On the role of S: Sulfotransferases in assimilatory sulfate reduction by plant cell suspension cultures.

Cell suspension cultures of Catharanthus roseus (L.) G. Don were grown under S-auxotrophic (1.8 mM sulfate) and under S-heterotrophic (0.5 and 1.0 mM cysteine or methionine) conditions. The development of activity of the thiol sulfotransferases was followed during the complete growth period. Under auxotrophic growth, an NADPH-dependent S: sulfotransferase and a GSH-dependent S: sulfotransferase developed identically, whereas under heterotrophic growth, differences in the amount of enzymes and in the time course of their development occurred. The NADPH-dependent sulfotransferase appeared "repressed" by the S-amino acids but the GSH-dependent enzyme was "derepressed." In that phenomenon, the development of the GSH sulfotransferase paralleled the development of the ATP-sulfurylase (EC 2774) activity of the cells.