Cloning and expression analysis of a key device of HMGR gene involved in ginsenoside biosynthesis of Panax ginseng via synthetic biology approach

3-Hydroxy-3-methylglutaryl coenzyme-A reductase (HMGR), the first enzyme of mavalonic acid pathway, is one of the key devices involved in ginsenoside biosynthesis based on synthetic biology approach.  The open reading frame of a novel HMGR gene from Panax ginseng (PgHMGR2) was cloned and analyzed in this study.  PgHMGR2-encoding protein showed 71.6% sequence similarity to a P. ginseng HMGR in GenBank.  The full-length cDNA sequence of PgHMGR2 containing 1 770 bp, which encodes 589 amino acids, was cloned by RT-PCR strategy from P. ginseng.  The bioinformatic analysis showed that PgHMGR2-encoding protein contained two transmembrane regions and the HMG_CoA_reductase domain, without signal peptide.  The protein sequence of PgHMGR2 had the highest sequence similarity (99%) with Panax quinquefolius HMGR (GenBank accession No. ACV65036).  The expression level of PgHMGR2 was the highest in flower based on a real-time PCR analysis, followed by leaf and root, and the lowest was in stem.  The result will provide a foundation for exploring the molecular function of PgHMGR2 involved in ginsenoside biosynthesis based on synthetic biology approach in P. ginseng plants.