances of the upper product have been observed, but no examples of the bracketed, lower, product. Crossovers are shown as being restricted to minimum efficient processing segments of greater than 200 bp of sequence identity between the repeats.

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References

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Further Reading

Cooper DN (1999) Human Gene Evolution. Oxford: Bios.

Jonkman MF (1999) Revertant mosaicism in human genetic disorders. American Journal of Medical Genetics 85: 361–364.

Papadakis MN and Patrinos GP (1999) Contribution of gene conversion in the evolution of the human beta‐like globin gene family. Human Genetics 104: 117–125.

Paques F and Haber JE (1999) Multiple pathways of recombination induced by double‐strand breaks in Saccharomyces cerevisiae. Microbiology and Molecular Biology Reviews 63: 349–404.

Rice MC, Czymmek K and Kmiec EB (2001) The potential of nucleic acid repair in functional genomics. Nature Biotechnology 19: 321–326.

Stahl FW (1994) The Holliday junction on its thirtieth anniversary. Genetics 138: 241–246.

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How to Cite close
Hurles, Matthew E(Feb 2003) Gene Conversion. In: eLS. John Wiley & Sons Ltd, Chichester. http://www.els.net [doi: 10.1038/npg.els.0000816]