Expression and Secretion of Glucoamylase of Aspergillus niger in Saccharomyces cerevisiae
黑曲霉糖化酶在酿酒酵母中的表达和分泌

Glucoamylase cDNA synthesized from A. niger mutant T21 was modified at 5'and 3'ends in order to clone it into yeast shuttle plasmid YFD18 and to make fusion between cDNA and leader region of yeast mating pheromone a-factor. The modified cDNA was then inserted into YFD18 at Hind I site. Saccharomyces cerevisiae Y33 was transformed with the resultant recombinant plasmid YFD18HH6. Analysis of transfor-mants including halo formation on starch medium plate, SDS-PAGE of culture filtration and determination of glucoamylase activity showed that the yeast transformed with plasmid containing glucoamylase cDNA efficiently secreted glucoamylase into the medium. This fact indicated that yeast a-factor was able to direct the synthesis and secretion of functional glucoamylase of Aspergillus. In addition the proteolytic cleavage site involved in the maturation of glucoamylase in.A. niger also worked in 5. cerevisiae.