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Pérez-Mejías G, Olloqui-Sariego JL, Guerra-Castellano A, Díaz-Quintana A, Calvente JJ, Andreu R, De la Rosa MA, Díaz-Moreno I. Physical contact between cytochrome c1 and cytochrome c increases the driving force for electron transfer. BIOCHIMICA ET BIOPHYSICA ACTA-BIOENERGETICS 2020; 1861:148277. [DOI: 10.1016/j.bbabio.2020.148277] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/30/2020] [Revised: 06/29/2020] [Accepted: 07/09/2020] [Indexed: 01/09/2023]
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2
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Wang HW, Lei J, Shi Y. Biological cryo-electron microscopy in China. Protein Sci 2016; 26:16-31. [PMID: 27534377 PMCID: PMC5192968 DOI: 10.1002/pro.3018] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/06/2016] [Revised: 08/11/2016] [Accepted: 08/11/2016] [Indexed: 12/16/2022]
Abstract
Cryo‐electron microscopy (cryo‐EM) plays an increasingly more important role in structural biology. With the construction of an arm of the Chinese National Protein Science Facility at Tsinghua University, biological cryo‐EM has entered a phase of rapid development in China. This article briefly reviews the history of biological cryo‐EM in China, describes its current status, comments on its impact on the various biological research fields, and presents future outlook.
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Affiliation(s)
- Hong-Wei Wang
- Beijing Advanced Innovation Center for Structural Biology, School of Life Sciences, Tsinghua University, Beijing, 100084, China
| | - Jianlin Lei
- Beijing Advanced Innovation Center for Structural Biology, School of Life Sciences, Tsinghua University, Beijing, 100084, China
| | - Yigong Shi
- Beijing Advanced Innovation Center for Structural Biology, School of Life Sciences, Tsinghua University, Beijing, 100084, China
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3
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Moreno-Beltrán B, Díaz-Quintana A, González-Arzola K, Velázquez-Campoy A, De la Rosa MA, Díaz-Moreno I. Cytochrome c1 exhibits two binding sites for cytochrome c in plants. BIOCHIMICA ET BIOPHYSICA ACTA-BIOENERGETICS 2014; 1837:1717-29. [PMID: 25091281 DOI: 10.1016/j.bbabio.2014.07.017] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [Subscribe] [Scholar Register] [Received: 03/17/2014] [Revised: 07/23/2014] [Accepted: 07/26/2014] [Indexed: 11/27/2022]
Abstract
In plants, channeling of cytochrome c molecules between complexes III and IV has been purported to shuttle electrons within the supercomplexes instead of carrying electrons by random diffusion across the intermembrane bulk phase. However, the mode plant cytochrome c behaves inside a supercomplex such as the respirasome, formed by complexes I, III and IV, remains obscure from a structural point of view. Here, we report ab-initio Brownian dynamics calculations and nuclear magnetic resonance-driven docking computations showing two binding sites for plant cytochrome c at the head soluble domain of plant cytochrome c1, namely a non-productive (or distal) site with a long heme-to-heme distance and a functional (or proximal) site with the two heme groups close enough as to allow electron transfer. As inferred from isothermal titration calorimetry experiments, the two binding sites exhibit different equilibrium dissociation constants, for both reduced and oxidized species, that are all within the micromolar range, thus revealing the transient nature of such a respiratory complex. Although the docking of cytochrome c at the distal site occurs at the interface between cytochrome c1 and the Rieske subunit, it is fully compatible with the complex III structure. In our model, the extra distal site in complex III could indeed facilitate the functional cytochrome c channeling towards complex IV by building a "floating boat bridge" of cytochrome c molecules (between complexes III and IV) in plant respirasome.
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Affiliation(s)
- Blas Moreno-Beltrán
- Instituto de Bioquímica Vegetal y Fotosíntesis, cicCartuja, Universidad de Sevilla - CSIC, Avda. Américo Vespucio 49, Sevilla 41092, Spain
| | - Antonio Díaz-Quintana
- Instituto de Bioquímica Vegetal y Fotosíntesis, cicCartuja, Universidad de Sevilla - CSIC, Avda. Américo Vespucio 49, Sevilla 41092, Spain
| | - Katiuska González-Arzola
- Instituto de Bioquímica Vegetal y Fotosíntesis, cicCartuja, Universidad de Sevilla - CSIC, Avda. Américo Vespucio 49, Sevilla 41092, Spain
| | - Adrián Velázquez-Campoy
- 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
| | - Miguel A De la Rosa
- Instituto de Bioquímica Vegetal y Fotosíntesis, cicCartuja, Universidad de Sevilla - CSIC, Avda. Américo Vespucio 49, Sevilla 41092, Spain
| | - Irene Díaz-Moreno
- Instituto de Bioquímica Vegetal y Fotosíntesis, cicCartuja, Universidad de Sevilla - CSIC, Avda. Américo Vespucio 49, Sevilla 41092, Spain.
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4
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Nucleotide sequence of the gene for pre-apocytochrome f in the spinach plastid chromosome. Curr Genet 2013; 8:551-7. [PMID: 24177957 DOI: 10.1007/bf00410443] [Citation(s) in RCA: 73] [Impact Index Per Article: 6.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/07/1984] [Indexed: 10/26/2022]
Abstract
We have characterized a cloned fragment of the spinach plastid chromosome encoding the gene for apocytochrome f. Northern blot analysis and hybrid selection translation discloses that the gene is expressed. From the nucleotide sequence, we deduce that the protein contains 285 amino acids and an amino-terminal signal sequence of 35 amino acid residues. The calculated molecular mass of pre-apocytochrome f is 35.3 kd. The clustering of hydrophobic residues indicates that the processed protein (31.3 kd) possesses only a single anchoring transmembrane domain close to the C terminus, and that 75% of the polypeptide chain including the heme-binding site protrudes into the thylakoid lumen. This topology resembles that reported for beef heart mitochondrial cytochrome c1.
