title: DNA binding site of the yeast heteromeric Ino2p/Ino4p basic helix-loop-helix transcription factor: structural requirements as defined by saturation mutagenesis.
abstract: The inositol/choline-responsive element (ICRE) is an 11 bp cis-activating sequence motif with central importance for the regulated expression of phospholipid biosynthetic genes in the yeast Saccharomyces cerevisiae. The ICRE containing the CANNTG core binding sequence (E-box) of basic helix-loop-helix (bHLH) regulatory proteins is recognized by the heteromeric bHLH transcription factor Ino2p/Ino4p. In this study, we define the Ino2p/Ino4p consensus binding sequence (5'-WYTTCAYR-TGS-3') based on the characterization of all possible single nucleotide substitutions. Interestingly, this analysis also identified a single functional deviation (CACATTC) from the CANNTG core recognition element of bHLH proteins. The DNA binding specificities of different yeast bHLH proteins may now be explained by distinct nucleotide preferences especially at two positions immediately preceding the CANNTG core motif.
authors.affiliation: Institut für Mikrobiologie, Biochemie und Genetik, Universität Erlangen/Nürnberg, Germany.
authors.forename: H J
authors.initials: HJ
authors.lastname: Schüller
authors.forename: K
authors.initials: K
authors.lastname: Richter
authors.forename: B
authors.initials: B
authors.lastname: Hoffmann
authors.forename: R
authors.initials: R
authors.lastname: Ebbert
authors.forename: E
authors.initials: E
authors.lastname: Schweizer
mesh_terms: D001483:Base Sequence; D002352:Carrier Proteins; D016384:Consensus Sequence; D004247:DNA / Q000737:chemistry*; D005800:Genes, Fungal; D005809:Genes, Regulator; D018257:Helix-Loop-Helix Motifs; D046911:Macromolecular Substances; D008969:Molecular Sequence Data; D016296:Mutagenesis; D009838:Oligodeoxyribonucleotides / Q000737:chemistry*; D010743:Phospholipids / Q000096:biosynthesis; D012441:Saccharomyces cerevisiae / Q000235:genetics / Q000378:metabolism*; D012689:Sequence Homology, Nucleic Acid; D014157:Transcription Factors / Q000378:metabolism*
chemical_list: D002352:Carrier Proteins; D046911:Macromolecular Substances; D009838:Oligodeoxyribonucleotides; D010743:Phospholipids; D014157:Transcription Factors; D004247:DNA