title: Solution structure and backbone dynamics of the XPC-binding domain of the human DNA repair protein hHR23B.
abstract: Human cells contain two homologs of the yeast RAD23 protein, hHR23A and hHR23B, which participate in the DNA repair process. hHR23B houses a domain (residues 277-332, called XPCB) that binds specifically and directly to the xeroderma pigmentosum group C protein (XPC) to initiate nucleotide excision repair (NER). This domain shares sequence homology with a heat shock chaperonin-binding motif that is also found in the stress-inducible yeast phosphoprotein STI1. We determined the solution structure of a protein fragment containing amino acids 275-342 of hHR23B (termed XPCB-hHR23B) and compared it with the previously reported solution structures of the corresponding domain of hHR23A. The periodic positioning of proline residues in XPCB-hHR23B produced kinked alpha helices and assisted in the formation of a compact domain. Although the overall structure of the XPCB domain was similar in both XPCB-hHR23B and XPCB-hHR23A, the N-terminal part (residues 275-283) of XPCB-hHR23B was more flexible than the corresponding part of hHR23A. We tried to infer the characteristics of this flexibility through (15)N-relaxation studies. The hydrophobic surface of XPCB-hHR23B, which results from the diverse distribution of N-terminal region, might give rise to the functional pleiotropy observed in vivo for hHR23B, but not for hHR23A.
authors.affiliation: Department of Chemistry, and National Creative Research Initiative Center for the Repair System of Damaged DNA, Korea Advanced Institute of Science and Technology, South Korea.
authors.forename: Byoungkook
authors.initials: B
authors.lastname: Kim
authors.forename: Kyoung-Seok
authors.initials: KS
authors.lastname: Ryu
authors.forename: Hyun-Jin
authors.initials: HJ
authors.lastname: Kim
authors.forename: Sung-Jae
authors.initials: SJ
authors.lastname: Cho
authors.forename: Byong-Seok
authors.initials: BS
authors.lastname: Choi
mesh_terms: D000595:Amino Acid Sequence; D003001:Cloning, Molecular; D004260:DNA Repair; D045643:DNA Repair Enzymes; D004268:DNA-Binding Proteins / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism*; D006801:Humans; D008958:Models, Molecular; D008969:Molecular Sequence Data; D019906:Nuclear Magnetic Resonance, Biomolecular; D011487:Protein Conformation; D016415:Sequence Alignment
chemical_list: D004268:DNA-Binding Proteins; C513287:RAD23B protein, human; C086985:RAD23A protein, human; C086984:XPC protein, human; D045643:DNA Repair Enzymes