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5
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Williams G, Moore GR, Williams RJP. Biological Electron Transfer: The Structure, Dynamics and Reactivity of Cytochromec. COMMENT INORG CHEM 2006. [DOI: 10.1080/02603598508072253] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/23/2022]
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7
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Abstract
The cytochrome bc complexes represent a phylogenetically diverse group of complexes of electron-transferring membrane proteins, most familiarly represented by the mitochondrial and bacterial bc1 complexes and the chloroplast and cyanobacterial b6f complex. All these complexes couple electron transfer to proton translocation across a closed lipid bilayer membrane, conserving the free energy released by the oxidation-reduction process in the form of an electrochemical proton gradient across the membrane. Recent exciting developments include the application of site-directed mutagenesis to define the role of conserved residues, and the emergence over the past five years of X-ray structures for several mitochondrial complexes, and for two important domains of the b6f complex.
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Affiliation(s)
- E A Berry
- Physical Biosciences Division, Lawrence Berkeley National Laboratory, Berkeley, California 94720, USA.
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8
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Hamel P, Lemaire C, Bonnefoy N, Brivet-Chevillotte P, Dujardin G. Mutations in the membrane anchor of yeast cytochrome c1 compensate for the absence of Oxa1p and generate carbonate-extractable forms of cytochrome c1. Genetics 1998; 150:601-11. [PMID: 9755193 PMCID: PMC1460358 DOI: 10.1093/genetics/150.2.601] [Citation(s) in RCA: 33] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
Oxa1p is a mitochondrial inner membrane protein that is mainly required for the insertion/assembly of complex IV and ATP synthase and is functionally conserved in yeasts, humans, and plants. We have isolated several independent suppressors that compensate for the absence of Oxa1p. Molecular cloning and sequencing reveal that the suppressor mutations (CYT1-1 to -6) correspond to amino acid substitutions that are all located in the membrane anchor of cytochrome c1 and decrease the hydrophobicity of this anchor. Cytochrome c1 is a catalytic subunit of complex III, but the CYT1-1 mutation does not seem to affect the electron transfer activity. The double-mutant cyt1-1,164, which has a drastically reduced electron transfer activity, still retains the suppressor activity. Altogether, these results suggest that the suppressor function of cytochrome c1 is independent of its electron transfer activity. In addition to the membrane-bound cytochrome c1, carbonate-extractable forms accumulate in all the suppressor strains. We propose that these carbonate-extractable forms of cytochrome c1 are responsible for the suppressor function by preventing the degradation of the respiratory complex subunits that occur in the absence of Oxa1p.
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Affiliation(s)
- P Hamel
- Centre de Génétique Moléculaire du Centre National de la Recherche Scientifique, 91198 Gif-sur-Yvette Cedex, France
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9
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Howe G, Merchant S. The biosynthesis of bacterial and plastidic c-type cytochromes. PHOTOSYNTHESIS RESEARCH 1994; 40:147-165. [PMID: 24311284 DOI: 10.1007/bf00019332] [Citation(s) in RCA: 19] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/18/1993] [Accepted: 12/12/1993] [Indexed: 06/02/2023]
Abstract
The biosynthesis of bacterial and plastidic c-type cytochromes includes several steps that occur post-translationally. In the case of bacterial cytochromes, the cytosolically synthesized pre-proteins are translocated across the cytoplasmic membrane, the pre-proteins are cleaved to their mature forms and heme is ligated to the processed apoprotein. Although heme attachment has not been studied extensively at the biochemical level, molecular genetic approaches suggest that the reaction generally occurs after translocation of the apoprotein to the periplasm. Recent studies with Bradyrhizobium japonicum and Rhodobacter capsulatus indicate that the process of heme attachment requires the function of a large number of genes. Mutation of these genes generates a pleiotropic deficiency in all c-type cytochromes, suggesting that the gene products participate in processes required for the biosynthesis of all c-type cytochromes. In eukaryotic cells, the biosynthesis of photosynthetic c-type cytochromes is somewhat more complex owing to the additional level of compartmentation. Nevertheless, the basic features of the pathway appear to be conserved. For instance, as is the case in bacteria, translocation and processing of the pre-proteins is not dependent on heme attachment. Genetic analysis suggests that the nuclear as well as the plastid genomes encode functions required for heme attachment, and that these genes function in the biosynthesis of the membrane-associated as well as the soluble c-type cytochrome of chloroplasts. A feature of cytochromes c biogenesis that appears to be conserved between chloroplasts and mitochondria is the sub-cellular location of the heme attachment reaction (p-side of the energy transducing membrane). Continued investigation of all three experimental systems (bacteria, chloroplasts, mitochondria) is likely to lead to a greater understanding of the biochemistry of cytochrome maturation as well as the more general problem of cofactor-protein association during the assembly of an energy transducing membrane.
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Affiliation(s)
- G Howe
- Department of Chemistry and Biochemistry, UCLA, 405 Hilgard Avenue, 90024-1569, Los Angeles, CA, USA
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10
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Abstract
The cytochrome bc1 complex is an oligomeric electron transfer enzyme located in the inner membrane of mitochondria and the plasma membrane of bacteria. The cytochrome bc1 complex participates in respiration in eukaryotic cells and also participates in respiration, cyclic photosynthetic electron transfer, denitrification, and nitrogen fixation in a phylogenetically diverse collection of bacteria. In all of these organisms, the cytochrome bc1 complex transfers electrons from ubiquinol to cytochrome c and links this electron transfer to translocation of protons across the membrane in which it resides, thus converting the available free energy of the oxidation-reduction reaction into an electrochemical proton gradient. The mechanism by which the cytochrome bc1 complex achieves this energy transduction is the protonmotive Q cycle. The Q cycle mechanism has been documented by extensive experimentation, and recent investigations have focused on structural features of the three redox subunits of the bc1 complex essential to the protonmotive and electrogenic activities of this membranous enzyme.
