A highly selective alkaloid uptake system in vacuoles of higher plants |
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Authors: | B Deus-Neumann M H Zenk |
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Institution: | (1) Lehrstuhl Pharmazeutische Biologie der Universität, Karlstrasse 29, D-8000 München 2, Germany |
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Abstract: | Vacuoles were isolated from different plant cell cultures and the transport mechanism for alkaloid uptake at the tonoplast membrane, as well as the compartmentation of enzymes and products inside the cells were investigated. While serpentine, the major alkaloid of Catharanthus roseus cells, is definitely located inside the vacuole, two key enzymes of the indole-alkaloid pathway, strictosidine synthase and a specific glucosidase, are located in the cytosol. Transport of alkaloids across the tonoplast into the vacuolar space has been characterized as an active, engergy-requiring mechanism, which is sensitive to the temperature and pH of the surrounding medium, stimulated by K+ and Mg2+, and inhibited by N,N -dicyclohexylcarbodiimid and Cu2+. The alkaloids accumulate inside the vacuoles against a concentration gradient, and the uptake system is specific for alkaloids indigenous to the plant from which the vacuoles have been isolated.Abbreviation DCCD
N,N -dicyclohexylcarbodiimid
Dedicated to Professor Dr. Hubert Ziegler on the occasion of his 60th birthday |
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Keywords: | Alkaloid (vacuole uptake) Catharanthus Compartmentation (alkaloids) Uptake (alkaloids) Vacuole (alkaloid uptake) |
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