Emergence of cytochrome bc complexes in the context of photosynthesis.

Autor: Dibrova DV; A.N. Belozersky Institute of Physico-Chemical Biology, Lomonosov Moscow State University, Moscow, 119991, Russia., Shalaeva DN; School of Bioengineering and Bioinformatics, Lomonosov Moscow State University, Moscow, 119991, Russia.; School of Physics, University of Osnabrueck, Osnabrueck, D-49069, Germany., Galperin MY; National Center for Biotechnology Information, National Library of Medicine, National Institutes of Health, Bethesda, MD, 20894, USA., Mulkidjanian AY; A.N. Belozersky Institute of Physico-Chemical Biology, Lomonosov Moscow State University, Moscow, 119991, Russia.; School of Bioengineering and Bioinformatics, Lomonosov Moscow State University, Moscow, 119991, Russia.; School of Physics, University of Osnabrueck, Osnabrueck, D-49069, Germany.
Jazyk: angličtina
Zdroj: Physiologia plantarum [Physiol Plant] 2017 Sep; Vol. 161 (1), pp. 150-170. Date of Electronic Publication: 2017 Jul 04.
DOI: 10.1111/ppl.12586
Abstrakt: The cytochrome bc (cyt bc) complexes are involved in Q-cycling; they oxidize membrane quinols by high-potential electron acceptors, such as cytochromes or plastocyanin, and generate transmembrane proton gradient. In several prokaryotic lineages, and also in plant chloroplasts, the catalytic core of the cyt bc complexes is built of a four-helical cytochrome b (cyt b) that contains three hemes, a three-helical subunit IV, and an iron-sulfur Rieske protein (cytochrome b 6 f-type complexes). In other prokaryotic lineages, and also in mitochondria, the cyt b subunit is fused with subunit IV, yielding a seven- or eight-helical cyt b with only two hemes (cyt bc 1 -type complexes). Here we present an updated phylogenomic analysis of the cyt b subunits of cyt bc complexes. This analysis provides further support to our earlier suggestion that (1) the ancestral version of cyt bc complex contained a small four-helical cyt b with three hemes similar to the plant cytochrome b 6 and (2) independent fusion events led to the formation of large cyts b in several lineages. In the search for a primordial function for the ancestral cyt bc complex, we address the intimate connection between the cyt bc complexes and photosynthesis. Indeed, the Q-cycle turnover in the cyt bc complexes demands high-potential electron acceptors. Before the Great Oxygenation Event, the biosphere had been highly reduced, so high-potential electron acceptors could only be generated upon light-driven charge separation. It appears that an ancestral cyt bc complex capable of Q-cycling has emerged in conjunction with the (bacterio)chlorophyll-based photosynthetic systems that continuously generated electron vacancies at the oxidized (bacterio)chlorophyll molecules.
(© 2017 The Authors. Physiologia Plantarum published by John Wiley & Sons Ltd on behalf of Scandinavian Plant Physiology Society.)
Databáze: MEDLINE
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