Behavior of heterogeneous proteins on the cell surface in Saccharomyces cerevisiae endowed novel functions

摘要

Immobilization of proteins on the cell surface of microorganisms has been studied using genetic engineering techniques. We attempted to immobilize heterogeneous proteins on the cell surface of the yeast Saccharomyces cerevisiae to endow them with novel functions. Since S.cerevisiae is widely used in the industrial production of proteins and chemicals, this expression system for cell surface display of proteins offers greater advantages than expression systems using other microorganisms. Its applications in food and pharmaceutical products like antifungal agents is also anticipated because of its safety fororal use. To immobilize proteins on the cell surface, a part of cell wall mannoprotein #alpha# -agglutinin, which is involved in the secual adhesion of mating type #alpah# cells with mating type a cells, was used to anchor them to the cell wall. The gene encooding the C-terminal half of #alpha# -agglutinin, the region involved in anchoring to cell wall, was fused with Rhizopus oryzae glucoamylase gene including its secretion signal, and was introduced into S. cerevisiae cells. The glucoamylase activity was detected on the cell pellet but not in the culture medium, and cells could grow only on starch as a sole carbon source. We also succeeded in immobilizing carboxymethyl cellulase (CMCase) by the same genetic method.