Catalytic and activating protons follow different pathways in the H⁺‐ATPase of potato tuber mitochondria

Abstract

The effect of some F0F1 inhibitors on the activation of the H+‐ATPase by the electrochemical proton gradient was investigated in mitochondria extracted from potato tubers. Transient activated state of the ATPase was revealed by addition of ATP and of the detergent lauryldimethylamine oxide (LDAO) to energized mitochondria. Venturicidin, tri‐n‐butyltin and aurovertin at high concentrations did not affect the process of Δ/̃gmH+‐activation, whereas oligomycin fully blocked it. The results support the idea of separate pathways or binding sites for catalytic and activating protons.

Deactivation of F0F1 ATPase in intact plant mitochondria

“…4). The effect of oligomycin could simply be time-dependent, but one may also remark that oligomycin differs from other inhibitors in the following ways: (a) it is fully specific of the mitochondrial ATPase (no effect in chloroplasts or bacteria like Escherichia coli); (b) it interferes with the process of activatioddeactivation of the ATPase in plant mitochondria, contrary to the other F, inhibitors, that is venturicidin and tri-n-butyl tin (Valerio and Haraux, 1993 ; venturicidin was previously shown to be also without effect on the activation of the chloroplast ATPase: Valerio et al, 1992). This shows that complex relationships exist between A$;, inhibition by oligomycin and probably IF1 binding, and could explain the delayed inhibition observed in Fig.…”