Artificial recruitment of mediator by the DNA-binding domain of Adr1 overcomes glucose repression of ADH2 expression.
The transcription factor Adr1 activates numerous genes in nonfermentable carbon source metabolism. An unknown mechanism prevents Adr1 from stably binding to the promoters of these genes in glucose-grown cells. Glucose depletion leads to Snf1-dependent binding. Chromatin immunoprecipitation showed that the Adr1 DNA-binding domain could not be detected at the ADH2 promoter under conditions in which the binding of the full-length protein occurred. This suggested that an activation domain is required for stable binding, and coactivators may stabilize the interaction with the promoter. Artificial recruitment of Mediator tail subunits by fusion to the Adr1 DNA-binding domain overcame both the inhibition of promoter binding and glucose repression of ADH2 expression. In contrast, an Adr1 DNA-binding domain-Tbp fusion did not overcome glucose repression, although it was an efficient activator of ADH2 expression under derepressing conditions. When Mediator was artificially recruited, ADH2 expression was independent of SNF1, SAGA, and Swi/Snf, whereas ADH2 expression was dependent on these factors with wild-type Adr1. These results suggest that in the presence of glucose, the ADH2 promoter is accessible to Adr1 but that other interactions that occur when glucose is depleted do not take place. Artificial recruitment of Mediator appears to overcome this requirement and to allow stable binding and transcription under normally inhibitory conditions.
Young
Elton T
ET
Department of Biochemistry, Box 357350, University of Washington, Seattle, WA 98195-7350, USA. ety@u.washington.edu
Tachibana
Christine
C
Chang
Hsin-Wen Ella
HW
Dombek
Kenneth M
KM
Arms
Erin M
EM
Biddick
Rhiannon
R
D000426:Alcohol Dehydrogenase / Q000235:genetics / Q000378:metabolism*; D001665:Binding Sites; D002868:Chromosomal Proteins, Non-Histone / Q000235:genetics / Q000378:metabolism; D004271:DNA, Fungal / Q000378:metabolism*; D004268:DNA-Binding Proteins / Q000235:genetics / Q000378:metabolism*; D015966:Gene Expression Regulation, Fungal; D005947:Glucose / Q000378:metabolism*; D011401:Promoter Regions, Genetic / Q000235:genetics; D011485:Protein Binding; D021122:Protein Subunits / Q000235:genetics / Q000378:metabolism; D012441:Saccharomyces cerevisiae / Q000235:genetics / Q000378:metabolism; D029701:Saccharomyces cerevisiae Proteins / Q000235:genetics / Q000378:metabolism*; D015534:Trans-Activators / Q000235:genetics / Q000378:metabolism; D014157:Transcription Factors / Q000235:genetics / Q000378:metabolism*; D014158:Transcription, Genetic / Q000235:genetics
C074682:ADR1 protein, S cerevisiae; D002868:Chromosomal Proteins, Non-Histone; D004271:DNA, Fungal; D004268:DNA-Binding Proteins; D021122:Protein Subunits; C507785:SAGA complex, S cerevisiae; C445179:SWI-SNF-B chromatin-remodeling complex; D029701:Saccharomyces cerevisiae Proteins; D015534:Trans-Activators; D014157:Transcription Factors; C509911:ADH2 protein, S cerevisiae; D000426:Alcohol Dehydrogenase; D005947:Glucose