Cloning and in vitro expression of sulfotransferase genes from Ilex asprella / 中草药

ABSTRACT

Objective: The medicinal plant Ilex asprella contains various biologically active sulfonated triterpenoids and triterpenoid saponins. The objective of this study was to clone sulfotransferases (ST) from I. asprella and facilitate the elucidation of the sulfonation mechanism therein. Methods: The physicochemical properties, secondary structure and tertiary structure of two ST candidates of IaST1 and IaST2 were forecasted and analyzed using related software. IaST1 and IaST2 were cloned by RT-PCR and expressed in Escherichia coli. Results: The open reading frame (ORF) of IaST1 was 1 002 bp long and encoded a protein of 333 amino acids with the calculated molecular weight of 55 500, while the ORF of IaST2 was 993 bp long and encoded a protein of 330 amino acids with the calculated molecular weight of 54 700. Both contain the five highly conserved domains of ST. Phylogenetic analysis revealed that IaST1 and IaST2 were genetically closely related and clustered together with flavonol C-3 ST of Flaveria bidentis. Conclusion: This is the first report on the cloning of STs from I. asprella, providing an important basis for further investigations into their functions and roles in the biosynthesis of sulfonated triterpenoids in I. asprella.