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Affiliation(s)
- U Brandt
- Department of Biochemistry, Dartmouth Medical School, Hanover, NH 03755
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11
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Mutations in a 19-amino-acid hydrophobic region of the yeast cytochrome c1 presequence prevent sorting to the mitochondrial intermembrane space. Mol Cell Biol 1992. [PMID: 1328858 DOI: 10.1128/mcb.12.10.4677] [Citation(s) in RCA: 19] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Most mitochondrial proteins destined for the intermembrane space (IMS) carry in their presequence information for localization to the IMS in addition to information for their import. By selecting for mutants in the yeast Saccharomyces cerevisiae that mislocalize an IMS-targeted fusion protein, we identified mutations in the IMS sorting signal of the cytochrome c1 protein. Amino acid substitutions or deletions in a stretch of 19 hydrophobic amino acids of the cytochrome c1 presequence resulted in accumulation of the intermediate form of the cytochrome c1 protein in the matrix. In some cases, the accumulated intermediate appeared to be slowly exported from the matrix, across the inner membrane to the IMS. Our results support the hypothesis that the cytochrome c1 precursor is normally imported completely into the matrix and then exported to the IMS.
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12
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Jensen RE, Schmidt S, Mark RJ. Mutations in a 19-amino-acid hydrophobic region of the yeast cytochrome c1 presequence prevent sorting to the mitochondrial intermembrane space. Mol Cell Biol 1992; 12:4677-86. [PMID: 1328858 PMCID: PMC360394 DOI: 10.1128/mcb.12.10.4677-4686.1992] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/26/2022] Open
Abstract
Most mitochondrial proteins destined for the intermembrane space (IMS) carry in their presequence information for localization to the IMS in addition to information for their import. By selecting for mutants in the yeast Saccharomyces cerevisiae that mislocalize an IMS-targeted fusion protein, we identified mutations in the IMS sorting signal of the cytochrome c1 protein. Amino acid substitutions or deletions in a stretch of 19 hydrophobic amino acids of the cytochrome c1 presequence resulted in accumulation of the intermediate form of the cytochrome c1 protein in the matrix. In some cases, the accumulated intermediate appeared to be slowly exported from the matrix, across the inner membrane to the IMS. Our results support the hypothesis that the cytochrome c1 precursor is normally imported completely into the matrix and then exported to the IMS.
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Affiliation(s)
- R E Jensen
- Department of Cell Biology and Anatomy, Johns Hopkins University School of Medicine, Baltimore, Maryland 21205
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13
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Bechmann G, Schulte U, Weiss H. Chapter 8 Mitochondrial ubiquinol—cytochrome c oxidoreductase. ACTA ACUST UNITED AC 1992. [DOI: 10.1016/s0167-7306(08)60176-3] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 03/08/2023]
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14
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Konishi K, Van Doren S, Kramer D, Crofts A, Gennis R. Preparation and characterization of the water-soluble heme-binding domain of cytochrome c1 from the Rhodobacter sphaeroides bc1 complex. J Biol Chem 1991. [DOI: 10.1016/s0021-9258(18)98678-3] [Citation(s) in RCA: 38] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022] Open
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15
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Gennis RB. Some recent advances relating to prokaryotic cytochrome c reductases and cytochrome c oxidases. BIOCHIMICA ET BIOPHYSICA ACTA 1991; 1058:21-4. [PMID: 1646011 DOI: 10.1016/s0005-2728(05)80260-9] [Citation(s) in RCA: 35] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/28/2022]
Abstract
Prokaryotic systems provide excellent experimental opportunities for exploring structure/function relationships for the complex, membrane-bound, multisubunit enzymes responsible for the reduction and subsequent oxidation of c-type cytochromes in respiratory or photosynthetic electron transport chains. Two points are made in this mini-review: (1) The eukaryotic and prokaryotic aa3-type cytochrome c oxidases are members of an apparently large superfamily of structurally related respiratory oxidases. This superfamily displays considerable variation in terms of the heme prosthetic groups (a or b) as well as the substrate oxidized (quinol or cytochrome c). The relationships among these enzymes help to facilitate explorations of how they work. (2) Molecular biology techniques can be used to generate intact, redox-active, water-soluble domains of membrane-bound subunits. These soluble domains can be used for detailed examination, including obtaining high resolution structure by NMR techniques or by X-ray crystallography. This approach is being used to study the soluble heme-binding domain of cytochrome c1 from the bc1 complex of Rhodobacter sphaeroides.
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Affiliation(s)
- R B Gennis
- Department of Biochemistry and Chemistry, University of Illinois, Urbana 61801
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16
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Hemrika W, Berden JA. Membrane topography of the subunits of ubiquinol-cytochrome-c oxidoreductase of Saccharomyces cerevisiae. The 14-kDa and the 11-kDa subunits face opposite sides of the mitochondrial inner membrane. EUROPEAN JOURNAL OF BIOCHEMISTRY 1990; 192:761-5. [PMID: 2170131 DOI: 10.1111/j.1432-1033.1990.tb19287.x] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/30/2022]
Abstract
The topology of the subunits of ubiquinol-cytochrome-c oxidoreductase of the yeast Saccharomyces cerevisiae has been determined using a digitonin/proteinase K assay. With this assay we were able selectively to disrupt the mitochondrial membranes and to identify the subunits which became proteinase-K sensitive after disruption of either the outer or both outer and inner membranes. This approach confirmed previous indications for the localization of the core I protein, cytochrome c1, cytochrome b, the FeS protein and the 17-kDa subunit, while it also provided direct evidence for the site of accessibility to proteinase K of the 14-kDa and 11-kDa subunits. The 14-kDa subunit faces the mitochondrial matrix and the 11-kDa subunit faces the intermembrane space.
