title: DNA strand breaks signal the induction of DNA double-strand break repair in Saccharomyces cerevisiae.
abstract: Genotoxic stress induces a checkpoint signaling cascade to generate a stress response. Saccharomyces cerevisiae shows an altered radiation response under different type of stress. Although the induction of repair has been implicated in enhanced survival after exposure to the challenging stress, the nature of the signal remains poorly understood. This study demonstrates that low doses of gamma radiation and bleomycin induce RAD52-dependent recombination repair pathway in the wild-type strain D-261. Prior exposure of cells to DNA-damaging agents (gamma radiation or bleomycin) equips them better for the subsequent damage caused by challenging doses. However, exposure to UV light, which does not cause strand breaks, was ineffective. This was confirmed by PFGE studies. This indicates that the strand breaks probably serve as the signal for induction of the recombination repair pathway while pyrimidine dimers do not. The nature of the induced repair was investigated by mutation scoring in special strain D-7, which showed that the induced repair is essentially error free.
authors.affiliation: Radiation Biology and Health Sciences Division, Bhabha Atomic Research Centre, Mumbai, India 400085. ksrakesh@yahoo.com
authors.forename: Rakesh Kumar
authors.initials: RK
authors.lastname: Singh
authors.forename: Malini
authors.initials: M
authors.lastname: Krishna
mesh_terms: D001761:Bleomycin / Q000494:pharmacology; D002470:Cell Survival / Q000187:drug effects / Q000528:radiation effects; D015825:Chromosomes, Fungal / Q000235:genetics; D004249:DNA Damage / Q000502:physiology*; D004260:DNA Repair / Q000187:drug effects / Q000528:radiation effects; D005720:Gamma Rays; D009154:Mutation / Q000528:radiation effects; D051721:Rad52 DNA Repair and Recombination Protein / Q000235:genetics / Q000378:metabolism; D012441:Saccharomyces cerevisiae / Q000166:cytology / Q000187:drug effects / Q000235:genetics* / Q000528:radiation effects*; D029701:Saccharomyces cerevisiae Proteins / Q000235:genetics / Q000378:metabolism; D014466:Ultraviolet Rays
chemical_list: C497197:RAD52 protein, S cerevisiae; D051721:Rad52 DNA Repair and Recombination Protein; D029701:Saccharomyces cerevisiae Proteins; D001761:Bleomycin