The Rieske/cytochrome b complex of Heliobacteria |
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Authors: | AL Ducluzeau |
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Institution: | Laboratoire de Bioénergétique et Ingénierie des protéines, Institut de Biologie Structurale et Microbiologie, Unité Propre de Recherche 9036, Centre National de la Recherche Scientifique, 31, chemin Joseph Aiguier, 13402 Marseille Cedex 20, France |
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Abstract: | Heliobacteria have a Rieske/cytochrome b complex composed of a Rieske protein, a cytochrome b6, a subunit IV and a di-heme cytochrome c. The overall structure of the complex seems close to the b6f complex from cyanobacteria and chloroplasts to the exception of the di-heme cytochrome. We show here by biochemical and biophysical studies that a heme ci is covalently attached to the Rieske/cytochrome b complex from Heliobacteria. We studied the EPR signature of this heme in two different species, Heliobacterium modesticaldum and Heliobacillus mobilis. In contrast to the case of b6f complex, a strong axial ligand to the heme is present, most probably a protonatable amino acid residue. |
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Keywords: | bc complex Heme ci Heliobacteria EPR b6f complex |
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