A cellulose synthase-derived enzyme catalyses 3-O-glucuronosylation in saponin biosynthesis

Abstract

Triterpenoid saponins are specialised metabolites distributed widely in the plant kingdom that consist of one or more sugar moieties attached to triterpenoid aglycones. Despite the widely accepted view that glycosylation is catalysed by UDP-dependent glycosyltransferase (UGT), the UGT which catalyses the transfer of the conserved glucuronic acid moiety at the C-3 position of glycyrrhizin and various soyasaponins has not been determined. Here, we report that a cellulose synthase superfamily-derived glycosyltransferase (CSyGT) catalyses 3-O-glucuronosylation of triterpenoid aglycones. Gene co-expression analyses of three legume species (Glycyrrhiza uralensis, Glycine max, and Lotus japonicus) reveal the involvement of CSyGTs in saponin biosynthesis, and we characterise CSyGTs in vivo using Saccharomyces cerevisiae. CSyGT mutants of L. japonicus do not accumulate soyasaponin, but the ectopic expression of endoplasmic reticulum membrane–localised CSyGTs in a L. japonicus mutant background successfully complement soyasaponin biosynthesis. Finally, we produced glycyrrhizin de novo in yeast, paving the way for sustainable production of high-value saponins.

BAHD acetyltransferase contributes to wound‐induced biosynthesis of oleo‐gum resin triterpenes in Boswellia

“…A few glycosyltransferases involved in triterpene glycosylation have also been characterized (Chung et al. , 2020; Jozwiak et al. , 2020; Louveau et al.…”

Metabolite Profiling and Transcriptome Analysis Explains Difference in Accumulation of Bioactive Constituents in Licorice (Glycyrrhiza uralensis) Under Salt Stress

“…The screening methods, experimental materials, and even the content of the databases were different in each research study, and the identified licorice UGTs were different (Huang et al, 2019). For example, with the biosynthesis pathway of glycyrrhizin, multiple different UGT genes such as GuUGAT (Xu et al, 2016), UGT73P12 (Nomura et al, 2019), GuCSyGT (Chung et al, 2020), and GuGT14 (UGT73F15) (Chen et al, 2019) were obtained through a single step involving the conversion of glycyrrhetinic acid to glycyrrhizin.…”

“…These findings provide necessary and important genetic clues for developing strategies for effective molecular breeding and crop-quality control (Mochida et al, 2017). Currently, several key enzymes including cytochrome P450 88D6 (CYP88D6), CYP72A154, UDP-glycosyltransferase (UGT73P12), and GuCSyGT have been successfully characterized in the downstream biosynthetic pathway of glycyrrhizin (Seki et al, 2008(Seki et al, , 2011Chung et al, 2020). A comprehensive understanding of the regulatory mechanisms involved in the synthesis of bioactive constituents in licorice is critical to the breeding of high-quality cultivated licorice.…”

Yeast Synthetic Biology for the Production of Lycium barbarum Polysaccharides

“…The enzymatic characterization of the glycosyltransferases was identified ( Figure 2 ), and the characterized glycosyltransferases were used for adding activated sugars to the substrates [ 28 , 29 , 30 , 31 ]. Recently, another two cellulose synthases were identified to function as glycosyltransferases in saponin biosynthesis [ 47 , 48 ], showing identification of glycosyltransferases for LBP synthesis is complex. Nowadays, the use of gene similarity and network analysis have been widely used for gene identification [ 46 ].…”