title: The dimerization of the yeast cytochrome bc1 complex is an early event and is independent of Rip1.
abstract: In Saccharomyces cerevisiae the mature cytochrome bc1 complex exists as an obligate homo-dimer in which each monomer consists of ten distinct protein subunits inserted into or bound to the inner mitochondrial membrane. Among them, the Rieske iron-sulfur protein (Rip1), besides its catalytic role in electron transfer, may be implicated in the bc1 complex dimerization. Indeed, Rip1 has the globular domain containing the catalytic center in one monomer while the transmembrane helix interacts with the adjacent monomer. In addition, the lack of Rip1 leads to the accumulation of an immature bc1 intermediate, only loosely associated with cytochrome c oxidase. In this study we have investigated the biogenesis of the yeast cytochrome bc1 complex using epitope tagged proteins to purify native assembly intermediates. We showed that the dimerization process is an early event during bc1 complex biogenesis and that the presence of Rip1, differently from previous proposals, is not essential for this process. We also investigated the multi-step model of bc1 assembly thereby lending further support to the existence of bona fide subcomplexes during bc1 maturation in the inner mitochondrial membrane. Finally, a new model of cytochrome bc1 complex assembly, in which distinct intermediates sequentially interact during bc1 maturation, has been proposed.
authors: Department of Biological and Environmental Sciences and Technologies, University of Salento, Via Prov.le Lecce-Monteroni, I-73100 Lecce, Italy.
authors: Annalea
authors: A
authors: Conte
authors: Department of Biological and Environmental Sciences and Technologies, University of Salento, Via Prov.le Lecce-Monteroni, I-73100 Lecce, Italy.
authors: Benedetta
authors: B
authors: Papa
authors: Department of Biological and Environmental Sciences and Technologies, University of Salento, Via Prov.le Lecce-Monteroni, I-73100 Lecce, Italy.
authors: Alessandra
authors: A
authors: Ferramosca
authors: Department of Biological and Environmental Sciences and Technologies, University of Salento, Via Prov.le Lecce-Monteroni, I-73100 Lecce, Italy. Electronic address: vincenzo.zara@unisalento.it.
authors: Vincenzo
authors: V
authors: Zara
mesh_terms: D014450:Electron Transport Complex III / Q000378:metabolism*; D003576:Electron Transport Complex IV / Q000378:metabolism; D017353:Gene Deletion; D008928:Mitochondria / Q000378:metabolism; D008954:Models, Biological; D046912:Multiprotein Complexes / Q000378:metabolism; D028861:Nuclear Pore Complex Proteins / Q000378:metabolism*; D055503:Protein Multimerization; D012441:Saccharomyces cerevisiae / Q000378:metabolism*; D029701:Saccharomyces cerevisiae Proteins / Q000378:metabolism*
chemical_list: D046912:Multiprotein Complexes; C109212:NUP42 protein, S cerevisiae; D028861:Nuclear Pore Complex Proteins; D029701:Saccharomyces cerevisiae Proteins; D003576:Electron Transport Complex IV; D014450:Electron Transport Complex III
keywords: Cytochrome bc(1) biogenesis; Cytochrome bc(1) complex; Rip1; Yeast mitochondria