title: Requirement for end-joining and checkpoint functions, but not RAD52-mediated recombination, after EcoRI endonuclease cleavage of Saccharomyces cerevisiae DNA.
abstract: RAD52 and RAD9 are required for the repair of double-strand breaks (DSBs) induced by physical and chemical DNA-damaging agents in Saccharomyces cerevisiae. Analysis of EcoRI endonuclease expression in vivo revealed that, in contrast to DSBs containing damaged or modified termini, chromosomal DSBs retaining complementary ends could be repaired in rad52 mutants and in G1-phase Rad+ cells. Continuous EcoRI-induced scission of chromosomal DNA blocked the growth of rad52 mutants, with most cells arrested in G2 phase. Surprisingly, rad52 mutants were not more sensitive to EcoRI-induced cell killing than wild-type strains. In contrast, endonuclease expression was lethal in cells deficient in Ku-mediated end joining. Checkpoint-defective rad9 mutants did not arrest cell cycling and lost viability rapidly when EcoRI was expressed. Synthesis of the endonuclease produced extensive breakage of nuclear DNA and stimulated interchromosomal recombination. These results and those of additional experiments indicate that cohesive ended DSBs in chromosomal DNA can be accurately repaired by RAD52-mediated recombination and by recombination-independent complementary end joining in yeast cells.
authors.affiliation: Laboratory of Molecular Genetics, National Institute of Environmental Health Sciences, Research Triangle Park, North Carolina 27709, USA.
authors.forename: L K
authors.initials: LK
authors.lastname: Lewis
authors.forename: J M
authors.initials: JM
authors.lastname: Kirchner
authors.forename: M A
authors.initials: MA
authors.lastname: Resnick
mesh_terms: D034961:Antigens, Nuclear; D018797:Cell Cycle Proteins; D004265:DNA Helicases; D004260:DNA Repair; D004271:DNA, Fungal / Q000378:metabolism*; D004268:DNA-Binding Proteins / Q000378:metabolism*; D015246:Deoxyribonuclease EcoRI / Q000378:metabolism*; D005656:Fungal Proteins / Q000378:metabolism*; D000072200:Ku Autoantigen; D009687:Nuclear Proteins / Q000378:metabolism; D051721:Rad52 DNA Repair and Recombination Protein; D011995:Recombination, Genetic; D012441:Saccharomyces cerevisiae / Q000235:genetics* / Q000378:metabolism; D029701:Saccharomyces cerevisiae Proteins
chemical_list: D034961:Antigens, Nuclear; D018797:Cell Cycle Proteins; D004271:DNA, Fungal; D004268:DNA-Binding Proteins; D005656:Fungal Proteins; D009687:Nuclear Proteins; C497197:RAD52 protein, S cerevisiae; D051721:Rad52 DNA Repair and Recombination Protein; D029701:Saccharomyces cerevisiae Proteins; C081647:high affinity DNA-binding factor, S cerevisiae; C069930:rad9 protein; D015246:Deoxyribonuclease EcoRI; D004265:DNA Helicases; C106893:XRCC5 protein, human; C000606509:Xrcc6 protein, human; D000072200:Ku Autoantigen