The cloning and expression of a gene encoding Old Yellow Enzyme from Saccharomyces carlsbergensis

We have identified a gene that encodes Old Yellow Enzyme in brewer's bottom yeast. The open reading frame encodes a polypeptide of 400 amino acids with Mr = 45,021. Using the T7 RNA polymerase system, recombinant enzyme was expressed in Escherichia coli. 17 mg of Old Yellow Enzyme was obtained from a 3-liter cell culture, and the recombinant enzyme had NADPH oxidase activity. On fast protein liquid chromatography separation, the recombinant enzyme showed a single large peak, while native enzyme from brewer's bottom yeast separated into five fractions on fast protein liquid chromatography. Southern blot analysis showed that there are at least two Old Yellow Enzyme genes in brewer's bottom yeast genomic DNA. These results suggest that the heterogeneity of Old Yellow Enzyme in Saccharomyces carlsbergensis is due to the presence of multiple genes.