Recombinases are genetic recombination enzymes.

Site specific recombinases

DNA recombinases are widely used in multicellular organisms to manipulate the structure of

genome In the fields of molecular biology and genetics, a genome is all the genetic information of an organism. It consists of nucleotide sequences of DNA (or RNA in RNA viruses). The nuclear genome includes protein-coding genes and non-coding ...

s, and to control gene expression. These enzymes, derived from

bacteria Bacteria (; singular: bacterium) are ubiquitous, mostly free-living organisms often consisting of one biological cell. They constitute a large domain of prokaryotic microorganisms. Typically a few micrometres in length, bacteria were am ...

(

bacteriophages A bacteriophage (), also known informally as a ''phage'' (), is a duplodnaviria virus that infects and replicates within bacteria and archaea. The term was derived from "bacteria" and the Greek φαγεῖν ('), meaning "to devour". Bacter ...

) and

fungi A fungus ( : fungi or funguses) is any member of the group of eukaryotic organisms that includes microorganisms such as yeasts and molds, as well as the more familiar mushrooms. These organisms are classified as a kingdom, separately fr ...

, catalyze directionally sensitive DNA exchange reactions between short (30–40

nucleotide Nucleotides are organic molecules consisting of a nucleoside and a phosphate. They serve as monomeric units of the nucleic acid polymers – deoxyribonucleic acid (DNA) and ribonucleic acid (RNA), both of which are essential biomolecu ...

s) target site sequences that are specific to each recombinase. These reactions enable four basic functional modules: excision/insertion, inversion, translocation and cassette exchange, which have been used individually or combined in a wide range of configurations to control gene expression. Types include: *

Cre recombinase Cre recombinase is a tyrosine recombinase enzyme derived from the P1 bacteriophage. The enzyme uses a topoisomerase I-like mechanism to carry out site specific recombination events. The enzyme (38kDa) is a member of the integrase family of sit ...

* Hin recombinase * Tre recombinase * FLP recombinase

Homologous recombination

Recombinases have a central role in

homologous recombination Homologous recombination is a type of genetic recombination in which genetic information is exchanged between two similar or identical molecules of double-stranded or single-stranded nucleic acids (usually DNA as in cellular organisms but may ...

in a wide range of organisms. Such recombinases have been described in archaea,

, eukaryotes and

virus A virus is a submicroscopic infectious agent that replicates only inside the living cells of an organism. Viruses infect all life forms, from animals and plants to microorganisms, including bacteria and archaea. Since Dmitri Ivanovsk ...

es.

Archaea

The archaeon '' Sulfolobus solfataricus'' RadA recombinase catalyzes DNA pairing and strand exchange, central steps in recombinational repair. The RadA recombinase has greater similarity to the eukaryotic Rad51 recombinase than to the bacterial RecA recombinase.

Bacteria

RecA recombinase appears to be universally present in bacteria. RecA has multiple functions, all related to

DNA repair DNA repair is a collection of processes by which a cell identifies and corrects damage to the DNA molecules that encode its genome. In human cells, both normal metabolic activities and environmental factors such as radiation can cause DNA d ...

. RecA has a central role in the repair of replication forks stalled by

DNA damage DNA repair is a collection of processes by which a cell identifies and corrects damage to the DNA molecules that encode its genome. In human cells, both normal metabolic activities and environmental factors such as radiation can cause DNA d ...

and in the bacterial sexual process of natural genetic transformation.

Eukaryotes

Eukaryotic Rad51 and its related family members are homologous to the archaeal RadA and bacterial RecA recombinases. Rad51 is highly conserved from yeast to humans. It has a key function in the recombinational repair of DNA damages, particularly double-strand damages such as double-strand breaks. In humans, over- or under- expression of Rad51 occurs in a wide variety of

cancer Cancer is a group of diseases involving abnormal cell growth with the potential to invade or spread to other parts of the body. These contrast with benign tumors, which do not spread. Possible signs and symptoms include a lump, abnormal b ...

s. During

meiosis Meiosis (; , since it is a reductional division) is a special type of cell division of germ cells in sexually-reproducing organisms that produces the gametes, such as sperm or egg cells. It involves two rounds of division that ultimately ...

Rad51 interacts with another recombinase,

Dmc1 Meiotic recombination protein DMC1/LIM15 homolog is a protein that in humans is encoded by the ''DMC1'' gene. Meiotic recombination protein Dmc1 is a homolog of the bacterial strand exchange protein RecA. Dmc1 plays the central role in homologou ...

, to form a presynaptic filament that is an intermediate in

. Dmc1 function appears to be limited to meiotic recombination. Like Rad51, Dmc1 is homologous to bacterial RecA.

Viruses

Some DNA viruses encode a recombinase that facilitates homologous recombination. A well-studied example is the UvsX recombinase encoded by bacteriophage T4.Bernstein C, Bernstein H (2001). DNA repair in bacteriophage. In: Nickoloff JA, Hoekstra MF (Eds.) DNA Damage and Repair, Vol.3. Advances from Phage to Humans. Humana Press, Totowa, NJ, pp. 1–19. UvsX is homologous to bacterial RecA. UvsX, like RecA, can facilitate the assimilation of linear single-stranded DNA into an homologous DNA duplex to produce a D-loop.

References

External links

* Modification of genetic information Molecular biology {{Genetics-stub