1rie
From Proteopedia
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STRUCTURE OF A WATER SOLUBLE FRAGMENT OF THE RIESKE IRON-SULFUR PROTEIN OF THE BOVINE HEART MITOCHONDRIAL CYTOCHROME BC1-COMPLEX
Overview
BACKGROUND: The 'Rieske' iron-sulfur protein is the primary electron, acceptor during hydroquinone oxidation in cytochrome bc complexes. The, spectroscopic and electrochemical properties of the 'Rieske' [2Fe-2S], cluster differ significantly from those of other iron-sulfur clusters. A, 129-residue water soluble fragment containing the intact [2Fe-2S] cluster, was isolated following proteolytic digestion of the bc1 complex and used, for structural studies. RESULTS: The structure of the Rieske iron-sulfur, fragment containing the reduced [2Fe-2S] cluster has been determined using, the multiwavelength anomalous diffraction (MAD) technique and refined at, 1.5 A resolution. The fragment has a novel overall fold that includes, three sheets of beta strands. The iron atoms of the [2Fe-2S] cluster are, coordinated by two cysteine (Fe-1) and two histidine (Fe-2) residues, respectively, with the histidine ligands completely exposed to the, solvent. This is in contrast to the four cysteine coordination pattern, observed in previously characterised [2Fe-2S] ferredoxins. The, cluster-binding fold is formed by two loops connected by a disulfide, bridge; these loops superpose with the metal-binding loops of rubredoxins., The environment of the cluster is stabilised by an extensive hydrogen-bond, network. CONCLUSIONS: The high-resolution structure supports the proposed, coordination pattern involving histidine ligands and provides a basis for, a detailed analysis of the spectroscopic and electrochemical properties., As the cluster is located at the tip of the protein, it might come into, close contact with cytochrome b. The exposed N epsilon atoms of the, histidine ligands of the cluster are readily accessible to quinones and, inhibitors within the hydroquinone oxidation (QP) pocket of the bc1, complex and may undergo redox-dependent protonation/deprotonation.
About this Structure
1RIE is a Single protein structure of sequence from Bos taurus with FES as ligand. Active as Ubiquinol--cytochrome-c reductase, with EC number 1.10.2.2 Known structural/functional Site: . Full crystallographic information is available from OCA.
Reference
Structure of a water soluble fragment of the 'Rieske' iron-sulfur protein of the bovine heart mitochondrial cytochrome bc1 complex determined by MAD phasing at 1.5 A resolution., Iwata S, Saynovits M, Link TA, Michel H, Structure. 1996 May 15;4(5):567-79. PMID:8736555
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