Discrimination between transmembrane ion gradient-driven and electron transfer-driven ATP synthesis in the methanogenic bacteria

AbstractAs with Methanococcus voltae [(1986) FEBS Lett. 200, 177–180], ATP synthesis in Methanobacterium thermoautotrophicum (ΔH) can be driven by the imposition of a sodium gradient, but only in the presence of a counterion. Monensin (but not SF6847) inhibits this synthesis. Methanogenic electron transfer-driven ATP synthesis, however, is insensitive to the combination of these two ionophores. In M. voltae, 117 μM diethylstilbestrol effectively inhibits both membrane potential- and sodium gradient-driven ATP synthesis, but has no effect on ATP production coupled to methanogenesis. In Mb. thermoautotrophicum (ΔH), a similar pattern of inhibition is exhibited by harmaline, an inhibitor of sodium-linked membrane transport systems. We conclude that ATP-driven sodium translocation and electron transfer-driven ATP synthesis are accomplished by separate entities, at least for these two only distantly related species of methanogen