Identification of Functional Regions of the Positively Acting Regulatory Gene amdR From Aspergillus Nidulans

Mol Microbiol. 1992 Oct;6(20):2999-3007. doi: 10.1111/j.1365-2958.1992.tb01758.x.


The amdR (intA) regulatory gene of Aspergillus nidulans encodes a 765-amino-acid polypeptide which determines the omega-amino acid induction of at least five structural genes. The AmdR polypeptide contains a potential Zn(II)2Cys6 DNA-binding motif which has been shown to be present in the N-terminal region of a large number of fungal activator proteins. In vitro mutagenesis of the fourth cysteine of this motif abolishes AmdR function as shown by loss of complementation of an amdR- mutation and by the AmdR- phenotype of a mutant gene replacement strain. Studies using constructs in which the proposed AmdR DNA-binding motif is replaced with that from another activator, FacB, shows that induction is independent of DNA-binding specificity and that sequences in the C-terminal region of AmdR are activation domains. Sequencing of several amdR mutant alleles which affect activation and/or induction, together with studies of deletion constructs indicate that changes in the conformation of the protein determines its activity and that this is modulated by inducers.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Aspergillus nidulans / genetics*
  • Base Sequence
  • Cloning, Molecular
  • DNA Mutational Analysis
  • DNA-Binding Proteins / genetics*
  • Enzyme Induction
  • Fungal Proteins / biosynthesis
  • Fungal Proteins / genetics*
  • Genes, Fungal / genetics*
  • Genes, Regulator / genetics*
  • Genetic Complementation Test
  • Molecular Sequence Data
  • Mutation
  • Protein Conformation
  • Structure-Activity Relationship
  • Transformation, Genetic
  • beta-Galactosidase / biosynthesis


  • AmdR protein, Aspergillus nidulans
  • DNA-Binding Proteins
  • Fungal Proteins
  • beta-Galactosidase