8H8S

Bovine Heart Cytochrome c Oxidase in the Calcium-bound Fully Reduced State

Summary for 8H8S

• Entry DOI: 10.2210/pdb8h8s/pdb
• Related: 5b1b
• Descriptor: Cytochrome c oxidase subunit 1, Cytochrome c oxidase subunit 7A1, Cytochrome c oxidase subunit 7B, mitochondrial, ... (28 entities in total)
• Functional Keywords: calcium, fully reduced, oxidoreductase
• Biological source: Bos taurus (cattle); More
• Total number of polymer chains: 26
• Total formula weight: 460022.51

Authors

Muramoto, K.,Shinzawa-Itoh, K. (deposition date: 2022-10-24, release date: 2023-02-08, Last modification date: 2024-10-23)

Primary citation

Muramoto, K.,Shinzawa-Itoh, K.
Calcium-bound structure of bovine cytochrome c oxidase.
Biochim Biophys Acta Bioenerg, 1864:148956-148956, 2023

PubMed Abstract: The crystal structure of bovine cytochrome c oxidase (CcO) shows a sodium ion (Na) bound to the surface of subunit I. Changes in the absorption spectrum of heme a caused by calcium ions (Ca) are detected as small red shifts, and inhibition of enzymatic activity under low turnover conditions is observed by addition of Ca in a competitive manner with Na. In this study, we determined the crystal structure of Ca-bound bovine CcO in the oxidized and reduced states at 1.7 Å resolution. Although Ca and Na bound to the same site of oxidized and reduced CcO, they led to different coordination geometries. Replacement of Na with Ca caused a small structural change in the loop segments near the heme a propionate and formyl groups, resulting in spectral changes in heme a. Redox-coupled structural changes observed in the Ca-bound form were the same as those previously observed in the Na-bound form, suggesting that binding of Ca does not severely affect enzymatic function, which depends on these structural changes. The relation between the Ca binding and the inhibitory effect during slow turnover, as well as the possible role of bound Ca are discussed.

PubMed: 36708913
DOI: 10.1016/j.bbabio.2023.148956

Experimental method

X-RAY DIFFRACTION (1.7 Å)