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Affiliation(s)
- W Hemrika
- E.C. Slater Institute for Biochemical Research, University of Amsterdam, The Netherlands
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17
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The protonmotive Q cycle. Energy transduction by coupling of proton translocation to electron transfer by the cytochrome bc1 complex. J Biol Chem 1990. [DOI: 10.1016/s0021-9258(19)38410-8] [Citation(s) in RCA: 439] [Impact Index Per Article: 12.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022] Open
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18
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19
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Mukai K, Yoshida M, Toyosaki H, Yao Y, Wakabayashi S, Matsubara H. An atypical heme-binding structure of cytochrome c1 of Euglena gracilis mitochondrial complex III. EUROPEAN JOURNAL OF BIOCHEMISTRY 1989; 178:649-56. [PMID: 2536325 DOI: 10.1111/j.1432-1033.1989.tb14494.x] [Citation(s) in RCA: 32] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/01/2023]
Abstract
Complex III was purified from submitochondrial particles prepared from Euglena gracilis. The purified complex consisted of 10 subunits and lost antimycin sensitivity. The Euglena complex III showed an atypical difference absorption spectrum for cytochrome c1 with its alpha-band maximum at 561 nm. The pyridine ferrohemochrome prepared from covalently bound heme in the Euglena complex III had an alpha-peak at 553 nm. This wavelength is the same as that of pyridine ferrohemochrome prepared from Euglena mitochondrial cytochrome c (c-558), the heme of which is linked to only a single cysteine residue through a thioether bond. Cytochrome c1 which was a heme-stained subunit with a molecular mass of 32.5 kDa was isolated from the purified complex III and its N-terminal sequence of 46 amino acids was determined. On the basis of apparent homologies to cytochromes c1 from other sources, this sequence included the heme-binding region. However, the amino acid at position 36, corresponding to the first cysteine involved in heme linkage in other cytochromes c1, was phenylalanine. Position 39, corresponding to the second cysteine, was not identified despite the treatment for removal of the heme and carboxymethylation of the expected cysteine. The unidentified amino acid is assumed to be a derivative of cysteine to which the heme is linked through a single thioether bond. The histidine-40 corresponding to the probable fifth ligand for heme iron was conserved in Euglena cytochrome c1.
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Affiliation(s)
- K Mukai
- Department of Biology, Faculty of Science, Osaka University, Japan
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20
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Lactic acidosis and mitochondrial myopathy in a young woman. Nutr Rev 1988; 46:157-63. [PMID: 3368126 DOI: 10.1111/j.1753-4887.1988.tb05412.x] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/05/2023] Open
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21
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Hartl FU, Ostermann J, Guiard B, Neupert W. Successive translocation into and out of the mitochondrial matrix: targeting of proteins to the intermembrane space by a bipartite signal peptide. Cell 1987; 51:1027-37. [PMID: 2826012 DOI: 10.1016/0092-8674(87)90589-7] [Citation(s) in RCA: 237] [Impact Index Per Article: 6.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/02/2023]
Abstract
We investigated the import and sorting pathways of cytochrome b2 and cytochrome c1, which are functionally located in the intermembrane space of mitochondria. Both proteins are synthesized on cytoplasmic ribosomes as larger precursors and are processed in mitochondria in two steps upon import. The precursors are first translocated across both mitochondrial membranes via contact sites into the matrix. Processing by the matrix peptidase leads to intermediate-sized forms, which are subsequently redirected across the inner membrane. The second proteolytic processing occurs in the intermembrane space. We conclude that the hydrophobic stretches in the presequences of the intermediate-sized forms do not stop transfer across the inner membrane, but rather act as transport signals to direct export from the matrix into the intermembrane space.
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Affiliation(s)
- F U Hartl
- Institut für Physiologische Chemie, München, Federal Republic of Germany
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22
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Wittenberg BA, Wittenberg JB. Myoglobin-mediated oxygen delivery to mitochondria of isolated cardiac myocytes. Proc Natl Acad Sci U S A 1987; 84:7503-7. [PMID: 3118370 PMCID: PMC299324 DOI: 10.1073/pnas.84.21.7503] [Citation(s) in RCA: 94] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/04/2023] Open
Abstract
Myoglobin-mediated oxygen delivery to intracellular mitochondria is demonstrated in cardiac myocytes isolated from the hearts of mature rats. Myocytes are held at high ambient oxygen pressure, 40-340 torr (5-45 kPa); sarcoplasmic myoglobin is fully oxygenated. In this condition oxygen availability does not limit respiratory rate; myoglobin-facilitated diffusion contributes no additional oxygen flux and, since oxygen consumption is measured in steady states, the storage function of myoglobin vanishes. Carbon monoxide, introduced stepwise, displaces oxygen from intracellular oxymyoglobin without altering the optical spectrum of the largely oxidized intracellular mitochondria. A large part, about one-third, of the steady-state oxygen uptake is abolished by carbon monoxide blockade of myoglobin oxygenation. The myoglobin-dependent component of the oxygen uptake decreases linearly with decreasing fraction of intracellular oxymyoglobin, with a slope near unity. Studies using inhibitors of mitochondrial electron transport indicate that myoglobin-delivered oxygen uptake depends on electron flow through the mitochondrial electron transport chain. We conclude that cardiac mitochondria accept two additive simultaneous flows of oxygen: a flow of dissolved oxygen to cytochrome oxidase and a flow of myoglobin-bound oxygen to a mitochondrial terminus. Myoglobin-mediated oxygen delivery supports ATP generation by heart cells at physiological ambient oxygen pressure.
