title: Dynamic regulatory interactions of rad51, rad52, and replication protein-a in recombination intermediates.
abstract: Rad51, Rad52, and replication protein-A (RPA) play crucial roles in the repair of DNA double-strand breaks in Saccharomyces cerevisiae. Rad51 mediates DNA strand exchange, a key reaction in DNA recombination. Rad52 recruits Rad51 into single-stranded DNAs (ssDNAs) that are saturated with RPA. Rad52 also promotes annealing of ssDNA strands that are complexed with RPA. Specific protein-protein interactions are involved in these reactions. Here we report new biochemical characteristics of these protein interactions. First, Rad52-RPA interaction requires multiple molecules of RPA to be associated with ssDNA, suggesting that multiple contacts between the Rad52 ring and RPA-ssDNA filament are needed for stable binding. Second, RPA-t11, which is a recombination-deficient mutant of RPA, displays a defect in interacting with Rad52 in the presence of salt above 50 mM, explaining the defect in Rad52-mediated ssDNA annealing in the presence of this mutation. Third, ssDNA annealing promoted by Rad52 is preceded by aggregation of multiple RPA-ssDNA complexes with Rad52, and Rad51 inhibits this aggregation. These results suggest a regulatory role for Rad51 that suppresses ssDNA annealing and facilitates DNA strand invasion. Finally, the Rad51-double-stranded DNA complex disrupts Rad52-RPA interaction in ssDNA and titrates Rad52 from RPA. This suggests an additional regulatory role for Rad51 following DNA strand invasion, where Rad51-double-stranded DNA may inhibit illegitimate second-end capture to ensure the error-free repair of a DNA double-strand break.
authors.affiliation: Department of Biological Sciences, Ohio University, Athens, 45701, USA. sugiyama@ohio.edu
authors.forename: Tomohiko
authors.initials: T
authors.lastname: Sugiyama
authors.forename: Noriko
authors.initials: N
authors.lastname: Kantake
mesh_terms: D004247:DNA / Q000378:metabolism; D004260:DNA Repair; D004277:DNA, Single-Stranded / Q000378:metabolism; D008954:Models, Biological; D011485:Protein Binding; D025941:Protein Interaction Mapping; D051135:Rad51 Recombinase / Q000378:metabolism*; D051721:Rad52 DNA Repair and Recombination Protein / Q000378:metabolism*; D011995:Recombination, Genetic; D051716:Replication Protein A / Q000378:metabolism*; D012441:Saccharomyces cerevisiae / Q000502:physiology*; D029701:Saccharomyces cerevisiae Proteins / Q000378:metabolism*
chemical_list: D004277:DNA, Single-Stranded; C497197:RAD52 protein, S cerevisiae; D051721:Rad52 DNA Repair and Recombination Protein; D051716:Replication Protein A; D029701:Saccharomyces cerevisiae Proteins; D004247:DNA; C495151:RAD51 protein, S cerevisiae; D051135:Rad51 Recombinase