Mycochromone decreases ATP-driven proton translocation in plant plasma membrane- and tonoplast-enriched vesicles

Abstract Mycochromone, a metabolite produced by Mycosphaerella rosigena, inhibits the ATP-dependent proton translocation and the ATP-generated electrical potential in pea stem tonoplast-enriched vesicles, without affecting the H⁺/K⁺ exchange induced by nigericin or an artificially imposed proton gradient. The inhibition is dependent on the time of pre-incubation and mycochromone concentration. In addition, mycochromone inhibits the ATP-dependent proton translocation in radish plasma membrane-enriched vesicles, though it does not alter ATPase activity (evaluated by hydrolysis of ATP) in either type of plant vesicle. Mycochromone seems to act on the H⁺ channels for proton translocation of the H⁺-pumping ATPase localized on plasmalemma and tonoplast, without affecting the catalytic site of ATP hydrolysis.