1
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Nieto-Panqueva F, Vázquez-Acevedo M, Hamel PP, González-Halphen D. Identification of factors limiting the allotopic production of the Cox2 subunit of yeast cytochrome c oxidase. Genetics 2024; 227:iyae058. [PMID: 38626319 DOI: 10.1093/genetics/iyae058] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/01/2024] [Revised: 03/29/2024] [Accepted: 04/01/2024] [Indexed: 04/18/2024] Open
Abstract
Mitochondrial genes can be artificially relocalized in the nuclear genome in a process known as allotopic expression, such is the case of the mitochondrial cox2 gene, encoding subunit II of cytochrome c oxidase (CcO). In yeast, cox2 can be allotopically expressed and is able to restore respiratory growth of a cox2-null mutant if the Cox2 subunit carries the W56R substitution within the first transmembrane stretch. However, the COX2W56R strain exhibits reduced growth rates and lower steady-state CcO levels when compared to wild-type yeast. Here, we investigated the impact of overexpressing selected candidate genes predicted to enhance internalization of the allotopic Cox2W56R precursor into mitochondria. The overproduction of Cox20, Oxa1, and Pse1 facilitated Cox2W56R precursor internalization, improving the respiratory growth of the COX2W56R strain. Overproducing TIM22 components had a limited effect on Cox2W56R import, while overproducing TIM23-related components showed a negative effect. We further explored the role of the Mgr2 subunit within the TIM23 translocator in the import process by deleting and overexpressing the MGR2 gene. Our findings indicate that Mgr2 is instrumental in modulating the TIM23 translocon to correctly sort Cox2W56R. We propose a biogenesis pathway followed by the allotopically produced Cox2 subunit based on the participation of the 2 different structural/functional forms of the TIM23 translocon, TIM23MOTOR and TIM23SORT, that must follow a concerted and sequential mode of action to insert Cox2W56R into the inner mitochondrial membrane in the correct Nout-Cout topology.
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Affiliation(s)
- Felipe Nieto-Panqueva
- Departamento de Genética Molecular, Instituto de Fisiología Celular, Universidad Nacional Autónoma de México, Apartado Postal 70-243, 04510 D.F. (Mexico), México
| | - Miriam Vázquez-Acevedo
- Departamento de Genética Molecular, Instituto de Fisiología Celular, Universidad Nacional Autónoma de México, Apartado Postal 70-243, 04510 D.F. (Mexico), México
| | - Patrice P Hamel
- Department of Molecular Genetics and Department of Biological Chemistry and Pharmacology, The Ohio State University, 582 Aronoff laboratory, 318 W. 12th Avenue, Columbus, OH 43210, USA
- School of BioScience and Technology, Vellore Institute of Technology (VIT), Vellore, Tamil Nadu, 632 014, India
| | - Diego González-Halphen
- Departamento de Genética Molecular, Instituto de Fisiología Celular, Universidad Nacional Autónoma de México, Apartado Postal 70-243, 04510 D.F. (Mexico), México
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2
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Siletsky SA. Investigation of the Mechanism of Membrane Potential Generation by Heme-Copper Respiratory Oxidases in a Real Time Mode. BIOCHEMISTRY. BIOKHIMIIA 2023; 88:1513-1527. [PMID: 38105021 DOI: 10.1134/s0006297923100085] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/29/2023] [Revised: 08/15/2023] [Accepted: 08/15/2023] [Indexed: 12/19/2023]
Abstract
Heme-copper respiratory oxidases are highly efficient molecular machines. These membrane enzymes catalyze the final step of cellular respiration in eukaryotes and many prokaryotes: the transfer of electrons from cytochromes or quinols to molecular oxygen and oxygen reduction to water. The free energy released in this redox reaction is converted by heme-copper respiratory oxidases into the transmembrane gradient of the electrochemical potential of hydrogen ions H+). Heme-copper respiratory oxidases have a unique mechanism for generating H+, namely, a redox-coupled proton pump. A combination of direct electrometric method for measuring the kinetics of membrane potential generation with the methods of prestationary kinetics and site-directed mutagenesis in the studies of heme-copper oxidases allows to obtain a unique information on the translocation of protons inside the proteins in real time. The review summarizes the data of studies employing time-resolved electrometry to decipher the mechanisms of functioning of these important bioenergetic enzymes.
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Affiliation(s)
- Sergei A Siletsky
- Belozersky Institute of Physico-Chemical Biology, Lomonosov Moscow State University, Moscow, 119991, Russia.
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3
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Structures of the intermediates in the catalytic cycle of mitochondrial cytochrome c oxidase. BIOCHIMICA ET BIOPHYSICA ACTA. BIOENERGETICS 2023; 1864:148933. [PMID: 36403794 DOI: 10.1016/j.bbabio.2022.148933] [Citation(s) in RCA: 18] [Impact Index Per Article: 18.0] [Reference Citation Analysis] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/10/2022] [Revised: 10/30/2022] [Accepted: 11/07/2022] [Indexed: 11/18/2022]
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4
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Franco LVR, Su CH, Tzagoloff A. Modular assembly of yeast mitochondrial ATP synthase and cytochrome oxidase. Biol Chem 2021; 401:835-853. [PMID: 32142477 DOI: 10.1515/hsz-2020-0112] [Citation(s) in RCA: 20] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/13/2020] [Accepted: 02/24/2020] [Indexed: 12/27/2022]
Abstract
The respiratory pathway of mitochondria is composed of four electron transfer complexes and the ATP synthase. In this article, we review evidence from studies of Saccharomyces cerevisiae that both ATP synthase and cytochrome oxidase (COX) are assembled from independent modules that correspond to structurally and functionally identifiable components of each complex. Biogenesis of the respiratory chain requires a coordinate and balanced expression of gene products that become partner subunits of the same complex, but are encoded in the two physically separated genomes. Current evidence indicates that synthesis of two key mitochondrial encoded subunits of ATP synthase is regulated by the F1 module. Expression of COX1 that codes for a subunit of the COX catalytic core is also regulated by a mechanism that restricts synthesis of this subunit to the availability of a nuclear-encoded translational activator. The respiratory chain must maintain a fixed stoichiometry of the component enzyme complexes during cell growth. We propose that high-molecular-weight complexes composed of Cox6, a subunit of COX, and of the Atp9 subunit of ATP synthase play a key role in establishing the ratio of the two complexes during their assembly.
