2EIK

Cadmium ion binding structure of bovine heart cytochrome C oxidase in the fully reduced state

2EIK の概要

• エントリーDOI: 10.2210/pdb2eik/pdb
• 関連するPDBエントリー: 1OCC 1OCO 1OCR 1OCZ 1V54 1V55 2DYR 2DYS 2OCC 2eij 2eil 2eim 2ein
• 分子名称: Cytochrome c oxidase subunit 1, Cytochrome c oxidase polypeptide VIIa-heart, Cytochrome c oxidase polypeptide VIIb, ... (28 entities in total)
• 機能のキーワード: oxidoreductase
• 由来する生物種: Bos taurus (cattle); 詳細
• 細胞内の位置: 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
• タンパク質・核酸の鎖数: 26
• 化学式量合計: 443430.46

構造登録者

Muramoto, K.,Hirata, K.,Shinzawa-Itoh, K.,Yoko-O, S.,Yamashita, E.,Aoyama, H.,Tsukihara, T.,Yoshikawa, S. (登録日: 2007-03-13, 公開日: 2007-05-29, 最終更新日: 2023-10-25)

主引用文献

Muramoto, K.,Hirata, K.,Shinzawa-Itoh, K.,Yoko-O, S.,Yamashita, E.,Aoyama, H.,Tsukihara, T.,Yoshikawa, S.
A histidine residue acting as a controlling site for dioxygen reduction and proton pumping by cytochrome c oxidase
Proc.Natl.Acad.Sci.Usa, 104:7881-7886, 2007

PubMed Abstract: Cytochrome c oxidase transfers electrons and protons for dioxygen reduction coupled with proton pumping. These electron and proton transfers are tightly coupled with each other for the effective energy transduction by various unknown mechanisms. Here, we report a coupling mechanism by a histidine (His-503) at the entrance of a proton transfer pathway to the dioxygen reduction site (D-pathway) of bovine heart cytochrome c oxidase. In the reduced state, a water molecule is fixed by hydrogen bonds between His-503 and Asp-91 of the D-pathway and is linked via two water arrays extending to the molecular surface. The microenvironment of Asp-91 appears in the x-ray structure to have a proton affinity as high as that of His-503. Thus, Asp-91 and His-503 cooperatively trap, on the fixed water molecule, the proton that is transferred through the water arrays from the molecular surface. On oxidation, the His-503 imidazole plane rotates by 180 degrees to break the hydrogen bond to the protonated water and releases the proton to Asp-91. On reduction, Asp-91 donates the proton to the dioxygen reduction site through the D-pathway. The proton collection controlled by His-503 was confirmed by partial electron transfer inhibition by binding of Zn2+ and Cd2+ to His-503 in the x-ray structures. The estimated Kd for Zn2+ binding to His-503 in the x-ray structure is consistent with the reported Kd for complete proton-pumping inhibition by Zn2+ [Kannt A, Ostermann T, Muller H, Ruitenberg M (2001) FEBS Lett 503:142-146]. These results suggest that His-503 couples the proton transfer for dioxygen reduction with the proton pumping.

PubMed: 17470809
DOI: 10.1073/pnas.0610031104

実験手法

X-RAY DIFFRACTION (2.1 Å)