title: Structure of the BRCT repeat domain of MDC1 and its specificity for the free COOH-terminal end of the gamma-H2AX histone tail.
abstract: MDC1 (mediator of DNA damage checkpoint protein 1) regulates the recognition and repair of DNA double strand breaks in mammalian cells through its interactions with nuclear foci containing the COOH-terminally phosphorylated form of the histone variant, H2AX. Here we demonstrate that the tandem BRCT repeats of MDC1 directly bind to the phosphorylated tail of H2AX-Ser(P)-Gln-Glu-Tyr, in a manner that is critically dependent on the free carboxylate group of the COOH-terminal Tyr residue. We have determined the x-ray crystal structure of the MDC1 BRCT repeats at 1.45 Angstroms resolution. By a comparison with the structure of the BRCA1 BRCT bound to a phosphopeptide, we suggest that two arginine residues in MDC1, Arg(1932) and Arg(1933) may recognize the COOH terminus of the peptide as well as the penultimate Glu of H2AX, while Gln(2013) may provide additional specificity for the COOH-terminal Tyr.
authors.affiliation: Department of Biochemistry, University of Alberta, Edmonton, Canada.
authors.forename: Megan S
authors.initials: MS
authors.lastname: Lee
authors.forename: Ross A
authors.initials: RA
authors.lastname: Edwards
authors.forename: Gina L
authors.initials: GL
authors.lastname: Thede
authors.forename: J N Mark
authors.initials: JN
authors.lastname: Glover
mesh_terms: D048868:Adaptor Proteins, Signal Transducing; D000595:Amino Acid Sequence; D001943:Breast Neoplasms / Q000378:metabolism; D002151:Calorimetry; D018797:Cell Cycle Proteins; D018360:Crystallography, X-Ray; D004249:DNA Damage; D004268:DNA-Binding Proteins / Q000737:chemistry / Q000378:metabolism; D004926:Escherichia coli / Q000378:metabolism; D018698:Glutamic Acid / Q000737:chemistry; D005973:Glutamine / Q000737:chemistry; D005982:Glutathione Transferase / Q000378:metabolism; D006657:Histones / Q000737:chemistry*; D006801:Humans; D008958:Models, Molecular; D015233:Models, Statistical; D008969:Molecular Sequence Data; D009687:Nuclear Proteins / Q000737:chemistry* / Q000378:metabolism; D010455:Peptides / Q000737:chemistry; D010710:Phosphates / Q000737:chemistry; D010748:Phosphopeptides / Q000737:chemistry; D010766:Phosphorylation; D011487:Protein Conformation; D017434:Protein Structure, Tertiary; D011993:Recombinant Fusion Proteins / Q000737:chemistry; D017386:Sequence Homology, Amino Acid; D012694:Serine / Q000737:chemistry; D015534:Trans-Activators / Q000737:chemistry* / Q000378:metabolism; D014443:Tyrosine / Q000737:chemistry
chemical_list: D048868:Adaptor Proteins, Signal Transducing; D018797:Cell Cycle Proteins; D004268:DNA-Binding Proteins; C468783:H2AX protein, human; D006657:Histones; C413163:MDC1 protein, human; D009687:Nuclear Proteins; D010455:Peptides; D010710:Phosphates; D010748:Phosphopeptides; D011993:Recombinant Fusion Proteins; D015534:Trans-Activators; D005973:Glutamine; D018698:Glutamic Acid; D014443:Tyrosine; D012694:Serine; D005982:Glutathione Transferase