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Affiliation(s)
- Leticia Veloso Ribeiro Franco
- Department of Biological Sciences, Columbia University, New York City, NY 10027, USA.,Instituto de Ciências Biomédicas, Universidade de São Paulo, São Paulo, 05508-000, Brasil
| | - Chen Hsien Su
- Department of Biological Sciences, Columbia University, New York City, NY 10027, USA
| | - Alexander Tzagoloff
- Department of Biological Sciences, Columbia University, New York City, NY 10027, USA
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5
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Sztachova T, Pechova I, Mikulova L, Stupak M, Jancura D, Fabian M. Peroxide stimulated transition between the ferryl intermediates of bovine cytochrome c oxidase. BIOCHIMICA ET BIOPHYSICA ACTA-BIOENERGETICS 2021; 1862:148447. [PMID: 33971156 DOI: 10.1016/j.bbabio.2021.148447] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Subscribe] [Scholar Register] [Received: 02/17/2021] [Revised: 04/28/2021] [Accepted: 05/01/2021] [Indexed: 10/21/2022]
Abstract
During catalysis of cytochrome c oxidases (CcO) several ferryl intermediates of the catalytic heme a3-CuB center are observed. In the PM ferryl state, produced by the reaction of two-electron reduced CcO with O2, the ferryl iron of heme a3 and a free radical are present at the catalytic center. The radical reduction stimulates the transition of the PM into another ferryl F state. Similar ferryl states can be also generated from the oxidized CcO (O) in the reaction with H2O2. The PM, the product of the reaction of the O with one molecule of peroxide, is transformed into the F state by the second molecule of H2O2. However, the chemical nature of this transition has not been unambiguously elucidated yet. Here, we examined the redox state of the peroxide-produced PM and F states by the one-electron reduction. The F form and interestingly also the major fraction of the PM sample, likely another P-type ferryl form (PR), were found to be the one oxidizing equivalent above the O state. However, the both P-type forms are transformed into the F state by additional molecule of H2O2. It is suggested that the PR-to-F transition is due to the binding of H2O2 to CuB triggering a structural change together with the uptake of H+ at the catalytic center. In the PM-to-F conversion, these two events are complemented with the annihilation of radical by the intrinsic oxidation of the enzyme.
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Affiliation(s)
- T Sztachova
- Department of Biophysics, Faculty of Science, University of P. J. Safarik, Jesenna 5, 041 54 Kosice, Slovak Republic
| | - I Pechova
- Department of Biophysics, Faculty of Science, University of P. J. Safarik, Jesenna 5, 041 54 Kosice, Slovak Republic
| | - L Mikulova
- Center for Interdisciplinary Biosciences, Technology and Innovation Park, University of P. J. Safarik, Jesenna 5, 041 54 Kosice, Slovak Republic
| | - M Stupak
- Department of Medical and Clinical Biochemistry, Faculty of Medicine, University of P. J. Safarik, Trieda SNP 1, 040 11 Kosice, Slovak Republic
| | - D Jancura
- Department of Biophysics, Faculty of Science, University of P. J. Safarik, Jesenna 5, 041 54 Kosice, Slovak Republic.
| | - M Fabian
- Center for Interdisciplinary Biosciences, Technology and Innovation Park, University of P. J. Safarik, Jesenna 5, 041 54 Kosice, Slovak Republic.
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6
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Human Mitochondrial Pathologies of the Respiratory Chain and ATP Synthase: Contributions from Studies of Saccharomyces cerevisiae. Life (Basel) 2020; 10:life10110304. [PMID: 33238568 PMCID: PMC7700678 DOI: 10.3390/life10110304] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/27/2020] [Revised: 11/18/2020] [Accepted: 11/19/2020] [Indexed: 12/14/2022] Open
Abstract
The ease with which the unicellular yeast Saccharomyces cerevisiae can be manipulated genetically and biochemically has established this organism as a good model for the study of human mitochondrial diseases. The combined use of biochemical and molecular genetic tools has been instrumental in elucidating the functions of numerous yeast nuclear gene products with human homologs that affect a large number of metabolic and biological processes, including those housed in mitochondria. These include structural and catalytic subunits of enzymes and protein factors that impinge on the biogenesis of the respiratory chain. This article will review what is currently known about the genetics and clinical phenotypes of mitochondrial diseases of the respiratory chain and ATP synthase, with special emphasis on the contribution of information gained from pet mutants with mutations in nuclear genes that impair mitochondrial respiration. Our intent is to provide the yeast mitochondrial specialist with basic knowledge of human mitochondrial pathologies and the human specialist with information on how genes that directly and indirectly affect respiration were identified and characterized in yeast.
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7
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Hayashi M, Takahashi Y, Yoshida Y, Sugimoto K, Kitagawa H. Role of d-Elements in a Proton–Electron Coupling of d–π Hybridized Electron Systems. J Am Chem Soc 2019; 141:11686-11693. [DOI: 10.1021/jacs.9b04937] [Citation(s) in RCA: 19] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
Affiliation(s)
- Mikihiro Hayashi
- Division of Chemistry, Graduate School of Science, Kyoto University, Kitashirakawa-Oiwakecho, Sakyo-ku, Kyoto 606-8502, Japan
- Faculty of Education, Nagasaki University, 1-14 Bunkyo-machi, Nagasaki 852-8521, Japan
| | - Yuki Takahashi
- Division of Chemistry, Graduate School of Science, Kyoto University, Kitashirakawa-Oiwakecho, Sakyo-ku, Kyoto 606-8502, Japan
| | - Yukihiro Yoshida
- Division of Chemistry, Graduate School of Science, Kyoto University, Kitashirakawa-Oiwakecho, Sakyo-ku, Kyoto 606-8502, Japan
| | - Kunihisa Sugimoto
- Japan Synchrotron Radiation Research Institute (JASRI), SPring-8, 1-1-1 Kouto, Sayo-cho, Sayo-gun, Hyogo 679-5198, Japan
| | - Hiroshi Kitagawa
- Division of Chemistry, Graduate School of Science, Kyoto University, Kitashirakawa-Oiwakecho, Sakyo-ku, Kyoto 606-8502, Japan
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8
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Blomberg MRA. Active Site Midpoint Potentials in Different Cytochrome c Oxidase Families: A Computational Comparison. Biochemistry 2019; 58:2028-2038. [PMID: 30892888 DOI: 10.1021/acs.biochem.9b00093] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Cytochrome c oxidase (C cO) is the terminal enzyme in the respiratory electron transport chain, reducing molecular oxygen to water. The binuclear active site in C cO comprises a high-spin heme associated with a CuB complex and a redox active tyrosine. The electron transport in the respiratory chain is driven by increasing midpoint potentials of the involved cofactors, resulting in a release of free energy, which is stored by coupling the electron transfer to proton translocation across a membrane, building up an electrochemical gradient. In this context, the midpoint potentials of the active site cofactors in the C cOs are of special interest, since they determine the driving forces for the individual oxygen reduction steps and thereby affect the efficiency of the proton pumping. It has been difficult to obtain useful information on some of these midpoint potentials from experiments. However, since each of the reduction steps in the catalytic cycle of oxygen reduction to water corresponds to the formation of an O-H bond, they can be calculated with a reasonably high accuracy using quantum chemical methods. From the calculated O-H bond strengths, the proton-coupled midpoint potentials of the active site cofactors can be estimated. Using models representing the different families of C cO's (A, B, and C), the calculations give midpoint potentials that should be relevant during catalytic turnover. The calculations also suggest possible explanations for why some experimentally measured potentials deviate significantly from the calculated ones, i.e., for CuB in all oxidase families, and for heme b3 in the C family.
