Transport of Oxidized Glutathione into Barley Vacuoles: Evidence for the Involvement of the Glutathione-S-Conjugate ATPase

Roberto Tommasini, Enrico Martinoia, Erwin Grill, Karl-Josef Dietz*, and Nikolaus Amrhein Institut für Pflanzenwissenschaften, ETH Zürich, Sonneggstraße 5, CH-8092 Zürich, Switzerland * Julius-von-Sachs-Institut für Biowissenschaften, Mittlerer Dallenbergweg 64, D-97082 Würzburg, Bundesrepublik Deutschland Z. Naturforsch. 48c, 867-871 (1993); received August 23, 1993 Glutathione, Transport, Vacuole Glutathione in its oxidized form (GSSG) is rapidly taken up into isolated barley vacuoles, while uptake o f reduced glutathione (GSH) is only marginal. GSSG transport is strictly ATPdependent and is a saturable process (Km 0.4 to 0.6 m M ). Uptake is inhibited by vanadate, but not by bafilomycin, a specific inhibitor o f the vacuolar H +-ATPase. The observation that i) the non-hydrolysable ATP analogue adenylylimidodiphosphate does not stimulate, but rather inhibits the ATP-dependent uptake o f GSSG and ii) that a four-fold accumulation o f GSSG is observed in the presence o f bafilomycin, suggests that GSSG is transported into the vacuole by a primary active process similar to that o f glutathione S-conjugates (E. Martinoia, E. Grill, R. Tommasini, K. Kreuz, N . Amrhein, Nature 364, 2 4 7 -2 4 9 (1993)). Uptake o f GSSG is competitively inhibited by the glutathione S-conjugate o f the herbicide metolachlor (K{ 80 |̂ m), indicating that transport o f GSSG is mediated by the glutathione S-conjugate ATPase.