Identification of Aspergillus brlA response elements (BREs) by genetic selection in yeast.
The brlA gene of Aspergillus nidulans plays a central role in controlling conidiophore development. To test the hypothesis that brlA encodes a transcriptional regulator and to identify sites of interaction for the BrlA polypeptide, we expressed brlA in Saccharomyces cerevisiae (yeast) strains containing Aspergillus DNA sequences inserted upstream of a minimal yeast promoter fused to the Escherichia coli lacZ gene. Initially, a DNA fragment from the promoter region of the developmentally regulated rodA gene was tested and shown to mediate brlA-dependent transcriptional activation. Two additional DNA fragments were selected from an Aspergillus genomic library by their ability to respond to brlA in yeast. These fragments contained multiple copies of a sequence motif present in the rodA fragment, which we propose to be sites for BrlA interaction and designate brlA response elements (BREs). DNA fragments containing BREs upstream of a minimal Aspergillus promoter were capable of conferring developmental regulation in Aspergillus. Deletion of BREs from the upstream region of rodA greatly decreased its developmental induction. Multiple copies of a synthetic oligonucleotide with the consensus sequence identified among the BREs mediated brlA-dependent transcriptional activation in yeast. The results show that a primary activity of brlA is transcriptional activation and tentatively identify sites of interaction for the BrlA polypeptide.
Chang
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YC
Department of Genetics, University of Georgia, Athens 30602-7223.
Timberlake
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WE
D001233:Aspergillus nidulans / Q000235:genetics*; D001483:Base Sequence; D004271:DNA, Fungal; D005656:Fungal Proteins / Q000235:genetics*; D015966:Gene Expression Regulation, Fungal; D005800:Genes, Fungal; D008969:Molecular Sequence Data; D010957:Plasmids; D011401:Promoter Regions, Genetic; D012045:Regulatory Sequences, Nucleic Acid; D012441:Saccharomyces cerevisiae / Q000235:genetics*; D012641:Selection, Genetic; D012689:Sequence Homology, Nucleic Acid; D014157:Transcription Factors; D016335:Zinc Fingers / Q000235:genetics*
C063497:BRLA protein, Emericella nidulans; D004271:DNA, Fungal; D005656:Fungal Proteins; D014157:Transcription Factors