Abstract

Vietnamese ginseng (Panax vietnamensis Ha et Grushv.), a traditional Vietnamese medicinal herb, has been demonstrated to produce triterpenoids with anti-cancer effects. However, the mechanism of triterpenoid biosynthesis in this species remains poorly understood. 3-Hydroxy-3-methylgutary coenzyme A reductase (HMGR, EC 1.1.1.34) catalyzes the NAD(P)H-dependent reduction of 3-hydroxy-3-methylglutaryl-coenzyme A (HMG-CoA) to mevalonate, the first committed step in the isoprenoid pathway, which generates the majority of modern natural products. To investigate the triterpenoid’s biosynthetic mechanism, the HMG-CoA reductase (named PvH_HMGR) gene of Vietnamese ginseng was identified. A BLASTp search against the non-redundant (nr) protein sequence showed that PvH_HMGR has 88.13–98.98% identity with HMGRs from different plant species, and multi-alignment comparison analysis showed the presence of two motifs, each corresponding to HMG-CoA-binding and NADP(H)- binding. PvH_HMGR belongs to Class I HMG-CoA reductase, according to the conserved domain analysis. The secondary structure of the enzyme, as well as its hydrophilicity scales, transmembrane topology, and core promoter, were predicted and described. Three-dimensional enzyme modeling was predicted and annotated by various software with high coverage and confidence. Furthermore, the abiotic stress induced by the various concentrations of salts significantly improved the expression of PvH_HMGR in the adventitious root of Vietnamese ginseng in vitro.

Key words: Elicitor, HMG-CoA reductase, Panax vietnamensis, PvH_HMGR