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Affiliation(s)
- Margareta R A Blomberg
- Department of Organic Chemistry, Arrhenius Laboratory , Stockholm University , Stockholm SE-106 91 , Sweden
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9
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Melin F, Sabuncu S, Choi SK, Leprince A, Gennis RB, Hellwig P. Role of the tightly bound quinone for the oxygen reaction of cytochrome
bo
3
oxidase from
Escherichia coli. FEBS Lett 2018; 592:3380-3387. [DOI: 10.1002/1873-3468.13263] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/25/2018] [Revised: 09/21/2018] [Accepted: 09/24/2018] [Indexed: 01/24/2023]
Affiliation(s)
- Frédéric Melin
- Chimie de la Matière Complexe UMR 7140 Laboratoire de Bioélectrochimie et Spectroscopie CNRS‐Université de Strasbourg France
| | - Sinan Sabuncu
- Chimie de la Matière Complexe UMR 7140 Laboratoire de Bioélectrochimie et Spectroscopie CNRS‐Université de Strasbourg France
| | - Sylvia K. Choi
- Center for Biophysics and Computational Biology University of Illinois Urbana IL USA
- Department of Biochemistry University of Illinois Urbana IL USA
| | - Agathe Leprince
- Chimie de la Matière Complexe UMR 7140 Laboratoire de Bioélectrochimie et Spectroscopie CNRS‐Université de Strasbourg France
| | | | - Petra Hellwig
- Chimie de la Matière Complexe UMR 7140 Laboratoire de Bioélectrochimie et Spectroscopie CNRS‐Université de Strasbourg France
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10
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Vilhjálmsdóttir J, Gennis RB, Brzezinski P. The electron distribution in the "activated" state of cytochrome c oxidase. Sci Rep 2018; 8:7502. [PMID: 29760451 PMCID: PMC5951807 DOI: 10.1038/s41598-018-25779-w] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/20/2017] [Accepted: 04/26/2018] [Indexed: 11/09/2022] Open
Abstract
Cytochrome c oxidase catalyzes reduction of O2 to H2O at a catalytic site that is composed of a copper ion and heme group. The reaction is linked to translocation of four protons across the membrane for each O2 reduced to water. The free energy associated with electron transfer to the catalytic site is unequal for the four electron-transfer events. Most notably, the free energy associated with reduction of the catalytic site in the oxidized cytochrome c oxidase (state O) is not sufficient for proton pumping across the energized membrane. Yet, this electron transfer is mechanistically linked to proton pumping. To resolve this apparent discrepancy, a high-energy oxidized state (denoted OH) was postulated and suggested to be populated only during catalytic turnover. The difference between states O and OH was suggested to be manifested in an elevated midpoint potential of CuB in the latter. This proposal predicts that one-electron reduction of cytochrome c oxidase after its oxidation would yield re-reduction of essentially only CuB. Here, we investigated this process and found ~5% and ~6% reduction of heme a3 and CuB, respectively, i.e. the apparent redox potentials for heme a3 and CuB are lower than that of heme a.
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Affiliation(s)
- Jóhanna Vilhjálmsdóttir
- Department of Biochemistry and Biophysics, The Arrhenius Laboratories for Natural Sciences, Stockholm University, SE-106 91, Stockholm, Sweden
| | - Robert B Gennis
- Department of Biochemistry, University of Illinois at Urbana Champaign, Urbana, Illinois, 61801, United States
| | - Peter Brzezinski
- Department of Biochemistry and Biophysics, The Arrhenius Laboratories for Natural Sciences, Stockholm University, SE-106 91, Stockholm, Sweden.
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11
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Wikström M, Krab K, Sharma V. Oxygen Activation and Energy Conservation by Cytochrome c Oxidase. Chem Rev 2018; 118:2469-2490. [PMID: 29350917 PMCID: PMC6203177 DOI: 10.1021/acs.chemrev.7b00664] [Citation(s) in RCA: 245] [Impact Index Per Article: 40.8] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022]
Abstract
![]()
This review focuses on the type
A cytochrome c oxidases (CcO), which
are found in all mitochondria
and also in several aerobic bacteria. CcO catalyzes
the respiratory reduction of dioxygen (O2) to water by
an intriguing mechanism, the details of which are fairly well understood
today as a result of research for over four decades. Perhaps even
more intriguingly, the membrane-bound CcO couples
the O2 reduction chemistry to translocation of protons
across the membrane, thus contributing to generation of the electrochemical
proton gradient that is used to drive the synthesis of ATP as catalyzed
by the rotary ATP synthase in the same membrane. After reviewing the
structure of the core subunits of CcO, the active
site, and the transfer paths of electrons, protons, oxygen, and water,
we describe the states of the catalytic cycle and point out the few
remaining uncertainties. Finally, we discuss the mechanism of proton
translocation and the controversies in that area that still prevail.
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Affiliation(s)
- Mårten Wikström
- Institute of Biotechnology , University of Helsinki , P.O. Box 56 , Helsinki FI-00014 , Finland
| | - Klaas Krab
- Department of Molecular Cell Physiology , Vrije Universiteit , P.O. Box 7161 , Amsterdam 1007 MC , The Netherlands
| | - Vivek Sharma
- Institute of Biotechnology , University of Helsinki , P.O. Box 56 , Helsinki FI-00014 , Finland.,Department of Physics , University of Helsinki , P.O. Box 64 , Helsinki FI-00014 , Finland
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12
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Pierre S, Duke JR, Hele TJH, Ananth N. A mapping variable ring polymer molecular dynamics study of condensed phase proton-coupled electron transfer. J Chem Phys 2017; 147:234103. [DOI: 10.1063/1.4986517] [Citation(s) in RCA: 22] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/30/2022] Open
Affiliation(s)
- Sadrach Pierre
- Department of Chemistry and Chemical Biology, Cornell University, Ithaca, New York 14853, USA
| | - Jessica R. Duke
- Department of Chemistry and Chemical Biology, Cornell University, Ithaca, New York 14853, USA
| | - Timothy J. H. Hele
- Department of Chemistry and Chemical Biology, Cornell University, Ithaca, New York 14853, USA
| | - Nandini Ananth
- Department of Chemistry and Chemical Biology, Cornell University, Ithaca, New York 14853, USA
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13
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Yosca TH, Langston MC, Krest CM, Onderko EL, Grove TL, Livada J, Green MT. Spectroscopic Investigations of Catalase Compound II: Characterization of an Iron(IV) Hydroxide Intermediate in a Non-thiolate-Ligated Heme Enzyme. J Am Chem Soc 2016; 138:16016-16023. [PMID: 27960340 PMCID: PMC5987761 DOI: 10.1021/jacs.6b09693] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
We report on the protonation state of Helicobacter pylori catalase compound II. UV/visible, Mössbauer, and X-ray absorption spectroscopies have been used to examine the intermediate from pH 5 to 14. We have determined that HPC-II exists in an iron(IV) hydroxide state up to pH 11. Above this pH, the iron(IV) hydroxide complex transitions to a new species (pKa = 13.1) with Mössbauer parameters that are indicative of an iron(IV)-oxo intermediate. Recently, we discussed a role for an elevated compound II pKa in diminishing the compound I reduction potential. This has the effect of shifting the thermodynamic landscape toward the two-electron chemistry that is critical for catalase function. In catalase, a diminished potential would increase the selectivity for peroxide disproportionation over off-pathway one-electron chemistry, reducing the buildup of the inactive compound II state and reducing the need for energetically expensive electron donor molecules.
