Specific binding sites in the alcR and alcA promoters of the ethanol regulon for the CREA repressor mediating carbon cataboiite repression in Aspergillus nidulans

Authors

  • P. Kulmburg,

    1. Institut de Génétique et Microbiologie, UPS, Bâtiment 409, Centre Scientifique d'Orsay, 91405 Orsay Cedex, France.
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    • Sandoz Research Institute, Brunnerstrasse 59, A-1235 Vienna, Austria

  • M. Mathieu,

    1. Institut de Génétique et Microbiologie, UPS, Bâtiment 409, Centre Scientifique d'Orsay, 91405 Orsay Cedex, France.
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  • C. Dowzer,

    1. Institut de Génétique et Microbiologie, UPS, Bâtiment 409, Centre Scientifique d'Orsay, 91405 Orsay Cedex, France.
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    • IMP, Dr Bohr-Gasse 7, A-1030 Vienna, Austria

  • J. Kelly,

    1. Institut de Génétique et Microbiologie, UPS, Bâtiment 409, Centre Scientifique d'Orsay, 91405 Orsay Cedex, France.
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    • §

      Department of Genetics, University of Adelaide, GPO Box 498, Adelaide, Australia.

  • B. Felenbok

    Corresponding author
    1. Institut de Génétique et Microbiologie, UPS, Bâtiment 409, Centre Scientifique d'Orsay, 91405 Orsay Cedex, France.
    • *For correspondence. Tel. (1) 69 41 63 28; Fax (1) 69 41 78 08.

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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 (C2H2 class family) and an alanine-rich region was expressed in Escherichia colias 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.

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