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Pérez-Mejías G, Díaz-Quintana A, Guerra-Castellano A, Díaz-Moreno I, De la Rosa MA. Novel insights into the mechanism of electron transfer in mitochondrial cytochrome c. Coord Chem Rev 2022. [DOI: 10.1016/j.ccr.2021.214233] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/03/2022]
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2
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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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3
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Mitochondrial respirasome works as a single unit and the cross-talk between complexes I, III 2 and IV stimulates NADH dehydrogenase activity. BIOCHIMICA ET BIOPHYSICA ACTA-BIOENERGETICS 2019; 1860:618-627. [PMID: 31251900 DOI: 10.1016/j.bbabio.2019.06.017] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/01/2018] [Revised: 06/20/2019] [Accepted: 06/22/2019] [Indexed: 11/20/2022]
Abstract
Ustilago maydis is an aerobic basidiomycete that depends on oxidative phosphorylation for its ATP supply, pointing to the mitochondrion as a key player in its energy metabolism. Mitochondrial respiratory complexes I, III2, and IV occur in supramolecular structures named respirasome. In this work, we characterized the subunit composition and the kinetics of NADH:Q oxidoreductase activity of the digitonine-solubilized respirasome (1600 kDa) and the free-complex I (990 kDa). In the presence of 2,6-dimethoxy-1,4-benzoquinone (DBQ) and cytochrome c, both the respirasome NADH:O2 and the NADH:DBQ oxidoreductase activities were inhibited by rotenone, antimycin A or cyanide. A value of 2.4 for the NADH oxidized/oxygen reduced ratio was determined for the respirasome activity, while ROS production was less than 0.001% of the oxygen consumption rate. Analysis of the NADH:DBQ oxidoreductase activity showed that respirasome was 3-times more active and showed higher affinity than free-complex I. The results suggest that the contacts between complexes I, III2 and IV in the respirasome increase the catalytic efficiency of complex I and regulate its activity to prevent ROS production.
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4
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Long distance electron transfer through the aqueous solution between redox partner proteins. Nat Commun 2018; 9:5157. [PMID: 30514833 PMCID: PMC6279779 DOI: 10.1038/s41467-018-07499-x] [Citation(s) in RCA: 23] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/06/2018] [Accepted: 11/06/2018] [Indexed: 11/25/2022] Open
Abstract
Despite the importance of electron transfer between redox proteins in photosynthesis and respiration, the inter-protein electron transfer rate between redox partner proteins has never been measured as a function of their separation in aqueous solution. Here, we use electrochemical tunneling spectroscopy to show that the current between two protein partners decays along more than 10 nm in the solution. Molecular dynamics simulations reveal a reduced ionic density and extended electric field in the volume confined between the proteins. The distance-decay factor and the calculated local barrier for electron transfer are regulated by the electrochemical potential applied to the proteins. Redox partners could use electrochemically gated, long distance electron transfer through the solution in order to conciliate high specificity with weak binding, thus keeping high turnover rates in the crowded environment of cells. Electron transport chains rely on interactions between redox proteins, but the distance-dependence of the electron transfer rate through the solution is unknown. Here, the authors show that the current between two redox protein partners occurs at long distances and is electrochemically gated.
