Intermonomer interactions in dimer of bovine heart cytochrome c oxidase.
The X-ray structure of bovine heart cytochrome c oxidase solved for orthorhombic crystals showed a dimeric structure stabilized by four subunit-subunit contacts, namely, subunit Vb-subunit Vb on the matrix side, subunit I-subunit VIa, subunit VIa-subunit I in the transmembrane region and subunit VIb-subunit VIb on the intermembrane side. The same intermonomer contacts as in the orthorhombic crystals were observed in both hexagonal and tetragonal crystals, the X-ray structures of which were determined by the molecular-replacement method. These results suggest that the dimeric structure also exists under physiological conditions. These contacts, especially the subunit IVa-subunit I contact, in which the N-terminal portion of subunit IVa is placed on the surface of subunit I near the dioxygen-reduction site, indicate that the function of the bovine heart enzyme is likely to be controlled by perturbation of the monomer-monomer association.
Lee
S J
SJ
Institute for Protein Research, Osaka University, 3-2 Yamada-oka, Suita 565-0871, Japan.
Yamashita
E
E
Abe
T
T
Fukumoto
Y
Y
Tsukihara
T
T
Shinzawa-Itoh
K
K
Ueda
H
H
Yoshikawa
S
S
D000818:Animals; D002417:Cattle; D019281:Dimerization; D003576:Electron Transport Complex IV / Q000737:chemistry*; D008958:Models, Molecular; D009206:Myocardium / Q000201:enzymology*; D011487:Protein Conformation
D003576:Electron Transport Complex IV