Identification of functional regions of the positively acting regulatory gene amdR from Aspergillus nidulans.
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.
Parsons
L M
LM
Department of Genetics, University of Melbourne, Parkville, Victoria, Australia.
Davis
M A
MA
Hynes
M J
MJ
D001233:Aspergillus nidulans / Q000235:genetics*; D001483:Base Sequence; D003001:Cloning, Molecular; D004252:DNA Mutational Analysis; D004268:DNA-Binding Proteins / Q000235:genetics*; D004790:Enzyme Induction; D005656:Fungal Proteins / Q000096:biosynthesis / Q000235:genetics*; D005800:Genes, Fungal / Q000235:genetics*; D005809:Genes, Regulator / Q000235:genetics*; D005816:Genetic Complementation Test; D008969:Molecular Sequence Data; D009154:Mutation; D011487:Protein Conformation; D013329:Structure-Activity Relationship; D014170:Transformation, Genetic; D001616:beta-Galactosidase / Q000096:biosynthesis
C079045:AmdR protein, Aspergillus nidulans; D004268:DNA-Binding Proteins; D005656:Fungal Proteins; D001616:beta-Galactosidase