Regulation of two homodimer hexosaminidases in the mycoparasitic fungus Trichoderma asperellum by glucosamine

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, beta- N-acetyl- d-glucosaminidas...

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Bibliographic Details
Published in:Current genetics 2004-04, Vol.45 (4), p.205-213
Main Authors: Ramot, O, Viterbo, A, Friesem, D, Oppenheim, A, Chet, I
Format: Article
Language:English
Subjects:
Bacteria
beta-N-acetylhexosaminidase
Biological control
biological control agents
Chitin
Dimerization
enzyme activity
Enzymes
EXC1Y protein
gene expression regulation
Gene Expression Regulation, Fungal - physiology
gene induction
genes
glucosamine
Glucosamine - metabolism
Hexosaminidases - genetics
Hexosaminidases - metabolism
Hexosaminidases - secretion
Mass spectrometry
Microbiology
molecular sequence data
mycoparasites
nucleotide sequences
Pathogens
promoter regions
Promoter Regions, Genetic
Regulation
Sequence Analysis, DNA
Trichoderma
Trichoderma - enzymology
Trichoderma - genetics
Trichoderma - metabolism
Trichoderma asperellum
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Summary: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, beta- 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 beta-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.
ISSN:0172-8083
1432-0983
DOI:10.1007/s00294-003-0478-0