title: RAD51-independent inverted-repeat recombination by a strand-annealing mechanism.
abstract: Recombination between inverted repeats is RAD52 dependent, but reduced only modestly in the rad51Δ mutant. RAD59 is required for RAD51-independent inverted-repeat recombination, but no clear mechanism for how recombination occurs in the absence of RAD51 has emerged. Because Rad59 is thought to function as an accessory factor for the single-strand annealing activity of Rad52 one possible mechanism for spontaneous recombination could be by strand annealing between repeats at a stalled replication fork. Here we demonstrate the importance of the Rad52 single-strand annealing activity for generating recombinants by showing suppression of the rad52Δ, rad51Δ rad52Δ and rad52Δ rad59Δ inverted-repeat recombination defects by the rfa1-D228Y mutation. In addition, formation of recombinants in the rad51Δ mutant was sensitive to the distance between the inverted repeats, consistent with a replication-based mechanism. Deletion of RAD5 or RAD18, which are required for error-free post-replication repair, reduced the recombination rate in the rad59Δ mutant, but not in wild type. These data are consistent with RAD51-independent recombinants arising by a faulty template switch mechanism that is distinct from nascent strand template switching.
authors.affiliation: Department of Microbiology & Immunology, Columbia University Medical Center, 701 W. 168th St, New York, NY 10032, USA.
authors.forename: Christina
authors.initials: C
authors.lastname: Mott
authors.forename: Lorraine S
authors.initials: LS
authors.lastname: Symington
mesh_terms: D000483:Alleles; D004260:DNA Repair; D004277:DNA, Single-Stranded / Q000235:genetics / Q000378:metabolism; D023061:Gene Order; D005800:Genes, Fungal / Q000235:genetics; D055029:Inverted Repeat Sequences / Q000235:genetics*; D009154:Mutation; D051135:Rad51 Recombinase / Q000235:genetics; D051721:Rad52 DNA Repair and Recombination Protein / Q000235:genetics / Q000378:metabolism; D011995:Recombination, Genetic / Q000235:genetics*; D015003:Yeasts / Q000235:genetics / Q000378:metabolism
chemical_list: D004277:DNA, Single-Stranded; D051721:Rad52 DNA Repair and Recombination Protein; D051135:Rad51 Recombinase