A compilation of mutations located in the cytochrome b subunit of the bacterial and mitochondrial bc1 complex

Brasseur, Gaël; Sarıbaş, A. Sami; Daldal, Fevzi

doi:10.1016/0005-2728(96)00051-5

Cited by 174 publications

(145 citation statements)

References 34 publications

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“…Y132F QCR exhibits unchanged sensitivity to stigmatellin but is resistant to myxothiazol (Table 1). This agrees with results obtained for the equivalent mutation in bacterial QCR (9). Each of the substitutions in position 279 altered the sensitivity for both inhibitors.…”

Section: Thesupporting

confidence: 90%

“…This residue is a locus of center P inhibitor resistance both in yeast and bacterial QCR (17)(18)(19). Mutational analysis of the equivalent residue in bacterial QCR (Phe 144 ) indicated that replacement of Phe 144 affects ubiquinol binding and oxidation (9). The residue Tyr 279 is close to the highly conserved PEWY (Pro 271 -Tyr 274 ) motif, and it has been suggested to take part in positioning ubiquinol prior to oxidation and in stabilizing the enzyme-substrate complex by weak hydrogen bonds (6).…”

Section: /Ementioning

confidence: 99%

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Mutational Analysis of Cytochrome b at the Ubiquinol Oxidation Site of Yeast Complex III

Wenz

Covián

Hellwig

et al. 2007

Journal of Biological Chemistry

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The cytochrome bc 1 complex is a dimeric enzyme of the inner mitochondrial membrane that links electron transfer from ubiquinol to cytochrome c by a protonmotive Q cycle mechanism in which ubiquinol is oxidized at one center in the enzyme, referred to as center P, and ubiquinone is rereduced at a second center, referred to as center N. To better understand the mechanism of ubiquinol oxidation, we have examined catalytic activities and pre-steady-state reduction kinetics of yeast cytochrome bc 1 complexes with mutations in cytochrome b that we expected would affect oxidation of ubiquinol. We mutated two residues thought to be involved in proton conduction linked to ubiquinol oxidation, Tyr 132 and Glu 272 , and two residues proposed to be involved in docking ubiquinol into the center P pocket, Phe

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Section: Thesupporting

confidence: 90%

Section: /Ementioning

confidence: 99%

Mutational Analysis of Cytochrome b at the Ubiquinol Oxidation Site of Yeast Complex III

Wenz

Covián

Hellwig

et al. 2007

Journal of Biological Chemistry

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“…Glu-295 in cytochrome b is important for the release of the second proton, as proposed previously (31)(32)(33). Glu-295 is completely conserved in mitochondrial cytochrome b (34), and the importance of the residue in proton transfer is indicated by mutagenesis studies because alteration of glutamine abolishes ubiquinol oxidation in R. sphaeroides (35). Additionally, recent kinetic studies showed that protonation of a group with a pK a of 5.7 blocked catalysis, and this effect was attributed to Glu-295 (36).…”

Section: Photosynthetic Growth Behaviors Of the Wild-type Andsupporting

confidence: 53%

Effect of Mutations of Arginine 94 on Proton Pumping, Electron Transfer, and Superoxide Anion Generation in Cytochrome b of the bc1 Complex from Rhodobacter sphaeroides

Zhou

2013

Journal of Biological Chemistry

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Background:The bc 1 complex catalyzes electron transfer from ubiquinol to cytochrome c and translocates protons across the membrane. Results: Substitution of Arg-94 decreased the electron transfer activity and proton pumping capability and increased the superoxide production. Conclusion: Arg-94 is an important amino acid for the proton pumping capability of the bc 1 complex. Significance: The result is significant for understanding the catalytic mechanism of the bc 1 complex.

