title: Conservative repair of a chromosomal double-strand break by single-strand DNA through two steps of annealing.
abstract: The repair of chromosomal double-strand breaks (DSBs) is essential to normal cell growth, and homologous recombination is a universal process for DSB repair. We explored DSB repair mechanisms in the yeast Saccharomyces cerevisiae using single-strand oligonucleotides with homology to both sides of a DSB. Oligonucleotide-directed repair occurred exclusively via Rad52- and Rad59-mediated single-strand annealing (SSA). Even the SSA domain of human Rad52 provided partial complementation for a null rad52 mutation. The repair did not involve Rad51-driven strand invasion, and moreover the suppression of strand invasion increased repair with oligonucleotides. A DSB was shown to activate targeting by oligonucleotides homologous to only one side of the break at large distances (at least 20 kb) from the break in a strand-biased manner, suggesting extensive 5' to 3' resection, followed by the restoration of resected DNA to the double-strand state. We conclude that long resected chromosomal DSB ends are repaired by a single-strand DNA oligonucleotide through two rounds of annealing. The repair by single-strand DNA can be conservative and may allow for accurate restoration of chromosomal DNAs with closely spaced DSBs.
authors.affiliation: Head Chromosome Stability Section, Laboratory of Molecular Genetics, National Institute of Environmental Health Sciences, NIH, Research Triangle Park, NC 27709, USA.
authors.forename: Francesca
authors.initials: F
authors.lastname: Storici
authors.forename: Joyce R
authors.initials: JR
authors.lastname: Snipe
authors.forename: Godwin K
authors.initials: GK
authors.lastname: Chan
authors.forename: Dmitry A
authors.initials: DA
authors.lastname: Gordenin
authors.forename: Michael A
authors.initials: MA
authors.lastname: Resnick
mesh_terms: D015825:Chromosomes, Fungal / Q000235:genetics*; D004249:DNA Damage / Q000235:genetics*; D004260:DNA Repair / Q000235:genetics*; D004271:DNA, Fungal / Q000235:genetics*; D009841:Oligonucleotides / Q000235:genetics; D051721:Rad52 DNA Repair and Recombination Protein / Q000235:genetics; D011995:Recombination, Genetic / Q000235:genetics; D012441:Saccharomyces cerevisiae / Q000235:genetics*; D029701:Saccharomyces cerevisiae Proteins / Q000235:genetics
chemical_list: D004271:DNA, Fungal; D009841:Oligonucleotides; C497197:RAD52 protein, S cerevisiae; D051721:Rad52 DNA Repair and Recombination Protein; D029701:Saccharomyces cerevisiae Proteins