Structure of complex III with bound cytochrome c in reduced state and definition of a minimal core interface for electron transfer.Solmaz, S.R., Hunte, C.
(2008) J Biol Chem 283: 17542-17549
- PubMed: 18390544
- DOI: https://doi.org/10.1074/jbc.M710126200
- Primary Citation of Related Structures:
- PubMed Abstract:
In cellular respiration, cytochrome c transfers electrons from cytochrome bc(1) complex (complex III) to cytochrome c oxidase by transiently binding to the membrane proteins. Here, we report the structure of isoform-1 cytochrome c bound to cytochrome bc(1) complex at 1.9 A resolution in reduced state. The dimer structure is asymmetric. Monovalent cytochrome c binding is correlated with conformational changes of the Rieske head domain and subunit QCR6p and with a higher number of interfacial water molecules bound to cytochrome c(1). Pronounced hydration and a "mobility mismatch" at the interface with disordered charged residues on the cytochrome c side are favorable for transient binding. Within the hydrophobic interface, a minimal core was identified by comparison with the novel structure of the complex with bound isoform-2 cytochrome c. Four core interactions encircle the heme cofactors surrounded by variable interactions. The core interface may be a feature to gain specificity for formation of the reactive complex.
Department of Molecular Membrane Biology, Max Planck Institute of Biophysics, 60438 Frankfurt am Main, Germany.