UVA-induced binding of 8-methoxypsoralen to cells of Saccharomyces cerevisiae: separation and characterization of DNA photoadducts.
We present methods for the determination of UVA-induced binding of 8-methoxypsoralen (8-MOP) to nucleic acids and protein and for a quantitative assay of radioactively labelled 8-MOP plus UVA induced DNA photoproducts in the yeast Saccharomyces cerevisiae. For the dose range up to 60 kJ m-2, with a wild-type survival of 1% or higher, binding to DNA is 100-fold and to RNA 10- to 20-fold more efficient than that to protein. Between 20% and 65% of the 8-MOP binds to macromolecules that are neither nucleic acids nor protein. The number of DNA-bound 8-MOP molecules for the haploid genome rises from 14 (unirradiated control) to 349 at the highest UVA exposure dose (60 kJ m-2). Gel chromatography reveals three types of DNA thymine photoproduct, the pyrone-side monoadducts, the furan-side monoadducts and the diadducts. Among these, pyrone-side monoadducts always constitute the smallest fraction, regardless of whether the treatment is with in vitro or in vivo 8-MOP plus UVA.
Bankmann
M
M
Institut für Mikrobiologie der J. W. Goethe-Universität, Frankfurt/Main, F.R.G.
Brendel
M
M
D002853:Chromatography, Liquid; D002855:Chromatography, Thin Layer; D004249:DNA Damage; D004271:DNA, Fungal / Q000378:metabolism* / Q000528:radiation effects; D008730:Methoxsalen / Q000378:metabolism*; D010777:Photochemistry; D012441:Saccharomyces cerevisiae / Q000378:metabolism*; D014466:Ultraviolet Rays
D004271:DNA, Fungal; D008730:Methoxsalen