Analysis of the α‐amylase gene of Schwanniomyces occidentalis and the secretion of its gene product in transformants of different yeast genera

Abstract

We have cloned and characterized the .alpha.-amylase gene (AMY1) of the yeast Schwanniomyces occidentalis. A cosmid gene library of S. occidentalis DNA was screened in Saccharomyces cerevisiae for .alpha.-amylase secretion. The positive clone contained a DNA fragment harbouring an open reading frame of 1536 nucleotides coding for a 512-amino-acid polypeptide with a calculated Mr of 56 5000. The deduced amino acid sequence reveals significant similarity to the sequence of the Saccharomycopsis fibuligera and Aspergillus oryzae .alpha.-amylases. The AMY1 gene was found to be expressed from its original promoter in S. cerevisiae, Kluyveromyces lactis and Schizosaccharomyces pombe leading to an active secreted gene product and thus enabling the different yeast transformants to grow on starch as a sole carbon source.