title: Central role for the XRCC1 BRCT I domain in mammalian DNA single-strand break repair.
abstract: The DNA single-strand break repair (SSBR) protein XRCC1 is required for genetic stability and for embryonic viability. XRCC1 possesses two BRCA1 carboxyl-terminal (BRCT) protein interaction domains, denoted BRCT I and II. BRCT II is required for SSBR during G(1) but is dispensable for this process during S/G(2) and consequently for cell survival following DNA alkylation. Little is known about BRCT I, but this domain has attracted considerable interest because it is the site of a genetic polymorphism that epidemiological studies have associated with altered cancer risk. We report that the BRCT I domain comprises the evolutionarily conserved core of XRCC1 and that this domain is required for efficient SSBR during both G(1) and S/G(2) cell cycle phases and for cell survival following treatment with methyl methanesulfonate. However, the naturally occurring human polymorphism in BRCT I supported XRCC1-dependent SSBR and cell survival after DNA alkylation equally well. We conclude that while the BRCT I domain is critical for XRCC1 to maintain genetic integrity and cell survival, the polymorphism does not impact significantly on this function and therefore is unlikely to impact significantly on susceptibility to cancer.
authors.affiliation: School of Biological Sciences, University of Manchester, Manchester M13 9PT, United Kingdom.
authors.forename: Richard M
authors.initials: RM
authors.lastname: Taylor
authors.forename: Angela
authors.initials: A
authors.lastname: Thistlethwaite
authors.forename: Keith W
authors.initials: KW
authors.lastname: Caldecott
mesh_terms: D000478:Alkylation; D000595:Amino Acid Sequence; D000818:Animals; D017360:Arabidopsis / Q000235:genetics; D016466:CHO Cells; D002453:Cell Cycle; D002460:Cell Line; D017124:Conserved Sequence; D006224:Cricetinae; D004247:DNA / Q000737:chemistry / Q000235:genetics; D004260:DNA Repair / Q000502:physiology*; D004268:DNA-Binding Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D017343:Genes, Plant; D006801:Humans; D051379:Mice; D008969:Molecular Sequence Data; D016297:Mutagenesis, Site-Directed; D009369:Neoplasms / Q000209:etiology / Q000235:genetics; D011110:Polymorphism, Genetic; D017434:Protein Structure, Tertiary; D011994:Recombinant Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism; D017386:Sequence Homology, Amino Acid; D000076105:X-ray Repair Cross Complementing Protein 1
chemical_list: D004268:DNA-Binding Proteins; D011994:Recombinant Proteins; D000076105:X-ray Repair Cross Complementing Protein 1; C000619371:XRCC1 protein, human; C000619352:Xrcc1 protein, mouse; D004247:DNA