title: Heterologous co-production of Thermobifida fusca Cel9A with other cellulases in Saccharomyces cerevisiae.
abstract: The processive endoglucanase Cel9A of the moderately thermophilic actinomycete Thermobifida fusca was functionally produced in Saccharomyces cerevisiae. Recombinant Cel9A displayed activity on both soluble (carboxymethylcellulose) and insoluble (Avicel) cellulose substrates confirming its processive endoglucanase activity. High-performance anionic exchange chromatography analyses of soluble sugars released from Avicel revealed a cellobiose/glucose ratio of 2.5 +/- 0.1. Growth by the recombinant strain on amorphous cellulose was possible due to the sufficient amount of glucose cleaved from the cellulose chain. This is the first confirmed report of S. cerevisiae growing on a cellulosic substrate as sole carbohydrate source while only expressing one recombinant gene. To improve the cellulolytic capability of S. cerevisiae and to investigate the level of synergy among cellulases produced by a recombinant host, the cel9A gene was co-expressed with four cellulase-coding genes of Trichoderma reesei: two endoglucanases cel5A (egII) and cel7B (egI), and two cellobiohydrolases cel6A (cbhII) and cel7A (cbhI). Synergy, especially between the Cel9A and the two cellobiohydrolases, resulted in a higher cellulolytic capability of the recombinant host.
authors.affiliation: Department of Microbiology, University of Stellenbosch, De Beer Street, Stellenbosch 7600, South Africa.
authors.forename: Niel
authors.initials: N
authors.lastname: van Wyk
authors.forename: Riaan
authors.initials: R
authors.lastname: den Haan
authors.forename: Willem H
authors.initials: WH
authors.lastname: van Zyl
mesh_terms: D000192:Actinomycetales / Q000201:enzymology / Q000235:genetics; D001426:Bacterial Proteins / Q000235:genetics / Q000378:metabolism; D044602:Cellulases / Q000096:biosynthesis* / Q000235:genetics; D002482:Cellulose / Q000378:metabolism*; D002852:Chromatography, Ion Exchange; D005656:Fungal Proteins / Q000235:genetics / Q000378:metabolism; D005947:Glucose / Q000032:analysis; D011994:Recombinant Proteins / Q000096:biosynthesis / Q000235:genetics; D012441:Saccharomyces cerevisiae / Q000201:enzymology* / Q000235:genetics / Q000254:growth & development / Q000378:metabolism; D014242:Trichoderma / Q000201:enzymology / Q000235:genetics
chemical_list: D001426:Bacterial Proteins; D005656:Fungal Proteins; D011994:Recombinant Proteins; D002482:Cellulose; D044602:Cellulases; D005947:Glucose