Multiple basic helix-loop-helix proteins regulate expression of the ENO1 gene of Saccharomyces cerevisiae.

TitleMultiple basic helix-loop-helix proteins regulate expression of the ENO1 gene of Saccharomyces cerevisiae.
Publication TypeJournal Article
Year of Publication2007
AuthorsChen M, Lopes JM
JournalEukaryot Cell
Date Published2007 May
KeywordsBasic Helix-Loop-Helix Transcription Factors, beta-Galactosidase, Chromatin Immunoprecipitation, E-Box Elements, Epistasis, Genetic, Evolution, Molecular, Gene Expression Regulation, Fungal, Genes, Dominant, Models, Biological, Mutation, Phosphopyruvate Hydratase, Promoter Regions, Genetic, Recombinant Fusion Proteins, Saccharomyces cerevisiae, Saccharomyces cerevisiae Proteins

The basic helix-loop-helix (bHLH) eukaryotic transcription factors have the ability to form multiple dimer combinations. This property, together with limited DNA-binding specificity for the E box (CANNTG), makes them ideally suited for combinatorial control of gene expression. We tested the ability of all nine 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 eight bHLH proteins, namely, Ino2p, Ino4p, Cbf1p, Rtg1p, Rtg3p, Pho4p, Hms1p, and Ygr290wp. ENO1-lacZ expression was also repressed by growth in inositol-choline-containing medium. Epistatic analysis and chromatin immunoprecipitation experiments showed that regulation by Sgc1p, Ino2p, Ino4p, and Cbf1p and repression by inositol-choline required three distal E boxes, E1, E2, and E3. The pattern of bHLH binding to the three 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.

Alternate JournalEukaryotic Cell
PubMed ID17351075