1kb9

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Revision as of 07:27, 18 November 2007

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spinqualitylabelsall models 1kb9, resolution 2.30Å Show:Asymmetric Unit Biological Assembly Drag the structure with the mouse to rotate   Export Animated Image

YEAST CYTOCHROME BC1 COMPLEX

Overview

Biochemical data have shown that specific, tightly bound phospholipids are, essential for activity of the cytochrome bc1 complex (QCR), an integral, membrane protein of the respiratory chain. However, the structure and, function of such phospholipids are not yet known. Here we describe five, phospholipid molecules and one detergent molecule in the X-ray structure, of yeast QCR at 2.3 A resolution. Their individual binding sites suggest, specific roles in facilitating structural and functional integrity of the, enzyme. Interestingly, a phosphatidylinositol molecule is bound in an, unusual interhelical position near the flexible linker region of the, Rieske iron-sulfur protein. Two possible proton uptake pathways at the, ubiquinone reduction site have been identified: the E/R and the CL/K, pathway. Remarkably, cardiolipin is positioned at the entrance to the, latter. We propose that cardiolipin ensures structural integrity of the, proton-conducting protein environment and takes part directly in proton, uptake. Site-directed mutagenesis of ligating residues confirmed the, importance of the phosphatidylinositol- and cardiolipin-binding sites.

About this Structure

1KB9 is a Protein complex structure of sequences from Mus musculus and Saccharomyces cerevisiae with HEM, FES, SMA, UQ6, PIE, PEF, CDL, PCF and UMQ as ligands. Active as Ubiquinol--cytochrome-c reductase, with EC number 1.10.2.2 Full crystallographic information is available from OCA.

Reference

Specific roles of protein-phospholipid interactions in the yeast cytochrome bc1 complex structure., Lange C, Nett JH, Trumpower BL, Hunte C, EMBO J. 2001 Dec 3;20(23):6591-600. PMID:11726495

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