Glycosylation of Aromatic Glycosides by a Promiscuous Glycosyltransferase UGT71BD1 from Cistanche tubulosa

Abstract

Multiple-glycosylated glycosides are a major source of bioactive leads. However, most of the currently reported glycosyltransferases (GTases) mainly catalyze glycosylation of aglycones without sugar group substitution. GTases accepting diverse glycosides as substrates are rarely reported. In this article, a new GTase UGT71BD1 was identified from Cistanche tubulosa, a desert herb plant abundant with various phenylethanoid glycosides (PhGs). Interestingly, UGT71BD1 showed no activity toward the aglycone of PhGs. Instead, it could catalyze the further glycosylation of PhG compounds to produce new phenylethanoid multiglycosylated glycosides, including the natural rarely separated tetraglycoside PhGs. Extensive assays found the unprecedented substrate promiscuity of UGT71BD1 toward diverse glycosides including flavonoid glycosides, stilbene glycosides, and coumarin glycosides, performing further mono-or diglycosylation with efficient conversion rates. Using UGT71BD1, six multiglycosylated glycosides were prepared and structurally identified by NMR spectroscopy. These products showed enhanced pharmacological activities compared with the substrates. Docking, dynamic simulation, and mutagenesis studies identified key residues for UGT71BD1's activity and revealed that the sugar modules in glycosides play crucial roles in substrate recognition, thus partly illuminating the unusual substrate preference of UGT71BD1 toward diverse glycosides. UGT71BD1 could be a potential enzyme tool for glycosylation of diverse glycosides.

Identification of a highly promiscuous glucosyltransferase from Penstemon barbatus for natural product glycodiversification

“…Recently, UGT71BD1 identified from Cistanche tubulosa , could catalyze the glycosylation of PhGs at the C-3′′ OH position of the caffeoyl group to produce new phenylethanoid multiglycosylated glycosides. 11 Actually, these two enzymes belonging to different UGT families shared only 25.25% protein sequence identity, reflecting a large variation in their tertiary structures. The UGT84 family and UGT71 family, respectively, can also glycosylate substances with different structural kinds, including flavonoids, 16,17 terpenoids, 18,19 and coumarins.…”

“…Recently, UGT71BD1 identified from Cistanche tubulosa, could catalyze the glycosylation of PhGs at the C-3″ OH position of the caffeoyl group to produce new phenylethanoid multiglycosylated glycosides. 11 Actually, these two enzymes belonging to different UGT…”

“…UGT71BD1 was identified from Cistanche tubulosa , catalyzing the glycosylation of PhG diglycoside or triglycoside. 11 In our previous study, we characterized three glycosyltransferases from Ligustrum robustum involved in the biosynthesis of ligupurpuroside B. 12 It is of great interest in further mining of permissive UGTs from plants for natural product glycodiversification.…”

Perplexing Polyphenolics: The Isolations, Syntheses, Reappraisals, and Bioactivities of Flavonoids, Isoflavonoids, and Neoflavonoids from 2016 to 2022

“…UGTs capable of transforming glycoside compounds are rare, but those with such substrate promiscuity are remarkable discoveries. Additionally, the enzyme could also utilize UDP-GlcA as a sugar donor and transfer glucuronic acid to 406 [ 109 ].…”

Substrate Promiscuity, Crystal Structure, and Application of a Plant UDP-Glycosyltransferase UGT74AN3

“…For example, Sb3GT1 prefers to glycosylate flavonoid compounds and UGT71BD1 prefers to recognize aromatic glycosides. 29,30 Moreover, the structural basis for substrate promiscuity of plant UGTs is still unclear. Since the first crystal structure of the plant UGT UGT71G1 was solved, the crystal structures of 27 plant UGTs have been reported.…”