MRE11A

Double-strand break repair protein MRE11A is a protein that in humans is encoded by the MRE11A gene.

Function

This gene encodes a nuclear protein involved in homologous recombination, telomere length maintenance, and DNA double-strand break repair. By itself, the protein has 3' to 5' exonuclease activity and endonuclease activity. The protein forms a complex with the RAD50 homolog; this complex is required for nonhomologous joining of DNA ends and possesses increased single-stranded DNA endonuclease and 3' to 5' exonuclease activities. In conjunction with a DNA ligase, this protein promotes the joining of noncomplementary ends in vitro using short homologies near the ends of the DNA fragments. This gene has a pseudogene on chromosome 3. Alternative splicing of this gene results in two transcript variants encoding different isoforms.

Orthologs of MRE11A

Mre11, an ortholog of human MRE11A, occurs in the prokaryote archaeon Sulfolobus acidocaldarius. In this organism the Mre11 protein interacts with the Rad50 protein and appears to have an active role in the repair of DNA damages experimentally introduced by gamma radiation. Similarly, during meiosis in the eukaryotic protist Tetrahymena Mre11 is required for repair of DNA damages, in this case double-strand breaks, by a process that likely involves homologous recombination. These observations suggest that human MRE11A is descended from prokaryotic and protist ancestral Mre11 proteins that served a role in early processes for repairing DNA damage.