Molecular dosimetry of 8-MOP + UVA-induced DNA photoadducts in Saccharomyces cerevisiae: correlation of lesions number with genotoxic potential.
Acid hydrolysis of purified DNA extracted from cells of a haploid repair-proficient (RAD) yeast strain that had been treated with 8-MOP + UVA revealed the existence of two major and one minor thymine photoproduct. At survival levels of the RAD strain between 100% and 1% furanside monoadducts constituted the major DNA lesion, followed by diadducts that, at the lowest survival level, nearly reached 50% of the thymine photoproducts; pyrone-side monoadducts were only detectable at the highest UVA exposure dose applied and clearly constitute a minority photoproduct. The number of induced diadducts was verified by determination of interstrand cross-links via denaturation and renaturation of 8-MOP + UVA-treated DNA from RAD and rad2 yeast strain. 8-MOP + UVA was shown to induce two types of locus-specific mutations: reversion of the lys1-1 ochre allele was between 20- to 50-fold higher than that of the his4-38 frameshift allele. Mutant yield for the lys 1-1 reversion was the same in RAD and excision repair-deficient rad2-20 strains whereas frameshift mutagenesis was about eightfold higher in the rad2-20 background.
Bankmann
M
M
Institut für Mikrobiologie der J.W. Goethe-Universität, Frankfurt Main F.R.G.
Brendel
M
M
D003432:Cross-Linking Reagents; D004271:DNA, Fungal / Q000187:drug effects / Q000235:genetics / Q000528:radiation effects*; D008730:Methoxsalen / Q000494:pharmacology; D009154:Mutation; D010777:Photochemistry; D012441:Saccharomyces cerevisiae / Q000187:drug effects / Q000235:genetics / Q000528:radiation effects*; D014466:Ultraviolet Rays
D003432:Cross-Linking Reagents; D004271:DNA, Fungal; D008730:Methoxsalen