title: Role for Nhp6, Gcn5, and the Swi/Snf complex in stimulating formation of the TATA-binding protein-TFIIA-DNA complex.
abstract: The TATA-binding protein (TBP), TFIIA, and TFIIB interact with promoter DNA to form a complex required for transcriptional initiation, and many transcriptional regulators function by either stimulating or inhibiting formation of this complex. We have recently identified TBP mutants that are viable in wild-type cells but lethal in the absence of the Nhp6 architectural transcription factor. Here we show that many of these TBP mutants were also lethal in strains with disruptions of either GCN5, encoding the histone acetyltransferase in the SAGA complex, or SWI2, encoding the catalytic subunit of the Swi/Snf chromatin remodeling complex. These synthetic lethalities could be suppressed by overexpression of TOA1 and TOA2, the genes encoding TFIIA. We also used TFIIA mutants that eliminated in vitro interactions with TBP. These viable TFIIA mutants were lethal in strains lacking Gcn5, Swi2, or Nhp6. These lethalities could be suppressed by overexpression of TBP or Nhp6, suggesting that these coactivators stimulate formation of the TBP-TFIIA-DNA complex. In vitro studies have previously shown that TBP binds very poorly to a TATA sequence within a nucleosome but that Swi/Snf stimulates binding of TBP and TFIIA. In vitro binding experiments presented here show that histone acetylation facilitates TBP binding to a nucleosomal binding site and that Nhp6 stimulates formation of a TBP-TFIIA-DNA complex. Consistent with the idea that Nhp6, Gcn5, and Swi/Snf have overlapping functions in vivo, nhp6a nhp6b gcn5 mutants had a severe growth defect, and mutations in both nhp6a nhp6b swi2 and gcn5 swi2 strains were lethal.
authors.affiliation: Department of Pathology, University of Utah Health Sciences Center, Salt Lake City, USA.
authors.forename: Debabrata
authors.initials: D
authors.lastname: Biswas
authors.forename: Anthony N
authors.initials: AN
authors.lastname: Imbalzano
authors.forename: Peter
authors.initials: P
authors.lastname: Eriksson
authors.forename: Yaxin
authors.initials: Y
authors.lastname: Yu
authors.forename: David J
authors.initials: DJ
authors.lastname: Stillman
mesh_terms: D000107:Acetylation; D000251:Adenosine Triphosphatases; D001483:Base Sequence; D002868:Chromosomal Proteins, Non-Histone; D004271:DNA, Fungal / Q000235:genetics / Q000378:metabolism*; D004268:DNA-Binding Proteins / Q000235:genetics / Q000378:metabolism; D005800:Genes, Fungal; D005804:Genes, Lethal; D024001:HMGN Proteins; D051548:Histone Acetyltransferases; D006657:Histones / Q000378:metabolism; D009154:Mutation; D009687:Nuclear Proteins / Q000235:genetics / Q000378:metabolism; D011401:Promoter Regions, Genetic; D011494:Protein Kinases / Q000235:genetics / Q000378:metabolism; D012441:Saccharomyces cerevisiae / Q000235:genetics / Q000378:metabolism; D029701:Saccharomyces cerevisiae Proteins / Q000235:genetics / Q000378:metabolism*; D035181:TATA-Box Binding Protein / Q000235:genetics / Q000378:metabolism*; D035561:Transcription Factor TFIIA / Q000235:genetics / Q000378:metabolism*; D014157:Transcription Factors / Q000235:genetics / Q000378:metabolism; D000099224:p300-CBP-Associated Factor
chemical_list: D000251:Adenosine Triphosphatases; D002868:Chromosomal Proteins, Non-Histone; D004271:DNA, Fungal; D004268:DNA-Binding Proteins; D024001:HMGN Proteins; D051548:Histone Acetyltransferases; D006657:Histones; D009687:Nuclear Proteins; D011494:Protein Kinases; D029701:Saccharomyces cerevisiae Proteins; D035181:TATA-Box Binding Protein; D035561:Transcription Factor TFIIA; D014157:Transcription Factors; C086471:NHP6A protein, S cerevisiae; C086472:NHP6B protein, S cerevisiae; C066190:SNF5 protein, S cerevisiae; C501392:GCN5 protein, S cerevisiae; D000099224:p300-CBP-Associated Factor; C499333:SNF2 protein, S cerevisiae