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Affiliation(s)
- Timothy H. Yosca
- Departments of Chemistry & Molecular Biology and Biochemistry, University of California, Irvine, California 92697, United States
| | - Matthew C. Langston
- Department of Chemistry, Pennsylvania State University, University Park, Pennsylvania 16802, United States
| | - Courtney M. Krest
- Stanford Synchrotron Radiation Lightsource, SLAC National Accelerator Laboratory, Menlo Park, California 94025, United States
| | - Elizabeth L. Onderko
- Department of Chemistry, Pennsylvania State University, University Park, Pennsylvania 16802, United States
| | - Tyler L. Grove
- Department of Chemistry, Pennsylvania State University, University Park, Pennsylvania 16802, United States
| | - Jovan Livada
- Department of Chemistry, Pennsylvania State University, University Park, Pennsylvania 16802, United States
| | - Michael T. Green
- Departments of Chemistry & Molecular Biology and Biochemistry, University of California, Irvine, California 92697, United States
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14
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Melin F, Xie H, Meyer T, Ahn YO, Gennis RB, Michel H, Hellwig P. The unusual redox properties of C-type oxidases. BIOCHIMICA ET BIOPHYSICA ACTA-BIOENERGETICS 2016; 1857:1892-1899. [PMID: 27664317 DOI: 10.1016/j.bbabio.2016.09.009] [Citation(s) in RCA: 25] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/30/2016] [Revised: 09/15/2016] [Accepted: 09/19/2016] [Indexed: 10/21/2022]
Abstract
Cytochrome cbb3 (also known as C-type) oxidases belong to the family of heme-copper terminal oxidases which couple at the end of the respiratory chain the reduction of molecular oxygen into water and the pumping of protons across the membrane. They are expressed most often at low pressure of O2 and they exhibit a low homology of sequence with the cytochrome aa3 (A-type) oxidases found in mitochondria. Their binuclear active site comprises a high-spin heme b3 associated with a CuB center. The protein also contains one low-spin heme b and 3 hemes c. We address here the redox properties of cbb3 oxidases from three organisms, Rhodobacter sphaeroides, Vibrio cholerae and Pseudomonas stutzeri by means of electrochemical and spectroscopic techniques. We show that the redox potential of the heme b3 exhibits a relatively low midpoint potential, as in related cytochrome c-dependent nitric oxide reductases. Potential implications for the coupled electron transfer and proton uptake mechanism of C-type oxidases are discussed.
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Affiliation(s)
- Frederic Melin
- Laboratoire de Bioélectrochimie et Spectroscopie, Chimie de la Matière Complexe, UMR 7140, Université de Strasbourg, 1 Rue Blaise Pascal, 67000 Strasbourg, France
| | - Hao Xie
- Max Planck Institute of Biophysics, Department of Molecular Membrane Biology, Max-von-Laue-Str. 3, D-60438 Frankfurt am Main, Germany
| | - Thomas Meyer
- Laboratoire de Bioélectrochimie et Spectroscopie, Chimie de la Matière Complexe, UMR 7140, Université de Strasbourg, 1 Rue Blaise Pascal, 67000 Strasbourg, France
| | - Young Ok Ahn
- Department of Biochemistry, University of Illinois at Urbana Champaign, USA
| | - Robert B Gennis
- Department of Biochemistry, University of Illinois at Urbana Champaign, USA
| | - Hartmut Michel
- Max Planck Institute of Biophysics, Department of Molecular Membrane Biology, Max-von-Laue-Str. 3, D-60438 Frankfurt am Main, Germany
| | - Petra Hellwig
- Laboratoire de Bioélectrochimie et Spectroscopie, Chimie de la Matière Complexe, UMR 7140, Université de Strasbourg, 1 Rue Blaise Pascal, 67000 Strasbourg, France.
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15
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Marreiros BC, Calisto F, Castro PJ, Duarte AM, Sena FV, Silva AF, Sousa FM, Teixeira M, Refojo PN, Pereira MM. Exploring membrane respiratory chains. BIOCHIMICA ET BIOPHYSICA ACTA-BIOENERGETICS 2016; 1857:1039-1067. [PMID: 27044012 DOI: 10.1016/j.bbabio.2016.03.028] [Citation(s) in RCA: 47] [Impact Index Per Article: 5.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/15/2016] [Revised: 03/16/2016] [Accepted: 03/18/2016] [Indexed: 01/20/2023]
Abstract
Acquisition of energy is central to life. In addition to the synthesis of ATP, organisms need energy for the establishment and maintenance of a transmembrane difference in electrochemical potential, in order to import and export metabolites or to their motility. The membrane potential is established by a variety of membrane bound respiratory complexes. In this work we explored the diversity of membrane respiratory chains and the presence of the different enzyme complexes in the several phyla of life. We performed taxonomic profiles of the several membrane bound respiratory proteins and complexes evaluating the presence of their respective coding genes in all species deposited in KEGG database. We evaluated 26 quinone reductases, 5 quinol:electron carriers oxidoreductases and 18 terminal electron acceptor reductases. We further included in the analyses enzymes performing redox or decarboxylation driven ion translocation, ATP synthase and transhydrogenase and we also investigated the electron carriers that perform functional connection between the membrane complexes, quinones or soluble proteins. Our results bring a novel, broad and integrated perspective of membrane bound respiratory complexes and thus of the several energetic metabolisms of living systems. This article is part of a Special Issue entitled 'EBEC 2016: 19th European Bioenergetics Conference, Riva del Garda, Italy, July 2-6, 2016', edited by Prof. Paolo Bernardi.
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Affiliation(s)
- Bruno C Marreiros
- Instituto de Tecnologia Química e Biológica-António Xavier, Universidade Nova de Lisboa, Av. da República EAN, 2780-157 Oeiras, Portugal
| | - Filipa Calisto
- Instituto de Tecnologia Química e Biológica-António Xavier, Universidade Nova de Lisboa, Av. da República EAN, 2780-157 Oeiras, Portugal
| | - Paulo J Castro
- Instituto de Tecnologia Química e Biológica-António Xavier, Universidade Nova de Lisboa, Av. da República EAN, 2780-157 Oeiras, Portugal
| | - Afonso M Duarte
- Instituto de Tecnologia Química e Biológica-António Xavier, Universidade Nova de Lisboa, Av. da República EAN, 2780-157 Oeiras, Portugal
| | - Filipa V Sena
- Instituto de Tecnologia Química e Biológica-António Xavier, Universidade Nova de Lisboa, Av. da República EAN, 2780-157 Oeiras, Portugal
| | - Andreia F Silva
- Instituto de Tecnologia Química e Biológica-António Xavier, Universidade Nova de Lisboa, Av. da República EAN, 2780-157 Oeiras, Portugal
| | - Filipe M Sousa
- Instituto de Tecnologia Química e Biológica-António Xavier, Universidade Nova de Lisboa, Av. da República EAN, 2780-157 Oeiras, Portugal
| | - Miguel Teixeira
- Instituto de Tecnologia Química e Biológica-António Xavier, Universidade Nova de Lisboa, Av. da República EAN, 2780-157 Oeiras, Portugal
| | - Patrícia N Refojo
- Instituto de Tecnologia Química e Biológica-António Xavier, Universidade Nova de Lisboa, Av. da República EAN, 2780-157 Oeiras, Portugal
| | - Manuela M Pereira
- Instituto de Tecnologia Química e Biológica-António Xavier, Universidade Nova de Lisboa, Av. da República EAN, 2780-157 Oeiras, Portugal.
