EXPRESSION OF THE Fusarium graminearum GALACTOSE OXIDASE GaoA IN Saccharomyces cerevisiae

Galactose oxidase, produced by fungi of the genus Fusarium, is an enzyme of great biotechnological importance. The gaoA gene has been recombinantly expressed in several hosts but has yet to be in Saccharomyces cerevisiae. This work aimed to express the Fusarium graminearum GaoA enzyme in S. cerevisiae. The full-length and truncated F. graminearum gaoA gene were subcloned into a yeast expression vector. The GaoA enzyme expression in S. cerevisiae was higher when the truncated gene, which codes for the mature form of the enzyme, was used. After purification of the expressed enzyme on a Sepharose 6B column, the obtained yield of the pure and active enzyme was 16.7 mg/L. The purified protein showed a KM of 9.8 mM, lower than that of the wild-type enzyme, and a kcat/KM of 2.9 × 107 M–1s–1, higher than that of the wild-type enzyme. The expressed recombinant protein used several common substrates for galactose oxidase, such as galactose, raffinose, and 1,3-dihydroxyacetone dimer. In addition, it had increased activity on guar gum, lactose, and Arabic gum compared with the wild-type enzyme. The obtained enzyme´s characteristics are compatible with the galactose oxidase biotechnological applications. •Yeast expression vectors were constructed with the entire and truncated gaoA gene.•The truncated gaoA gene was successfully expressed in Saccharomyces cerevisiae.•The produced F. graminearum galactose oxidase was purified and characterized.•This recombinant GaoA has a higher Kcat/KM compared with the wild-type enzyme.•The expressed GaoA also had increased activity on guar gum, lactose, and Arabic gum.