title: Respiratory complexes III and IV can each bind two molecules of cytochrome c at low ionic strength.
abstract: 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.
authors.affiliation: Instituto de Bioquímica Vegetal y Fotosíntesis, cicCartuja, Universidad de Sevilla-CSIC, Avda. Américo Vespucio 49, Sevilla 41092, Spain.
authors.forename: Blas
authors.initials: B
authors.lastname: Moreno-Beltrán
authors.affiliation: Instituto de Bioquímica Vegetal y Fotosíntesis, cicCartuja, Universidad de Sevilla-CSIC, Avda. Américo Vespucio 49, Sevilla 41092, Spain. Electronic address: idiazmoreno@us.es.
authors.forename: Irene
authors.initials: I
authors.lastname: Díaz-Moreno
authors.affiliation: Instituto de Bioquímica Vegetal y Fotosíntesis, cicCartuja, Universidad de Sevilla-CSIC, Avda. Américo Vespucio 49, Sevilla 41092, Spain.
authors.forename: Katiuska
authors.initials: K
authors.lastname: González-Arzola
authors.affiliation: Instituto de Bioquímica Vegetal y Fotosíntesis, cicCartuja, Universidad de Sevilla-CSIC, Avda. Américo Vespucio 49, Sevilla 41092, Spain.
authors.forename: Alejandra
authors.initials: A
authors.lastname: Guerra-Castellano
authors.affiliation: Institute of Biocomputation and Physics of Complex Systems (BIFI) - Joint Unit BIFI-IQFR (CSIC), Universidad de Zaragoza, Mariano Esquillor s/n, 50018 Zaragoza, Spain; Departamento de Bioquímica y Biología Molecular y Celular, Universidad de Zaragoza, Pedro Cerbuna 12, 50009 Zaragoza, Spain; Fundacion ARAID, Government of Aragon, Maria de Luna 11, 50018 Zaragoza, Spain.
authors.forename: Adrián
authors.initials: A
authors.lastname: Velázquez-Campoy
authors.affiliation: Instituto de Bioquímica Vegetal y Fotosíntesis, cicCartuja, Universidad de Sevilla-CSIC, Avda. Américo Vespucio 49, Sevilla 41092, Spain.
authors.forename: Miguel A
authors.initials: MA
authors.lastname: De la Rosa
authors.affiliation: Instituto de Bioquímica Vegetal y Fotosíntesis, cicCartuja, Universidad de Sevilla-CSIC, Avda. Américo Vespucio 49, Sevilla 41092, Spain.
authors.forename: Antonio
authors.initials: A
authors.lastname: Díaz-Quintana
mesh_terms: D000818:Animals; D002417:Cattle; D045304:Cytochromes c / Q000737:chemistry*; D014450:Electron Transport Complex III / Q000737:chemistry*; D003576:Electron Transport Complex IV / Q000737:chemistry*; D006801:Humans; D008958:Models, Molecular; D019906:Nuclear Magnetic Resonance, Biomolecular; D009994:Osmolar Concentration; D011485:Protein Binding; D020836:Protein Structure, Quaternary; D012996:Solutions
chemical_list: D012996:Solutions; D045304:Cytochromes c; D003576:Electron Transport Complex IV; D014450:Electron Transport Complex III
keywords: Cytochrome bc(1); Cytochrome c; Cytochrome c oxidase; Isothermal Titration Calorimetry; Nuclear Magnetic Resonance; Supercomplex