Identification of a Cryphonectria parasitica laccase gene promoter element involved in cycloheximide-inducible, hypovirus-repressible transcriptional activation.
The gene lac-1, encoding the enzyme laccase, is the best characterized of a number of genes in the chestnut blight fungus, Cryphonectria parasitica, that are repressed by hypoviruses, a group of virulence-attenuating mycoviruses. lac-1 has also been shown to be transcriptionally activated by low concentrations of the translational inhibitor cycloheximide (CHX) and by the immunosuppressant cyclosporin A. We now report the identification of a CHX responsive element within the lac-1 promoter region. Gel-mobility shift analysis revealed a 111-bp fragment located 1.8kb upstream of the lac-1 transcriptional start point that exhibited protein binding activity. Insertion of this element within a basal lac-1 promoter sequence conferred CHX responsive transcriptional activation. Moreover, this activation was prevented by hypovirus infection. A 22-bp sequence with an imperfect dyad symmetry located within the 111-bp element was found to be essential for sequence-specific protein binding and, thus, represents a putative target for interactions between the lac-1 promoter and proteins that are involved in mediating CHX inducible activation of lac-1 transcription.
Wang
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Center for Agricultural Biotechnology, University of Maryland Biotechnology Institute, University of Maryland, College Park, MD 20742-3351, USA.
Nuss
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D002472:Cell Transformation, Viral / Q000235:genetics; D003513:Cycloheximide / Q000494:pharmacology*; D016572:Cyclosporine / Q000494:pharmacology; D004268:DNA-Binding Proteins / Q000032:analysis; D005656:Fungal Proteins / Q000378:metabolism; D005658:Fungi / Q000201:enzymology* / Q000821:virology; D015971:Gene Expression Regulation, Enzymologic / Q000187:drug effects; D005800:Genes, Fungal / Q000235:genetics; D042845:Laccase; D010088:Oxidoreductases / Q000235:genetics*; D010935:Plant Diseases / Q000821:virology; D011401:Promoter Regions, Genetic / Q000235:genetics*; D015533:Transcriptional Activation / Q000235:genetics*; D014197:Trees
D004268:DNA-Binding Proteins; D005656:Fungal Proteins; D016572:Cyclosporine; D003513:Cycloheximide; D010088:Oxidoreductases; D042845:Laccase