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Publication Abstract from PubMed

C-Glycosyltransferases (CGTs) catalyze the formation of C-glycosidic bonds for the biosynthesis of C-glycosides, but the underlying mechanism is unclear. This process improves the solubility and bioavailability of specialized metabolites, which play important roles in plant growth and development and represent rich resources for drug discovery. Here, we performed functional and structural studies of the C-glycosyltransferase UGT708C1 from buckwheat (Fagopyrum esculentum). Enzymatic analysis showed that UGT708C1 is capable of utilizing both uridine-5' diphosphate galactose (UDP-galactose) and uridine-5'-diphosphate glucose (UDP-glucose) as sugar donors. Our structural studies of UGT708C1 complexed with UDP-glucose and uridine-5'-diphosphate (UDP) identified the key roles of Asp382, Gln383, Thr151, and Thr150 in recognizing the sugar moiety of the donor substrate and Phe130, Tyr102, and Phe198 in binding and stabilizing the acceptor. A systematic site-directed mutagenesis study confirmed the important roles of these residues. Further structural analysis combined with molecular dynamics simulations revealed that phloretin binds to the acceptor-binding pocket in a bent state with a precise spatial disposition and complementarity. These findings provide insights into a catalytic mechanism for C-glycosyltransferases.

Crystal Structures of C-glucosyltransferase UGT708C1 Provide Insights into the Mechanism of C-glycosylation.,Liu MZ, Wang D, Li Y, Li X, Zong G, Fei S, Yang X, Lin J, Wang X, Shen Y Plant Cell. 2020 Jul 22. pii: tpc.20.00002. doi: 10.1105/tpc.20.00002. PMID:32699169^[1]

From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine.