Photoreactivation of UV-induced cyclobutane pyrimidine dimers in the MFA2 gene of Saccharomyces cerevisiae.
Photoreactive repair (PR) of cyclobutane pyrimidine dimers (CPDs) was mapped at nucleotide resolution in nucleotide excision repair (NER) proficient and deficient strains for the transcriptionally active and inactive MFA2 gene. Enhanced PR in the control region occurred in areas where no nucleosomes were present, particularly linker regions in the alpha mating type. The presence of excision plus transcriptional activation alleviated this preference, causing repair in the regions that were linker and core in the alpha mating type to be the same in this strain. Transcription had no effect on photoreactive repair in transcribed and downstream regions of MFA2, where similar rates were observed for specific CPDs in both strands. The presence of positioned nucleosomes in alpha mating types revealed slow repair in the nucleosome core, with faster repair occurring at the 3' and 5' edges. These data support the evidence that CPDs are repaired quicker in nucleosome-free regions and at edges of nucleosomes. CPDs in the linker regions are repaired more efficiently in the transcriptionally inactive strains, suggesting that nucleosome movement associated with transcription of MFA2 hampers PR irrespective of the strand. Proficient NER influenced PR in the TATA and Mcm1 binding sites by enhancing it, particularly when transcription was activated.
Morse
Nerys R
NR
School of Biological Sciences, University of Wales Swansea, Singleton Park, Swansea SA2 8PP, UK.
Meniel
Valerie
V
Waters
Raymond
R
D001345:Autoradiography; D004249:DNA Damage; D004260:DNA Repair; D045643:DNA Repair Enzymes; D005656:Fungal Proteins / Q000235:genetics; D005800:Genes, Fungal; D049770:Genes, Mating Type, Fungal; D009154:Mutation; D009707:Nucleosomes / Q000378:metabolism; D011401:Promoter Regions, Genetic; D011740:Pyrimidine Dimers / Q000378:metabolism*; D012441:Saccharomyces cerevisiae / Q000235:genetics* / Q000378:metabolism; D029701:Saccharomyces cerevisiae Proteins; D014158:Transcription, Genetic; D014466:Ultraviolet Rays
D005656:Fungal Proteins; D009707:Nucleosomes; D011740:Pyrimidine Dimers; C072975:RAD14 protein, S cerevisiae; D029701:Saccharomyces cerevisiae Proteins; D045643:DNA Repair Enzymes