Construction of a Novel а-Agglutinin Expression System on the Surface of Wild-Type Saccharomyces cerevisiae Y5 and Genetic Immobilization of β-Glucosidase1

摘要

Saccharomyces cerevisiae Y5 is a newly developed wild-type strain demonstrating a strong bioethanol fermentation capacity. In the present study, we attempted to construct an а-agglutinin-displaying expression system for genetic immobilization β-glucosidase1 (BGL1) on a yeast cell surface in its active form. The AGA1 gene of native а-agglutinin under the control of a GAL1 promoter was integrated into the genomes of S. cerevisiae Y5. A cDNA-encoding BGL1 from the fungus Aspergillus aculeatus was fused with the gene encoding the C-terminal half of Aga2p. The multicopy plasmid containing this fusion gene was introduced into S. cerevisiae and expressed under the control of the GAL1 promoter as was the AGA1 gene. The display of the BGL1 protein on the cell surface was confirmed by immunofluorescence microscopy and Western blotting. The cells displaying BGL1 could produce 5.07 g/l ethanol from 20 g/l cellobiose as the sole carbon source. These results demonstrated that BGL1 was anchored on the cell wall in its active form.