Site and strand specificity of UVB mutagenesis in the SUP4-o gene of yeast

• Published in: Proceedings of the National Academy of Sciences - PNAS 1990-11, Vol.87 (22), p.9005-9009
• Main Authors: Armstrong, John D., Kunz, Bernard A.
• Format: Article
• Language: English
• Subjects: 560130 - Radiation Effects on Microorganisms; Base Sequence; Biological and medical sciences; BIOLOGICAL EFFECTS; BIOLOGICAL RADIATION EFFECTS; BIOLOGICAL RECOVERY; BIOLOGICAL REPAIR; Chromosome Deletion; Data transcription; Dimers; DNA; DNA Damage; DNA REPAIR; DNA SEQUENCING; ELECTROMAGNETIC RADIATION; EUMYCOTA; expresion genica; expression des genes; Fundamental and applied biological sciences. Psychology; FUNGI; gene expression; GENE MUTATIONS; GENES; Genes, Fungal; Genes, Suppressor; GENETIC EFFECTS; Genetic mutation; GENETIC RADIATION EFFECTS; Irradiation; Lesions; levadura; levure; MICROORGANISMS; Molecular and cellular biology; Molecular genetics; Molecular Sequence Data; mutacion; MUTAGENESIS; Mutagenesis. Repair; mutation; MUTATIONS; NUCLEIC ACIDS; nucleotide; nucleotides; nucleotidos; ORGANIC COMPOUNDS; PLANTS; PYRIMIDINE DIMERS; radiacion ultravioleta; RADIATION EFFECTS; RADIATION, THERMAL, AND OTHER ENVIRON. POLLUTANT EFFECTS ON LIVING ORGS. AND BIOL. MAT; RADIATIONS; RADIOINDUCTION; rayonnement ultraviolet; RECOVERY; REPAIR; RNA; RNA, Transfer, Tyr; SACCHAROMYCES; SACCHAROMYCES CEREVISIAE; Saccharomyces cerevisiae - genetics; STRUCTURAL CHEMICAL ANALYSIS; TRANSCRIPTION; TRANSFER RNA; ULTRAVIOLET RADIATION; Ultraviolet Rays; YEASTS
• ISSN: 0027-8424; 1091-6490
• DOI: 10.1073/pnas.87.22.9005

DNA sequencing was used to characterize 208 mutations induced in the SUP4-o tRNA gene of the yeast Saccharomyces cerevisiae by UVB (285-320 nm) radiation. The results were compared to those for an analysis of 211 SUP4-o mutations induced by 254-nm UVC light. In each case, > 90% of the mutations were single base-pair changes but G·C → A·T transitions predominated and accounted for more of the mutations induced by UVB than UVC. Double substitutions, single base-pair deletions, and more complex events were also recovered. However, UVB induced 3-fold more tandem substitutions than UVC and nontandem double events were detected only after irradiation with UVC. Virtually all induced substitutions occurred at sites where the pyrimidine of the base pair was part of a dipyrimidine sequence. Although the site specificities were consistent with roles for cyclobutane dimers and pyrimidine-pyrimidone(6-4) lesions in mutation induction, preliminary photoreactivation data implicated cyclobutane dimers as the major form of premutational DNA damage for both agents. Intriguingly, there was a preference for both UVB- and UVC-induced mutations to occur at sites where the dipyrimidine was on the transcribed strand.