1V55

Bovine heart cytochrome c oxidase at the fully reduced state

Summary for 1V55

• Entry DOI: 10.2210/pdb1v55/pdb
• Related: 1V54
• Descriptor: Cytochrome c oxidase polypeptide I, Cytochrome c oxidase polypeptide VIIa-heart, Cytochrome c oxidase polypeptide VIIb, ... (28 entities in total)
• Functional Keywords: oxidoreductase
• Biological source: Bos taurus (cattle); More
• Cellular location: Mitochondrion inner membrane; Multi-pass membrane protein: P00396 P68530 P00415; Mitochondrion inner membrane: P07470 P13183 P00430 P10175 P00423 P00426 P00428 P07471 P04038; Mitochondrion intermembrane space: P00429
• Total number of polymer chains: 26
• Total formula weight: 441790.87

Authors

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. (deposition date: 2003-11-21, release date: 2003-12-23, Last modification date: 2023-12-20)

Primary citation

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.
The low-spin heme of cytochrome c oxidase as the driving element of the proton-pumping process.
Proc.Natl.Acad.Sci.Usa, 100:15304-15309, 2003

PubMed Abstract: 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.

PubMed: 14673090
DOI: 10.1073/pnas.2635097100

Experimental method

X-RAY DIFFRACTION (1.9 Å)