Abstract
Mutations in the Artemis protein in humans result in hypersensitivity to DNA double-strand break-inducing agents and absence of B and T lymphocytes (radiosensitive severe combined immune deficiency [RS-SCID]). Here, we report that Artemis forms a complex with the 469 kDa DNA-dependent protein kinase (DNA-PKcs) in the absence of DNA. The purified Artemis protein alone possesses single-strand-specific 5' to 3' exonuclease activity. Upon complex formation, DNA-PKcs phosphorylates Artemis, and Artemis acquires endonucleolytic activity on 5' and 3' overhangs, as well as hairpins. Finally, the Artemis:DNA-PKcs complex can open hairpins generated by the RAG complex. Thus, DNA-PKcs regulates Artemis by both phosphorylation and complex formation to permit enzymatic activities that are critical for the hairpin-opening step of V(D)J recombination and for the 5' and 3' overhang processing in nonhomologous DNA end joining.
Publication types
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Research Support, U.S. Gov't, P.H.S.
MeSH terms
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Adenosine Triphosphate / metabolism
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Animals
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DNA, Single-Stranded / chemistry
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DNA, Single-Stranded / metabolism
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DNA-Activated Protein Kinase
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DNA-Binding Proteins / metabolism
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Endonucleases / genetics
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Endonucleases / metabolism
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Enzyme Activation
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HMGB1 Protein / metabolism
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Homeodomain Proteins / metabolism
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Humans
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Nuclear Proteins*
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Phosphorylation
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Protein Serine-Threonine Kinases / genetics
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Protein Serine-Threonine Kinases / metabolism*
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Recombination, Genetic / physiology*
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beta-Lactamases / genetics*
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beta-Lactamases / metabolism*
Substances
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DNA, Single-Stranded
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DNA-Binding Proteins
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HMGB1 Protein
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Homeodomain Proteins
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Nuclear Proteins
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RAG2 protein, human
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V(D)J recombination activating protein 2
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RAG-1 protein
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Adenosine Triphosphate
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DNA-Activated Protein Kinase
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PRKDC protein, human
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Protein Serine-Threonine Kinases
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DCLRE1C protein, human
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Endonucleases
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beta-Lactamases