Respiratory complexes III and IV can each bind two molecules of cytochrome c at low ionic strength

Description

The transient interactions of respiratory cytochrome c with complexes III and IV is herein investigated by using heterologous proteins, namely human cytochrome c, the soluble domain of plant cytochrome c1 and bovine cytochrome c oxidase. The binding molecular mechanisms of the resulting cross-complexes have been analyzed by Nuclear Magnetic Resonance and Isothermal Titration Calorimetry. Our data reveal that the two cytochrome c-involving adducts possess a 2:1 stoichiometry – that is, two cytochrome c molecules per adduct – at low ionic strength. We conclude that such extra binding sites at the surfaces of complexes III and IV can facilitate the turnover and sliding of cytochrome c molecules and, therefore, the electron transfer within respiratory supercomplexes.

Abstract

España, MINECO Grant Nos. BFU2010-19451/BMC and BFU2012-31670/BMC

Abstract

Junta de Andalucía Grant PAI, BIO198

Abstract

España Ministerio de Educación, y European Social Fund-ERDF AP2009-4092

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