Radiation-induced chromosome aberrations in Saccharomyces cerevisiae: influence of DNA repair pathways.
Radiation-induced chromosome aberrations, particularly exchange-type aberrations, are thought to result from misrepair of DNA double-strand breaks. The relationship between individual pathways of break repair and aberration formation is not clear. By electrophoretic karyotyping of single-cell clones derived from irradiated cells, we have analyzed the induction of stable aberrations in haploid yeast cells mutated for the RAD52 gene, the RAD54 gene, the HDF1(= YKU70) gene, or combinations thereof. We found low and comparable frequencies of aberrational events in wildtype and hdf1 mutants, and assume that in these strains most of the survivors descended from cells that were in G2 phase during irradiation and therefore able to repair breaks by homologous recombination between sister chromatids. In the rad52 and the rad54 strains, enhanced formation of aberrations, mostly exchange-type aberrations, was detected, demonstrating the misrepair activity of a rejoining mechanism other than homologous recombination. No aberration was found in the rad52 hdf1 double mutant, and the frequency in the rad54 hdf1 mutant was very low. Hence, misrepair resulting in exchange-type aberrations depends largely on the presence of Hdf1, a component of the nonhomologous end-joining pathway in yeast.
Friedl
A A
AA
GSF-Forschungszentrum für Umwelt und Gesundheit, Institut für Strahlenbiologie, Oberschleissheim, Germany. friedl@gsf.de
Kiechle
M
M
Fellerhoff
B
B
Eckardt-Schupp
F
F
D002869:Chromosome Aberrations; D015825:Chromosomes, Fungal / Q000235:genetics / Q000528:radiation effects*; D004265:DNA Helicases; D004260:DNA Repair; D045643:DNA Repair Enzymes; D004268:DNA-Binding Proteins / Q000235:genetics; D005656:Fungal Proteins / Q000235:genetics; D005720:Gamma Rays; D007621:Karyotyping; D051721:Rad52 DNA Repair and Recombination Protein; D012441:Saccharomyces cerevisiae / Q000235:genetics / Q000528:radiation effects*; D029701:Saccharomyces cerevisiae Proteins
D004268:DNA-Binding Proteins; D005656:Fungal Proteins; C497197:RAD52 protein, S cerevisiae; D051721:Rad52 DNA Repair and Recombination Protein; D029701:Saccharomyces cerevisiae Proteins; C520769:YKU70 protein, S cerevisiae; C081647:high affinity DNA-binding factor, S cerevisiae; C075468:RAD54 protein, S cerevisiae; D004265:DNA Helicases; D045643:DNA Repair Enzymes