Specific Binding Sites in the alcR and alcA Promoters of the Ethanol Regulon for the CREA Repressor Mediating Carbon Catabolite Repression in Aspergillus Nidulans

Mol Microbiol. 1993 Mar;7(6):847-57. doi: 10.1111/j.1365-2958.1993.tb01175.x.

Abstract

The CREA repressor responsible for carbon catabolite repression in Aspergillus nidulans represses the transcription of the ethanol regulon. The N-terminal part of the CREA protein encompassing the two zinc fingers (C2H2 class family) and an alanine-rich region was expressed in Escherichia coli as a fusion protein with glutathione-S-transferase. Our results show that CREA is a DNA-binding protein able to bind to the promoters of both the specific trans-acting gene, alcR, and of the structural gene, alcA, encoding the alcohol dehydrogenase I. DNase I protection footprinting experiments revealed several specific binding sites in the alcR and in the alcA promoters having the consensus sequence 5'-G/CPyGGGG-3'. The disruption of one of these CREA-binding sites in the alcR promoter overlapping the induction target for the trans-activator ALCR results in a partially derepressed alc phenotype and derepressed alcR transcription, showing that this binding site is functional in vivo. Our data suggest that CREA represses the ethanol regulon by a double lock mechanism repressing both the trans-acting gene, alcR, and the structural gene, alcA.

Publication types

  • Comparative Study
  • Research Support, Non-U.S. Gov't

MeSH terms

  • Alcohol Dehydrogenase / genetics*
  • Aspergillus nidulans / drug effects
  • Aspergillus nidulans / genetics*
  • Aspergillus nidulans / metabolism
  • Base Sequence
  • Binding Sites
  • Consensus Sequence
  • DNA-Binding Proteins / genetics*
  • DNA-Binding Proteins / metabolism*
  • Ethanol / pharmacology*
  • Fungal Proteins / genetics*
  • Fungal Proteins / metabolism*
  • Gene Expression Regulation, Fungal* / drug effects
  • Genes, Fungal*
  • Glucose / pharmacology
  • Molecular Sequence Data
  • Promoter Regions, Genetic*
  • Protein Binding
  • Recombinant Fusion Proteins / metabolism
  • Repressor Proteins / metabolism*
  • Transcription Factors / genetics*
  • Transcription Factors / metabolism
  • Transcription, Genetic
  • Zinc Fingers / genetics*

Substances

  • ALCR protein, Aspergillus nidulans
  • DNA-Binding Proteins
  • Fungal Proteins
  • Recombinant Fusion Proteins
  • Repressor Proteins
  • Transcription Factors
  • CreA protein, Aspergillus nidulans
  • Ethanol
  • Alcohol Dehydrogenase
  • Glucose