A common coupling mechanism for A-type heme-copper oxidases from bacteria to mitochondria
Amandine Maréchal, Jingyang Xu, Naho Genko, Andrew M. Hartley, Francis Haraux, Brigitte Meunier, Peter R. Rich
Abstract
Significance We present a comprehensive investigation of mitochondrial DNA-encoded variants of cytochrome c oxidase (C c O) that harbor mutations within their core catalytic subunit I, designed to interrogate the presently disputed functions of the three putative proton channels. We assess overall respiratory competence, specific C c O catalytic activity, and, most importantly, proton/electron (H + /e − ) stoichiometry from adenosine diphosphate to oxygen ratio measurements on preparations of intact mitochondria. We unequivocally show that yeast mitochondrial C c O uses the D-channel to translocate protons across its hydrophilic core, providing direct evidence in support of a common proton pumping mechanism across all members of the A-type heme-copper oxidase superfamily, independent of their bacterial or mitochondrial origin.