UV light-induced cyclobutane pyrimidine dimers are mutagenic in mammalian cells
We used a simian virus 40-based shuttle vector plasmid, pZ189, to determine the role of pyrimidine cyclobutane dimers in UV light-induced mutagenesis in monkey cells. The vector DNA was UV irradiated and then introduced into monkey cells by transfection. After replication, vector DNA was recovered from the cells and tested for mutations in its supF suppressor tRNA marker gene by transformation of Escherichia coli carrying a nonsense mutation in the beta-galactosidase gene. When the irradiated vector was treated with E. coli photolyase prior to transfection, pyrimidine cyclobutane dimers were removed selectively. Removal of approximately 90% of the pyrimidine cyclobutane dimers increased the biological activity of the vector by 75% and reduced its mutation frequency by 80%. Sequence analysis of 72 mutants recovered indicated that there were significantly fewer tandem double-base changes and G X C----A X T transitions (particularly at CC sites) after photoreactivation of the DNA. UV-induced photoproducts remained (although at greatly reduced levels) at all pyr-pyr sites after photoreactivation, but there was a relative increase in photoproducts at CC and TC sites and a relative decrease at TT and CT sites, presumably due to a persistence of (6-4) photoproducts at some CC and TC sites. These observations are consistent with the fact that mutations were found after photoreactivation at many sites at which only cyclobutane dimers would be expected to occur. From these results we conclude that UV-induced pyrimidine cyclobutane dimers are mutagenic in DNA replicated in monkey cells.
- Research Organization:
- National Cancer Institute, Bethesda, MD
- OSTI ID:
- 7084198
- Journal Information:
- Mol. Cell. Biol.; (United States), Vol. 10
- Country of Publication:
- United States
- Language:
- English
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Related Subjects
DNA
GENETIC RADIATION EFFECTS
IRRADIATION
PYRIMIDINE DIMERS
MUTAGENESIS
ANIMAL CELLS
DNA REPLICATION
ESCHERICHIA COLI
GENES
MONKEYS
MUTATION FREQUENCY
MUTATIONS
PHOTOREACTIVATION
PLASMIDS
SIMIAN VIRUS
ULTRAVIOLET RADIATION
ANIMALS
BACTERIA
BIOLOGICAL EFFECTS
BIOLOGICAL RADIATION EFFECTS
BIOLOGICAL RECOVERY
BIOLOGICAL REPAIR
CELL CONSTITUENTS
ELECTROMAGNETIC RADIATION
GENETIC EFFECTS
MAMMALS
MICROORGANISMS
NUCLEIC ACID REPLICATION
NUCLEIC ACIDS
ORGANIC COMPOUNDS
PARASITES
PRIMATES
RADIATION EFFECTS
RADIATIONS
RECOVERY
REPAIR
VERTEBRATES
VIRUSES
560120* - Radiation Effects on Biochemicals
Cells
& Tissue Culture