Subcellular localization of tryptophan decarboxylase, strictosidine synthase and strictosidine glucosidase in suspension cultured cells of Catharanthus roseus and Tabernaemontana divaricata.

The subcellular localization of tryptophan decarboxylase, strictosidine synthase and strictosidine glucosidase in suspension cultured cells of Catharanthus roseus (L.) G. Don and Tabernaemontana divaricata (L.) R. Br. ex Roem. et Schult, was investigated. It was found that tryptophan decarboxylase is an extra-vacuolar enzyme, whereas strictosidine synthase is active inside the vacuole. Strong indications were obtained for the localization of strictosidine glucosidase on the outside of the tonoplast. The results suggest that tryptamine is transported into the vacuole where it is condensed with secologanin to form strictosidine, and that strictosidine passes the tonoplast and is subsequently hydrolysed outside the vacuole.