Repair of 8-methoxypsoralen photoinduced cross-links in yeast. Analysis by alkaline step-elution and electron microscopy

The repair of interstrand cross-links induced by 8-methoxypsoralen plus UVA (365 nm) radiation DNA was analyzed in diploid strains of the yeast Saccharomyces cerevisiae. The strains employed were the wild-type D7 and derivatives homozygous for the rad18-1 or the rad3-12 mutation. Alkaline step-eluti...

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Published inMolecular & general genetics Vol. 228; no. 3; p. 335
Main Authors Cundari, E, Dardalhon, M, Rousset, S, Averbeck, D
Format Journal Article
LanguageEnglish
Published Germany 01.09.1991
Subjects
adn
Cross-Linking Reagents
dna
DNA Repair
DNA, Fungal - genetics
DNA, Fungal - ultrastructure
electrical engineering
Fungal Proteins - genetics
genie electrique
Hydrogen-Ion Concentration
immobilisation
immobilization
ingenieria electrica
inmovilizacion
light
lumiere
luz
Methoxsalen - toxicity
Microscopy, Electron
saccharomyces cerevisiae
Saccharomyces cerevisiae - drug effects
Ultraviolet Rays
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Summary:The repair of interstrand cross-links induced by 8-methoxypsoralen plus UVA (365 nm) radiation DNA was analyzed in diploid strains of the yeast Saccharomyces cerevisiae. The strains employed were the wild-type D7 and derivatives homozygous for the rad18-1 or the rad3-12 mutation. Alkaline step-elution and electron microscopy were performed to follow the process of induction and removal of photoinduced cross-links. In accordance with previous reports, the D7 rad3-12 strain failed to remove the induced lesions and could not incise cross-links. The strain D7 rad18-1 was nearly as efficient in the removal of 8-MOP photoadducts after 2 h of post-treatment incubation as the D7 RAD+ wild-type strain. However, as demonstrated by alkaline step-elution and electron microscopic analysis, the first incision step at DNA cross-links was three times more effective in D7 rad18-1 than in D7 RAD+. This is consistent with the hypothesis that the RAD18 gene product is involved in the filling of gaps resulting from persistent non-informational DNA lesions generated by the endonucleolytic processing of DNA cross-links. Absence of this gene product may lead to extensive strand breakage and decreased recognition of such lesions by structural repair systems.
Bibliography:F30
F
ISSN:0026-8925
1432-1874
DOI:10.1007/BF00260625