Direct activation of the ATM protein kinase by the Mre11/Rad50/Nbs1 complex.

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.
Mesh Terms:
Ataxia Telangiectasia, Cell Cycle Proteins, DNA, DNA Repair Enzymes, DNA-Binding Proteins, Enzyme Activation, Histones, Humans, Mutation, Mutation, Missense, Nuclear Proteins, Phosphorylation, Protein Binding, Protein-Serine-Threonine Kinases, Recombinant Proteins, Tumor Suppressor Protein p53, Tumor Suppressor Proteins
Science
Date: Apr. 02, 2004
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