Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: EC:3.2.1.21 (beta-glucosidase)
 3,280 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Enzyme engineering was performed to link the beta-glucosidase enzyme (BGL1) from Saccharomycopsis fibuligera to the cellulose-binding domain (CBD2) of Trichoderma reesei cellobiohydrolase (CBHII) to investigate the effect of a fungal CBD on the enzymatic characteristics of this non-cellulolytic yeast enzyme. Recombinant enzymes were constructed with single and double copies of CBD2 fused at the N-terminus of BGL1 to mimic the two-domain organization displayed by cellulolytic enzymes in nature. The engineered S. fibuligera beta-glucosidases were expressed in Saccharomyces cerevisiae under the control of phosphoglycerate-kinase-1 promoter (PGK1 ( P )) and terminator (PGK1 ( T )) and yeast mating pheromone alpha-factor secretion signal (MFalpha1 ( S )). The secreted enzymes were purified and characterized using a range of cellulosic and non-cellulosic substrates to illustrate the effect of the CBD on their enzymatic activity. The results indicated that the recombinant enzymes of BGL1 displayed a 2-4-fold increase in their hydrolytic activity toward cellulosic substrates like avicel, amorphous cellulose, bacterial microcrystalline cellulose, and carboxy methyl cellulose in comparison with the native enzyme. The organization of the CBD in these recombinant enzymes also resulted in enhanced substrate affinity, molecular flexibility and synergistic activity, thereby improving the ability of the enzymes to act on and hydrolyze cellulosic substrates, as characterized by adsorption, kinetics, thermal stability, and scanning electron microscopic analyses.
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PMID:Effect of the cellulose-binding domain on the catalytic activity of a beta-glucosidase from Saccharomycopsis fibuligera. 1733 92

The Aspergillus aculeatus beta-glucosidase 1 (bgl1) gene was expressed in a lactic-acid-producing Saccharomyces cerevisiae strain to enable lactic fermentation with cellobiose. The recombinant beta-glucosidase enzyme was expressed on the yeast cell surface by fusing the mature protein to the C-terminal half region of the alpha-agglutinin. The beta-glucosidase expression plasmids were integrated into the genome. Three strong promoters of S. cerevisiae, the TDH3, PGK1, and PDC1 promoters, were used for beta-glucosidase expression. The specific beta-glucosidase activity varied with the promoter used and the copy number of the bgl1 gene. The highest activity was obtained with strain PB2 that possessed two copies of the bgl1 gene driven by the PDC1 promoter. PB2 could grow on cellobiose and glucose minimal medium at the same rate. Fermentation experiments were conducted in non-selective-rich media containing 95 g l(-1) cellobiose or 100 g l(-1) glucose as a carbon source under microaerobic conditions. The maximum rate of L-lactate production by PB2 on cellobiose (2.8 g l(-1) h(-1)) was similar to that on glucose (3.0 g l(-1) h(-1)). This indicates that efficient fermentation of cellobiose to L-lactate can be accomplished using a yeast strain expressing beta-glucosidase from a mitotically stable genomic integration plasmid.
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PMID:Lactic fermentation of cellobiose by a yeast strain displaying beta-glucosidase on the cell surface. 1844 85

We demonstrate the value of the thermotolerant yeast Issatchenkia orientalis as a candidate microorganism for bioethanol production from lignocellulosic biomass with the goal of consolidated bioprocessing. The I. orientalis MF-121 strain is acid tolerant, ethanol tolerant, and thermotolerant, and is thus a multistress-tolerant yeast. To express heterologous proteins in I. orientalis, we constructed a transformation system for the MF-121 strain and then isolated the promoters of TDH1 and PGK1, two genes that were found to be strongly expressed during ethanol fermentation. As a result, expression of beta-glucosidase from Aspergillus aculeatus could be achieved with I. orientalis, demonstrating successful heterologous gene expression in I. orientalis for the first time. The transformant could convert cellobiose to ethanol under acidic conditions and at high temperature. Simultaneous saccharification and fermentation (SSF) was performed with the transformant, which produced 29 g l(-1) of ethanol in 72 h at 40 degrees C even without addition of beta-glucosidase when SSF was carried out in medium containing 100 g l(-1) of microcrystalline cellulose and a commercial cellulase preparation. These results suggest that using a genetically engineered thermotolerant yeast such as I. orientalis in SSF could lead to cost reduction because less saccharification enzymes are required.
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PMID:Construction of a beta-glucosidase expression system using the multistress-tolerant yeast Issatchenkia orientalis. 2046 39