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16
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Castro PJ, Silva AF, Marreiros BC, Batista AP, Pereira MM. Respiratory complex I: A dual relation with H(+) and Na(+)? BIOCHIMICA ET BIOPHYSICA ACTA-BIOENERGETICS 2015; 1857:928-37. [PMID: 26711319 DOI: 10.1016/j.bbabio.2015.12.008] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/17/2015] [Revised: 12/10/2015] [Accepted: 12/17/2015] [Indexed: 10/22/2022]
Abstract
Respiratory complex I couples NADH:quinone oxidoreduction to ion translocation across the membrane, contributing to the buildup of the transmembrane difference of electrochemical potential. H(+) is well recognized to be the coupling ion of this system but some studies suggested that this role could be also performed by Na(+). We have previously observed NADH-driven Na(+) transport opposite to H(+) translocation by menaquinone-reducing complexes I, which indicated a Na(+)/H(+) antiporter activity in these systems. Such activity was also observed for the ubiquinone-reducing mitochondrial complex I in its deactive form. The relation of Na(+) with complex I may not be surprising since the enzyme has three subunits structurally homologous to bona fide Na(+)/H(+) antiporters and translocation of H(+) and Na(+) ions has been described for members of most types of ion pumps and transporters. Moreover, no clearly distinguishable motifs for the binding of H(+) or Na(+) have been recognized yet. We noticed that in menaquinone-reducing complexes I, less energy is available for ion translocation, compared to ubiquinone-reducing complexes I. Therefore, we hypothesized that menaquinone-reducing complexes I perform Na(+)/H(+) antiporter activity in order to achieve the stoichiometry of 4H(+)/2e(-). In agreement, the organisms that use ubiquinone, a high potential quinone, would have kept such Na(+)/H(+) antiporter activity, only operative under determined conditions. This would imply a physiological role(s) of complex I besides a simple "coupling" of a redox reaction and ion transport, which could account for the sophistication of this enzyme. This article is part of a Special Issue entitled Respiratory complex I, edited by Volker Zickermann and Ulrich Brandt.
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Affiliation(s)
- Paulo J Castro
- Instituto de Tecnologia Química e Biológica, António Xavier, Universidade Nova de Lisboa, Av. da Republica EAN, 2780-157 Oeiras, Portugal
| | - Andreia F Silva
- Instituto de Tecnologia Química e Biológica, António Xavier, Universidade Nova de Lisboa, Av. da Republica EAN, 2780-157 Oeiras, Portugal
| | - Bruno C Marreiros
- Instituto de Tecnologia Química e Biológica, António Xavier, Universidade Nova de Lisboa, Av. da Republica EAN, 2780-157 Oeiras, Portugal
| | - Ana P Batista
- Instituto de Tecnologia Química e Biológica, António Xavier, Universidade Nova de Lisboa, Av. da Republica EAN, 2780-157 Oeiras, Portugal
| | - Manuela M Pereira
- Instituto de Tecnologia Química e Biológica, António Xavier, Universidade Nova de Lisboa, Av. da Republica EAN, 2780-157 Oeiras, Portugal.
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17
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Wikström M, Sharma V, Kaila VRI, Hosler JP, Hummer G. New Perspectives on Proton Pumping in Cellular Respiration. Chem Rev 2015; 115:2196-221. [DOI: 10.1021/cr500448t] [Citation(s) in RCA: 183] [Impact Index Per Article: 20.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
- Mårten Wikström
- Institute
of Biotechnology, University of Helsinki, Biocenter 3 (Viikinkaari 1), PB
65, Helsinki 00014, Finland
| | - Vivek Sharma
- Department
of Physics, Tampere University of Technology, Korkeakoulunkatu 3, Tampere 33720, Finland
| | - Ville R. I. Kaila
- Department
Chemie, Technische Universität München, Lichtenbergstraße 4, D-85748 Garching, Germany
| | - Jonathan P. Hosler
- Department
of Biochemistry, University of Mississippi Medical Center, Jackson, Mississippi 39216, United States
| | - Gerhard Hummer
- Department
of Theoretical Biophysics, Max Planck Institute of Biophysics, Max-von-Laue-Straße
3, 60438 Frankfurt
am Main, Germany
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18
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Blomberg MRA, Siegbahn PEM. Proton pumping in cytochrome c oxidase: energetic requirements and the role of two proton channels. BIOCHIMICA ET BIOPHYSICA ACTA-BIOENERGETICS 2014; 1837:1165-77. [PMID: 24418352 DOI: 10.1016/j.bbabio.2014.01.002] [Citation(s) in RCA: 35] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/31/2013] [Revised: 01/02/2014] [Accepted: 01/06/2014] [Indexed: 12/15/2022]
Abstract
Cytochrome c oxidase is a superfamily of membrane bound enzymes catalyzing the exergonic reduction of molecular oxygen to water, producing an electrochemical gradient across the membrane. The gradient is formed both by the electrogenic chemistry, taking electrons and protons from opposite sides of the membrane, and by proton pumping across the entire membrane. In the most efficient subfamily, the A-family of oxidases, one proton is pumped in each reduction step, which is surprising considering the fact that two of the reduction steps most likely are only weakly exergonic. Based on a combination of quantum chemical calculations and experimental information, it is here shown that from both a thermodynamic and a kinetic point of view, it should be possible to pump one proton per electron also with such an uneven distribution of the free energy release over the reduction steps, at least up to half the maximum gradient. A previously suggested pumping mechanism is developed further to suggest a reason for the use of two proton transfer channels in the A-family. Since the rate of proton transfer to the binuclear center through the D-channel is redox dependent, it might become too slow for the steps with low exergonicity. Therefore, a second channel, the K-channel, where the rate is redox-independent is needed. A redox-dependent leakage possibility is also suggested, which might be important for efficient energy conservation at a high gradient. A mechanism for the variation in proton pumping stoichiometry over the different subfamilies of cytochrome oxidase is also suggested. This article is part of a Special Issue entitled: 18th European Bioenergetic Conference.
