Antagonistic remodelling by Swi-Snf and Tup1-Ssn6 of an extensive chromatin region forms the background for FLO1 gene regulation.
Novel yeast histone mutations that confer Swi-Snf independence (Sin(-)) were used to investigate the mechanisms by which transcription coactivator complexes relieve chromatin repression in vivo. Derepression of the flocculation gene FLO1, which is normally repressed by the Tup1-Ssn6 corepressor, leads to its identification as a constitutive Swi-Snf-dependent gene. We demonstrate that Tup1-Ssn6 is a chromatin remodelling complex that rearranges and also orders nucleosomal arrays on the promoter and over 5 kb of upstream intergenic region. Our results confirm that the Swi-Snf complex disrupts nucleosome positioning on promoters, but reveal that it can also rearrange nucleosomes several kilobases upstream from the transcription start site. The antagonistic chromatin remodelling activities of Swi-Snf and Tup1-Ssn6 detected in an array of 32 nucleosomes upstream of FLO1 extend far beyond the scale of promoter-based models of chromatin-mediated gene regulation. The Swi-Snf coactivator and Tup1-Ssn6 corepressor control an extensive chromatin domain in which regulation of the FLO1 gene takes place.
Fleming
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Genes and Development Group, Department of Biomedical Sciences, University of Edinburgh, Edinburgh EH8 9XD, UK.
Pennings
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D000251:Adenosine Triphosphatases; D002843:Chromatin / Q000235:genetics* / Q000378:metabolism; D021901:DNA, Intergenic / Q000235:genetics; D004268:DNA-Binding Proteins / Q000235:genetics / Q000502:physiology*; D005656:Fungal Proteins / Q000502:physiology*; D015966:Gene Expression Regulation, Fungal; D006657:Histones / Q000235:genetics; D037241:Mannose-Binding Lectins; D008565:Membrane Proteins / Q000096:biosynthesis / Q000235:genetics; D009154:Mutation; D009687:Nuclear Proteins; D009707:Nucleosomes / Q000235:genetics; D011401:Promoter Regions, Genetic; D012331:RNA, Fungal / Q000096:biosynthesis; D012097:Repressor Proteins / Q000502:physiology; D012441:Saccharomyces cerevisiae / Q000235:genetics* / Q000378:metabolism; D029701:Saccharomyces cerevisiae Proteins; D014157:Transcription Factors / Q000235:genetics / Q000502:physiology*; D015533:Transcriptional Activation
C065455:CYC8 protein, S cerevisiae; D002843:Chromatin; D021901:DNA, Intergenic; D004268:DNA-Binding Proteins; C087578:FLO1 protein, S cerevisiae; D005656:Fungal Proteins; D006657:Histones; D037241:Mannose-Binding Lectins; D008565:Membrane Proteins; D009687:Nuclear Proteins; D009707:Nucleosomes; D012331:RNA, Fungal; D012097:Repressor Proteins; D029701:Saccharomyces cerevisiae Proteins; C066502:TUP1 protein, S cerevisiae; D014157:Transcription Factors; D000251:Adenosine Triphosphatases; C499333:SNF2 protein, S cerevisiae