Mechanisms of UV Mutagenesis in Yeast

  • Christopher W. Lawrence
  • Roshan Christensen
  • Ann Schwartz


UV mutagenesis in yeast depends on the function of the RAD6 locus, a gene that is also responsible for a substantial fraction of wild-type resistance, suggesting that this eukaryote may possess a misrepair mechanism analogous to that proposed for Escherichia coli. The molecular mechanism responsible for RAD6 repair or recovery is not yet known, but it is different from either excision or recombination-dependent repair, processes carried out by the other two main repair pathways in yeast. RAD6-dependent mutagenesis has been found to have the following characteristics.

It is associated at best with only a small fraction of RAD6- dependent repair, the majority of the sensitivity of rad6 mutants being due to their lack of nonmutagenic repair. SRS2 metabolic suppressors restore a substantial fraction of UV resistance to rad6 mutants but do not restore their UV mutability. Strains containing mutations at loci (rev, umr) that are probably more directly involved in mutagenesis are only mildly sensitive, and there is a poor correlation between their sensitivity and mutational deficiency.

UV mutagenesis appears to require a large number of gene functions, perhaps ten or more. Where examined in detail, these genes have been found to be concerned in the production of only a specific range of mutational events, not all of them.

Mating experiments have shown that a substantial fraction, probably 40% or more, of UV-induced mutations are untargeted, that is, occur in lesion-free regions of DNA, UV irradiation, therefore, produces a general reduction in the normally high f fidelity with which DNA is replicated on undamaged templates. It does not appear to be necessary for the causal lesion to be present in the same chromosome as the mutation it induces. The reduction in fidelity may be the consequence of the production of a diffusible factor in UV-irradiated cells, but definite evidence supporting this proposal has not yet been obtained.


Mating Experiment Opposite Mating Type Causal Lesion Frameshift Event Ochre Mutant 
These keywords were added by machine and not by the authors. This process is experimental and the keywords may be updated as the learning algorithm improves.


Unable to display preview. Download preview PDF.

Unable to display preview. Download preview PDF.


