The respiratory complex I of bacteria, archaea and eukarya and its module common with membrane-bound multisubunit hydrogenases

The proton-pumping NADH:ubiquinone oxidoreductase, also called complex I, i s the first of the respiratory complexes providing the proton motive force which is essential for energy consuming processes like the synthesis of ATP , Homologues of this complex exist in bacteria, archaea, in mitochondria of eukaryotes and in chloroplasts of plants. The bacterial and mitochondrial complexes function as NADH dehydrogenase, while the archaeal complex,works as F420H2 dehydrogenase. The electron donor of the cyanobacterial and plast idal complex is not yet known. Despite the different electron input sites, 11 polypeptides constitute the structural framework for proton translocatio n and quinone binding in the complex of all three domains of life, Sis of t hem are also present in a family of membrane-bound multisubunit [NiFe] hydr ogenases. it is discussed that they build a module for electron transfer co upled to proton translocation, (C) 2000 Federation of European Biochemical Societies, Published by Elsevier Science B.V. All rights reserved.