Protonation-State-Dependent Communication in Cytochrome c Oxidase.
Biophys J
; 113(4): 817-828, 2017 Aug 22.
Article
em En
| MEDLINE
| ID: mdl-28834718
ABSTRACT
Proton transfer in cytochrome c oxidase from the cellular inside to the binuclear redox center (BNC) can occur through two distinct pathways, the D- and K-channels. For the protein to function as both a redox enzyme and a proton pump, proton transfer into the protein toward the BNC or toward a proton loading site (and ultimately through the membrane) must be highly regulated. The PR â F transition is the first step in a catalytic cycle that requires proton transfer from the bulk at the N-side to the BNC. Molecular dynamics simulations of the PR â F intermediate of this transition, with 16 different combinations of protonation states of key residues in the D- and K-channel, show the impact of the K-channel on the D-channel to be protonation-state dependent. Strength as well as means of communication, correlations in positions, or communication along the hydrogen-bonded network depends on the protonation state of the K-channel residue K362. The conformational and hydrogen-bond dynamics of the D-channel residue N139 is regulated by an interplay of protonation in the D-channel and K362. N139 thus assumes a gating function by which proton passage through the D-channel toward E286 is likely facilitated for states with protonated K362 and unprotonated E286. In contrast, proton passage through the D-channel is hindered by N139's preference for a closed conformation in situations with protonated E286.
Texto completo:
1
Coleções:
01-internacional
Base de dados:
MEDLINE
Assunto principal:
Prótons
/
Complexo IV da Cadeia de Transporte de Elétrons
/
Simulação de Dinâmica Molecular
Idioma:
En
Revista:
Biophys J
Ano de publicação:
2017
Tipo de documento:
Article
País de afiliação:
Alemanha