6JUW

BOVINE HEART CYTOCHROME C OXIDASE IN CATALITIC INTERMEDIATES AT 1.80 ANGSTROM RESOLUTION

Summary for 6JUW

• Entry DOI: 10.2210/pdb6juw/pdb
• Descriptor: Cytochrome c oxidase subunit 1, Cytochrome c oxidase subunit 7A1, mitochondrial, Cytochrome c oxidase subunit 7B, mitochondrial, ... (29 entities in total)
• Functional Keywords: cytochrome c oxidase membrane protein respiratory enzyme heme protein, membrane protein, oxidoreductase
• Biological source: Bos taurus (Bovine); More
• Total number of polymer chains: 26
• Total formula weight: 452577.27

Authors

Shimada, A.,Muramoto, K.,Shinzawa-Itoh, K.,Yoshikawa, S.,Tsukihara, T. (deposition date: 2019-04-15, release date: 2020-03-25, Last modification date: 2023-11-22)

Primary citation

Shimada, A.,Etoh, Y.,Kitoh-Fujisawa, R.,Sasaki, A.,Shinzawa-Itoh, K.,Hiromoto, T.,Yamashita, E.,Muramoto, K.,Tsukihara, T.,Yoshikawa, S.
X-ray structures of catalytic intermediates of cytochromecoxidase provide insights into its O2activation and unidirectional proton-pump mechanisms.
J.Biol.Chem., 295:5818-5833, 2020

PubMed Abstract: Cytochrome oxidase (CcO) reduces O to water, coupled with a proton-pumping process. The structure of the O-reduction site of CcO contains two reducing equivalents, Fe and Cu, and suggests that a peroxide-bound state (Fe -O-O-Cu) rather than an O-bound state (Fe -O) is the initial catalytic intermediate. Unexpectedly, however, resonance Raman spectroscopy results have shown that the initial intermediate is Fe -O, whereas Fe -O-O-Cu is undetectable. Based on X-ray structures of static noncatalytic CcO forms and mutation analyses for bovine CcO, a proton-pumping mechanism has been proposed. It involves a proton-conducting pathway (the H-pathway) comprising a tandem hydrogen-bond network and a water channel located between the N- and P-side surfaces. However, a system for unidirectional proton-transport has not been experimentally identified. Here, an essentially identical X-ray structure for the two catalytic intermediates (P and F) of bovine CcO was determined at 1.8 Å resolution. A 1.70 Å Fe-O distance of the ferryl center could best be described as Fe = O, not as Fe -OH The distance suggests an ∼800-cm Raman stretching band. We found an interstitial water molecule that could trigger a rapid proton-coupled electron transfer from tyrosine-OH to the slowly forming Fe -O-O-Cu state, preventing its detection, consistent with the unexpected Raman results. The H-pathway structures of both intermediates indicated that during proton-pumping from the hydrogen-bond network to the P-side, a transmembrane helix closes the water channel connecting the N-side with the hydrogen-bond network, facilitating unidirectional proton-pumping during the P-to-F transition.

PubMed: 32165497
DOI: 10.1074/jbc.RA119.009596

Experimental method

X-RAY DIFFRACTION (1.8 Å)