A SAGA-independent function of SPT3 mediates transcriptional deregulation in a mutant of the Ccr4-not complex in Saccharomyces cerevisiae.
The conserved multi-subunit Ccr4-Not complex regulates gene expression in diverse ways. In this work, we characterize the suppression of temperature sensitivity associated with a mutation in the gene encoding the scaffold subunit of the Ccr4-Not complex, NOT1, by the deletion of SPT3. We determine that the deletion of SPT3, but not the deletion of genes encoding other subunits of the SAGA complex, globally suppresses transcriptional defects of not1-2. We find that transcriptional activation in not1-2 is associated with increased binding of TFIID and SAGA at promoters of upregulated genes, and this is suppressed by the deletion of SPT3. Interestingly, Spt3p-dependent activation of transcription occurs in not1-2 even if the SAGA complex is disrupted by the deletion of SPT7 that encodes a subunit of SAGA required for its integrity. Consistent with a SAGA-independent function of Spt3p, the deletion of SPT3 displays synthetic phenotypes when combined with a deletion of SPT7. Taken together, our results provide a new view of the Spt3 protein by identifying a SAGA-independent function of this protein that is functionally linked to the Ccr4-Not complex.
Department of Microbiology and Molecular Medicine, University of Geneva Medical School, Geneva 1211, Switzerland.
Nicole
N
James
Emilie
E
Landrieux
Martine A
MA
Collart
D015153:Blotting, Western; D018797:Cell Cycle Proteins / Q000502:physiology; D047369:Chromatin Immunoprecipitation; D020869:Gene Expression Profiling; D009154:Mutation; D020411:Oligonucleotide Array Sequence Analysis; D012331:RNA, Fungal / Q000235:genetics / Q000378:metabolism; D012260:Ribonucleases / Q000235:genetics* / Q000378:metabolism; D012441:Saccharomyces cerevisiae / Q000235:genetics* / Q000254:growth & development / Q000378:metabolism; D029701:Saccharomyces cerevisiae Proteins / Q000235:genetics* / Q000378:metabolism / Q000502:physiology*; D017384:Sequence Deletion; D013696:Temperature; D015534:Trans-Activators / Q000502:physiology*; D035362:Transcription Factor TFIID / Q000502:physiology; D014157:Transcription Factors / Q000502:physiology; D014158:Transcription, Genetic
C079592:CDC39 protein, S cerevisiae; D018797:Cell Cycle Proteins; D012331:RNA, Fungal; C507785:SAGA complex, S cerevisiae; C075582:SPT3 protein, S cerevisiae; D029701:Saccharomyces cerevisiae Proteins; D015534:Trans-Activators; D035362:Transcription Factor TFIID; D014157:Transcription Factors; C078657:CCR4 protein, S cerevisiae; D012260:Ribonucleases