Molecular cloning and characterization of GuHMGR, an HMG-CoA reductase gene from liquorice (Glycyrrhiza uralensis)

A full length cDNA encoding HMGR (designated as GuHMGR) was isolated from liquorice (Glycyrrhiza uralensis) based on degenerated PCR and genome walking. The full length cDNA of GuHMGR was 2330 bp with a 1518-bp open reading frame (ORF) encoding a 505-aa polypeptide. Bioinformatics analysis indicated that there were two trans-membrane domains in GuHMGR. A molecular model of tertiary structure showed that GuHMGR is a novel HMGR with a similar spatial structure to other plant HMGRs. The deduced polypeptide of GuHMGR has an isoelectric point (pI) of 6.41 and a calculated molecular weight of about 54.7 kDa. Sequence comparison and phylogenetic tree analysis showed that GuHMGR had the highest homology with HMGRs from Pisum sativum and Medicago truncatula, indicating that GuHMGR belongs to the plant HMGR group. Expression analysis showed the similar amount of transcript level of GuHMGR in roots and leaves, suggesting that this gene was expressed constitutively in plants. Therefore, this novel HMGR gene would possibly provide a new strategy for studying the glycyrrhizin metabolism at the molecular level in the future.