homologous recombination

WKP

Definition : Homologous recombination is a type of genetic recombination in which nucleotide sequences are exchanged between two similar or identical molecules of DNA.

Homologous recombination is most widely used by cells to accurately repair harmful breaks that occur on both strands of DNA, known as double-strand breaks (DSB). Homologous recombination also produces new combinations of DNA sequences during meiosis, the process by which eukaryotes make gamete cells, like sperm and egg cells in animals.

Homologous recombination (HR) is an important mechanism for the repair of damaged chromosomes, for preventing the demise of damaged replication forks, and for several other aspects of chromosome maintenance.

HR is indispensable for genome integrity, but it must be regulated to avoid deleterious events.

Mutations in the tumour-suppressor protein BRCA2, which has a mediator function in HR, lead to cancer formation.

DNA helicases, such as Bloom’s syndrome protein (BLM), regulate HR at several levels, in attenuating unwanted HR events and in determining the outcome of HR.

Pathology

 Defects in BLM are also associated with the cancer phenotype.

References

 Barzel A, Kupiec M. Finding a match: how do homologous sequences get together for recombination? Nat Rev Genet. 2008 Jan;9(1):27-37. PMID: 18040271

 Sung P, Klein H. Mechanism of homologous recombination: mediators and helicases take on regulatory functions. Nat Rev Mol Cell Biol. 2006 Oct;7(10):739-50. PMID: 16926856

 Bishop AJ, Schiestl RH. Homologous recombination as a mechanism for genome rearrangements: environmental and genetic effects. Hum Mol Genet. 2000 Oct;9(16):2427-334. PMID: 11005798