Biotechnological Production of Dimethoxyflavonoids Using a Fusion Flavonoid O-Methyltransferase Possessing Both 3′- and 7-O-Methyltransferase Activities

Although they are less abundant in nature, methoxyflavonoids have distinct physicochemical and pharmacological properties compared to common nonmethylated flavonoids. Thus, enzymatic conversion and biotransformation using genetically engineered microorganisms of flavonoids have been attempted for the efficient production of methoxyflavonoids. Because of their regiospecificity, more than two flavonoid O-methyltransferases (FOMTs) and enzyme reactions are required to biosynthesize di(or poly)-methoxyflavonoids. For the one-step biotechnological production of bioactive di-O-methylflavonoids, we generated a multifunctional FOMT fusing a 3′-OMT (SlOMT3) and a 7-OMT (OsNOMT). The SlOMT3/OsNOMT fusion enzyme possessed both 3′- and 7-OMT activities to diverse flavonoid substrates, which were comparable to those of individual SlOMT3 and OsNOMT. The SlOMT3/OsNOMT enzyme also showed 3′- and 7-OMT activity for 7- or 3′-O-methylflavonoids, respectively, suggesting that the fusion enzyme can sequentially methylate flav...