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Specific binding sites in the alcR and alcA promoters of the ethanol regulon for the CREA repressor mediating carbon cataboiite repression in Aspergillus nidulans
Author(s) -
Kulmburg P.,
Mathieu M.,
Dowzer C.,
Kelly J.,
Felenbok B.
Publication year - 1993
Publication title -
molecular microbiology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.857
H-Index - 247
eISSN - 1365-2958
pISSN - 0950-382X
DOI - 10.1111/j.1365-2958.1993.tb01175.x
Subject(s) - aspergillus nidulans , regulon , promoter , repressor , biology , psychological repression , catabolite repression , gene , transcription (linguistics) , activator (genetics) , transcription factor , microbiology and biotechnology , biochemistry , gene expression , mutant , linguistics , philosophy
Summary 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 (C 2 H 2 class family) and an alanine‐rich region was expressed in Escherichia coli as a fusion protein with giutathione‐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 foot‐printing 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, alc A.