JBIC Journal of Biological Inorganic Chemistry

, Volume 10, Issue 6, pp 613–624

A structural model for the adduct between cytochrome c and cytochrome c oxidase

  • Ivano Bertini
  • Gabriele Cavallaro
  • Antonio Rosato
Original Article

DOI: 10.1007/s00775-005-0011-7

Cite this article as:
Bertini, I., Cavallaro, G. & Rosato, A. J Biol Inorg Chem (2005) 10: 613. doi:10.1007/s00775-005-0011-7

Abstract

An ensemble of structural models of the adduct between cytochrome c and cytochrome c oxidase from Paracoccus denitrificans has been calculated based on the experimental data from site-directed mutagenesis and NMR experiments that have accumulated over the last years of research on this system. The residues from each protein that are at the protein–protein interface have been identified by the above experimental work, and this information has been converted in a series of restraints explicitly used in calculations. It is found that a single static structural model cannot satisfy all experimental data simultaneously. Therefore, it is proposed that the adduct exists as a dynamic ensemble of different orientations in equilibrium, and may be represented by a combination or average of the various limiting conformations calculated here. The equilibrium involves both conformations that are competent for electron transfer and conformations that are not. Long-range recognition of the partners is driven by non-specific electrostatic interactions, while at shorter distances hydrophobic contacts tune the reciprocal orientation. Electron transfer from cytochrome bc1 to cytochrome c oxidase is mediated through cytochrome c experiencing multiple encounters with both of its partners, only part of which are productive. The number of encounters, and thus the electron transfer rate, may be increased by the formation of a cytochrome bc1–cytochrome c oxidase supercomplex and/or (in human) by increasing the concentration of the two enzymes in the membrane space.

Keywords

Cytochrome c, Cytochrome c oxidase, Electron transfer, CuA, Docking

Copyright information

© SBIC 2005

Authors and Affiliations

  • Ivano Bertini
    • 1
    • 2
  • Gabriele Cavallaro
    • 1
    • 2
  • Antonio Rosato
    • 1
    • 2
  1. 1.Magnetic Resonance CenterUniversity of FlorenceSesto FiorentinoItaly
  2. 2.Department of ChemistryUniversity of FlorenceSesto FiorentinoItaly