title: Strand exchange activity of human recombination protein Rad52.
abstract: Repair of double-strand breaks is essential for the maintenance of genome integrity and cell survival. In eukaryotes, double-strand-break repair by homologous recombination requires the Rad52 group of proteins. Human Rad52 protein (HsRad52)-mediated annealing of complementary strands has been studied in detail, but little has been reported on the recombinase activities of HsRad52. For this study, we purified HsRad52 from Escherichia coli. DNase I protection experiments indicated that HsRad52 binds preferentially to single-stranded DNA and protects it against digestion by DNase I. HsRad52 catalyzed D-loop formation in superhelical DNA, as well as strand exchange among oligonucleotide substrates. The formation of a stoichiometric complex between HsRad52 and single-stranded DNA was found to be critical for strand exchange activity, and the coating of both the single- and double-stranded oligonucleotides inhibited the exchange reaction.
authors.affiliation: Department of Biological Sciences, University at Albany, State University of New York, 1400 Washington Avenue, Albany, NY 12222, USA.
authors.forename: Jaspal K
authors.initials: JK
authors.lastname: Kumar
authors.forename: Ravindra C
authors.initials: RC
authors.lastname: Gupta
mesh_terms: D001665:Binding Sites; D002384:Catalysis; D023902:Chromosome Pairing; D004277:DNA, Single-Stranded / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D004268:DNA-Binding Proteins / Q000378:metabolism*; D003850:Deoxyribonuclease I / Q000378:metabolism; D004926:Escherichia coli; D006801:Humans; D023282:Nuclease Protection Assays; D009690:Nucleic Acid Conformation; D009838:Oligodeoxyribonucleotides / Q000737:chemistry / Q000235:genetics / Q000378:metabolism; D011485:Protein Binding; D051135:Rad51 Recombinase; D051721:Rad52 DNA Repair and Recombination Protein; D011938:Rec A Recombinases / Q000378:metabolism; D011994:Recombinant Proteins / Q000378:metabolism; D011995:Recombination, Genetic
chemical_list: D004277:DNA, Single-Stranded; D004268:DNA-Binding Proteins; D009838:Oligodeoxyribonucleotides; C497194:RAD52 protein, human; D051721:Rad52 DNA Repair and Recombination Protein; D011994:Recombinant Proteins; C495153:RAD51 protein, human; D051135:Rad51 Recombinase; D011938:Rec A Recombinases; D003850:Deoxyribonuclease I