Cloning, bioinformatics study and gene expression evaluation of Squalene Synthase 1 in Iranian native licorice

Licorice (Glycyrrhiza glabra L.) is one of the most important medicinal plants and contains bioactive compounds such as triterpene saponins (glycyrrhizin) and phytosterols. Squalene synthase (EC 2.5.1.21) is a membrane- bound enzyme that converts two farnesyl diphosphate molecules into squalene, a key precursor for sterol and triterpene biosynthesis. In this study, the coding sequence of squalene synthase 1 in Iranian native licorice was cloned in pTZ57R/T and the characterization of its polypeptide was predicted by using bioinformatic tools. The cDNA of GgSQS1 is 1242bp and encodes a 413 amino acid polypeptide. Bioinformatic analysis revealed that the deduced GgSQS1 polypeptide had high similarity with squalene synthase1 of members of the glycyrrhiza genus. Subcellular analysis showed that the activity of this polypeptide is in the endoplasmic reticulum. The molecular weight of this polypeptide is 47.3 kDa with a pI value of 8.18. Two transmembrane domains and two protected regions were detected in the amino acid sequence. The three-dimensional protein structure was predicted using I-TASSER software. In the predicted structure, transmembrane helixes, hydrophobic amino acids, the conserved sequence and amino acids on the protein surface were identified using Chimera software. Studies of Squalene synthases1 gene expression showed that the highest and lowest expression occur in the root and green organs of the plant, respectively.