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Affiliation(s)
- Margareta R A Blomberg
- Department of Organic Chemistry, Arrhenius Laboratory, Stockholm University, SE-106 91, Stockholm, Sweden.
| | - Per E M Siegbahn
- Department of Organic Chemistry, Arrhenius Laboratory, Stockholm University, SE-106 91, Stockholm, Sweden
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19
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Karpefors M, Ädelroth P, Aagaard A, Smirnova IA, Brzezinski P. The Deuterium Isotope Effect as a Tool to Investigate Enzyme Catalysis: Proton-Transfer Control Mechanisms in CytochromecOxidase. Isr J Chem 2013. [DOI: 10.1002/ijch.199900048] [Citation(s) in RCA: 30] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
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20
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Abriata LA, Vila AJ. Redox-state sensing by hydrogen bonds in the CuA center of cytochrome c oxidase. J Inorg Biochem 2013; 132:18-20. [PMID: 24012017 DOI: 10.1016/j.jinorgbio.2013.07.032] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/23/2013] [Revised: 07/18/2013] [Accepted: 07/23/2013] [Indexed: 11/25/2022]
Abstract
Cytochrome c oxidases (CcO) couple electron transfer to active proton translocation through a gated mechanism that minimizes energy losses by preventing protons from flowing backwards or leaking. Such a complex mechanism requires that information about the redox and protonation states of the different centers be transmitted between different parts of the oxidase. Here we report a network of residues located around the electron entry point of CcO, the CuA site in subunit II, that experience collective pH equilibria around neutral pH. This network starts at the occluded side of the CuA site and extends to the interface between subunits I and II of the CcO, where the proton exit is located and through which electrons flow into subunit I. One of the residues in this network is directly involved in a hydrogen bond to one of the CuA ligands, whose strength is highly sensitive to the redox state of the metal center. We propose that this interaction mediates the transmission of redox changes from ET centers to other functional regions of the oxidase, and possibly also in other similar machineries, as part of their gating and regulatory mechanisms.
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Affiliation(s)
- Luciano A Abriata
- Instituto de Biología Molecular y Celular de Rosario (IBR, CONICET-UNR) and Área Biofísica, Facultad de Ciencias Bioquímicas y Farmacéuticas, Universidad Nacional de Rosario, Rosario, Argentina
| | - Alejandro J Vila
- Instituto de Biología Molecular y Celular de Rosario (IBR, CONICET-UNR) and Área Biofísica, Facultad de Ciencias Bioquímicas y Farmacéuticas, Universidad Nacional de Rosario, Rosario, Argentina.
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21
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Pinakoulaki E, Daskalakis V, Ohta T, Richter OMH, Budiman K, Kitagawa T, Ludwig B, Varotsis C. The protein effect in the structure of two ferryl-oxo intermediates at the same oxidation level in the heme copper binuclear center of cytochrome c oxidase. J Biol Chem 2013; 288:20261-6. [PMID: 23723073 DOI: 10.1074/jbc.m113.468488] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/25/2022] Open
Abstract
Identification of the intermediates and determination of their structures in the reduction of dioxygen to water by cytochrome c oxidase (CcO) are particularly important to understanding both O2 activation and proton pumping by the enzyme. In this work, we report the products of the rapid reaction of O2 with the mixed valence form (CuA(2+), heme a(3+), heme a3(2+)-CuB(1+)) of the enzyme. The resonance Raman results show the formation of two ferryl-oxo species with characteristic Fe(IV)=O stretching modes at 790 and 804 cm(-1) at the peroxy oxidation level (PM). Density functional theory calculations show that the protein environment of the proximal H-bonded His-411 determines the strength of the distal Fe(IV)=O bond. In contrast to previous proposals, the PM intermediate is also formed in the reaction of Y167F with O2. These results suggest that in the fully reduced enzyme, the proton pumping ν(Fe(IV)=O) = 804 cm(-1) to ν(Fe(IV)=O) = 790 cm(-1) transition (P→F, where P is peroxy and F is ferryl) is triggered not only by electron transfer from heme a to heme a3 but also by the formation of the H-bonded form of the His-411-Fe(IV)=O conformer in the proximal site of heme a3. The implications of these results with respect to the role of an O=Fe(IV)-His-411-H-bonded form to the ring A propionate of heme a3-Asp-399-H2O site and, thus, to the exit/output proton channel (H2O) pool during the proton pumping P→F transition are discussed. We propose that the environment proximal to the heme a3 controls the spectroscopic properties of the ferryl intermediates in cytochrome oxidases.
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Affiliation(s)
- Eftychia Pinakoulaki
- Department of Chemistry, University of Cyprus, P. O. Box 20537, 1678 Nicosia, Cyprus
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22
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Chess DJ, Billings E, Covian R, Glancy B, French S, Taylor J, de Bari H, Murphy E, Balaban RS. Optical spectroscopy in turbid media using an integrating sphere: mitochondrial chromophore analysis during metabolic transitions. Anal Biochem 2013; 439:161-72. [PMID: 23665273 DOI: 10.1016/j.ab.2013.04.017] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/25/2013] [Revised: 04/03/2013] [Accepted: 04/12/2013] [Indexed: 01/16/2023]
Abstract
Recent evidence suggests that the activity of mitochondrial oxidative phosphorylation complexes (MOPCs) is modulated at multiple sites. Here, a method of optically monitoring electron distribution within and between MOPCs is described using a center-mounted sample in an integrating sphere (to minimize scattering effects) with a rapid-scanning spectrometer. The redox-sensitive MOPC absorbances (∼465-630 nm) were modeled using linear least squares analysis with individual chromophore spectra. Classical mitochondrial activity transitions (e.g., ADP-induced increase in oxygen consumption) were used to characterize this approach. Most notable in these studies was the observation that intermediates of the catalytic cycle of cytochrome oxidase are dynamically modulated with metabolic state. The MOPC redox state, along with measurements of oxygen consumption and mitochondrial membrane potential, was used to evaluate the conductances of different sections of the electron transport chain. This analysis then was applied to mitochondria isolated from rabbit hearts subjected to ischemia/reperfusion (I/R). Surprisingly, I/R resulted in an inhibition of all measured MOPC conductances, suggesting a coordinated down-regulation of mitochondrial activity with this well-established cardiac perturbation.
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Affiliation(s)
- David J Chess
- Laboratory of Cardiac Energetics, National Heart, Lung, and Blood Institute, National Institutes of Health, Bethesda, MD 20892, USA.
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23
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Ashe D, Alleyne T, Sampson V. Substrate binding-dissociation and intermolecular electron transfer in cytochrome c oxidase are driven by energy-dependent conformational changes in the enzyme and substrate. Biotechnol Appl Biochem 2013; 59:213-22. [PMID: 23586831 DOI: 10.1002/bab.1015] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/06/2011] [Accepted: 02/23/2012] [Indexed: 12/21/2022]
Abstract
Reduction of O₂ by cytochrome c oxidase (COX) is critical to the cellular production of adenosine-5'-triphosphate; COX obtains the four electrons required for this process from ferrocytochrome c. The COX-cytochrome c enzyme-substrate complex is stabilized by electrostatic interactions via carboxylates on COX and lysines on cytochrome c. Conformational changes are believed to play a role in ferrocytochrome c oxidation and release and in rapid intramolecular transfer of electrons within COX, but the details are unclear. To gather specific information about the extent and relevance of conformational changes, we performed bioinformatics studies using the published structures of both proteins. For both proteins, we studied the surface accessibility and energy, as a function of the proteins' oxidation state. The residues of reduced cytochrome c showed greater surface accessibility and were at a higher energy than those of the oxidized cytochrome c. Also, most residues of the core subunits (I, II, and III) of COX showed low accessibility, ∼35%, and compared to the oxidized subunits, the reduced subunits had higher energies. We concluded that substrate binding and dissociation is modulated by specific redox-dependent conformational changes. We further conclude that high energy and structural relaxation of reduced cytochrome c and core COX subunits drive their rapid electron transfer.
