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Lethal and mutagenic effects of 8-methoxypsoralen-induced lesions on plasmid DNA.
- Source :
-
Mutation research [Mutat Res] 1987 Jan; Vol. 176 (1), pp. 21-8. - Publication Year :
- 1987
-
Abstract
- The genotoxic effect of 8-methoxypsoralen damages (monoadducts and crosslinks) on plasmid DNA was studied. pBR322 DNA was treated with several concentrations of 8-methoxypsoralen plus fixed UVA light irradiation. After transformation into E. coli cells with different repair capacities (uvrA, recA and wild-type), plasmid survival and mutagenesis in ampicillin- and tetracycline-resistant genes were analysed. Results showed that crosslinks were extremely lethal in all 3 strains; indeed, it seemed that they were not repaired even in proficient bacteria. Monoadducts were also found to be lethal although they were removed to some extent by the excision-repair pathway (uvrA-dependent). Damaged plasmid DNA appeared to induce mutagenic repair, but only in the wild-type strain. In order to study the influence of the SOS response on plasmid recovery, preirradiation of the host cells was also performed. Preirradiation of the uvrA or wild-type strains significantly increased plasmid recovery. Consistent with the expectations of SOS repair, no effect was observed in preirradiated recA cells. Plasmid recovery in the excision-deficient strain was mainly achieved by the mutagenic repair of some fraction of the lesions, probably monoadducts. The greatest increase in plasmid recovery was found in the wild-type strain. This likely involved the repair of monoadducts and some fraction of the crosslinks. We conclude that repair in preirradiated repair-proficient cells is carried out mainly by an error-free pathway, suggesting enhancement of the excision repair promoted by the induction of SOS functions.
Details
- Language :
- English
- ISSN :
- 0027-5107
- Volume :
- 176
- Issue :
- 1
- Database :
- MEDLINE
- Journal :
- Mutation research
- Publication Type :
- Academic Journal
- Accession number :
- 3540649
- Full Text :
- https://doi.org/10.1016/0027-5107(87)90248-x