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Affiliation(s)
- B A Wittenberg
- Department of Physiology and Biophysics, Albert Einstein College of Medicine, Bronx, NY 10461
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23
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Römisch J, Tropschug M, Sebald W, Weiss H. The primary structure of cytochrome c1 from Neurospora crassa. EUROPEAN JOURNAL OF BIOCHEMISTRY 1987; 164:111-5. [PMID: 3030747 DOI: 10.1111/j.1432-1033.1987.tb11000.x] [Citation(s) in RCA: 36] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/03/2023]
Abstract
The primary structure of the cytochrome c1 subunit of ubiquinol-cytochrome-c reductase from mitochondria of Neurospora crassa was determined by sequencing the cDNA of a bank cloned in Escherichia coli. From the coding region the sequence of 332 amino acids, corresponding to the molecular mass of 36,496 Da, was derived for the precursor protein. The mature protein, the N terminus of which was previously sequenced [Tsugita et al. (1979) in Cytochrome oxidase (King, T. E. et al., eds) pp. 67-77, Elsevier, New York], consists of 262 amino acids and has the molecular mass of 29,908 Da including the heme. The sequence contains an N-terminal hydrophilic part of 211 residues, which carries the heme, a hydrophobic stretch of 15 residues, which is assumed to anchor the protein to the membrane, and a C-terminal hydrophilic part of 36 residues. The N-terminal presequence of 70 amino acids contains 9 positive charges but only 1 negative charge and is characterized by a stretch of 20 uncharged residues.
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24
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Structure of Mitochondrial Ubiquinol–Cytochrome-c Reductase (Complex III). ACTA ACUST UNITED AC 1987. [DOI: 10.1016/b978-0-12-152515-6.50007-2] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register]
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25
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de Vries S, Marres CA. The mitochondrial respiratory chain of yeast. Structure and biosynthesis and the role in cellular metabolism. BIOCHIMICA ET BIOPHYSICA ACTA 1987; 895:205-39. [PMID: 2849479 DOI: 10.1016/s0304-4173(87)80003-4] [Citation(s) in RCA: 150] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/02/2023]
Affiliation(s)
- S de Vries
- Laboratory of Biochemistry, University of Amsterdam, The Netherlands
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26
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27
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Hartl FU, Schmidt B, Wachter E, Weiss H, Neupert W. Transport into mitochondria and intramitochondrial sorting of the Fe/S protein of ubiquinol-cytochrome c reductase. Cell 1986; 47:939-51. [PMID: 3022944 DOI: 10.1016/0092-8674(86)90809-3] [Citation(s) in RCA: 239] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/03/2023]
Abstract
The Fe/S protein of complex III is encoded by a nuclear gene, synthesized in the cytoplasm as a precursor with a 32 residue amino-terminal extension, and transported to the outer surface of the inner mitochondrial membrane. Our data suggest the following transport pathway. First, the precursor is translocated via translocation contact sites into the matrix. There, cleavage to an intermediate containing an eight residue extension occurs. The intermediate is then redirected across the inner membrane, processed to the mature subunit, and assembled into complex III. We suggest that the folding and membrane-translocation pathway in the endosymbiotic ancestor of mitochondria has been conserved during evolution of eukaryotic cells; transfer of the gene for Fe/S protein to the nucleus has led to addition of the presequence, which routes the precursor back to its "ancestral" assembly pathway.
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28
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Haley PE, Yu L, Dong JH, Keyser GC, Sanborn MR, Yu CA. Immunological comparison of the b and c1 cytochromes from bovine heart mitochondria and the photosynthetic bacterium Rhodopseudomonas sphaeroides R-26. J Biol Chem 1986. [DOI: 10.1016/s0021-9258(18)66912-1] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/22/2022] Open
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van Loon AP, Brändli AW, Schatz G. The presequences of two imported mitochondrial proteins contain information for intracellular and intramitochondrial sorting. Cell 1986; 44:801-12. [PMID: 3004746 DOI: 10.1016/0092-8674(86)90846-9] [Citation(s) in RCA: 139] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/03/2023]
Abstract
Gene fusion experiments were used to identify signals that direct imported precursor proteins to specific intramitochondrial locations in yeast. The amino terminus of alcohol dehydrogenase III (ADHIII, a mitochondrial matrix enzyme) transported attached mouse dihydrofolate reductase (DHFR, a cytosolic enzyme) into the mitochondrial matrix. The presequence of cytochrome c1 (a mitochondrial inner membrane protein protruding into the intermembrane space) transported attached DHFR into the intermembrane space. The first half of the cytochrome c1 presequence, which resembles the ADHIII presequence, is a matrix-targeting sequence: it transported attached DHFR into the matrix. The second half of the cytochrome c1 presequence contains a stretch of 19 uncharged amino acids and may thus be a stop-transfer sequence. We conclude that intramitochondrial sorting involves matrix-targeting and stop-transfer sequences within the cleavable presequence.
