Stress Responsive Glycosyltransferase (UGT72Z7) from Glycyrrhiza glabra Showed Glycosylation of Azadirachtin.

Abstract

Uridine diphosphate glycosyltransferases (UGTs) play crucial roles in the glycosylation of plant metabolites, contributing to growth, defense, and stress adaptation. Despite their importance, UGT functions in Glycyrrhiza remain poorly understood, particularly in stress responses and xenobiotic metabolism. In this study, we report the cloning and functional characterization of GgUGT72Z7, a 1413 bp gene encoding a flavonol 3-O-glucosyltransferase that shares 74% sequence identity with Glycine max UGT72Z3. Structural modeling (AlphaFold, SWISS-MODEL, Phyre2) and molecular docking identified azadirachtin, a pharmacologically active tetranor-triterpenoid, as the most favorable ligand (binding energy -15 kcal/mol). In vitro enzymatic assays with recombinant protein validated its ability to glycosylate azadirachtin, a bioactive limonoid found in the seeds of the neem tree (Azadirachta indica) besides native flavonoids, kaempferol and quercetin. Among the models, the AlphaFold structure showed the best structural quality, highlighting interactions between azadirachtin and five key residues (Ser-249, Glu-370, Glu-251, Lys-53, Ala-348). Expression profiling demonstrated strong induction of GgUGT72Z under senescence (1136-fold), pathogen infection (33-fold), and phytohormone treatments, notably methyl jasmonate (1124-fold), auxin (568-fold), and abscisic acid (400-fold). These findings reveal a dual role of GgUGT72Z in xenobiotic glycosylation and stress tolerance, providing new insights into glycosylation-mediated defense in Glycyrrhiza.