Induction and repair of closely opposed pyrimidine dimers in Saccharomyces cerevisiae

Mutat Res. 1987 Nov;184(3):197-207. doi: 10.1016/0167-8817(87)90017-4.


Pyrimidine dimer-DNA glycosylase activity prepared from Micrococcus luteus has been used to develop an enzyme-sensitive site assay for the detection and quantification of closely opposed pyrimidine dimers in the nuclear DNA of UV-irradiated yeast. With this assay, closely opposed dimers were found to be induced as a linear function of dose from 0 to 200 J/m2 (254 nm). Closely opposed dimer frequencies decreased during the incubation of UV-irradiated, excision repair-proficient cells under liquid-holding conditions in the dark and during post-irradiation exposure of excision-deficient cells to photoreactivating light. Incubation of excision-deficient cells in the dark had no effect on the frequency of closely opposed dimers for up to 16 h. These results indicate that closely opposed dimers in UV-irradiated yeast are subject to repair by enzymatic photoreactivation and/or by dark-repair processes dependent, at least in part, upon functions necessary for normal excision repair. The genetic and biochemical implications of these results are discussed.

Publication types

  • Research Support, Non-U.S. Gov't
  • Research Support, U.S. Gov't, P.H.S.

MeSH terms

  • DNA Damage*
  • DNA Glycosylases*
  • DNA Repair* / radiation effects
  • DNA, Fungal / genetics
  • DNA, Fungal / radiation effects*
  • Dose-Response Relationship, Radiation
  • N-Glycosyl Hydrolases / metabolism
  • Pyrimidine Dimers / metabolism*
  • Saccharomyces cerevisiae / genetics*
  • Ultraviolet Rays


  • DNA, Fungal
  • Pyrimidine Dimers
  • DNA Glycosylases
  • N-Glycosyl Hydrolases
  • deoxyribopyrimidine endonucleosidase