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Evolution of cytochrome bc complexes: from membrane-anchored dehydrogenases of ancient bacteria to triggers of apoptosis in vertebrates.

ABSTRACT: This review traces the evolution of the cytochrome bc complexes from their early spread among prokaryotic lineages and up to the mitochondrial cytochrome bc1 complex (complex III) and its role in apoptosis. The results of phylogenomic analysis suggest that the bacterial cytochrome b6f-type complexes with short cytochromes b were the ancient form that preceded in evolution the cytochrome bc1-type complexes with long cytochromes b. The common ancestor of the b6f-type and the bc1-type complexes probably resembled the b6f-type complexes found in Heliobacteriaceae and in some Planctomycetes. Lateral transfers of cytochrome bc operons could account for the several instances of acquisition of different types of bacterial cytochrome bc complexes by archaea. The gradual oxygenation of the atmosphere could be the key evolutionary factor that has driven further divergence and spread of the cytochrome bc complexes. On the one hand, oxygen could be used as a very efficient terminal electron acceptor. On the other hand, auto-oxidation of the components of the bc complex results in the generation of reactive oxygen species (ROS), which necessitated diverse adaptations of the b6f-type and bc1-type complexes, as well as other, functionally coupled proteins. A detailed scenario of the gradual involvement of the cardiolipin-containing mitochondrial cytochrome bc1 complex into the intrinsic apoptotic pathway is proposed, where the functioning of the complex as an apoptotic trigger is viewed as a way to accelerate the elimination of the cells with irreparably damaged, ROS-producing mitochondria. This article is part of a Special Issue entitled: Respiratory complex III and related bc complexes.

SUBMITTER: Dibrova DV

PROVIDER: S-EPMC3839093 | biostudies-literature | 2013 Nov-Dec

REPOSITORIES: biostudies-literature

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Evolution of cytochrome bc complexes: from membrane-anchored dehydrogenases of ancient bacteria to triggers of apoptosis in vertebrates.

Dibrova Daria V DV Cherepanov Dmitry A DA Galperin Michael Y MY Skulachev Vladimir P VP Mulkidjanian Armen Y AY

Biochimica et biophysica acta 20130719 11-12

This review traces the evolution of the cytochrome bc complexes from their early spread among prokaryotic lineages and up to the mitochondrial cytochrome bc1 complex (complex III) and its role in apoptosis. The results of phylogenomic analysis suggest that the bacterial cytochrome b6f-type complexes with short cytochromes b were the ancient form that preceded in evolution the cytochrome bc1-type complexes with long cytochromes b. The common ancestor of the b6f-type and the bc1-type complexes pro ...[more]

PMID: 23871937

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Project description:Aspects of the crystal structures of the hetero-oligomeric cytochrome bc(1) and b(6)f ("bc") complexes relevant to their electron/proton transfer function and the associated redox reactions of the lipophilic quinones are discussed. Differences between the b(6)f and bc(1) complexes are emphasized. The cytochrome bc(1) and b(6)f dimeric complexes diverge in structure from a core of subunits that coordinate redox groups consisting of two bis-histidine coordinated hemes, a heme b(n) and b(p) on the electrochemically negative (n) and positive (p) sides of the complex, the high potential [2Fe-2S] cluster and c-type heme at the p-side aqueous interface and aqueous phase, respectively, and quinone/quinol binding sites on the n- and p-sides of the complex. The bc(1) and b(6)f complexes diverge in subunit composition and structure away from this core. b(6)f Also contains additional prosthetic groups including a c-type heme c(n) on the n-side, and a chlorophyll a and β-carotene. Common structure aspects; functions of the symmetric dimer. (I) Quinone exchange with the bilayer. An inter-monomer protein-free cavity of approximately 30Å along the membrane normal×25Å (central inter-monomer distance)×15Å (depth in the center), is common to both bc(1) and b(6)f complexes, providing a niche in which the lipophilic quinone/quinol (Q/QH(2)) can be exchanged with the membrane bilayer. (II) Electron transfer. The dimeric structure and the proximity of the two hemes b(p) on the electrochemically positive side of the complex in the two monomer units allow the possibility of two alternate routes of electron transfer across the complex from heme b(p) to b(n): intra-monomer and inter-monomer involving electron cross-over between the two hemes b(p). A structure-based summary of inter-heme distances in seven bc complexes, representing mitochondrial, chromatophore, cyanobacterial, and algal sources, indicates that, based on the distance parameter, the intra-monomer pathway would be favored kinetically. (III) Separation of quinone binding sites. A consequence of the dimer structure and the position of the Q/QH(2) binding sites is that the p-side QH(2) oxidation and n-side Q reduction sites are each well separated. Therefore, in the event of an overlap in residence time by QH(2) or Q molecules at the two oxidation or reduction sites, their spatial separation would result in minimal steric interference between extended Q or QH(2) isoprenoid chains. (IV) Trans-membrane QH(2)/Q transfer. (i) n/p-side QH(2)/Q transfer may be hindered by lipid acyl chains; (ii) the shorter less hindered inter-monomer pathway across the complex would not pass through the center of the cavity, as inferred from the n-side antimycin site on one monomer and the p-side stigmatellin site on the other residing on the same surface of the complex. (V) Narrow p-side portal for QH(2)/Q passage. The [2Fe-2S] cluster that serves as oxidant, and whose histidine ligand serves as a H(+) acceptor in the oxidation of QH(2), is connected to the inter-monomer cavity by a narrow extended portal, which is also occupied in the b(6)f complex by the 20 carbon phytyl chain of the bound chlorophyll.

Dataset Information

Evolution of cytochrome bc complexes: from membrane-anchored dehydrogenases of ancient bacteria to triggers of apoptosis in vertebrates.

Publications

Evolution of cytochrome bc complexes: from membrane-anchored dehydrogenases of ancient bacteria to triggers of apoptosis in vertebrates.

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