UDPglucosyltransferase

UDP-glucosyltransferases (UGTs) are enzymes that catalyze the transfer of a glucose moiety from uridine diphosphate glucose (UDP-glucose) to a wide range of acceptor molecules, producing glucosides and UDP as a byproduct. The general reaction is UDP-glucose + acceptor → UDP + glucoside. In plants, UGTs are a large gene family that glycosylates endogenous and xenobiotic compounds, increasing solubility, stability, and deterring or modulating biological activity. Plant UGTs mainly belong to the GT1 family and often contain a conserved Plant Secondary Product Glycosyltransferase (PSPG) motif near the C-terminus, which is used for identification and contributes to donor binding.

Structural and mechanistic features: UDP-glucosyltransferases typically adopt a GT-B fold with two Rossmann-like domains. The catalytic mechanism is generally an SN2-type glycosyl transfer, transferring the glucose from UDP-glucose to a hydroxyl or amino group on the acceptor and releasing UDP. The result is the formation of a glucoside, most commonly a beta-glucoside in plants.

Biological and applied significance: UGTs participate in detoxification of xenobiotics, hormone regulation, and the storage of metabolically important compounds. They influence the activity and transport of flavonoids, phenolics, and terpenoids, affecting plant defense and metabolism. In biotechnology, engineering UGT expression can modify phytochemical profiles or improve detoxification pathways, while in synthesis they enable production of glucoside derivatives with pharmaceutical or industrial value.

Note: In humans, a related but distinct family called UDP-glucuronosyltransferases transfers glucuronic acid (not glucose) from UDP-glucuronate.