1. Characterization of a glycosyltransferase from Paris polyphylla for application in biosynthesis of rare ophiopogonins and ginsenosides.
- Author
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Xu, Wen-Ke, Zhao, Chen-Xiao, Yang, Xiao-Wen, Chen, Yue-Gui, Long, Li-Ping, Yan, Yuan-Feng, Guo, Kai, Li, Sheng-Hong, and Liu, Yan
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GINSENOSIDES , *BIOSYNTHESIS , *SAPONINS , *BIOACTIVE compounds , *SITE-specific mutagenesis , *BIOCHEMICAL substrates - Abstract
Saponins are bioactive components of many medicinal plants, possessing complicated chemical structures and extensive pharmacological activities, but the production of high-value saponins remains challenging. In this study, a 6′- O -glucosyltransferase Pp UGT7 (Pp UGT91AH7) was functionally characterized from Paris polyphylla Smith var. y unnanensis (Franch.) Hand. -Mazz., which can transfer a glucosyl group to the C-6′ position of diosgenin-3- O -rhamnosyl-(1 → 2)-glucoside (1), pennogenin-3- O -rhamnosyl-(1 → 2)-glucoside (2), and diosgenin-3- O -glucoside (5). The K M and K cat values of Pp UGT7 towards the substrate 2 were 8.4 μM and 2 × 10−3 s−1, respectively. Through molecular docking and site-directed mutagenesis, eight residues were identified to interact with the sugar acceptor 2 and be crucial for enzyme activity. Moreover, four rare ophiopogonins and ginsenosides were obtained by combinatorial biosynthesis, including an undescribed compound ruscogenin-3- O -glucosyl-(1 → 6)-glucoside (10). Firstly, two monoglycosides 9 and 11 were generated using a known sterol 3- O - β -glucosyltransferase Pp UGT80A40 with ruscogenin (7) and 20(S)-protopanaxadiol (8) as substrates, which were further glycosylated to the corresponding diglycosides 10 and 12 under the catalysis of Pp UGT7. In addition, compounds 7 – 11 were found to show inhibitory effects on the secretion of TNF- α and IL-6 in macrophages RAW264.7. The findings provide valuable insights into the enzymatic glycosylation processes in the biosynthesis of bioactive saponins in P. polyphylla var. yunnanensis , and also serve as a reference for utilizing UDP-glycosyltransferases to construct high-value or rare saponins for development of new therapeutic agents. A 6′- O -glucosyltransferase Pp UGT7 was functionally characterized from Paris polyphylla var. yunnanensis , and four rare ophiopogonins and ginsenosides including an undescribed compound were obtained by combinatorial biosynthesis. [Display omitted] • A 6′- O -glucosyltransferase Pp UGT7 was functionally characterized from Paris polyphylla var. yunnanensis. • Two ophiopogonins and two ginsenosides, including an undescribed compound, were biosynthesized using Pp UGT7 and Pp UGT80A40. • The biosynthetic ophiopogonins and ginsenosides as well as their aglycones showed immunosuppressive activity. [ABSTRACT FROM AUTHOR]
- Published
- 2024
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