Multiple environmental signals determine the transcriptional activation of the mycoparasitism related gene prb1 in Trichoderma atroviride.
Trichoderma atroviride parasitizes a large variety of phytopathogenic fungi. This characteristic has allowed its use as a biological control agent. The production of hydrolytic enzymes appears to be a key element in the parasitic process. Among the enzymes released by Trichoderma, the proteinase Prb1 plays a major role. We show here that the corresponding gene ( prb1) is subject to nitrogen catabolite repression. Accordingly, induction of prb1 transcription by Rhizoctonia solani cell walls and by osmotic stress requires release from a repressed condition, which is determined by nitrogen availability. Furthermore, the transcription pattern of the prb1 gene was not affected when an inhibitor of p38-Hog1, a regulator of the response to osmotic shock, was used. In contrast, a MEK1/2 (MAPK/ERK) inhibitor blocked prb1 transcription in response to nitrogen limitation, indicating that the pathway employed in the nitrogen response involves proteins similar to p42-p44. Fusion of the prb1 promoter to the gfp reporter gene allowed the detection of a novel regulatory element, providing an initial insight into the nature of the sites that control prb1 expression.
Department of Plant Genetic Engineering, Centro de Investigación y Estudios Avanzados, Unidad Irapuato, Apartado Postal 629, 36500 Irapuato, Gto., México.
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V
Olmedo-Monfil
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Mendoza-Mendoza
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Gómez
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Cortés
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Herrera-Estrella
D015152:Blotting, Northern; D002473:Cell Wall / Q000378:metabolism; D005656:Fungal Proteins; D015971:Gene Expression Regulation, Enzymologic; D015966:Gene Expression Regulation, Fungal; D020935:MAP Kinase Signaling System / Q000502:physiology; D017672:Nitrogen Compounds / Q000378:metabolism; D030781:Organisms, Genetically Modified; D009997:Osmotic Pressure; D010957:Plasmids; D011401:Promoter Regions, Genetic; D012697:Serine Endopeptidases / Q000235:genetics*; D014158:Transcription, Genetic; D014242:Trichoderma / Q000201:enzymology / Q000235:genetics*
D005656:Fungal Proteins; D017672:Nitrogen Compounds; D012697:Serine Endopeptidases