Exploring the Catalytic Flexibility and Reversibility of Plant Glycosyltransferase HtUGT72AS1 for Glycodiversification of Phenolic Compounds
Chao Wen, He-Chun Wu, Wenhong Ouyang, Jia-Xing Nie, Yiping Guo, Feng Wang, Lili Hu, Jinhua Yang, Lijuan Zheng, Jialu Wang, Wei Huang, Guangping Liang, Ren-Wang Jiang
Abstract
Plant bioactive metabolites such as flavonoids are usually present in glycosylated forms by the attachment of various sugar groups. In this study, a catalytically flexible and reversible glycosyltransferase (HtUGT72AS1) was cloned and characterized from Helleborus thibetanus . HtUGT72AS1 could directly accept six sugar donors (UDP-glucose/-arabinose/-galactose/-xylose/- N -acetylglucosamine/-rhamnose) to catalyze the 3-OH glycosylation of flavonols. It also catalyzed the 4′ and 7-OH glycosylation of other types of flavonoids, which lacked the 3-OH group. Additionally, the HtUGT72AS1-catalyzed reaction was highly reversible when using 2-chloro-4-nitrophenyl glycosides as substrates, which could be used for one-pot or coupled production of bioactive glycosides. It is the first reported UGT for the synthesis of arabinosides and galactosides using a transglycosylation platform. Based on structural modeling and mutagenetic analysis, the mutation of Tyr377 to Ara enhanced the catalytic efficiency of HtUGT72AS1 toward UDP- N -acetylglucosamine, and the V146S mutant gained an improvement in the regioselectivity toward 7-OH of flavonoids.