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Weiss H, Hovmöller S, Leonard K. Preparation of membrane crystals of ubiquinol-cytochrome-c reductase from Neurospora mitochondria and structure analysis by electron microscopy. Methods Enzymol 1986; 126:191-201. [PMID: 2856126 DOI: 10.1016/s0076-6879(86)26021-8] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/03/2023]
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31
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Harnisch U, Weiss H, Sebald W. The primary structure of the iron-sulfur subunit of ubiquinol-cytochrome c reductase from Neurospora, determined by cDNA and gene sequencing. EUROPEAN JOURNAL OF BIOCHEMISTRY 1985; 149:95-9. [PMID: 2986972 DOI: 10.1111/j.1432-1033.1985.tb08898.x] [Citation(s) in RCA: 115] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/03/2023]
Abstract
The primary structure of the iron-sulfur subunit of ubiquinol-cytochrome c reductase from Neurospora mitochondria was determined by cDNA and genomic DNA sequencing. A first cDNA was identified from a cDNA bank cloned in Escherichia coli by hybridization selection of mRNA, cell-free protein synthesis and immunoadsorption. Further cDNA and geonomic DNA were identified by colony filter hybridization. The N-terminal sequence of the mature protein was determined by automated Edman degradation. From the sequence a molecular mass of 24749 Da results for the precursor protein and of 21556 Da for the mature protein. The presequence consists of 32 amino acids with four arginines as the only charged residues. The mature protein consists of 199 amino acids. It is characterized by a small N-terminal hydrophilic part of 29 residues, a hydrophobic stretch of 25 residues and a large C-terminal hydrophilic domain of 145 residues. The only four cysteines of the protein, which are assumed to bind the 2 Fe-2S cluster, are located in a moderate hydrophobic region of this large domain. Cysteines 3 and 4 are unusually arranged in that they are separated by only one proline. From sequence data the arrangement of the subunit in the membrane is deduced.
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32
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Reid GA. Chapter 7 Transport of Proteins into Mitochondria. ACTA ACUST UNITED AC 1985. [DOI: 10.1016/s0070-2161(08)60329-9] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/19/2023]
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33
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Abstract
A transmembrane arrangement of cytochrome f in chloroplast thylakoid membranes, with the N-terminal heme-containing region in the intrathylakoid space and a 15 amino acid C-terminal sequence in the stroma, is suggested by the amino acid sequence deduced from the nucleotide sequence of the pea chloroplast gene. This topology has been confirmed by partial proteolysis of the polypeptide in intact and disrupted thylakoid membranes and in inside-out and right-side-out vesicles of chloroplast membranes.
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Ludwig B, Suda K, Cerletti N. Cytochrome c1 from Paracoccus denitrificans. EUROPEAN JOURNAL OF BIOCHEMISTRY 1983; 137:597-602. [PMID: 6319128 DOI: 10.1111/j.1432-1033.1983.tb07867.x] [Citation(s) in RCA: 31] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/19/2023]
Abstract
Cytochrome c1 was purified from the bacterium Paracoccus denitrificans. It is an acidic, hydrophobic polypeptide with an apparent molecular weight of around 65000 and a single, covalently attached heme; it cross-reacts immunologically with cytochrome c1 from yeast mitochondria. The amino acid sequence of the tryptic heme peptide of the bacterial cytochrome c1 shows extensive homology to the corresponding region of beef heart cytochrome c1 [Wakabayashi, S. et al. (1982) J. Biol. Chem. 257, 9335-9344]. Positive evidence for a stable association of the Paracoccus cytochrome c1 with other polypeptides and b-type heme components ('bc1-complex') has not yet been obtained.
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36
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Gutweniger HE, Grassi C, Bisson R. Interaction between cytochrome c and ubiquinone-cytochrome c oxidoreductase: a study with water-soluble carbodiimides. Biochem Biophys Res Commun 1983; 116:272-83. [PMID: 6315005 DOI: 10.1016/0006-291x(83)90411-4] [Citation(s) in RCA: 19] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/19/2023]
Abstract
The role of carboxyl groups on the interaction between ubiquinone-cytochrome c oxidoreductase (Complex III) and cytochrome c has been probed using the two water-soluble carbodiimides EDC (1-Ethyl-3-(3-dimethylaminopropyl) carbodiimide) and CMC (1-cyclohexyl-3-(2-morpholinyl-4-ethyl) carbodiimide metho-p-toluensulphonate). The results suggest that: 1) carboxyl groups present on both cytochrome c1 and subunit VIII are modified. Some of these residues are shielded by cytochrome c. 2) The enzyme activity decreases during the carbodiimide treatment and the extent of inhibition is larger in the presence of cytochrome c. 3) Cytochrome c, equimolar with the enzyme, cross-links to cytochrome c1 and subunit VIII via the carbodiimide-activated carboxyl groups. The two subunits appear to be in contact in the isolated enzyme.
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37
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Sidhu A, Clejan L, Beattie DS. Topographical orientation of complex III in the yeast mitochondrial membrane. J Biol Chem 1983. [DOI: 10.1016/s0021-9258(17)44175-5] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/22/2022] Open
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38
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Malatesta F, Darley-Usmar V, de Jong C, Prochaska LJ, Bisson R, Capaldi RA, Steffens GC, Buse G. Arrangement of subunit IV in beef heart cytochrome c oxidase probed by chemical labeling and protease digestion experiments. Biochemistry 1983; 22:4405-11. [PMID: 6313039 DOI: 10.1021/bi00288a010] [Citation(s) in RCA: 26] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/19/2023]
Abstract
The arrangement of subunit IV in beef heart cytochrome c oxidase has been explored by chemical labeling and protease digestion studies. This subunit has been purified from four samples of cytochrome c oxidase that had been reacted with N-(4-azido-2-nitrophenyl)-2-aminoethyl[35S]-sulfonate (NAP-taurine), diazobenzene[35S]sulfonate, 1-myristoyl-2-[12-[(4-azido-2-nitrophenyl)amino]lauroyl]-sn-glycero-3- [14C]phosphocholine (I), and 1-palmitoyl-2-(2-azido-4-nitrobenzoyl)-sn-glycero-3-[3H]phosphocholine (II), respectively. The labeled polypeptide was then fragmented by cyanogen bromide, at arginyl side chains with trypsin (after maleylation), and the distribution of the labeling within the sequence was analyzed. The N-terminal part of subunit IV (residues 1-71) was shown to be heavily labeled by water-soluble, lipid-insoluble reagents but not by the phospholipid derivatives. These latter reagents labeled only in the region of residues 62-122, containing the long hydrophobic and putative membrane-spanning stretch. Trypsin cleavage of native cytochrome c oxidase complex at pH 8.2 was shown to clip the first seven amino acids from subunit IV. This cleavage was found to occur in submitochondrial particles but not in mitochondria or mitoplasts. These results are interpreted to show that subunit IV is oriented with its N terminus on the matrix side of the mitochondrial inner membrane and spans the membrane with the extended sequence of hydrophobic lipid residues 79-98 buried in the bilayer.
