The ataxia-telangiectasia mutated (ATM) kinase signals the presence of DNA double-strand breaks in mammalian cells by phosphorylating proteins that initiate cell-cycle arrest, apoptosis, and DNA repair. We show that the Mre11-Rad50-Nbs1 (MRN) complex acts as a double-strand break sensor for ATM and recruits ATM to broken DNA molecules. Inactive ATM dimers were activated in vitro with DNA in the presence of MRN, leading to phosphorylation of the downstream cellular targets p53 and Chk2. ATM autophosphorylation was not required for monomerization of ATM by MRN. The unwinding of DNA ends by MRN was essential for ATM stimulation, which is consistent with the central role of single-stranded DNA as an evolutionarily conserved signal for DNA damage.
Pubmed ID: 15790808 RIS Download
Mesh terms: Amino Acid Substitution | Ataxia Telangiectasia Mutated Proteins | Cell Cycle Proteins | Cell Line | DNA | DNA Damage | DNA Repair | DNA Repair Enzymes | DNA, Single-Stranded | DNA-Binding Proteins | Dimerization | Enzyme Activation | Humans | Mutation | Nuclear Proteins | Nucleic Acid Conformation | Phosphorylation | Protein Binding | Protein-Serine-Threonine Kinases | Recombinant Proteins | Serine | Signal Transduction | Transfection | Tumor Suppressor Proteins
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