Madagascar periwinkle (
Catharanthus roseus) is the sole source of the anticancer drugs vinblastine and vincristine, bisindole alkaloids derived from the dimerization of the terpenoid indole alkaloids vindoline and catharanthine. Full elucidation of the biosynthetic pathways of these compounds is a prerequisite for metabolic engineering efforts that will improve production of these costly molecules. However, despite the medical and commercial importance of these natural products, the biosynthetic pathways remain poorly understood. Here we report the identification and characterization of a C. roseuscDNA encoding an S-adenosyl-L-methionine-dependent Nmethyltransferase that catalyzes a nitrogen methylation involved in vindoline biosynthesis. Recombinant enzyme produced in Escherichia coliis highly substrate specific, displaying a strict requirement for a 2,3-dihydro bond in the aspidosperma skeleton. The corresponding gene transcript is induced in methyl jasmonate-elicited seedlings, along with the other known vindoline biosynthetic transcripts. Intriguingly, this unique Nmethyltransferase is most similar at the amino acid level to the plastidic γ-tocopherol Cmethyltransferases of vitamin E biosynthesis, suggesting an evolutionary link between these two functionally disparate methyltransferases.