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Yeast

Title:		Engineering yeast for efficient cellulose degradation
Author(s):		van Rensburg P; van Zyl WH; Pretorius IS;
Address:		"Institute for Wine Biotechnology, University of Stellenbosch, South Africa"
Journal Title:		Yeast
Year:		1998
Volume:		14
Issue:		1
Page Number:		67 - 76
DOI:		10.1002/(SICI)1097-0061(19980115)14:1<67::AID-YEA200>3.0.CO;2-T
ISSN/ISBN:		0749-503X (Print) 0749-503X (Linking)
Abstract:		"Saccharomyces cerevisiae produces several beta-1,3-glucanases, but lacks the multicomponent cellulase complexes that hydrolyse the beta-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-beta-1,4-glucanase (END1), the Phanerochaete chrysosporium cellobiohydrolase (CBH1) and the Ruminococcus flavefacies 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 alpha-factor (MF alpha 1), 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-beta-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-beta-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"
Keywords:		"*Bacterial Proteins Blotting, Northern Blotting, Southern Cellulase/biosynthesis/*genetics/metabolism Cellulose/*metabolism Cellulose 1, 4-beta-Cellobiosidase *Cloning, Molecular Gene Expression Regulation, Fungal Genes, Fungal Plasmids/genetics Recombinan;"
Notes:		"MedlineVan Rensburg, P Van Zyl, W H Pretorius, I S eng Research Support, Non-U.S. Gov't England 1998/03/04 Yeast. 1998 Jan 15; 14(1):67-76. doi: 10.1002/(SICI)1097-0061(19980115)14:1<67::AID-YEA200>3.0.CO; 2-T"