Single amino acid substitutions alter helix-loop-helix protein specificity for bases flanking the core CANNTG motif.
While all basic region/helix-loop-helix (bHLH) proteins bind the consensus CANNTG motif, other factors must be involved in determining regulatory specificity. In this report we show that bases outside this core 6 bp are involved in determining the specificity of binding. Thus, binding of the yeast bHLH protein PHO4, but not CPF-1, is inhibited by the presence of a T residue immediately 5' to their common CACGTG recognition sequence. PHO4 binding specificity is altered by mutation at any of three different positions in the basic region, including a single Glu to Asp substitution. The significance of these data for DNA-binding and transcription regulation by the bHLH family of transcription factors is discussed.
Fisher
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Marie Curie Research Institute, Oxted, Surrey, UK.
Goding
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CR
D000595:Amino Acid Sequence; D001483:Base Sequence; D051778:Basic Helix-Loop-Helix Leucine Zipper Transcription Factors; D001665:Binding Sites; D004268:DNA-Binding Proteins / Q000235:genetics* / Q000378:metabolism*; D005656:Fungal Proteins / Q000235:genetics* / Q000378:metabolism*; D005800:Genes, Fungal; D008715:Methionine / Q000096:biosynthesis; D008969:Molecular Sequence Data; D016297:Mutagenesis, Site-Directed; D015345:Oligonucleotide Probes; D010744:Phosphoric Monoester Hydrolases / Q000235:genetics; D011487:Protein Conformation; D012441:Saccharomyces cerevisiae / Q000235:genetics*; D029701:Saccharomyces cerevisiae Proteins; D012689:Sequence Homology, Nucleic Acid; D014157:Transcription Factors / Q000235:genetics* / Q000378:metabolism*
D051778:Basic Helix-Loop-Helix Leucine Zipper Transcription Factors; C064042:CBF1 protein, S cerevisiae; D004268:DNA-Binding Proteins; D005656:Fungal Proteins; D015345:Oligonucleotide Probes; C060292:PHO4 protein, S cerevisiae; D029701:Saccharomyces cerevisiae Proteins; D014157:Transcription Factors; D008715:Methionine; D010744:Phosphoric Monoester Hydrolases