1v54

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spinqualitylabelsall models 1v54, resolution 1.8Å Show:Asymmetric Unit Biological Assembly Drag the structure with the mouse to rotate   Export Animated Image

Bovine heart cytochrome c oxidase at the fully oxidized state

Overview

Mitochondrial cytochrome c oxidase plays an essential role in aerobic, cellular respiration, reducing dioxygen to water in a process coupled with, the pumping of protons across the mitochondrial inner membrane. An, aspartate residue, Asp-51, located near the enzyme surface, undergoes a, redox-coupled x-ray structural change, which is suggestive of a role for, this residue in redox-driven proton pumping. However, functional or, mechanistic evidence for the involvement of this residue in proton pumping, has not yet been obtained. We report that the Asp-51 --> Asn mutation of, the bovine enzyme abolishes its proton-pumping function without impairment, of the dioxygen reduction activity. Improved x-ray structures (at, 1.8/1.9-A resolution in the fully oxidized/reduced states) show that the, net positive charge created upon oxidation of the low-spin heme of the, enzyme drives the active proton transport from the interior of the, mitochondria to Asp-51 across the enzyme via a water channel and a, hydrogen-bond network, located in tandem, and that the enzyme reduction, induces proton ejection from the aspartate to the mitochondrial exterior., A peptide bond in the hydrogen-bond network critically inhibits reverse, proton transfer through the network. A redox-coupled change in the, capacity of the water channel, induced by the hydroxyfarnesylethyl group, of the low-spin heme, suggests that the channel functions as an effective, proton-collecting region. Infrared results indicate that the conformation, of Asp-51 is controlled only by the oxidation state of the low-spin heme., These results indicate that the low-spin heme drives the proton-pumping, process.

About this Structure

1V54 is a Protein complex structure of sequences from Bos taurus with DMU, CU, MG, NA, ZN, HEA, CHD, CDL, TGL, PSC, PEK, PGV, CUA and UNX as ligands. Active as Cytochrome-c oxidase, with EC number 1.9.3.1 Full crystallographic information is available from OCA.

Reference

The low-spin heme of cytochrome c oxidase as the driving element of the proton-pumping process., Tsukihara T, Shimokata K, Katayama Y, Shimada H, Muramoto K, Aoyama H, Mochizuki M, Shinzawa-Itoh K, Yamashita E, Yao M, Ishimura Y, Yoshikawa S, Proc Natl Acad Sci U S A. 2003 Dec 23;100(26):15304-9. Epub 2003 Dec 12. PMID:14673090

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