Abstract
Lithospermum erythrorhizon produce a red naphtoquinone pigment shikonin in the root epidermis, which exhibits various biological activities, including antibiotic, anti-inflammatory, hemostatic and antitumoral activities. The key enzyme of shikonin biosynthesis is p-hydroxybenzoate(PHB):geranyltransferase (LePGT). The enzyme shows strict substrate specificity for geranyl diphosphate (GPP), as the prenyl substrate and catalyses the aromatic proton substitution with the geranyl residue. LePGT is composed of 307 amino acids and has 9 transmembrane domains. LePGT could be functionally expressed in yeast, but the protein yield was very low. In this study we have expressed LePGT in insect cells, Sf9, in order to apply it to the X-ray crystallographic analysis. The recombinant LePGT expressed in Sf9 shows higher specific activity than that in yeast, and high protein yield, which was functionally solubilized.
