Functional characterization, structural basis, and regio-selectivity control of a promiscuous flavonoid 7, 4′-di-O-glycosyltransferase from Ziziphus jujuba var. spinosa. Issue 16 (4th April 2023) - Wang, Zi-Long
Abstract : We report a promiscuous flavonoid 7, 4′-di- O -glycosyltransferase (ZjOGT3), which shows high catalytic efficiency and regio-selectivity. And the regio-selectivity of ZjOGT3 was controlled by intrinsic reactivity and the enzyme microenvironment. Abstract : A highly efficient and promiscuous 7, 4′-di- O -glycosyltransferase ZjOGT3 was discovered from the medicinal plant Ziziphus jujuba var. spinosa . ZjOGT3 could sequentially catalyse 4′- and 7- O -glycosylation of flavones to produce 7, 4′-di- O -glycosides with obvious regio-selectivity. For 7, 4′-dihydroxyl flavanones and 3- O -glycosylated 7, 4′-dihydroxyl flavones, ZjOGT3 selectively catalyses 7- O -glycosylation. The crystal structure of ZjOGT3 was solved. Structural analysis, DFT calculations, MD simulations, and site-directed mutagenesis reveal that the regio-selectivity is mainly controlled by the enzyme microenvironment for 7, 4′-dihydroxyl flavones and 3- O -glycosylated 7, 4′-dihydroxyl flavones. For 7, 4′-dihydroxyl flavanones, the selectivity is mainly controlled by intrinsic reactivity. ZjOGT3 is the first plant flavonoid 7, 4′-di- O -glycosyltransferase with a crystal structure. This work could help understand the catalytic mechanisms of multi-site glycosyltransferases and provides an efficient approach to synthesise O -glycosides with medicinal potential.