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Affiliation(s)
- Damian Ashe
- Department of Preclinical Sciences, Biochemistry Unit, Faculty of Medical Sciences, The University of the West Indies, St. Augustine, Trinidad, West Indies
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24
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The mechanism for proton pumping in cytochrome c oxidase from an electrostatic and quantum chemical perspective. BIOCHIMICA ET BIOPHYSICA ACTA-BIOENERGETICS 2011; 1817:495-505. [PMID: 21978537 DOI: 10.1016/j.bbabio.2011.09.014] [Citation(s) in RCA: 52] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/30/2011] [Revised: 09/02/2011] [Accepted: 09/03/2011] [Indexed: 11/21/2022]
Abstract
The mechanism for proton pumping in cytochrome c oxidase in the respiratory chain, has for decades been one of the main unsolved problems in biochemistry. However, even though several different suggested mechanisms exist, many of the steps in these mechanisms are quite similar and constitute a general consensus framework for discussing proton pumping. When these steps are analyzed, at least three critical gating situations are found, and these points are where the suggested mechanisms in general differ. The requirements for gating are reviewed and analyzed in detail, and a mechanism is suggested, where solutions for all the gating situations are formulated. This mechanism is based on an electrostatic analysis of a kinetic experiment fior the O to E transition. The key component of the mechanism is a positively charged transition state. An electron on heme a opens the gate for proton transfer from the N-side to a pump loading site (PLS). When the negative charge of the electron is compensated by a chemical proton, the positive transition state prevents backflow from the PLS to the N-side at the most critical stage of the pumping process. The mechanism has now been tested by large model DFT calculations, and these calculations give strong support for the suggested mechanism.
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25
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Oztürk M, Watmough NJ. Mutagenesis of tyrosine residues within helix VII in subunit I of the cytochrome cbb₃ oxidase from Rhodobacter capsulatus. Mol Biol Rep 2010; 38:3319-26. [PMID: 21107730 DOI: 10.1007/s11033-010-0437-z] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/01/2010] [Accepted: 11/08/2010] [Indexed: 10/18/2022]
Abstract
The cbb (3)-type oxidases are members of the heme-copper oxidase superfamily, distant by sequence comparisons, but sharing common functional characteristics. The cbb (3) oxidases are missing an active-site tyrosine residue that is absolutely conserved in all A and B-type heme-copper oxidases. This tyrosine is known to play a critical role in the catalytic mechanisms of A and B-type oxidases. The absence of this tyrosine in the cbb (3) oxidases raises the possibility that the cbb (3) oxidases utilize a different catalytic mechanism from that of the other members of the superfamily, or have this conserved residue in different helices. Recently sequence comparisons indicate that, a tyrosine residues that might be analogous to the active-site tyrosine in other oxidases are present in the cbb (3) oxidases but these tyrosines originates from a different transmembrane helix within the protein. In this research, three conserved tyrosine residues, Y294, Y308 and Y318, in helix VII were substituted for phenylalanine. Y318F mutant in the Rhodobacter capsulatus oxidase resulted in a fully assembled enzyme with nativelike structure and activity, but Y294F mutant is not assembled and have a catalytic activity. On the other hand, Y308F mutant is fully assembled enzyme with nativelike structure, but lacking catalytic activity. This result indicates that Y308 should be crucial in catalytic activity of the cbb (3) oxidase of R. capsulatus. These findings support the assumption that all of the heme-copper oxidases utilize the same catalytic mechanism and provide a residue originates from different places within the primary sequence for different members of the same superfamily.
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Affiliation(s)
- Mehmet Oztürk
- Department of Biology, Faculty of Literature and Science, Abant İzzet Baysal University, 14280 Bolu, Turkey.
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26
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Borisov VB, Davletshin AI, Konstantinov AA. Peroxidase activity of cytochrome bd from Escherichia coli. BIOCHEMISTRY (MOSCOW) 2010; 75:428-36. [PMID: 20618131 DOI: 10.1134/s000629791004005x] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
Abstract
Cytochrome bd from Escherichia coli is able to oxidize such substrates as guaiacol, ferrocene, benzohydroquinone, and potassium ferrocyanide through the peroxidase mechanism, while none of these donors is oxidized in the oxidase reaction (i.e. in the reaction that involves molecular oxygen as the electron acceptor). Peroxidation of guaiacol has been studied in detail. The dependence of the rate of the reaction on the concentration of the enzyme and substrates as well as the effect of various inhibitors of the oxidase reaction on the peroxidase activity have been tested. The dependence of the guaiacol-peroxidase activity on the H2O2 concentration is linear up to the concentration of 8 mM. At higher concentrations of H2O2, inactivation of the enzyme is observed. Guaiacol markedly protects the enzyme from inactivation induced by peroxide. The peroxidase activity of cytochrome bd increases with increasing guaiacol concentration, reaching saturation in the range from 0.5 to 2.5 mM, but then starts falling. Such inhibitors of the ubiquinol-oxidase activity of cytochrome bd as cyanide, pentachlorophenol, and 2-n-heptyl 4-hydroxyquinoline-N-oxide also suppress its guaiacol-peroxidase activity; in contrast, zinc ions have no influence on the enzyme-catalyzed peroxidation of guaiacol. These data suggest that guaiacol interacts with the enzyme in the center of ubiquinol binding and donates electrons into the di-heme center of oxygen reduction via heme b(558), and H2O2 is reduced by heme d. Although the peroxidase activity of cytochrome bd from E. coli is low compared to peroxidases, it might be of physiological significance for the bacterium itself and plays a pathophysiological role for humans and animals.
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Affiliation(s)
- V B Borisov
- Belozersky Institute of Physico-Chemical Biology, Lomonosov Moscow State University, Moscow, 119991, Russia.
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27
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Leonard M, Eryl Sharp R, Darrouzet E, Moser C, Ohnishi T, Gibney B, Daldal F, Leslie Dutton P. Coenzyme Q Oxidation Reduction Reactions in Mitochondrial Electron Transport. ACTA ACUST UNITED AC 2010. [DOI: 10.1201/9781420036701.sec1b] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 03/07/2023]
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28
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Abstract
Despite growing up amid humble surroundings, I ended up receiving an excellent education at the University of California at Berkeley and postdoctoral training at Harvard. My academic career at Caltech was shaped by serendipity, inspirational colleagues, and a stimulating research environment, as well as smart, motivated students and postdocs who were willing to join my search for molecular understanding of complex biological systems. From chemical physics I allowed my research to evolve, beginning with the application of NMR to investigate the base stacking of nucleic acid bases in solution, the dynamic structure of membranes, and culminating with the use of various forms of spectroscopy to elucidate the structure and function of membrane proteins and the early kinetic events in protein folding. The journey was a biased random walk driven by my own intellectual curiosity and instincts and by the pace at which I learned biochemistry from my students and postdocs, my colleagues, and the literature and through osmosis during seminars and scientific meetings.
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Affiliation(s)
- Sunney I Chan
- Noyes Laboratory of Chemical Physics 127-72, California Institute of Technology, Pasadena, CA 91125, USA.
