Regulation of two homodimer hexosaminidases in the mycoparasitic fungus Trichoderma asperellum by glucosamine |
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Authors: | Ramot Ofir Viterbo Ada Friesem Dana Oppenheim Amos Chet Ilan |
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Affiliation: | (1) Otto Warburg Center for Agricultural Biotechnology, Faculty of Agricultural, Food and Environmental Quality Sciences, Rehovot, The Hebrew University of Jerusalem, P.O. Box 12, 76100 Rehovot, Israel;(2) Department of Biological Chemistry, The Weizmann Institute of Science, Rehovot, Israel;(3) Department of Molecular Genetics and Biotechnology, Hadassah Medical School, Jerusalem, The Hebrew University of Jerusalem, Jerusalem, Israel |
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Abstract: | Trichoderma asperellum is a mycoparasitic fungus which is used as a biocontrol agent against plant pathogens. Its hydrolytic enzymes take part in its parasitic interaction, degrading the pathogen cell wall and thereby helping to control disease. One of those enzymes, -N-acetyl-d-glucosaminidase (GlcNAcase), degrades chitin, which is a major component of the cell wall of many plant-pathogenic fungi. Two GlcNAcases of T. asperellum T203, designated EXC1Y and EXC2Y, were purified, their genes and their promoters were sequenced, and their regulation was studied. The enzymes share homology (59% identity) but are easily distinguished by PAGE assay. Biochemical characterization, Edman degradation, and mass spectrometry demonstrated that EXC1Y and EXC2Y are both active as homodimers. Both genes are up-regulated by glucosamine (GlcN), in contrast to two endochitinases of this fungus. GlcN induces the secretion of several proteins (including a -glucosidase), among which EXC1Y is the most abundant. An exc2y knockout was constructed, to study the regulation of EXC1Y expression and secretion. The fungus has the ability to store a high amount of this enzyme in an active form and secrete it into the medium later.Communicated by J. Heitman |
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Keywords: | /content/1qvrcm26tvcxcavd/xxlarge946.gif" alt=" beta" align=" MIDDLE" BORDER=" 0" >-N-Acetylglucosaminidase Biocontrol Secretion regulation Promoter Chitinase /content/1qvrcm26tvcxcavd/xxlarge946.gif" alt=" beta" align=" MIDDLE" BORDER=" 0" >-Glucosidase |
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