title: Hybrid fusions show that inter-monomer electron transfer robustly supports cytochrome bc1 function in vivo.
abstract: Electronic connection between Qo and Qi quinone catalytic sites of dimeric cytochrome bc1 is a central feature of the energy-conserving Q cycle. While both the intra- and inter-monomer electron transfers were shown to connect the sites in the enzyme, mechanistic and physiological significance of the latter remains unclear. Here, using a series of mutated hybrid cytochrome bc1-like complexes, we show that inter-monomer electron transfer robustly sustains the function of the enzyme in vivo, even when the two subunits in a dimer come from different species. This indicates that minimal requirement for bioenergetic efficiency is to provide a chain of cofactors for uncompromised electron flux between the catalytic sites, while the details of protein scaffold are secondary.
authors.affiliation: Department of Molecular Biophysics, Faculty of Biochemistry, Biophysics and Biotechnology, Jagiellonian University, 30-387 Kraków, Poland.
authors.forename: Robert
authors.initials: R
authors.lastname: Ekiert
authors.affiliation: Department of Molecular Biophysics, Faculty of Biochemistry, Biophysics and Biotechnology, Jagiellonian University, 30-387 Kraków, Poland.
authors.forename: Monika
authors.initials: M
authors.lastname: Czapla
authors.affiliation: Department of Molecular Biophysics, Faculty of Biochemistry, Biophysics and Biotechnology, Jagiellonian University, 30-387 Kraków, Poland.
authors.forename: Marcin
authors.initials: M
authors.lastname: Sarewicz
authors.affiliation: Department of Molecular Biophysics, Faculty of Biochemistry, Biophysics and Biotechnology, Jagiellonian University, 30-387 Kraków, Poland. Electronic address: artur.osyczka@uj.edu.pl.
authors.forename: Artur
authors.initials: A
authors.lastname: Osyczka
mesh_terms: D001426:Bacterial Proteins / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism*; D004579:Electron Transport; D014450:Electron Transport Complex III / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism*; D005798:Genes, Bacterial; D008958:Models, Molecular; D050505:Mutant Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism; D052817:Phototrophic Processes; D011487:Protein Conformation; D011993:Recombinant Fusion Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism; D016354:Rhodobacter capsulatus / Q000201:enzymology* / Q000235:genetics / Q000254:growth & development
chemical_list: D001426:Bacterial Proteins; D050505:Mutant Proteins; D011993:Recombinant Fusion Proteins; D014450:Electron Transport Complex III
keywords: Cytochrome bc(1); Electron transfer; Energy conversion; Hybrid fusion protein; Mitochondrial complex III
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