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The Alternative complex III: Properties and possible mechanisms for electron transfer and energy conservation

Alternative complexes III (ACIII) are recently identified membrane-bound enzymes that replace functionally the cytochrome bc1/b6f complexes. In general, ACIII are composed of four transmembrane proteins and three peripheral subunits that contain iron–sulfur centers and C-type hemes. ACIII are built...

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Bibliographic Details
Published in:Biochimica et biophysica acta 2012-10, Vol.1817 (10), p.1852-1859
Main Authors: Refojo, Patrícia N., Teixeira, Miguel, Pereira, Manuela M.
Format: Article
Language:English
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Summary:Alternative complexes III (ACIII) are recently identified membrane-bound enzymes that replace functionally the cytochrome bc1/b6f complexes. In general, ACIII are composed of four transmembrane proteins and three peripheral subunits that contain iron–sulfur centers and C-type hemes. ACIII are built by a combination of modules present in different enzyme families, namely the complex iron–sulfur molybdenum containing enzymes. In this article a historical perspective on the investigation of ACIII is presented, followed by an overview of the present knowledge on these enzymes. Electron transfer pathways within the protein are discussed taking into account possible different locations (cytoplasmatic or periplasmatic) of the iron–sulfur containing protein and their contribution to energy conservation. In this way several hypotheses for energy conservation modes are raised including linear and bifurcating electron transfer pathways. This article is part of a Special Issue entitled: 17th European Bioenergetics Conference (EBEC 2012). ► ACIII are quinol: electron acceptors oxidoreductases. ► The orientation of the peripheral subunit ActB is discussed. ► Electron transfer in ACIII may be linear or bifurcated. ► ACIII may contribute to energy conservation.
ISSN:0005-2728
0006-3002
1879-2650
DOI:10.1016/j.bbabio.2012.05.003