Regio-specific prenylation of pterocarpans by a membrane-bound prenyltransferase from Psoralea corylifolia.

Prenylated pterocarpans are valuable natural products that play significant roles in plant defence and possess diverse biological activities. However, structural diversity of prenylated pterocarpans is still limited. Prenyltransferases (PTs) could catalyze the transfer of prenyl moieties to acceptor molecules and increase the structural diversity and biological activity of natural products. Up to date, only two pterocarpan PTs have been identified from plants. In this study, a new pterocarpan prenyltransferase gene, designated as PcM4DT, was identified from Psoralea corylifolia. The deduced polypeptide is predicted to be a membrane-bound protein with eight transmembrane regions. Functional characterization of recombinant PcM4DT demonstrated this enzyme could catalyze C-4 prenylation of pterocarpans, and exhibited strict substrate specificity to maackiain and 3-hydroxy-9-methoxy-pterocarpan. It also showed a strict donor specificity to DMAPP. Furthermore, removal of the putative transit peptide of PcM4DT obviously increased the catalytic activity (up to 90%). PcM4DT represents the first PT identified from the Psoralea genus.