Transcription-coupled DNA repair in yeast transcription factor IIE (TFIIE) mutants

We examined the role of yeast transcription initiation factor IIE (TFIIE) in eukaryotic transcription-coupled repair (TCR), the preferential removal of DNA damage from the transcribed strands of genes over non-transcribed sequences. TFIIE can recruit the transcription initiation/repair factor TFIIH to the RNA polymerase II (RNA pol II) initiation complex to facilitate promoter clearance. Following exposure to UV radiation, the RNA pol II elongation complex is blocked at sites of UV-induced DNA damage, and may be recognized by nucleotide excision repair proteins, thus enabling TCR. The TFA1 gene encodes the large subunit of TFIIE. We determined how DNA repair is affected by TFA1 conditional mutations. In particular, we find proficient TCR in a heat-sensitive tfa1 mutant at the non-permissive temperature during which growth is inhibited and overall RNA pol II transcription is reported to be inhibited. We demonstrate that transcription of the RPB2 gene was reduced, but readily detectable, in the heat-sensitive tfa1 mutant at the non-permissive temperature and thereby prove that TCR does occur in an expressed gene in the absence of TFIIE in vivo. We demonstrate that TCR occurs even at low levels of transcription.