Synthesis and secretion of bacterial alpha-amylase by the yeast Saccharomyces cerevisiae

Alpha-amylase from Bacillus amyloliquefaciens, synthesized in yeast Saccharomyces cerevisiae without substitution of the signal sequence, is efficiently secreted from yeast cells: 60-70% of the overall amount of the enzyme is found in the culture fluid. In contrast to many yeast secretory proteins, which accumulate in the periplasmic space and in the cell wall, intracellular alpha-amylase is localized mainly in the cytoplasm. Obviously, transfer across the cell wall is not a rate-limiting step in alpha-amylase export from the cell. The glycosylated forms of proteins are predominantly found both inside the cell and in the culture medium.