Molecular cloning and expression analysis of two distinct β-glucosidase genes, bg1 and aven1, with very different biological roles from the thermophilic, saprophytic fungus Talaromyces emersonii
Autor: | Catherine Majella Collins, Stuart E. Denman, John P. Morrissey, Lucy Byrnes, Tuula T. Teeri, Patrick Murray, Maria G. Tuohy |
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Rok vydání: | 2007 |
Předmět: |
Hot Temperature
Sequence analysis Molecular Sequence Data Penicillium purpurogenum Plant Science Cellulase Microbiology Fungal Proteins chemistry.chemical_compound Gene Expression Regulation Fungal Genetics Gentiobiose Amino Acid Sequence Cloning Molecular Gene Ecology Evolution Behavior and Systematics Trichoderma reesei Regulation of gene expression biology beta-Glucosidase fungi Sequence Analysis DNA Saponins biology.organism_classification Culture Media Talaromyces chemistry Biochemistry biology.protein Glucosidases Biotechnology |
Zdroj: | Mycological Research. 111:840-849 |
ISSN: | 0953-7562 |
Popis: | Recent sequencing of a number of fungal genomes has revealed the presence of multiple putative beta-glucosidases. Here, we report the cloning of two beta-glucosidase genes (bg1 and aven1), which have very different biological functions and represent two of a number of beta-glucosidases from Talaromyces emersonii. The bg1 gene, encoding a putative intracellular beta-glucosidase, shows significant similarity to other fungal glucosidases from glycosyl hydrolase family 1, known to be involved in cellulose degradation. Solka floc, methyl-xylose, gentiobiose, beech wood xylan, and lactose induced expression of bg1, whereas glucose repressed expression. A second beta-glucosidase gene isolated from T. emersonii, aven1, encodes a putative avenacinase, an enzyme that deglucosylates the anti-fungal saponin, avenacin, rendering it less toxic to the fungus. This gene displays high homology with other fungal saponin-hydrolysing enzymes and beta-glucosidases within GH3. A putative secretory signal peptide of 21 amino acids was identified at the N-terminus of the predicted aven1 protein sequence suggesting that this enzyme is extracellular. Furthermore, T. emersonii cultivated on oat plant biomass was shown to deglucosylate avenacin. The presence of the avenacinase transcript was confirmed by RT-PCR on RNA extracted from mycelia grown in the presence of avenacin. The expression pattern of aven1 on various carbon sources was distinctly different from that of bg1. Only methyl-xylose and gentiobiose induced transcription of aven1. Gentiobiose induces synthesis of a number of cellulase genes by T. emersonii and it may be a possible candidate for the natural cellulase inducer observed in Penicillium purpurogenum. This work represents the first report of an avenacinase gene from a thermophilic, saprophytic fungal source, and suggests that this gene is not exclusive to plant pathogens. |
Databáze: | OpenAIRE |
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