Abstract
The complex containing the Mre11, Rad50, and Nbs1 proteins (MRN) is essential for the cellular response to DNA double-strand breaks, integrating DNA repair with the activation of checkpoint signaling through the protein kinase ATM (ataxia telangiectasia mutated). We demonstrate that MRN stimulates the kinase activity of ATM in vitro toward its substrates p53, Chk2, and histone H2AX. MRN makes multiple contacts with ATM and appears to stimulate ATM activity by facilitating the stable binding of substrates. Phosphorylation of Nbs1 is critical for MRN stimulation of ATM activity toward Chk2, but not p53. Kinase-deficient ATM inhibits wild-type ATM phosphorylation of Chk2, consistent with the dominant-negative effect of kinase-deficient ATM in vivo.
Publication types
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Research Support, Non-U.S. Gov't
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Research Support, U.S. Gov't, P.H.S.
MeSH terms
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Acid Anhydride Hydrolases
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Ataxia Telangiectasia / genetics
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Ataxia Telangiectasia Mutated Proteins
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Cell Cycle Proteins / genetics
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Cell Cycle Proteins / metabolism*
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Checkpoint Kinase 2
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DNA / metabolism
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DNA Repair Enzymes*
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DNA-Binding Proteins / metabolism*
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Enzyme Activation
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Histones / metabolism
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Humans
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MRE11 Homologue Protein
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Mutation
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Mutation, Missense
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Nuclear Proteins / genetics
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Nuclear Proteins / metabolism*
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Phosphorylation
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Protein Binding
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Protein Serine-Threonine Kinases / genetics
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Protein Serine-Threonine Kinases / metabolism*
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Recombinant Proteins / metabolism
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Tumor Suppressor Protein p53 / metabolism
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Tumor Suppressor Proteins
Substances
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Cell Cycle Proteins
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DNA-Binding Proteins
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H2AX protein, human
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Histones
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MRE11 protein, human
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NBN protein, human
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Nuclear Proteins
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Recombinant Proteins
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Tumor Suppressor Protein p53
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Tumor Suppressor Proteins
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DNA
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Checkpoint Kinase 2
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ATM protein, human
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Ataxia Telangiectasia Mutated Proteins
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CHEK2 protein, human
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Protein Serine-Threonine Kinases
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MRE11 Homologue Protein
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Acid Anhydride Hydrolases
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RAD50 protein, human
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DNA Repair Enzymes