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Shimada S, Maeda S, Hikita M, Mieda-Higa K, Uene S, Nariai Y, Shinzawa-Itoh K. Solubilization conditions for bovine heart mitochondrial membranes allow selective purification of large quantities of respiratory complexes I, III, and V. Protein Expr Purif 2018; 150:33-43. [PMID: 29702187 DOI: 10.1016/j.pep.2018.04.015] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/15/2018] [Revised: 04/20/2018] [Accepted: 04/23/2018] [Indexed: 11/28/2022]
Abstract
Ascertaining the structure and functions of mitochondrial respiratory chain complexes is essential to understanding the biological mechanisms of energy conversion; therefore, numerous studies have examined these complexes. A fundamental part of that research involves devising a method for purifying samples with good reproducibility; the samples obtained need to be stable and their constituents need to retain the same structure and functions they possess when in mitochondrial membranes. Submitochondrial bovine heart particles were isolated using differential centrifugation to adjust to a membrane concentration of 46.0% (w/v) or 31.5% (w/v) based on weight. After 0.7% (w/v) deoxycholic acid, 0.4% (w/v) decyl maltoside, and 7.2% (w/v) potassium chloride were added to the mitochondrial membranes, those membranes were solubilized. At a membrane concentration of 46%, complex V was selectively solubilized, whereas at a concentration of 31.5% (w/v), complexes I and III were solubilized. Two steps-sucrose density gradient centrifugation and anion-exchange chromatography on a POROS HQ 20 μm column-enabled selective purification of samples that retained their structure and functions. These two steps enabled complexes I, III, and V to be purified in two days with a high yield. Complexes I, III, and V were stabilized with n-decyl-β-D-maltoside. A total of 200 mg-300 mg of those complexes from one bovine heart (1.1 kg muscle) was purified with good reproducibility, and the complexes retained the same functions they possessed while in mitochondrial membranes.
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Affiliation(s)
- Satoru Shimada
- Department of Life Science, Graduate School of Life Science, University of Hyogo, Koto 3-2-1, Kamighori, Ako, Hyogo, 678-1297, Japan
| | - Shintaro Maeda
- Department of Life Science, Graduate School of Life Science, University of Hyogo, Koto 3-2-1, Kamighori, Ako, Hyogo, 678-1297, Japan
| | - Masahide Hikita
- Department of Life Science, Graduate School of Life Science, University of Hyogo, Koto 3-2-1, Kamighori, Ako, Hyogo, 678-1297, Japan
| | - Kaoru Mieda-Higa
- Department of Life Science, Graduate School of Life Science, University of Hyogo, Koto 3-2-1, Kamighori, Ako, Hyogo, 678-1297, Japan
| | - Shigefumi Uene
- Department of Life Science, Graduate School of Life Science, University of Hyogo, Koto 3-2-1, Kamighori, Ako, Hyogo, 678-1297, Japan
| | - Yukiko Nariai
- Department of Life Science, Graduate School of Life Science, University of Hyogo, Koto 3-2-1, Kamighori, Ako, Hyogo, 678-1297, Japan
| | - Kyoko Shinzawa-Itoh
- Department of Life Science, Graduate School of Life Science, University of Hyogo, Koto 3-2-1, Kamighori, Ako, Hyogo, 678-1297, Japan.
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6
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Alvarez-Paggi D, Hannibal L, Castro MA, Oviedo-Rouco S, Demicheli V, Tórtora V, Tomasina F, Radi R, Murgida DH. Multifunctional Cytochrome c: Learning New Tricks from an Old Dog. Chem Rev 2017; 117:13382-13460. [DOI: 10.1021/acs.chemrev.7b00257] [Citation(s) in RCA: 135] [Impact Index Per Article: 19.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022]
Affiliation(s)
- Damián Alvarez-Paggi
- Departamento
de Química Inorgánica, Analítica y Química
Física and INQUIMAE (CONICET-UBA), Facultad de Ciencias Exactas
y Naturales, Universidad de Buenos Aires, Ciudad Universitaria, Pab. 2, piso 1, Buenos Aires C1428EHA, Argentina
| | - Luciana Hannibal
- Department
of Pediatrics, Universitätsklinikum Freiburg, Mathildenstrasse 1, Freiburg 79106, Germany
- Departamento
de Bioquímica and Center for Free Radical and Biomedical Research,
Facultad de Medicina, Universidad de la República, Av.
Gral. Flores 2125, Montevideo 11800, Uruguay
| | - María A. Castro
- Departamento
de Química Inorgánica, Analítica y Química
Física and INQUIMAE (CONICET-UBA), Facultad de Ciencias Exactas
y Naturales, Universidad de Buenos Aires, Ciudad Universitaria, Pab. 2, piso 1, Buenos Aires C1428EHA, Argentina
| | - Santiago Oviedo-Rouco
- Departamento
de Química Inorgánica, Analítica y Química
Física and INQUIMAE (CONICET-UBA), Facultad de Ciencias Exactas
y Naturales, Universidad de Buenos Aires, Ciudad Universitaria, Pab. 2, piso 1, Buenos Aires C1428EHA, Argentina
| | - Veronica Demicheli
- Departamento
de Bioquímica and Center for Free Radical and Biomedical Research,
Facultad de Medicina, Universidad de la República, Av.
