5XDX

Bovine heart cytochrome c oxidase in the reduced state with pH 7.3 at 1.99 angstrom resolution

Summary for 5XDX

• Entry DOI: 10.2210/pdb5xdx/pdb
• Related: 5XDQ
• Descriptor: Cytochrome c oxidase subunit 1, Cytochrome c oxidase subunit VIIa-heart, Cytochrome c oxidase subunit VIIb, ... (28 entities in total)
• Functional Keywords: oxidoreductase, proton pump, heme protein, respiratory chain
• Biological source: Bos taurus (Bovine); More
• Total number of polymer chains: 26
• Total formula weight: 444651.93

Authors

Luo, F.J.,Shimada, A.,Hagimoto, N.,Shimada, S.,Shinzawa-Itoh, K.,Yamashita, E.,Yoshikawa, S.,Tsukihara, T. (deposition date: 2017-03-30, release date: 2018-02-07, Last modification date: 2023-11-22)

Primary citation

Luo, F.,Shinzawa-Itoh, K.,Hagimoto, K.,Shimada, A.,Shimada, S.,Yamashita, E.,Yoshikawa, S.,Tsukihara, T.
Structure of bovine cytochrome c oxidase in the ligand-free reduced state at neutral pH.
Acta Crystallogr F Struct Biol Commun, 74:92-98, 2018

PubMed Abstract: Cytochrome c oxidase (CcO), the terminal oxidase in cellular respiration, couples proton pumping to O reduction. Mammalian CcO resides in the inner mitochondrial membrane. Previously, a model of H-pathway proton pumping was proposed based on various CcO crystal structures. However, all previously determined structures were solved using crystals obtained at pH 5.7, which differs from the environmental pH of CcO in the inner membrane. The structures of fully oxidized and ligand-free reduced CcO at pH 7.3 have now been determined. Structural comparison between the oxidized and reduced states revealed that the structural alterations that occurred upon redox change at pH 5.7 in Asp51, the magnesium-containing cluster, haem groups and helix X, which provide important structural evidence for the H-pathway proton-pumping proposal, also occur at pH 7.3. These structural alterations were restricted to a local region of CcO; no domain movement was detected, nor were significant structural alterations detected in peripheral regions at either pH value. These observations indicate that the small and precise structural alterations that occur over the course of the reaction cycle are not affected by pH change, and that isolated CcO precisely performs proton pumping via the H-pathway over a wide pH range. Because the pH is not uniform across the molecular surface of CcO, the fact that the overall structure of CcO is not affected by pH changes ensures the high enzymatic efficiency of this protein in the mitochondria.

PubMed: 29400318
DOI: 10.1107/S2053230X17018532

Experimental method

X-RAY DIFFRACTION (1.99 Å)