A Poised Initiation Complex Is Activated by SNF1

• Published in: The Journal of biological chemistry Vol. 282; no. 52; pp. 37308 - 37315
• Main Authors: Tachibana, Christine, Biddick, Rhiannon, Law, G. Lynn, Young, Elton T.
• Format: Journal Article
• Language: English
• Published: United States Elsevier Inc 28-12-2007; American Society for Biochemistry and Molecular Biology
• Subjects: Chromatin - chemistry; DNA - chemistry; DNA Primers - chemistry; DNA-Binding Proteins - chemistry; DNA-Binding Proteins - physiology; Gene Deletion; Glucose - metabolism; Histone Deacetylases - metabolism; Models, Biological; Mutation; Nucleosomes - metabolism; Protein Binding; Protein-Serine-Threonine Kinases - chemistry; Protein-Serine-Threonine Kinases - physiology; RNA Polymerase II - metabolism; Saccharomyces cerevisiae Proteins - chemistry; Saccharomyces cerevisiae Proteins - metabolism; Saccharomyces cerevisiae Proteins - physiology; Trans-Activators - metabolism; Transcription Factors - chemistry; Transcription Factors - physiology
• ISSN: 0021-9258; 1083-351X
• DOI: 10.1074/jbc.M707363200

Snf1, the yeast AMP kinase homolog, is essential for derepression of glucose-repressed genes that are activated by Adr1. Although required for Adr1 DNA binding, the precise role of Snf1 is unknown. Deletion of histone deacetylase genes allowed constitutive promoter binding of Adr1 and Cat8, another activator of glucose-repressed genes. In repressed conditions, at the Adr1-and Cat8-dependent ADH2 promoter, partial chromatin remodeling had occurred, and the activators recruited a partial preinitiation complex that included RNA polymerase II. Transcription did not occur, however, unless Snf1 was activated, suggesting a Snf1-dependent event that occurs after RNA polymerase II recruitment. Glucose regulation persisted because shifting to low glucose increased expression. Glucose repression could be completely relieved by combining the three elements of 1) chromatin perturbation by mutation of histone deacetylases, 2) activation of Snf1, and 3) the addition of an Adr1 mutant that by itself confers only weak constitutive activity.