FIG 6.

Redox processes catalyzed by the 11-subunit core complexes and their specific electron-transferring modules in Methanosarcina mazei (Fpo) and Escherichia coli (Nuo) and hypothetical processes and potential interaction partners of the Fpo-like complexes in Methanosaeta thermophila (59) and Methanomassiliicoccales (this study). The common core complex of 11 subunits is shown in gray, and specific subunits of the different complexes are indicated by different colors. In all cases, the complex serves as a redox-driven proton pump. For further explanations, see the text. F₄₂₀, coenzyme F₄₂₀; Fd, ferredoxin; MP, methanophenazine; UQ, ubiquinone.