Artemis is a

protein Proteins are large biomolecules and macromolecules that comprise one or more long chains of amino acid residues. Proteins perform a vast array of functions within organisms, including catalysing metabolic reactions, DNA replication, res ...

that in humans is encoded by the ''DCLRE1C'' (DNA cross-link repair 1C)

gene In biology, the word gene (from , ; "... Wilhelm Johannsen coined the word gene to describe the Mendelian units of heredity..." meaning ''generation'' or ''birth'' or ''gender'') can have several different meanings. The Mendelian gene is a b ...

Function

Artemis is a nuclear protein that is involved in

V(D)J recombination V(D)J recombination is the mechanism of somatic recombination that occurs only in developing lymphocytes during the early stages of T and B cell maturation. It results in the highly diverse repertoire of antibodies/immunoglobulins and T cell re ...

and

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 da ...

. The protein has endonuclease activity on 5' and 3' overhangs and hairpins when complexed with PRKDC.

Immune response

Artemis plays an essential role in

, the process by which B cell

antibody An antibody (Ab), also known as an immunoglobulin (Ig), is a large, Y-shaped protein used by the immune system to identify and neutralize foreign objects such as pathogenic bacteria and viruses. The antibody recognizes a unique molecule of the ...

genes and

T cell receptor The T-cell receptor (TCR) is a protein complex found on the surface of T cells, or T lymphocytes, that is responsible for recognizing fragments of antigen as peptides bound to major histocompatibility complex (MHC) molecules. The binding ...

genes are assembled from individual V (variable), D (diversity), and J (joining) segments. For example, in joining a V segment to a D segment, the RAG (recombination activating gene) nuclease cuts both DNA strands adjacent to a V segment and adjacent to a D segment. The intervening DNA between the V and D segments is ligated to form a circular DNA molecule that is lost from the chromosome. At each of the two remaining ends, called the coding ends, the two strands of DNA are joined to form a hairpin structure. Artemis nuclease, in a complex with the DNA-dependent protein kinase (DNA‑PK), binds to these DNA ends and makes a single cut near the tip of the hairpin. The exposed 3' termini are subject to deletion and addition of nucleotides by a variety of exonucleases and DNA polymerases, before the V and D segments are ligated to restore the integrity of the chromosome. The exact site of cleavage of the hairpin by Artemis is variable, and this variability, combined with random nucleotide deletion and addition, confers extreme diversity upon the resulting antibody and T-cell receptor genes, thus allowing the immune system to mount an immune response to virtually any foreign antigen. In Artemis-deficient individuals, V(D)J recombination is blocked because the hairpin ends cannot be opened, and so no mature B or T cells are produced, a condition known as severe combined immune deficiency (SCID). Artemis was first identified as the gene defective in a subset of SCID patients that were unusually sensitive to radiation.

Repair of DNA breaks

Cells deficient in Artemis are more sensitive than normal cells to X‑rays and to chemical agents that induce

double-strand breaks 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 dama ...

(DSBs), and they show a higher incidence of chromosome breaks following irradiation. Direct measurement of DSBs by pulsed-field electrophoresis indicates that in Artemis-deficient cells 75-90% of DSBs are repaired rapidly, just as in normal cells. However, the remaining 10-20% of DSBs that are repaired more slowly (2-24 hr) in normal cells, are not repaired at all in Artemis-deficient cells. Repair of these presumably difficult-to-rejoin breaks also requires several other proteins, including the Mre11/Rad50/NBS1 complex, the ataxia telangiectasia mutated ATM kinase, and 53BP1. Because Artemis can remove damaged ends from DNA, it has been proposed that these DSBs are those whose damaged ends require trimming by Artemis. However, evidence that both ATM and Artemis are specifically required for repair of DSBs in heterochromatin, has called this interpretation into question. Artemis functions in the repair of DNA

that arise by induced oxidative reactions, or by endogenous reactions. Such

occurs in heterochromatin as well as in

euchromatin Euchromatin (also called "open chromatin") is a lightly packed form of chromatin ( DNA, RNA, and protein) that is enriched in genes, and is often (but not always) under active transcription. Euchromatin stands in contrast to heterochromatin, whi ...

Clinical significance

Mutations in this gene cause Athabascan-type

severe combined immunodeficiency Severe combined immunodeficiency (SCID), also known as Swiss-type agammaglobulinemia, is a rare genetic disorder characterized by the disturbed development of functional T cells and B cells caused by numerous genetic mutations that result in diffe ...

(SCIDA).

Interactions

DCLRE1C has been shown to

interact Advocates for Informed Choice, dba interACT or interACT Advocates for Intersex Youth, is a 501(c)(3) nonprofit organization using innovative strategies to advocate for the legal and human rights of children with intersex traits. The organizati ...

with

DNA-PKcs DNA-dependent protein kinase, catalytic subunit, also known as DNA-PKcs, is an enzyme that in humans is encoded by the gene designated as ''PRKDC'' or ''XRCC7''. DNA-PKcs belongs to the phosphatidylinositol 3-kinase-related kinase protein family. ...

References

External links

* {{PDBe-KB2, Q96SD1, Protein artemis