title: MDC1 directly binds phosphorylated histone H2AX to regulate cellular responses to DNA double-strand breaks.
abstract: Histone variant H2AX phosphorylation in response to DNA damage is the major signal for recruitment of DNA-damage-response proteins to regions of damaged chromatin. Loss of H2AX causes radiosensitivity, genome instability, and DNA double-strand-break repair defects, yet the mechanisms underlying these phenotypes remain obscure. Here, we demonstrate that mammalian MDC1/NFBD1 directly binds to phospho-H2AX (gammaH2AX) by specifically interacting with the phosphoepitope at the gammaH2AX carboxyl terminus. Moreover, through a combination of biochemical, cell-biological, and X-ray crystallographic approaches, we reveal the molecular details of the MDC1/NFBD1-gammaH2AX complex. These data provide compelling evidence that the MDC1/NFBD1 BRCT repeat domain is the major mediator of gammaH2AX recognition following DNA damage. We further show that MDC1/NFBD1-gammaH2AX complex formation regulates H2AX phosphorylation and is required for normal radioresistance and efficient accumulation of DNA-damage-response proteins on damaged chromatin. Thus, binding of MDC1/NFBD1 to gammaH2AX plays a central role in the mammalian response to DNA damage.
authors.affiliation: The Wellcome Trust/Cancer Research UK Gurdon Institute and Department of Zoology, Cambridge University, Tennis Court Road, Cambridge CB2 1QN, United Kingdom.
authors.forename: Manuel
authors.initials: M
authors.lastname: Stucki
authors.forename: Julie A
authors.initials: JA
authors.lastname: Clapperton
authors.forename: Duaa
authors.initials: D
authors.lastname: Mohammad
authors.forename: Michael B
authors.initials: MB
authors.lastname: Yaffe
authors.forename: Stephen J
authors.initials: SJ
authors.lastname: Smerdon
authors.forename: Stephen P
authors.initials: SP
authors.lastname: Jackson
mesh_terms: D048868:Adaptor Proteins, Signal Transducing; D000595:Amino Acid Sequence; D000818:Animals; D002453:Cell Cycle / Q000502:physiology; D018797:Cell Cycle Proteins; D017124:Conserved Sequence; D004249:DNA Damage / Q000502:physiology*; D004268:DNA-Binding Proteins / Q000378:metabolism / Q000502:physiology; D006657:Histones / Q000378:metabolism*; D006801:Humans; D008958:Models, Molecular; D008969:Molecular Sequence Data; D015394:Molecular Structure; D009687:Nuclear Proteins / Q000378:metabolism*; D019151:Peptide Library; D010766:Phosphorylation; D017434:Protein Structure, Tertiary / Q000502:physiology; D015534:Trans-Activators / Q000378:metabolism*
chemical_list: D048868:Adaptor Proteins, Signal Transducing; D018797:Cell Cycle Proteins; D004268:DNA-Binding Proteins; D006657:Histones; C413163:MDC1 protein, human; D009687:Nuclear Proteins; D019151:Peptide Library; D015534:Trans-Activators