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39
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Perkins SJ, Weiss H. Low-resolution structural studies of mitochondrial ubiquinol:cytochrome c reductase in detergent solutions by neutron scattering. J Mol Biol 1983; 168:847-66. [PMID: 6310128 DOI: 10.1016/s0022-2836(83)80078-3] [Citation(s) in RCA: 92] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/19/2023]
Abstract
Mitochondrial ubiquinol:cytochrome c reductase (Mr approximately 600,000) was cleaved into a complex (Mr approximately 280,000) of the subunits III (cytochrome b), IV (cytochrome c1) and VI to IX, a complex (Mr approximately 300,000) of the subunits I and II, and the single subunit V (iron-sulphur subunit, Mr approximately 25,000). Neutron scattering was applied to the whole enzyme, the cytochrome bc1 complex, both in hydrogenated and deuterated alkyl (phenyl) polyoxyethylene detergents, and the complex of subunits I and II in detergent-free solution. The neutron parameters were compared with the structures of the enzyme and the cytochrome bc1 complex previously determined by electron microscopy. Using the method of hard spheres, comparison of the calculated and experimental radius of gyration implies that the length of the enzyme across the bilayer or the detergent micelle is between 150 and 175 A and of the cytochrome bc1 complex between 90 and 115 A. The subunit topography was confirmed. The cleavage plane between the cytochrome bc1 complex and the complex of subunits I and II lies at the centre of the enzyme and runs parallel to the membrane just outside the bilayer. The detergent uniformly surrounds the protein as a belt, which is displaced by 30 to 40 A from the protein centre of the enzyme and by about 20 A from the protein centre of the cytochrome bc1 complex. The low protein matchpoint of the whole enzyme as compared to the subunit complexes is accounted for in terms of the non-exchange of about 30 to 60% of the exchangeable protons within the intact enzyme. Polar residues are, on average, at the protein surface and non-polar residues and polar residues with non-exchanged protons are buried within the enzyme.
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Darley-Usmar VM, Kennaway NG, Buist NR, Capaldi RA. Deficiency in ubiquinone cytochrome c reductase in a patient with mitochondrial myopathy and lactic acidosis. Proc Natl Acad Sci U S A 1983; 80:5103-6. [PMID: 6308671 PMCID: PMC384197 DOI: 10.1073/pnas.80.16.5103] [Citation(s) in RCA: 59] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/19/2023] Open
Abstract
The skeletal muscle of a patient with a mitochondrial myopathy was examined. A defect in the electron transport chain was identified at the position of complex III by activity measurements and the low levels of reducible cytochrome b. The polypeptide composition of complex III in the patient's mitochondria was determined by antibody binding experiments. The method allowed detection of individual polypeptides at a lower limit of 10-40 ng of protein. Characterization of protein composition is thus possible by using a biopsy sample of 1 g of tissue. The level of core proteins, FeS protein, and subunit VI was greatly diminished in the patient's mitochondria. Cytochrome c1 polypeptide was found at normal levels but was sensitive to proteolysis by trypsin. These results show that complex III is not assembled in the patient's mitochondria. The possible role of cytochrome b as the site of the primary lesion is discussed.
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41
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Hauska G, Hurt E, Gabellini N, Lockau W. Comparative aspects of quinol-cytochrome c/plastocyanin oxidoreductases. BIOCHIMICA ET BIOPHYSICA ACTA 1983; 726:97-133. [PMID: 6307358 DOI: 10.1016/0304-4173(83)90002-2] [Citation(s) in RCA: 360] [Impact Index Per Article: 8.8] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/19/2023]
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42
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Karlsson B, Hovmöller S, Weiss H, Leonard K. Structural studies of cytochrome reductase. Subunit topography determined by electron microscopy of membrane crystals of a subcomplex. J Mol Biol 1983; 165:287-302. [PMID: 6302289 DOI: 10.1016/s0022-2836(83)80258-7] [Citation(s) in RCA: 59] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/19/2023]
Abstract
Ubiquinol: cytochrome c reductase was isolated from Neurospora mitochondria as a protein-detergent complex and dissociated by mild salt treatment. Three parts were obtained and characterized. Firstly, a complex containing the subunits III (cytochrome b), IV (cytochrome c1), VI, VII, VIII and IX; secondly, a complex containing the subunits I and II; and thirdly, the single subunit V (iron-sulphur subunit). Membrane crystals were prepared from the cytochrome bc1 subunit complex and by combining tilted electron microscopic views of the crystals, a low-resolution three-dimensional structure was calculated. This structure was compared to that of the whole cytochrome reductase (previously determined by electron microscopy of membrane crystals). Protein density absent from the structure of the subunit complex was then attributed to the missing subunits according to their size and shape and their association with the phospholipid bilayer.
