The NC2 repressor is dispensable in yeast mutated for the Sin4p component of the holoenzyme and plays roles similar to Mot1p in vivo.
NC2 (Dr1/DRAP1) and Mot1p are global repressors of transcription that have been isolated in both Saccharomyces cerevisiae and humans. NC2 is a dimeric histone-fold complex that represses RNA polymerase II transcription through binding to TBP and inhibition of TFIIA and TFIIB. Mot1p is an ATPase that removes DNA-bound TBP upon ATP hydrolysis. In this work, we studied the core promoter specificity of NC2 in vivo using a strain that carries mutated NC2beta activity. We show that NC2, like Mot1p, is required for transcription of the HIS3 and HIS4 TATA-less core promoters. Furthermore, whereas neither Mot1p nor NC2 appear to function as repressors of the HIS3 gene in cells growing exponentially in glucose, we find that both are required for repression of the HIS3 TATA promoter when cells go through the diauxic shift. Thus, the activity of these factors is similarly regulated depending upon the physiological conditions, and it appears that core promoters activated or repressed by them in vivo might be distinguishable by whether or not they contain a canonical TATA sequence. Finally, although NC2 is an essential factor for yeast viability, we isolated a mutation in a non-essential component of the holoenzyme, Sin4p, that bypasses the requirement for NC2.
Lemaire
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Département de Biochimie Médicale, CMU, 1 rue Michel Servet, 1211 Geneva 4, Switzerland.
Xie
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Meisterernst
M
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Collart
M A
MA
D000251:Adenosine Triphosphatases; D000429:Alcohol Oxidoreductases; D000619:Aminohydrolases; D004265:DNA Helicases / Q000378:metabolism*; D005656:Fungal Proteins / Q000235:genetics / Q000378:metabolism; D015698:Genomic Library; D006836:Hydro-Lyases / Q000235:genetics; D056892:Mediator Complex; D009154:Mutation; D010750:Phosphoproteins / Q000378:metabolism; D011755:Pyrophosphatases; D012319:RNA Polymerase II / Q000378:metabolism*; D012097:Repressor Proteins / Q000378:metabolism; D012441:Saccharomyces cerevisiae / Q000235:genetics*; D029701:Saccharomyces cerevisiae Proteins; D012641:Selection, Genetic; D013489:Suppression, Genetic; D016385:TATA Box; D035381:TATA-Binding Protein Associated Factors; D015534:Trans-Activators; D014157:Transcription Factors / Q000378:metabolism*; D014158:Transcription, Genetic
D005656:Fungal Proteins; D056892:Mediator Complex; D010750:Phosphoproteins; D012097:Repressor Proteins; C076878:SIN4 protein, S cerevisiae; D029701:Saccharomyces cerevisiae Proteins; D035381:TATA-Binding Protein Associated Factors; D015534:Trans-Activators; D014157:Transcription Factors; C075995:down-regulator of transcription 1; D000429:Alcohol Oxidoreductases; C092116:HIS4 protein, S cerevisiae; D012319:RNA Polymerase II; D000619:Aminohydrolases; D000251:Adenosine Triphosphatases; C073676:MOT1 protein, S cerevisiae; D011755:Pyrophosphatases; D004265:DNA Helicases; D006836:Hydro-Lyases; C021434:imidazoleglycerolphosphate dehydratase