The basic helix-loop-helix (bHLH) eukaryotic transcription factors have the ability to form multiple dimer combinations. This property together with the limited DNA-binding specificity to the E-box (CANNTG) makes them ideally suited for combinatorial control of gene expression. We tested the ability of all 9 Saccharomyces cerevisiae bHLH proteins to regulate the enolase-encoding gene, ENO1. ENO1 was known to be activated by the bHLH protein, Sgc1p. Here, we show that expression of an ENO1-lacZ reporter was also regulated by the other 8 bHLH proteins: Ino2p, Ino4p, Cbf1p, Rtg1p, Rtg3p, Pho4p, Hms1p, and Ygr290wp. ENO1-lacZ expression was also repressed by growth in inositol/choline-containing (I+C+) media. Epistatic analysis and Chromatin Immunoprecipitation (ChIP) experiments showed that regulation by Sgc1p, Ino2p, Ino4p, Cbf1p, and repression by inositol/choline required three distal E-boxes: E1, E2, and E3. The pattern of bHLH binding to the 3 E-boxes and experiments with two dominant-negative mutant alleles of INO4 and INO2 support the model that bHLH dimer selection affects ENO1-lacZ expression. These results support the general model that bHLH proteins can coordinate different biological pathways via multiple mechanisms.
|Evidence ID||Analyze ID||Interactor||Interactor Systematic Name||Interactor||Interactor Systematic Name||Type||Assay||Annotation||Action||Modification||Phenotype||Source||Reference||Note|
|Evidence ID||Analyze ID||Gene||Gene Systematic Name||Gene Ontology Term||Gene Ontology Term ID||Qualifier||Aspect||Method||Evidence||Source||Assigned On||Reference||Annotation Extension|
|Evidence ID||Analyze ID||Gene||Gene Systematic Name||Phenotype||Experiment Type||Experiment Type Category||Mutant Information||Strain Background||Chemical||Details||Reference|
|Evidence ID||Analyze ID||Regulator||Regulator Systematic Name||Target||Target Systematic Name||Experiment||Conditions||Strain||Source||Reference|