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Broger C, Salardi S, Azzi A. Interaction between isolated cytochrome c1 and cytochrome c. EUROPEAN JOURNAL OF BIOCHEMISTRY 1983; 131:349-52. [PMID: 6299737 DOI: 10.1111/j.1432-1033.1983.tb07269.x] [Citation(s) in RCA: 42] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/19/2023]
Abstract
Cytochrome c1 from bovine heart mitochondria was isolated by a modification of the technique of König et al. [(1980) Biochim. Biophys. Acta 621, 283-295] which involved an affinity chromatography step on a gel with yeast cytochrome c as a ligand. Its spectra, electrophoretic pattern in presence of sodium dodecylsulfate, its reducibility by ascorbate and cytochrome c were characteristic of a native cytochrome, with a single polypeptide having an apparent molecular weight of 30 000. By using an arylazido derivative of cytochrome c, having the photoactive group bound to lysine 13, upon illumination a cross-link with the described preparation of cytochrome c1 was obtained. By pepsin digestion of the cross-linked complex a limiting fragment was obtained and partially sequenced. It allowed to identify the site of binding of cytochrome c near the sequence 167-174 of cytochrome c1.
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44
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Tervoort MJ, Van Gelder BF. The interaction between heme and protein in cytochrome c1. BIOCHIMICA ET BIOPHYSICA ACTA 1983; 722:137-43. [PMID: 6297567 DOI: 10.1016/0005-2728(83)90166-4] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/19/2023]
Abstract
The optical spectrum of reduced bovine cytochrome c1 at 77 K shows a fine splitting of the beta-band, which is indicative of the native conformation of the protein. At room temperature, this conformation is reflected in an absorbance band at 530 nm. The exposure of the heme of ferrocytochrome c1, investigated by means of solvent-perturbation spectroscopy, appears to be extremely sensitive to temperature and SH reagents bound to the oxidized protein. Addition of combinations of potential ligands to the isolated tryptic heme peptide of cytochrome c1 reveals that only a mixture of methionine and cysteine (or their equivalents) generates a beta-band at 77 K which is identical in shape to that of native cytochrome c1. In the EPR spectrum of a complex of ferrocytochrome c1 and nitric oxide at pH 10.5, no hyperfine splitting derived from a second ligated nitrogen atom could be detected. The results indicate that methionine and cysteine are the axial ligands of heme in cytochrome c1. The EPR spectrum of isolated ferricytochrome c1 is that of a low-spin heme iron compound with a gz value of 3.36 and a gy value of 2.04.
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46
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Doi M, Takamiya K, Nishimura M. Isolation and properties of membrane-bound cytochrome c-552 from photosynthetic bacterium Chromatium vinosum. PHOTOSYNTHESIS RESEARCH 1983; 4:49-60. [PMID: 24458384 DOI: 10.1007/bf00041800] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/24/1982] [Revised: 07/16/1982] [Indexed: 06/03/2023]
Abstract
A membrane-bound cytochrome c-552 was isolated and purified from the photosynthetic bacterium Chromatium vinosum by treatment with sodium cholate, sodium deoxycholate and bacterial alkaline protease followed by gel filtration.The purified cytochrome c-552, which may have been modified by the protease treatment, was electrophoretically homogeneous. Its minimal molecular weight was estimated to be 19 and 20 kdaltons, respectively by SDS polyacrylamide gel electrophoresis and by gel filtration on Sephadex G-100.Cytochrome c-552 showed the absorption maxima at 419, 523 and 552 nm in the reduced form. Reduced-minus-oxidized difference millimolar absorption coefficient was 10.6 for the wavelength pair, 552 minus 540 nm. The midpoint potential at pH 8.0 was -130 mV. The polarity in the amino acid composition of cytochrome c-552 was 40.1% and reflected its hydrophobicity.The solubilized cytochrome c-552 was shown to be a different entity from the soluble flavocytochrome c-552 in several respects.
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Affiliation(s)
- M Doi
- Department of Biology, Faculty of Science, Kyushu University 33, 812, Fukuoka, Japan
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Tsou CL, Tang HL, Wang DC, Jin YZ. Multiphasic oxidation-reduction of cytochrome b in the succinate-cytochrome c reductase. BIOCHIMICA ET BIOPHYSICA ACTA 1982; 682:315-21. [PMID: 6295471 DOI: 10.1016/0005-2728(82)90044-5] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/19/2023]
Abstract
The triphasic course previously reported for the reduction of cytochrome b in the succinate-cytochrome c reductase by either succinate or duroquinol has been shown to be dependent on the redox state of the enzyme preparation. Prior reduction with increasing concentrations of ascorbate leads to partial reduction of cytochrome c1, and a gradual decrease in the magnitude of the oxidation phase of cytochrome b. At an ascorbate concentration sufficient to reduce cytochrome c1 almost completely, the reduction of cytochrome b by either succinate or duroquinol becomes monophasic. Owing to the presence of a trace amount of cytochrome oxidase in the reductase preparation employed, the addition of cytochrome c makes electron flow from substrate to oxygen possible. Under such circumstances, the addition of a limited amount of either succinate or duroquinol leads to a multiphasic reduction and oxidation of cytochrome b. After the initial three phases as described previously, cytochrome b becomes oxidized before cytochrome c1 when the limited amount of added substrate is being used up. However, at the end of the reaction when cytochrome c1 is being rapidly oxidized, cytochrome b becomes again reduced. The above observations support a cyclic scheme of electron flow in which the reduction of cytochrome b proceeds by two different routes and its oxidation controlled by the redox state of a component of the respiratory chain.
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48
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Ohashi A, Gibson J, Gregor I, Schatz G. Import of proteins into mitochondria. The precursor of cytochrome c1 is processed in two steps, one of them heme-dependent. J Biol Chem 1982. [DOI: 10.1016/s0021-9258(18)33619-6] [Citation(s) in RCA: 106] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/22/2022] Open
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49
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Biogenesis of mitochondrial ubiquinol:cytochrome c reductase (cytochrome bc1 complex). Precursor proteins and their transfer into mitochondria. J Biol Chem 1982. [DOI: 10.1016/s0021-9258(18)34028-6] [Citation(s) in RCA: 91] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022] Open
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50
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