Fructosyl-amino acid oxidases of Aspergillus oryzae are induced by the reaction product, glucosone

Aspergillus oryzae has two fructosyl-amino acid oxidase (FAOD) isozymes (AoFao1 and AoFao2), which are different in the substrate specificities. Northern blot analysis showed both FAO genes were induced by autoclave-browned medium containing l-lysine or l-valine. Studies with a mutant, that had a disrupted AoFAO2 gene, revealed that the expression of AoFAO1 by fructosyl l-valine depended on the expression of AoFAO2. Both genes were also induced by one of the FAOD-reaction products, glucosone. In contrast, other α-dicarbonyl compounds, which display a similar structure to that of glucosone were not able to induce the genes expression. These results imply that glucosone may contribute to the expression of FAO genes.