Engineering yeast for efficient cellulose degradation
Date
1998
Authors
Van Rensburg P.
Van Zyl W.H.
Pretorius I.S.
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Abstract
Saccharomyces cerevisiae produces several β-1,3-glucanases, but lacks the multicomponent cellulase complexes that hydrolyse the β-1,4-linked glucose polymers present in cellulose-rich biomass as well as in haze-forming glucans in certain wines and beers. We have introduced into S. cerevisiae a functional cellulase complex for efficient cellulose degradation by cloning the Endomyces fibuliger cellobiase (BGL1) gene and co-expressing it with the Butyrivibrio fibrisolvens endo-β-1,4-glucanase (END1), the Phanerochaete chrysosporium cellobiohydrolase (CBH1) and the Ruminococcus flavefaciens cellodextrinase (CEL1) gene constructs in this yeast. The END1, CBH1 and CEL1 genes were inserted into yeast expression/secretion cassettes. Expression of END1, CBH1 and CEL1 was directed by the promoter sequences derived from the alcohol dehydrogenase II (ADH2), the phosphoglycerate kinase I(PKG1) and the alcohol dehydrogenase I (ADH1) genes, respectively. In contrast, BGL1 was expressed under the control of its native promoter. Secretion of End1p and Cel1p was directed by the signal sequence of the yeast mating pheromone α-factor (MFα1), whereas Cbh1p and Bgl1p were secreted using their authentic leader peptides. The construction of a fur1 ura3 S. cerevisiae strain allowed for the autoselection of this multicopy URA3-based plasmid in rich medium. S. cerevisiae transformants secreting biologically active endo-β-1,4-glucanase, cellobiohydrolase, cellodextrinase and cellobiase were able to degrade various substrates including carboxymethylcellulose, hydroxyethylcellulose, laminarin, barley glucan, cellobiose, polypectate, birchwood xylan and methyl-β-D-glucopyranoside. This study could lead to the development of industrial strains of S. cerevisiae capable of converting cellulose in a one-step process into commercially important commodities.
Description
Keywords
beta glucosidase, cellulase, cellulose, cellulose 1,4 beta cellobiosidase, article, bioengineering, controlled study, degradation, gene construct, gene expression regulation, molecular cloning, nonhuman, phanerochaete, priority journal, promoter region, saccharomyces cerevisiae, yeast, Bacterial Proteins, beta-Glucosidase, Blotting, Northern, Blotting, Southern, Cellulase, Cellulose, Cellulose 1,4-beta-Cellobiosidase, Cloning, Molecular, Gene Expression Regulation, Fungal, Genes, Fungal, Plasmids, Recombinant Proteins, Saccharomyces cerevisiae, Transformation, Genetic, Butyrivibrio fibrisolvens, Chrysosporium, Endomyces, Hordeum vulgare subsp. vulgare, Phanerochaete, Phanerochaete chrysosporium, Ruminococcus flavefaciens, Saccharomyces cerevisiae, Saccharomycopsis fibuligera
Citation
Yeast
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14
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