Gral. Flores 2125, Montevideo 11800, Uruguay
| | - Veronica Tórtora
- Departamento
de Bioquímica and Center for Free Radical and Biomedical Research,
Facultad de Medicina, Universidad de la República, Av.
Gral. Flores 2125, Montevideo 11800, Uruguay
| | - Florencia Tomasina
- Departamento
de Bioquímica and Center for Free Radical and Biomedical Research,
Facultad de Medicina, Universidad de la República, Av.
Gral. Flores 2125, Montevideo 11800, Uruguay
| | - Rafael Radi
- Departamento
de Bioquímica and Center for Free Radical and Biomedical Research,
Facultad de Medicina, Universidad de la República, Av.
Gral. Flores 2125, Montevideo 11800, Uruguay
| | - Daniel H. Murgida
- Departamento
de Química Inorgánica, Analítica y Química
Física and INQUIMAE (CONICET-UBA), Facultad de Ciencias Exactas
y Naturales, Universidad de Buenos Aires, Ciudad Universitaria, Pab. 2, piso 1, Buenos Aires C1428EHA, Argentina
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7
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Singharoy A, Barragan AM, Thangapandian S, Tajkhorshid E, Schulten K. Binding Site Recognition and Docking Dynamics of a Single Electron Transport Protein: Cytochrome c2. J Am Chem Soc 2016; 138:12077-89. [PMID: 27508459 PMCID: PMC5518707 DOI: 10.1021/jacs.6b01193] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Small diffusible redox proteins facilitate electron transfer in respiration and photosynthesis by alternately binding to their redox partners and integral membrane proteins and exchanging electrons. Diffusive search, recognition, binding, and unbinding of these proteins often amount to kinetic bottlenecks in cellular energy conversion, but despite the availability of structures and intense study, the physical mechanisms controlling redox partner interactions remain largely unknown. The present molecular dynamics study provides an all-atom description of the cytochrome c2-docked bc1 complex in Rhodobacter sphaeroides in terms of an ensemble of favorable docking conformations and reveals an intricate series of conformational changes that allow cytochrome c2 to recognize the bc1 complex and bind or unbind in a redox state-dependent manner. In particular, the role of electron transfer in triggering a molecular switch and in altering water-mediated interface mobility, thereby strengthening and weakening complex formation, is described. The results resolve long-standing discrepancies between structural and functional data.
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Affiliation(s)
- Abhishek Singharoy
- Beckman Institute for Advanced Science and Technology, University of Illinois at Urbana–Champaign, 405 N. Mathews Ave., Urbana, IL 61801, USA
| | - Angela M. Barragan
- Beckman Institute for Advanced Science and Technology, University of Illinois at Urbana–Champaign, 405 N. Mathews Ave., Urbana, IL 61801, USA
- Department of Physics, University of Illinois at Urbana–Champaign, 1110 W. Green St., Urbana, IL 61801, USA
| | - Sundarapandian Thangapandian
- Beckman Institute for Advanced Science and Technology, University of Illinois at Urbana–Champaign, 405 N. Mathews Ave., Urbana, IL 61801, USA
| | - Emad Tajkhorshid
- Beckman Institute for Advanced Science and Technology, University of Illinois at Urbana–Champaign, 405 N. Mathews Ave., Urbana, IL 61801, USA
- Department of Biochemistry, University of Illinois Urbana–Champaign, 600 S. Mathews Ave., Urbana, IL 61801, USA
| | - Klaus Schulten
- Beckman Institute for Advanced Science and Technology, University of Illinois at Urbana–Champaign, 405 N. Mathews Ave., Urbana, IL 61801, USA
- Department of Physics, University of Illinois at Urbana–Champaign, 1110 W. Green St., Urbana, IL 61801, USA
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Osuda Y, Shinzawa-Itoh K, Tani K, Maeda S, Yoshikawa S, Tsukihara T, Gerle C. Two-dimensional crystallization of monomeric bovine cytochrome c oxidase with bound cytochrome c in reconstituted lipid membranes. Microscopy (Oxf) 2016; 65:263-7. [PMID: 26754561 PMCID: PMC4892887 DOI: 10.1093/jmicro/dfv381] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/25/2015] [Accepted: 12/09/2015] [Indexed: 12/27/2022] Open
Abstract
Mitochondrial cytochrome c oxidase utilizes electrons provided by cytochrome c for the active vectorial transport of protons across the inner mitochondrial membrane through the reduction of molecular oxygen to water. Direct structural evidence on the transient cytochrome c oxidase–cytochrome c complex thus far, however, remains elusive and its physiological relevant oligomeric form is unclear. Here, we report on the 2D crystallization of monomeric bovine cytochrome c oxidase with tightly bound cytochrome c at a molar ratio of 1:1 in reconstituted lipid membranes at the basic pH of 8.5 and low ionic strength.
