title: Cytochrome c Oxidase Biogenesis and Metallochaperone Interactions: Steps in the Assembly Pathway of a Bacterial Complex.
abstract: Biogenesis of mitochondrial cytochrome c oxidase (COX) is a complex process involving the coordinate expression and assembly of numerous subunits (SU) of dual genetic origin. Moreover, several auxiliary factors are required to recruit and insert the redox-active metal compounds, which in most cases are buried in their protein scaffold deep inside the membrane. Here we used a combination of gel electrophoresis and pull-down assay techniques in conjunction with immunostaining as well as complexome profiling to identify and analyze the composition of assembly intermediates in solubilized membranes of the bacterium Paracoccus denitrificans. Our results show that the central SUI passes through at least three intermediate complexes with distinct subunit and cofactor composition before formation of the holoenzyme and its subsequent integration into supercomplexes. We propose a model for COX biogenesis in which maturation of newly translated COX SUI is initially assisted by CtaG, a chaperone implicated in CuB site metallation, followed by the interaction with the heme chaperone Surf1c to populate the redox-active metal-heme centers in SUI. Only then the remaining smaller subunits are recruited to form the mature enzyme which ultimately associates with respiratory complexes I and III into supercomplexes.
authors.affiliation: Institute of Biochemistry, Membrane Transport Machineries, Goethe-University, Frankfurt am Main, Germany.
authors.forename: Sonja
authors.initials: S
authors.lastname: Schimo
authors.affiliation: Functional Proteomics, SFB 815 Core Unity, Faculty of Medicine, Goethe-University, Frankfurt am Main, Germany.
authors.forename: Ilka
authors.initials: I
authors.lastname: Wittig
authors.affiliation: Institute of Biochemistry, Membrane Transport Machineries, Goethe-University, Frankfurt am Main, Germany.
authors.forename: Klaas M
authors.identifier: http://orcid.org/0000-0001-9035-3827
authors.initials: KM
authors.lastname: Pos
authors.affiliation: Institute of Biochemistry, Molecular Genetics, Goethe-University, Frankfurt am Main, Germany.
authors.forename: Bernd
authors.initials: B
authors.lastname: Ludwig
mesh_terms: D003576:Electron Transport Complex IV / Q000096:biosynthesis* / Q000378:metabolism; D004591:Electrophoresis, Polyacrylamide Gel; D013058:Mass Spectrometry; D056511:Metallochaperones / Q000378:metabolism*; D010231:Paracoccus denitrificans / Q000378:metabolism*; D011485:Protein Binding
chemical_list: D056511:Metallochaperones; D003576:Electron Transport Complex IV