Recombinases are

genetic recombination Genetic recombination (also known as genetic reshuffling) is the exchange of genetic material between different organisms which leads to production of offspring with combinations of traits that differ from those found in either parent. In eukaryo ...

enzymes Enzymes () are proteins that act as biological catalysts by accelerating chemical reactions. The molecules upon which enzymes may act are called substrate (chemistry), substrates, and the enzyme converts the substrates into different molecule ...

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 ge ...

s, and to control

gene expression Gene expression is the process by which information from a gene is used in the synthesis of a functional gene product that enables it to produce end products, protein or non-coding RNA, and ultimately affect a phenotype, as the final effect. The ...

. 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 among ...

(

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". Bacterio ...

) 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 from ...

, 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 biomolecules wi ...

s) target site sequences that are specific to each recombinase. These reactions enable four basic functional modules: excision/insertion, inversion, translocation and

cassette Cassette may refer to: Technology * Cassette tape (or ''musicassette'', ''audio cassette'', ''cassette tape'', or ''tape''), a worldwide standard for analog audio recording and playback ** Cassette single (or "Cassingle"), a music single in th ...

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 site ...

Hin recombinase Hin recombinase is a 21kD protein composed of 198 amino acids that is found in the bacteria ''Salmonella''. Hin belongs to the serine recombinase family (B2) of DNA invertases in which it relies on the active site serine to initiate DNA cleavage ...

Tre recombinase Tre recombinase is an experimental enzyme that in lab tests has removed DNA inserted by HIV from infected cells. Through selective mutation, Cre recombinase which recognizes loxP sites are modified to identify HIV long terminal repeats (loxLTR) i ...

FLP recombinase In genetics, Flp-''FRT'' recombination is a site-directed recombination technology, increasingly used to manipulate an organism's DNA under controlled conditions ''in vivo''. It is analogous to Cre-''lox'' recombination but involves the recombi ...

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 Archaea ( ; singular archaeon ) is a domain of single-celled organisms. These microorganisms lack cell nuclei and are therefore prokaryotes. Archaea were initially classified as bacteria, receiving the name archaebacteria (in the Archaebac ...

eukaryote Eukaryotes () are organisms whose cells have a nucleus. All animals, plants, fungi, and many unicellular organisms, are Eukaryotes. They belong to the group of organisms Eukaryota or Eukarya, which is one of the three domains of life. Bacte ...

s 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 Ivanovsky's 1 ...

es.

Archaea

The archaeon ''

Sulfolobus solfataricus ''Saccharolobus solfataricus'' is a species of thermophilic archaeon. It was transferred from the genus ''Sulfolobus'' to the new genus ''Saccharolobus'' with the description of Saccharolobus caldissimus in 2018. It was first isolated and disco ...

'' RadA recombinase catalyzes DNA pairing and strand exchange, central steps in recombinational repair. The RadA recombinase has greater similarity to the eukaryotic

Rad51 DNA repair protein RAD51 homolog 1 is a protein encoded by the gene ''RAD51''. The enzyme encoded by this gene is a member of the RAD51 protein family which assists in repair of DNA double strand breaks. RAD51 family members are homologous to th ...

recombinase than to the bacterial RecA recombinase.

Bacteria

RecA RecA is a 38 kilodalton protein essential for the repair and maintenance of DNA. A RecA structural and functional homolog has been found in every species in which one has been seriously sought and serves as an archetype for this class of homolog ...

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 dam ...

. 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 da ...

and in the bacterial sexual process of natural genetic transformation.

Eukaryotes

Eukaryotic

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 Expression may refer to: Linguistics * Expression (linguistics), a word, phrase, or sentence * Fixed expression, a form of words with a specific meaning * Idiom, a type of fixed expression * Metaphorical expression, a particular word, phrase, o ...

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 resu ...

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 homologous ...

, 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 Escherichia virus T4 is a species of bacteriophages that infect ''Escherichia coli'' bacteria. It is a double-stranded DNA virus in the subfamily '' Tevenvirinae'' from the family Myoviridae. T4 is capable of undergoing only a lytic lifecycle ...

.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 In molecular biology, a displacement loop or D-loop is a DNA structure where the two strands of a double-stranded DNA molecule are separated for a stretch and held apart by a third strand of DNA. An R-loop is similar to a D-loop, but in this cas ...

References

External links

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