Expression of nutritionally well-balanced protein, AmA1, inSaccharomyces cerevisiae

Food yeast.Saccharomyces cerevisiae, is a safe organism with a long history of use for the production of biomass rich in high quality proteins and vitamins. AmA1, a seed storage albumin fromAmaranthus hypochondriacus, has a well-balanced amino acid composition and high levels of essential amino acids and offers the possibility of further improving food and animal feed additives. In order to find an effective means of expressingAmA1 in yeast, the gene was cloned into an episomal shuttle vector. Four different promoters were tested: the glyceraldehyde-3-phosphate dehydrogenase promoter, galactose dehydrogenase 10 promoter, alcohol dehydrogenase II promoter, and a hybrid ADH2-GPD promoter. The recombinantAmA1 genes were then introduced into the yeastSaccharomyces cerevisiae 2805. Northern and Western blot analyses of the yeast under appropriate conditions revealed thatAmA1 was expressed by all four promoters at varying levels. An enzyme-linked immunosorbent assay demonstrated that the amount of AmA1 protein in the recombinant yeast was 1.3–4.3% of the total soluble proteins. The highest expression level was obtained from the hybrid ADH2-GPD promoter.