Vacuolar Transport of the Medicinal Alkaloids from Catharanthus roseus Is Mediated by a Proton-Driven Antiport

• Type: Article in International Scientific Journal
• Date: 2013

Authors

Ines Carqueijeiro (Author) Other; Henrique Noronha (Author) Other; Patricia Duarte (Author) Other; Hernani Geros (Author) Other; Mariana Sottomayor (Author) FCUP

Journal

Title: Plant Physiology

Vol. 162

Pages: 1486-1496

ISSN: 0032-0889

Publisher: American Society of Plant Biologists

Indexing

ISI Web of Knowledge - 51 Citations

Scopus - 57 Citations

Scientific classification

FOS: Natural sciences > Biological sciences

Other information

Authenticus ID: P-006-9NK

DOI: 10.1104/pp.113.220558

Abstract (EN): Catharanthus roseus is one of the most studied medicinal plants due to the interest in their dimeric terpenoid indole alkaloids (TIAs) vinblastine and vincristine, which are used in cancer chemotherapy. These TIAs are produced in very low levels in the leaves of the plant from the monomeric precursors vindoline and catharanthine and, although TIA biosynthesis is reasonably well understood, much less is known about TIA membrane transport mechanisms. However, such knowledge is extremely important to understand TIA metabolic fluxes and to develop strategies aimed at increasing TIA production. In this study, the vacuolar transport mechanism of the main TIAs accumulated in C. roseus leaves, vindoline, catharanthine, and alpha-3',4'-anhydrovinblastine, was characterized using a tonoplast vesicle system. Vindoline uptake was ATP dependent, and this transport activity was strongly inhibited by NH4+ and carbonyl cyanide m-chlorophenyl hydrazine and was insensitive to the ATP-binding cassette (ABC) transporter inhibitor vanadate. Spectrofluorimetry assays with a pH-sensitive fluorescent probe showed that vindoline and other TIAs indeed were able to dissipate an H+ gradient preestablished across the tonoplast by either vacuolar H+-ATPase or vacuolar H+-pyrophosphatase. The initial rates of H+ gradient dissipation followed Michaelis-Menten kinetics, suggesting the involvement of mediated transport, and this activity was species and alkaloid specific. Altogether, our results strongly support that TIAs are actively taken up by C. roseus mesophyll vacuoles through a specific H+ antiport system and not by an ion-trap mechanism or ABC transporters.

Language: English

Type (Professor's evaluation): Scientific

No. of pages: 11