Identification of a permissive glycosyltransferase UGT73AC11 for flavonoids glycosylation

Flavonoids, natural products derived from plants, have shown promising potential in food and medicine. These compounds are commonly found in the form of glycosides, which exhibit increased solubility and improved bioavailability. The glycosylation of flavonoids is mainly catalyzed by UDP-glycosyltransferase (UGT). In this study, a new UDP-glucosyltransferase UGT73AC11 from Glycyrrhiza uralensis was identified which can efficiently transfer a glucose or xylose moiety to the 7-OH or 4′-OH position of flavonoids to yield glycosides. The biochemical properties of UGT73AC11 were extensively characterized. The substrate binding mechanism was also explored through molecular dynamics simulation. Finally, UGT73AC11 was successfully coupled with a sucrose synthase to synthesize the monoglucosides of liquiritigenin with sucrose as sugar donor, with 2.1 mM neoliquiritin produced, which was the highest level reported so far. Therefore, UGT73AC11 holds great potential as a broad-spectrum flavonoid biocatalyst for large-scale synthesis of flavonoid glycosides.