Identification of elements in the PDA1 promoter of Nectria haematococca necessary for a high level of transcription in vitro.
Expression of the PDA1 gene in the ascomycete Nectria haematococca MPVI (anamorph: Fusarium solani) is induced by exposure of mycelium to pisatin, an isoflavonoid phytoalexin produced by its host plant, garden pea. The PDA1 gene encodes a cytochrome P-450 monooxygenase which detoxifies pisatin. Regulatory elements controlling transcription from the PDA1 promoter were identified using a homologous Nectria in vitro transcription system through analysis of 5' deletions, specific oligonucleotide competition, and fusion of upstream segments to a heterologous promoter. A promoter-distal element which provided transcriptional activation was localized to a 35-bp region positioned -514 to -483 upstream of the transcriptional start site. This 35-bp region binds a previously characterized pisatin-responsive DNA-binding factor (PRF) and thus may provide pisatin-responsive control of transcription. A second promoter-proximal positive-acting region was found to be necessary for promoter transcription in both homologous and heterologous extracts, and so is likely to bind less genespecific transcription activator(s). A negative-acting element located between these two positive regions may act to make the positive-acting elements interdependent. The identification of an activator responding to pisatin provides a model for the control of a number of genes and processes controlled by host-specific signals, particularly the flavonoids.
Ruan
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Department of Plant Biology, University of Maryland, College Park, MD 20742, USA.
Straney
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DC
D001483:Base Sequence; D002874:Chromosome Mapping; D003577:Cytochrome P-450 Enzyme System / Q000235:genetics*; D004271:DNA, Fungal / Q000235:genetics; D005670:Fusarium / Q000201:enzymology* / Q000235:genetics; D015966:Gene Expression Regulation, Fungal; D008969:Molecular Sequence Data; D010090:Oxidoreductases, O-Demethylating / Q000235:genetics*; D011401:Promoter Regions, Genetic; D014158:Transcription, Genetic
D004271:DNA, Fungal; D003577:Cytochrome P-450 Enzyme System; D010090:Oxidoreductases, O-Demethylating; C057976:pisatin demethylase