Verhage R A, Van de Putte P, Brouwer J
Laboratory of Molecular Genetics, Leiden Institute of Chemistry, Leiden University, The Netherlands.
Nucleic Acids Res. 1996 Mar 15;24(6):1020-5. doi: 10.1093/nar/24.6.1020.
Removal of UV-induced pyrimidine dimers from the individual strands of the rDNA locus in Saccharomyces cerevisiae was studied. Yeast rDNA, that is transcribed by RNA polymerase I(RNA pol I), is repaired efficiently, slightly strand-specific and independently of RAD26, which has been implicated in transcription-coupled repair of the RNA pol II transcribed RPB2 gene. No repair of rDNA is observed in rad1,2,3 and 14 mutants, demonstrating that dimer removal from this highly repetitive DNA is accomplished by nucleotide excision repair (NER). In rad7 and rad16 mutants, which are specifically deficient in repair of non-transcribed DNA, there is a clear preferential repair of the transcribed strand of rDNA, indicating that strand-specific and therefore probably transcription-coupled repair of RNA pol I transcribed genes does exist in yeast. Unexpectedly, the transcribed but not the non-transcribed strand of rDNA can be repaired in rad4 mutants, which seem otherwise completely NER-deficient.
研究了酿酒酵母rDNA基因座单链上紫外线诱导的嘧啶二聚体的去除情况。酵母rDNA由RNA聚合酶I(RNA pol I)转录,其修复效率高,具有轻微的链特异性,且独立于RAD26,而RAD26参与RNA聚合酶II转录的RPB2基因的转录偶联修复。在rad1、2、3和14突变体中未观察到rDNA的修复,这表明从这种高度重复的DNA中去除二聚体是通过核苷酸切除修复(NER)完成的。在rad7和rad16突变体中,它们在非转录DNA修复方面存在特异性缺陷,rDNA的转录链有明显的优先修复,这表明酵母中确实存在RNA聚合酶I转录基因的链特异性以及可能的转录偶联修复。出乎意料的是,在rad4突变体中,rDNA的转录链而非非转录链可以被修复,而rad4突变体在其他方面似乎完全缺乏核苷酸切除修复能力。