Characterization of a Highly Selective 2″-<i>O</i>-Galactosyltransferase from <i>Trollius chinensis</i> and Structure-Guided Engineering for Improving UDP-Glucose Selectivity
Shuang Liu, Meng Zhang, Yang‐Oujie Bao, Kuan Chen, Lulu Xu, Huifei Su, Yi Kuang, Zilong Wang, Xue Qiao, Min Ye
Abstract
A novel 2″-O-galactosyltransferase TcOGT4 was discovered from Trollius chinensis. TcOGT4 could regio-specifically catalyze 2″-O-galactosylation of 17 flavone 8-C-β-d-glucosides and shows high preference for UDP-Gal. Molecular docking indicated that Pro361 may play a key role in sugar donor selectivity, and the P361W mutant exhibited significantly enhanced selectivity toward UDP-Glc. A total of 21 products including 17 new compounds were obtained, and 5 of them showed potent COX-2 inhibitory activities. TcOGT4 is the first reported 2″-O-galactosyltransferase for flavone C-glycosides, and could be a powerful biocatalyst to synthesize bioactive flavone glycosides.