Derepression of INO1 transcription requires cooperation between the Ino2p-Ino4p heterodimer and Cbf1p and recruitment of the ISW2 chromatin-remodeling complex

Eukaryot Cell. 2010 Dec;9(12):1845-55. doi: 10.1128/EC.00144-10. Epub 2010 Oct 8.

Abstract

The Saccharomyces cerevisiae INO1 gene encodes the structural enzyme inositol-3-phosphate synthase for the synthesis de novo of inositol and inositol-containing phospholipids. The transcription of INO1 is completely derepressed in the absence of inositol and choline (I(-) C(-)). Derepression requires the binding of the Ino2p-Ino4p basic helix-loop-helix (bHLH) heterodimer to the UAS(INO) promoter element. We report here the requirement of a third bHLH protein, centromere-binding factor 1 (Cbf1p), for the complete derepression of INO1 transcription. We found that Cbf1p regulates INO1 transcription by binding to sites distal to the INO1 promoter and encompassing the upstream SNA3 open reading frame (ORF) and promoter. The binding of Cbf1p requires Ino2p-Ino4p binding to the UAS(INO) sites in the INO1 promoter and vice versa, suggesting a cooperative mechanism. Furthermore, Cbf1p binding to the upstream sites was required for the binding of the ISW2 chromatin-remodeling complex to the Ino2p-Ino4p-binding sites on the INO1 promoter. Consistent with this, ISW2 was also required for the complete derepression of INO1 transcription.

Publication types

  • Research Support, U.S. Gov't, Non-P.H.S.

MeSH terms

  • Adenosine Triphosphatases / genetics
  • Adenosine Triphosphatases / metabolism*
  • Basic Helix-Loop-Helix Leucine Zipper Transcription Factors / genetics
  • Basic Helix-Loop-Helix Leucine Zipper Transcription Factors / metabolism*
  • Basic Helix-Loop-Helix Transcription Factors / genetics
  • Basic Helix-Loop-Helix Transcription Factors / metabolism*
  • Chromatin / genetics
  • Chromatin / metabolism
  • Chromatin Assembly and Disassembly*
  • Dimerization
  • Gene Expression Regulation, Fungal*
  • Myo-Inositol-1-Phosphate Synthase / genetics*
  • Myo-Inositol-1-Phosphate Synthase / metabolism
  • Promoter Regions, Genetic
  • Protein Binding
  • Saccharomyces cerevisiae / genetics
  • Saccharomyces cerevisiae / metabolism
  • Saccharomyces cerevisiae Proteins / genetics*
  • Saccharomyces cerevisiae Proteins / metabolism*
  • Transcription Factors / genetics
  • Transcription Factors / metabolism*
  • Transcription, Genetic

Substances

  • Basic Helix-Loop-Helix Leucine Zipper Transcription Factors
  • Basic Helix-Loop-Helix Transcription Factors
  • CBF1 protein, S cerevisiae
  • Chromatin
  • INO2 protein, S cerevisiae
  • INO4 protein, S cerevisiae
  • ISWI protein
  • Saccharomyces cerevisiae Proteins
  • Transcription Factors
  • Adenosine Triphosphatases
  • INO1 protein, S cerevisiae
  • Myo-Inositol-1-Phosphate Synthase