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Affiliation(s)
- Yukiho Osuda
- Picobiology Institute, Department of Life Science, Graduate School of Life Science, University of Hyogo, 3-2-1 Kouto, Kamighori, Akoh, Hyogo 678-1297, Japan
| | - Kyoko Shinzawa-Itoh
- Picobiology Institute, Department of Life Science, Graduate School of Life Science, University of Hyogo, 3-2-1 Kouto, Kamighori, Akoh, Hyogo 678-1297, Japan
| | - Kazutoshi Tani
- Cellular and Structural Physiology Institute, Nagoya University, Chikusa-ku, Nagoya 464-8601, Japan
| | - Shintaro Maeda
- Institute for Protein Research, Osaka University, 3-2 Yamada-oka, Suita, Osaka 565-0871, Japan
| | - Shinya Yoshikawa
- Picobiology Institute, Department of Life Science, Graduate School of Life Science, University of Hyogo, 3-2-1 Kouto, Kamighori, Akoh, Hyogo 678-1297, Japan
| | - Tomitake Tsukihara
- Picobiology Institute, Department of Life Science, Graduate School of Life Science, University of Hyogo, 3-2-1 Kouto, Kamighori, Akoh, Hyogo 678-1297, Japan Institute for Protein Research, Osaka University, 3-2 Yamada-oka, Suita, Osaka 565-0871, Japan Japan Science and Technology Agency (JST), Core Research for Evolutional Science and Technology (CREST), Kawaguchi, Japan
| | - Christoph Gerle
- Picobiology Institute, Department of Life Science, Graduate School of Life Science, University of Hyogo, 3-2-1 Kouto, Kamighori, Akoh, Hyogo 678-1297, Japan Japan Science and Technology Agency (JST), Core Research for Evolutional Science and Technology (CREST), Kawaguchi, Japan
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9
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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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Kadenbach B. Introduction to mitochondrial oxidative phosphorylation. ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 2012; 748:1-11. [PMID: 22729852 DOI: 10.1007/978-1-4614-3573-0_1] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/11/2022]
Abstract
The basic mechanism of ATP synthesis in the mitochondria by oxidative phosphorylation (OxPhos) was revealed in the second half of the twentieth century. The OxPhos complexes I-V have been analyzed concerning their subunit composition, genes, and X-ray structures. This book presents new developments regarding the morphology, biogenesis, gene evolution, heat, and reactive oxygen species (ROS) generation in mitochondria, as well as the structure and supercomplex formation of OxPhos complexes. In addition, multiple mitochondrial diseases based on mutations of nuclear-encoded genes have been identified. Little is known, however, of the regulation of OxPhos according to the variable cellular demands of ATP. In particular, the functions of the supernumerary (nuclear-encoded) subunits of mitochondrial OxPhos complexes, which are mostly absent in bacteria, remain largely unknown, although the corresponding and conserved core subunits exhibit the same catalytic activity. Identification of regulatory pathways modulating OxPhos activity, by subunit isoform expression, by allosteric interaction with ATP/ADP, by reversible phosphorylation of protein subunits, or by supercomplex formation, will help to understand the role of mitochondria in the many degenerative diseases, mostly based on ROS formation in mitochondria and/or insufficient energy production.