  1. Conde, J., and Fink, G. R., 1976, A mutant of SaccharomycesGoogle Scholar
  2. cerevisiae defective for nuclear fusion, Proc. Natl. Acad. Sci. U.S.A., 73:3651.Google Scholar
  3. Culbertson, M. R., Charnas, L., Johnson, M. T., and Fink, G. R., 1977, Frameshifts and frameshift suppressors in Saccharomyces cerevisiae, Genetics, 86: 745.PubMedGoogle Scholar
  4. DiCaprio, L., and Cox, B. S., 1981, The effect of UV irradiation on the molecular weight of pre-existing and newly synthesized DNA, Mutat. Res., 82: 69.CrossRefGoogle Scholar
  5. Fabre, F., and Roman, H., 1977, Genetic evidence for inducibility of recombination competence in yeast, Proc. Natl. Acad. Sci. U.S.A., 74: 1667.PubMedCrossRefGoogle Scholar
  6. Hunnable, E. G., and Cox, B. S., 1971, The genetic control of dark recombination in yeast, Mutat. Res., 13: 297.CrossRefGoogle Scholar
  7. James, A. P., Kilbey, B. J., and Prefontaine, G. J., 1978, The timing of UV mutagenesis in yeast: Continuing mutation in an excision- defective (radl-1) strain, Mol. Gen. Genet., 165:207. 7. Kern, R., and Zimmermann, F. K., 1978, The influence of defects in excision and error-prone repair on spontaneous and induced mitotic recombination and mutation in Saccharomyces cerevisiae, Mol. Gen. Genet., 161: 81.CrossRefGoogle Scholar
  8. Kilbey, B. J., and James, A. P., 1979, The mutagenic potential of unexcised pyrimidine dimers in Saccharomyces cerevisiae radl-1. Evidence from photoreactivation and pedigree analysis, Mutat. Res., 60: 163.PubMedCrossRefGoogle Scholar
  9. Kondo, S., and Ichikawa, H., 1973, Evidence that pretreatment of Escherichia coli cells with N-methyl-N’-nitro-nitrosoguanidine enhances mutability of subsequently infecting phage λ, Mol. Gen. Genet., 126: 319.PubMedCrossRefGoogle Scholar
  10. Lawrence, C. W., 1981, Mutagenesis in Saccharomyces cerevisiae, Adv. Genet., 21, in press.Google Scholar
  11. Lawrence, C. W., and Christensen, R. B., 1979a, Metabolic suppressors of trimethoprim and ultraviolet light sensitivities of Saccharomyces cerevisiae rad6 mutants, J. Bacteriol., 139: 866.PubMedGoogle Scholar
  12. Lawrence, C. W., and Christensen, R. B., 1979b, Ultraviolet-induced reversion of cycl alleles in radiation-sensitive strains of yeast. III. rev3 mutant strains, Genetics, 92: 397.PubMedGoogle Scholar
  13. Lawrence, C. W., and Christensen, R. B., 1980, Undamaged DNA is replicated with low fidelity in UV-irradiated yeast, J. Supramol. Struct., Suppl. 4, 356, abstract.Google Scholar
  14. Lawrence, C. W., Stewart, J. W., Sherman, F., and Christensen, R., 1974, Specificity and frequency of ultraviolet-induced reversion of an iso-l-cytochrome c ochre mutant in radiation-sensitive strains of yeast, J. Mol. Biol., 85: 137.PubMedCrossRefGoogle Scholar
  15. Lawrence, C. W., Stewart, J. W., Sherman, F., and Thomas, F, L. X., 1970, Mutagenesis in ultraviolet-sensitive mutants of yeast, Genetics, 64: s36.Google Scholar
  16. Lemontt, J. F., 1971, Mutants of yeast defective in mutation induced by ultraviolet light, Genetics, 68: 21.PubMedGoogle Scholar
  17. Lemontt, J. F., 1977, Pathways of ultraviolet mutability in Saccharomyces cerevisiae. III. Genetic analysis and properties of mutants resistant to ultraviolet-induced forward mutation, Mutat. Res., 43: 179.PubMedCrossRefGoogle Scholar
  18. Prakash, L., 1977, Repair of pyrimidine dimers in radiation-sensitive mutants rad3, rad4, rad6, and rad9 of Saccharomyces cerevisiae, Mutat. Res., 45: 13.PubMedCrossRefGoogle Scholar
  19. Prakash, L., and Sherman, F., 1973, Mutagenic specificity: Reversion of iso-l-cytochrome £ mutants of yeast, J. Mol, Biol., 79: 65.CrossRefGoogle Scholar
  20. Prakash, S., Prakash, L., Burke, W., and Montelone, B. A., 1979, Effects of the rad52 gene on recombination in Saccharomyces cerevisiae, Genetics, 94: 31.Google Scholar
  21. Resnick, M. A., 1975, The repair of double-strand breaks in chromosomal DNA of yeast, in: “Molecular Mechanisms for Repair of DNA,” Part B, P. C. Hanawalt, and R. M. Setlow, eds., Plenum Press, New York.Google Scholar
  22. Saeki, T., Machida, I., and Nakai, S., 1980, Genetic control of diploid recovery after λ-irradiation in the yeast Saccharomyces cerevisiae, Mutat. Res., 73: 251.PubMedCrossRefGoogle Scholar
  23. Sherman, F., and Slonimski, P.P., 1964, Respiration-deficient mutants of yeast. II. Biochemistry, Biochim. Biophys. Acta, 90: 1.CrossRefGoogle Scholar
  24. Sherman, F., and Stewart, J. W. 1978, The genetic control of yeast iso-1 and iso-2-cytochrome c after 15 years, in: “Biochemistry and Genetics of Yeasts, Pure and Applied Aspects,”M. Bacila, B.L. Horecker, and A.O.M. Stoppani, eds., Academic Press, New YorkGoogle Scholar
  25. Tuite, M. F., and Cox, B. S., 1981, The RAD6+ gene of Saccharomyces cerevisiae codes for two mutationally separable deoxyribonucleic acid repair functions, Mol. Cell. Biol., 1: 153.PubMedGoogle Scholar
  26. Witkin, E. M., and Wermundsen, I. E., 1979, Targeted and untargeted mutagenesis by various inducers of SOS function in Escherichia coli, Cold Spring Harbor Symp. Quant. Biol., 43: 881.PubMedGoogle Scholar

Copyright information

© Plenum Press, New York 1982

Authors and Affiliations

  • Christopher W. Lawrence
    • 1
  • Roshan Christensen
    • 1
  • Ann Schwartz
    • 1
  1. 1.Department of Radiation Biology and BiophysicsUniversity of Rochester, School of Medicine and DentistryRochesterUSA

Personalised recommendations