title: Chromatin disassembly mediated by the histone chaperone Asf1 is essential for transcriptional activation of the yeast PHO5 and PHO8 genes.
abstract: Nucleosome loss from a promoter region has recently been described as a potential mechanism for transcriptional regulation. We investigated whether H3/H4 histone chaperones mediate the loss of nucleosomes from the promoter of the yeast PHO5 gene during transcriptional activation. We found that antisilencing function 1 (Asf1p) mediates nucleosome disassembly from the PHO5 promoter in vivo. We show that nucleosome disassembly also occurs at a second promoter, that of the PHO8 gene, during activation, and we demonstrate that this is also mediated by Asf1p. Furthermore, we show that nucleosome disassembly is essential for PHO5 and PHO8 activation. Contrary to the current dogma, we demonstrate that nucleosome disassembly is not required to enable binding of the Pho4p activator to its PHO5 UASp2 site in vivo. Finally, we show that nucleosomes are reassembled over the PHO5 promoter during repression. As such, nucleosome disassembly and reassembly are important mechanisms for transcriptional activation and repression, respectively.
authors.affiliation: Department of Biochemistry and Molecular Genetics, B121, School of Medicine, University of Colorado, 4200 East Ninth Avenue, Denver, CO 80262, USA.
authors.forename: Melissa W
authors.initials: MW
authors.lastname: Adkins
authors.forename: Susan R
authors.initials: SR
authors.lastname: Howar
authors.forename: Jessica K
authors.initials: JK
authors.lastname: Tyler
mesh_terms: D000135:Acid Phosphatase; D001665:Binding Sites / Q000235:genetics; D002352:Carrier Proteins / Q000235:genetics / Q000378:metabolism*; D018797:Cell Cycle Proteins / Q000235:genetics / Q000378:metabolism*; D042002:Chromatin Assembly and Disassembly / Q000235:genetics*; D004268:DNA-Binding Proteins / Q000235:genetics / Q000378:metabolism; D015966:Gene Expression Regulation, Fungal / Q000235:genetics*; D006657:Histones / Q000235:genetics / Q000378:metabolism; D008958:Models, Molecular; D018832:Molecular Chaperones / Q000235:genetics / Q000378:metabolism; D009707:Nucleosomes / Q000235:genetics / Q000378:metabolism; D011401:Promoter Regions, Genetic / Q000235:genetics*; D011485:Protein Binding / Q000502:physiology; D012097:Repressor Proteins / Q000235:genetics / Q000378:metabolism; D029701:Saccharomyces cerevisiae Proteins / Q000235:genetics / Q000378:metabolism; D014157:Transcription Factors / Q000235:genetics / Q000378:metabolism; D015533:Transcriptional Activation / Q000235:genetics*; D015003:Yeasts / Q000235:genetics / Q000378:metabolism*
chemical_list: C109731:ASF1 protein, S cerevisiae; D002352:Carrier Proteins; D018797:Cell Cycle Proteins; D004268:DNA-Binding Proteins; D006657:Histones; D018832:Molecular Chaperones; D009707:Nucleosomes; C060292:PHO4 protein, S cerevisiae; D012097:Repressor Proteins; D029701:Saccharomyces cerevisiae Proteins; D014157:Transcription Factors; C026989:thiamine-binding protein; D000135:Acid Phosphatase; C488913:PHO3 protein, S cerevisiae; C488916:PHO5 protein, S cerevisiae