Phenylpropanoid glycosyltransferases from osage orange (Maclura pomifera) fruit.

Flavonoids and isoflavonoids are well known for their beneficial effects on human health and their anti-insect and anti-microbial activities in plants. Osage orange fruit is rich in prenylated isoflavones and dihydrokaempferol and its glucoside. Four glycosyltransferases were identified from a collection of osage orange fruit expressed sequence tags. Biochemical characterization suggested that the glycosyltransferase UGT75L4 might be responsible for glucosylation of dihydrokaempferol in vivo, although this enzyme exhibited broad substrate recognition toward isoflavonoids and flavonoids in vitro. UGT88A4 was active on coumarin substrates. Identification of highly active phenylpropanoid glycosyltransferases will facilitate the metabolic engineering of glycosylated natural products in plants.