Artificial recruitment of certain Mediator components affects requirement of basal transcription factor IIE.
BACKGROUND
Basal transcription factors are essential for RNA polymerase II (RNAPII)-catalysed transcription of many but not all the mRNA-encoding genes in vivo as well as in vitro. For example, copper-inducible transcription of the copper metallothionein gene CUP1 occurs independently of basal factor TFIIE in budding yeast. To gain insight into the mechanism by which the requirement for TFIIE is bypassed, we artificially recruited certain constituents of Mediator, a large protein complex transmitting signals from various activators to the RNAPII machinery, to the CUP1 promoter by protein fusions with Ace1, the copper-inducible activator.


RESULTS
Fusions with Med2 or Pgd1 activated CUP1 independently of TFIIE. Surprisingly, fusions with neither Srb5 nor Med9 circumvented TFIIE requirement for the CUP1 activation. Components of TFIID were similarly recruited to the CUP1 promoter without activation. By using a chromatin immunoprecipitation technique, we found that TFIIE is necessary for stable binding of TFIIH and RNAPII to the ADH1 promoter, whose activation requires TFIIE. However, binding of TFIIH and RNAPII to CUP1 upon its activation did not require TFIIE.


CONCLUSIONS
Our results strongly suggest that the TFIIE requirement of a gene is determined by a target(s) in Mediator through which the signal of the cognate activator is transmitted.
Sakurai
Hiroshi
H
School of Health Sciences, Faculty of Medicine, Kanazawa University, 5-11-80 Kodatsuno, Kanazawa, Ishikawa 920-0942, Japan. sakurai@kenroku.kanazawa-u.ac.jp
Fukasawa
Toshio
T
D002352:Carrier Proteins; D003300:Copper / Q000494:pharmacology; D004268:DNA-Binding Proteins / Q000378:metabolism / Q000502:physiology; D000076249:Heat Shock Transcription Factors; D008668:Metallothionein / Q000235:genetics*; D011401:Promoter Regions, Genetic / Q000502:physiology*; D012441:Saccharomyces cerevisiae / Q000235:genetics* / Q000502:physiology; D014157:Transcription Factors; D019473:Transcription Factors, TFII / Q000235:genetics / Q000502:physiology*; D014158:Transcription, Genetic / Q000187:drug effects
C500769:CUP1-1 protein, S cerevisiae; D002352:Carrier Proteins; D004268:DNA-Binding Proteins; D000076249:Heat Shock Transcription Factors; D014157:Transcription Factors; D019473:Transcription Factors, TFII; C007121:copper thionein; C066644:transcription factor TFIIE; D003300:Copper; D008668:Metallothionein