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“…Spans contributing to the site include the C-terminal end of the transmembrane helix C (blue in Figure 2, middle), the cd1 helix (green-blue), the ef loop, including a coil from the end of the helix E (green), the -PEWY-turn (yellow), the small ef helix (orange) connecting the -PEWY-turn to transmembrane helix F, and the N-terminal end of helix F (red). These contributions had been predicted from model building based on sequence analysis and the sites at which inhibitor-resistant lesions had been identified or at which changes in function had been generated by specific mutagenesis (26,(35)(36)(37).…”

Section: Positionsmentioning

confidence: 99%

Mechanism of Ubiquinol Oxidation by the bc₁ Complex: Role of the Iron Sulfur Protein and Its Mobility

et al. 1999

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Native structures of ubihydroquinone:cytochrome c oxidoreductase (bc 1 complex) from different sources, and structures with inhibitors in place, show a 16-22 Å displacement of the [2Fe-2S] cluster and the position of the C-terminal extrinsic domain of the iron sulfur protein. None of the structures shows a static configuration that would allow catalysis of all partial reactions of quinol oxidation. We have suggested that the different conformations reflect a movement of the subunit necessary for catalysis. The displacement from an interface with cytochrome c 1 in native crystals to an interface with cytochrome b is induced by stigmatellin or 5-n-undecyl-6-hydroxy-4,7-dioxobenzothiazole (UHDBT) and involves ligand formation between His-161 of the [2Fe-2S] binding cluster and the inhibitor. The movement is a rotational displacement, so that the same conserved docking surface on the iron sulfur protein interacts with cytochrome c 1 and with cytochrome b. The mobile extrinsic domain retains essentially the same tertiary structure, and the anchoring N-terminal tail remains in the same position. The movement occurs through an extension of a helical segment in the short linking span. We report details of the protein structure for the two main configurations in the chicken heart mitochondrial complex and discuss insights into mechanism provided by the structures and by mutant strains in which the docking at the cytochrome b interface is impaired. The movement of the iron sulfur protein represents a novel mechanism of electron transfer, in which a tethered mobile head allows electron transfer through a distance without the entropic loss from free diffusion.The ubihydroquinone:cytochrome c oxidoreductase (bc 1 complex) 1 (E.C. 1.10.2.2) and the related b 6 f complex of oxygenic photosynthesis are central components of the major electron-transfer chains that carry the energy flux of the biosphere. The bc 1 complex of the mitochondrial respiratory chain transfers electrons from ubihydroquinone (quinol) to cytochrome (cyt) c in the aqueous phase and catalyzes the coupled transfer of protons across the membrane. Our understanding of the function of these enzymes at the atomic level has been greatly aided by structures recently solved by X-ray crystallography. These include cyt f (the equivalent of cyt c 1 in the b 6 f complex) from chloroplasts (1, 2) and the Rieske iron sulfur protein (ISP) from the beef heart mitochondrial complex (3) and chloroplasts (4), all crystallized as water-soluble fragments generated by proteolysis or mutagenesis. A partial structure of the beef heart mitochondrial complex at ∼2.9 Å resolution has been published by Xia and colleagues (5, 6). However, the crystals were disordered in the region of the ISP and cytochrome c 1 , and this precluded a detailed consideration of the mechanistic role of these subunits. More complete structures for the complexes from chicken, rabbit, and beef heart mitochondria have been provided by Zhang et al. ‡ University of Illinois. § University of California. ...

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A compilation of mutations located in the cytochrome b subunit of the bacterial and mitochondrial bc1 complex

Cited by 174 publications

References 34 publications

Mutational Analysis of Cytochrome b at the Ubiquinol Oxidation Site of Yeast Complex III

Mutational Analysis of Cytochrome b at the Ubiquinol Oxidation Site of Yeast Complex III

Effect of Mutations of Arginine 94 on Proton Pumping, Electron Transfer, and Superoxide Anion Generation in Cytochrome b of the bc1 Complex from Rhodobacter sphaeroides

Mechanism of Ubiquinol Oxidation by the bc₁ Complex: Role of the Iron Sulfur Protein and Its Mobility

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A compilation of mutations located in the cytochrome b subunit of the bacterial and mitochondrial bc1 complex

Cited by 174 publications

References 34 publications

Mutational Analysis of Cytochrome b at the Ubiquinol Oxidation Site of Yeast Complex III

Mutational Analysis of Cytochrome b at the Ubiquinol Oxidation Site of Yeast Complex III

Effect of Mutations of Arginine 94 on Proton Pumping, Electron Transfer, and Superoxide Anion Generation in Cytochrome b of the bc1 Complex from Rhodobacter sphaeroides

Mechanism of Ubiquinol Oxidation by the bc1 Complex: Role of the Iron Sulfur Protein and Its Mobility

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Mechanism of Ubiquinol Oxidation by the bc₁ Complex: Role of the Iron Sulfur Protein and Its Mobility