Dammarenediol‐II synthase, the first dedicated enzyme for ginsenoside biosynthesis, in Panax ginseng

Abstract

Panax ginseng produces triterpene saponins called ginsenosides, which are classified into two groups by the skeleton of aglycones, namely dammarane type and oleanane type. Dammarane-type ginsenosides dominate over oleanane type not only in amount but also in structural varieties. However, their sapogenin structure is restricted to two aglycones, protopanaxadiol and protopanaxatriol. So far, the genes encoding oxidosqualene cyclase (OSC) responsible for formation of dammarane skeleton have not been cloned, although OSC yielding oleanane skeleton (b-amyrin synthase) has been successfully cloned from this plant. In this study, cDNA cloning of OSC producing dammmarane triterpene was attempted from hairy root cultures of P. ginseng by homology based PCR method. A new OSC gene (named as PNA) obtained was expressed in a lanosterol synthase deficient (erg7) Saccharomyces cerevisiae strain GIL77. LC-MS and NMR analyses identified the accumulated product in the yeast transformant to be dammarenediol-II, demonstrating PNA to encode dammarenediol-II synthase.

OSC2 and CYP716A14v2 Catalyze the Biosynthesis of Triterpenoids for the Cuticle of Aerial Organs of Artemisia annua

“…OSC2 shows 83% sequence similarity to the multifunctional Centella asiatica dammarenediol synthase (DDS; Kim et al, 2009) and 81% sequence similarity to the Panax ginseng dammarenediol synthase (Tansakul et al, 2006). A phylogenetic analysis with characterized OSCs involved in triterpene biosynthesis grouped OSC2 with the multifunctional OSCs that cyclize 2,3-oxidosqualene to more than one product (Figure 2; Supplemental Data Set 1), such as CaDDS (Kim et al, 2009) and CrAS (Huang et al, 2012;Yu et al, 2013).…”

A conserved amino acid residue critical for product and substrate specificity in plant triterpene synthases

“…However, further experiments are required to investigate this mechanism in detail. The addition of water in triterpene cyclization is known for the triterpene synthases PgPNA, AtLUP1, and AtPEN1 (ARAB) (31)(32)(33)(34)(35). Unlike AtLUP1, which makes two stereoisomers of epDM (20R, 24S and 20S, 24S), S728F accumulates only 20S, 24S-epDM in a highly stereospecific manner.…”

Major repeat components covering one‐third of the ginseng (Panax ginseng C.A. Meyer) genome and evidence for allotetraploidy

“…Research on ginseng has historically focused mainly on its medicinal components and their efficacy (Shibata et al, 1966;Lee and Huemer, 1971;Coon and Ernst, 2002;Park et al, 2012a). Genetic and genomic studies, such as functional analyses of genes (Tansakul et al, 2006;Kim et al, 2008Kim et al, , 2011, marker development Jo et al, 2011;Sun et al, 2011;Kim et al, 2012), construction of DNA libraries (Hong et al, 2004;Bang et al, 2010) and transcriptome sequencing (Chen et al, 2011;Wu et al, 2012) have been initiated only recently.…”