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11
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Cytochrome c signalosome in mitochondria. EUROPEAN BIOPHYSICS JOURNAL: EBJ 2011; 40:1301-15. [DOI: 10.1007/s00249-011-0774-4] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/02/2011] [Revised: 10/12/2011] [Accepted: 10/21/2011] [Indexed: 10/15/2022]
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12
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Castellani M, Havens J, Kleinschroth T, Millett F, Durham B, Malatesta F, Ludwig B. The acidic domain of cytochrome c₁ in paracoccus denitrificans, analogous to the acidic subunits in eukaryotic bc₁ complexes, is not involved in the electron transfer reaction to its native substrate cytochrome c(552). BIOCHIMICA ET BIOPHYSICA ACTA-BIOENERGETICS 2011; 1807:1383-9. [PMID: 21856278 DOI: 10.1016/j.bbabio.2011.08.001] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/24/2011] [Revised: 08/03/2011] [Accepted: 08/05/2011] [Indexed: 11/19/2022]
Abstract
The cytochrome bc(1) complex is a key component in several respiratory pathways. One of the characteristics of the eukaryotic complex is the presence of a small acidic subunit, which is thought to guide the interaction of the complex with its electron acceptor and facilitate electron transfer. Paracoccus denitrificans represents the only example of a prokaryotic organism in which a highly acidic domain is covalently fused to the cytochrome c(1) subunit. In this work, a deletion variant lacking this acidic domain has been produced and purified by affinity chromatography. The complex is fully intact as shown by its X-ray structure, and is a dimer (Kleinschroth et al., subm.) compared to the tetrameric (dimer-of-dimer) state of the wild-type. The variant complex is studied by steady-state kinetics and flash photolysis, showing wild type turnover and a virtually identical interaction with its substrate cytochrome c(552).
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Affiliation(s)
- Michela Castellani
- Institute of Biochemistry, Molecular Genetics, Goethe University, D-60438 Frankfurt am Main and Cluster of Excellence "Macromolecular Complexes" (CEF-MC), D-60438 Frankfurt am Main, Germany
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Richter OMH, Ludwig B. Electron transfer and energy transduction in the terminal part of the respiratory chain - lessons from bacterial model systems. BIOCHIMICA ET BIOPHYSICA ACTA-BIOENERGETICS 2009; 1787:626-34. [PMID: 19268423 DOI: 10.1016/j.bbabio.2009.02.020] [Citation(s) in RCA: 56] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/27/2008] [Revised: 02/13/2009] [Accepted: 02/16/2009] [Indexed: 11/18/2022]
Abstract
This review focuses on the terminal part of the respiratory chain where, macroscopically speaking, electron transfer (ET) switches from the two-electron donor, ubiquinol, to the single-electron carrier, cytochrome c, to finally reduce the four-electron acceptor dioxygen. With 3-D structures of prominent representatives of such multi-subunit membrane complexes known for some time, this section of the ET chain still leaves a number of key questions unanswered. The two relevant enzymes, ubiquinol:cytochrome c oxidoreductase and cytochrome c oxidase, appear as rather diverse modules, differing largely in their design for substrate interaction, internal ET, and moreover, in their mechanisms of energy transduction. While the canonical mitochondrial complexes have been investigated for almost five decades, the corresponding bacterial enzymes have been established only recently as attractive model systems to address basic reactions in ET and energy transduction. Lacking the intricate coding background and mitochondrial assembly pathways, bacterial respiratory enzymes typically offer a much simpler subunit composition, while maintaining all fundamental functions established for their complex "relatives". Moreover, related issues ranging from primary steps in cofactor insertion to supramolecular architecture of ET complexes, can also be favourably addressed in prokaryotic systems to hone our views on prototypic structures and mechanisms common to all family members.
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Affiliation(s)
- Oliver-Matthias H Richter
- Institute of Biochemistry, Molecular Genetics, Biozentrum Goethe University, Max-von-Laue-Str. 9, D 60438 Frankfurt, Germany
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