title: Insights from the crystal structure of the sixth BRCT domain of topoisomerase IIbeta binding protein 1.
abstract: Topoisomerase IIbeta binding protein 1 (TopBP1) is a major player in the DNA damage response and interacts with a number of protein partners via its eight BRCA1 carboxy-terminal (BRCT) domains. In particular, the sixth BRCT domain of TopBP1 has been implicated in binding to the phosphorylated transcription factor, E2F1, and poly(ADP-ribose) polymerase 1 (PARP-1), where the latter interaction is responsible for the poly(ADP-ribosyl)ation of TopBP1. To gain a better understanding of the nature of TopBP1 BRCT6 interactions, we solved the crystal structure of BRCT6 to 1.34 A. The crystal structure reveals a degenerate phospho-peptide binding pocket and lacks conserved hydrophobic residues involved in packing of tandem BRCT repeats, which, together with results from phospho-peptide binding studies, strongly suggest that TopBP1 BRCT6 independently does not function as a phospho-peptide binding domain. We further provide insight into poly(ADP-ribose) binding and sites of potential modification by PARP-1.
authors: Department of Biochemistry, University of Alberta, Edmonton, Alberta, Canada T6G 2H7.
authors: Charles Chung Yun
authors: CC
authors: Leung
authors: Elizabeth
authors: E
authors: Kellogg
authors: Anja
authors: A
authors: Kuhnert
authors: Frank
authors: F
authors: Hänel
authors: David
authors: D
authors: Baker
authors: J N Mark
authors: JN
authors: Glover
mesh_terms: D000595:Amino Acid Sequence; D002352:Carrier Proteins / Q000737:chemistry* / Q000378:metabolism; D016384:Consensus Sequence; D018360:Crystallography, X-Ray / Q000379:methods*; D004249:DNA Damage; D004250:DNA Topoisomerases, Type II / Q000378:metabolism; D004268:DNA-Binding Proteins / Q000737:chemistry* / Q000378:metabolism; D008958:Models, Molecular; D008969:Molecular Sequence Data; D009687:Nuclear Proteins / Q000737:chemistry* / Q000378:metabolism; D011064:Poly Adenosine Diphosphate Ribose / Q000737:chemistry / Q000378:metabolism; D011065:Poly(ADP-ribose) Polymerases / Q000737:chemistry / Q000378:metabolism; D011485:Protein Binding; D025941:Protein Interaction Mapping; D017434:Protein Structure, Tertiary; D016415:Sequence Alignment; D020080:Tandem Repeat Sequences
chemical_list: D002352:Carrier Proteins; D004268:DNA-Binding Proteins; D009687:Nuclear Proteins; D011064:Poly Adenosine Diphosphate Ribose; D011065:Poly(ADP-ribose) Polymerases; D004250:DNA Topoisomerases, Type II