The RAD9-dependent gene trans-activation is required for excision repair of active genes but not for repair of non-transcribed DNA.
The Saccharomyces cerevisiae RAD9 and RAD24 are two cell cycle checkpoint genes required for UV-dependent up-regulation of a battery of genes involved in different metabolic pathways. RAD9 is also implicated in nucleotide excision repair (NER); however, its precise role is still unclear. For the present study, we made use of the high-resolution primer extension technique to show that the RAD9-deleted cells are deficient in the repair of both strands of the URA3 gene. Interestingly, this defect was suppressed by over-expressing the RAD24 gene, suggesting that the role of RAD9 in NER is indirect probably through the UV-dependent trans-activation of some NER factors. Accordingly, we present evidence that the inhibition of UV-related de novo protein synthesis by cycloheximide has no effect on the rad9Delta mutant while it suppresses the correcting effect of RAD24 over-expression. Importantly, we have also shown that RAD9 has no role in repair of transcriptionally inactive DNA sequences (URA3 promoter and transcriptionally silent GAL10 gene). Furthermore, de novo protein synthesis was not required for NER in the absence of transcription-coupled NER. This implies that RAD9-dependent gene up-regulation is required for NER only when this process is coupled to transcription.
King Faisal Specialist Hospital & Research Center, Department of Biological and Medical Research, Riyadh, Saudi Arabia.
Nisreen M
NM
Al-Moghrabi
Ibtehaj S
IS
Al-Sharif
Abdelilah
A
Aboussekhra
D018797:Cell Cycle Proteins / Q000378:metabolism*; D003513:Cycloheximide / Q000494:pharmacology; D004260:DNA Repair / Q000187:drug effects / Q000235:genetics* / Q000528:radiation effects; D004271:DNA, Fungal / Q000235:genetics*; D005656:Fungal Proteins / Q000235:genetics; D015966:Gene Expression Regulation, Fungal / Q000187:drug effects / Q000528:radiation effects; D005800:Genes, Fungal; D047908:Intracellular Signaling Peptides and Proteins / Q000378:metabolism; D009154:Mutation / Q000235:genetics; D011401:Promoter Regions, Genetic; D014176:Protein Biosynthesis / Q000187:drug effects / Q000528:radiation effects; D011740:Pyrimidine Dimers / Q000378:metabolism; D012441:Saccharomyces cerevisiae / Q000187:drug effects / Q000235:genetics* / Q000528:radiation effects; D014158:Transcription, Genetic / Q000187:drug effects / Q000528:radiation effects; D015533:Transcriptional Activation / Q000187:drug effects / Q000235:genetics* / Q000528:radiation effects; D014466:Ultraviolet Rays
D018797:Cell Cycle Proteins; D004271:DNA, Fungal; D005656:Fungal Proteins; D047908:Intracellular Signaling Peptides and Proteins; D011740:Pyrimidine Dimers; C088385:RAD24 protein, S cerevisiae; C069930:rad9 protein; D003513:Cycloheximide