Energy transduction in vesicles of the methanogenic strain Gö1

Abstract

Everted vesicles of the methanogenic strain Go1 synthesized ATP in response to methanogenesis from methyl-coenzyme M and H2. Simultaneously, a transmembrane pH gradient (ΔpH) was generated as evident from fluorescence quenching of acridine orange. Protonophorous uncouplers prevented ΔpH generation and ATP synthesis, but did not affect methanogenesis. The ATP synthase inhibitor diethylstilbestrol (DES) inhibited ATP synthesis but had no effect on methanogenesis and on ΔpH formation, indicating the essential role of the transmembrane proton potential in ATP synthesis. Progress has also been made in assigning specific functions to membrane components in methanogenesis from methyl-CoM and H2. Separation of cell extracts into cytoplasmic and membrane fraction revealed an essential role of membrane-bound components in electron transfer: methanogenesis catalyzed by the cytoplasmic fraction from strain Go1 was stimulated several fold by membranes from various methanogens. This stimulation was prevented if the membranes had been treated with oxidants (O2, K3[Fe(CN)6]) or SH reagents (Ag+, p-chloromercuribenzoate, iodoacetamide) pointing to the involvement of functional SH groups in methanogenesis from methyl-CoM and H2.