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29
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Fee JA, Case DA, Noodleman L. Toward a chemical mechanism of proton pumping by the B-type cytochrome c oxidases: application of density functional theory to cytochrome ba3 of Thermus thermophilus. J Am Chem Soc 2008; 130:15002-21. [PMID: 18928258 DOI: 10.1021/ja803112w] [Citation(s) in RCA: 59] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
A mechanism for proton pumping by the B-type cytochrome c oxidases is presented in which one proton is pumped in conjunction with the weakly exergonic, two-electron reduction of Fe-bound O 2 to the Fe-Cu bridging peroxodianion and three protons are pumped in conjunction with the highly exergonic, two-electron reduction of Fe(III)- (-)O-O (-)-Cu(II) to form water and the active oxidized enzyme, Fe(III)- (-)OH,Cu(II). The scheme is based on the active-site structure of cytochrome ba 3 from Thermus thermophilus, which is considered to be both necessary and sufficient for coupled O 2 reduction and proton pumping when appropriate gates are in place (not included in the model). Fourteen detailed structures obtained from density functional theory (DFT) geometry optimization are presented that are reasonably thought to occur during the four-electron reduction of O 2. Each proton-pumping step takes place when a proton resides on the imidazole ring of I-His376 and the large active-site cluster has a net charge of +1 due to an uncompensated, positive charge formally associated with Cu B. Four types of DFT were applied to determine the energy of each intermediate, and standard thermochemical approaches were used to obtain the reaction free energies for each step in the catalytic cycle. This application of DFT generally conforms with previously suggested criteria for a valid model (Siegbahn, P. E. M.; Blomberg, M. A. R. Chem. Rev. 2000, 100, 421-437) and shows how the chemistry of O 2 reduction in the heme a 3 -Cu B dinuclear center can be harnessed to generate an electrochemical proton gradient across the lipid bilayer.
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Affiliation(s)
- James A Fee
- The Scripps Research Institute, 10550 North Torrey Pines Road, La Jolla, California 92037, USA.
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30
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Rich PR. A perspective on Peter Mitchell and the chemiosmotic theory. J Bioenerg Biomembr 2008; 40:407-10. [PMID: 18846415 DOI: 10.1007/s10863-008-9173-7] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/11/2008] [Accepted: 07/15/2008] [Indexed: 11/26/2022]
Abstract
In 1991 Peter Mitchell wrote a last article that summarised his views on the origin, development and current status of his chemiosmotic ideas. I here review some of his views of that time on structures and mechanisms of several key bioenergetic components in relation to the subsequent advances that have been made.
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Affiliation(s)
- Peter R Rich
- Glynn Laboratory of Bioenergetics, Institute of Structural and Molecular Biology, University College London, Gower Street, London, UK.
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31
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Collman JP, Decréau RA. Functional biomimetic models for the active site in the respiratory enzyme cytochrome c oxidase. Chem Commun (Camb) 2008:5065-76. [PMID: 18956030 DOI: 10.1039/b808070b] [Citation(s) in RCA: 55] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
A functional analog of the active site in the respiratory enzyme, cytochrome c oxidase (CcO) reproduces every feature in CcO's active site: a myoglobin-like heme (heme a3), a distal tridentate imidazole copper complex (Cu(B)), a phenol (Tyr244), and a proximal imidazole. When covalently attached to a liquid-crystalline SAM film on an Au electrode, this functional model continuously catalyzes the selective four-electron reduction of dioxygen at physiological potential and pH, under rate-limiting electron flux (as occurs in CcO).
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Affiliation(s)
- James P Collman
- Stanford University, Chemistry Department, Stanford, CA-94305-5080, USA.
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32
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Belevich I, Verkhovsky MI. Molecular mechanism of proton translocation by cytochrome c oxidase. Antioxid Redox Signal 2008; 10:1-29. [PMID: 17949262 DOI: 10.1089/ars.2007.1705] [Citation(s) in RCA: 119] [Impact Index Per Article: 7.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
Abstract
Cytochrome c oxidase (CcO) is a terminal protein of the respiratory chain in eukaryotes and some bacteria. It catalyzes most of the biologic oxygen consumption on earth done by aerobic organisms. During the catalytic reaction, CcO reduces dioxygen to water and uses the energy released in this process to maintain the electrochemical proton gradient by functioning as a redox-linked proton pump. Even though the structures of several terminal oxidases are known, they are not sufficient in themselves to explain the molecular mechanism of proton pumping. Thus, additional extensive studies of CcO by varieties of biophysical and biochemical approaches are involved to shed light on the mechanism of proton translocation. In this review, we summarize the current level of knowledge about CcO, including the latest model developed to explain the CcO proton-pumping mechanism.
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Affiliation(s)
- Ilya Belevich
- Helsinki Bioenergetics Group, Program for Structural Biology and Biophysics, Institute of Biotechnology, University of Helsinki, Helsinki, Finland
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33
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Vygodina TV, Konstantinov AA. Peroxidase activity of mitochondrial cytochrome c oxidase. BIOCHEMISTRY (MOSCOW) 2007; 72:1056-64. [DOI: 10.1134/s0006297907100045] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
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Daskalakis V, Pinakoulaki E, Stavrakis S, Varotsis C. Probing the Environment of CuB in Heme−Copper Oxidases. J Phys Chem B 2007; 111:10502-9. [PMID: 17696387 DOI: 10.1021/jp0718597] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Time-resolved step-scan FTIR (TRS2-FTIR) and density functional theory have been applied to probe the structural dynamics of CuB in heme-copper oxidases at room temperature. The TRS2-FTIR data of cbb3 from Pseudomonas stutzeri indicate a small variation in the frequency of the transient CO bound to CuB in the pH/pD 7-9 range. This observation in conjunction with density functional theory calculations, in which significant frequency shifts of the nu(CO) are observed upon deprotonation and/or detachment of the CuB ligands, demonstrates that the properties of the CuB ligands including the cross-linked tyrosine, in contrast to previous reports, remain unchanged in the pH 7-9 range. We attribute the small variations in the nu(CO) of CuB to protein conformational changes in the vicinity of CuB. Consequently, the split of the heme Fe-CO vibrations (alpha-, beta-, and gamma-forms) is not due to changes in the ligation and/or protonation states of the CuB ligands or to the presence of one or more ionizable groups, as previously suggested, but the result of global protein conformational changes in the vicinity of CuB which, in turn, affect the position of CuB with respect to the heme Fe.
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Affiliation(s)
- Vangelis Daskalakis
- Department of Chemistry, University of Crete, 71003 Voutes, Heraklion, Crete, Greece
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Wikström M, Verkhovsky MI. Mechanism and energetics of proton translocation by the respiratory heme-copper oxidases. BIOCHIMICA ET BIOPHYSICA ACTA-BIOENERGETICS 2007; 1767:1200-14. [PMID: 17689487 DOI: 10.1016/j.bbabio.2007.06.008] [Citation(s) in RCA: 143] [Impact Index Per Article: 8.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/22/2007] [Revised: 06/24/2007] [Accepted: 06/26/2007] [Indexed: 11/24/2022]
Abstract
Recent time-resolved optical and electrometric experiments have provided a sequence of events for the proton-translocating mechanism of cytochrome c oxidase. These data also set limits for the mechanistic, kinetic, and thermodynamic parameters of the proton pump, which are analysed here in some detail. The analysis yields limit values for the pK of the "pump site", its modulation during the proton-pumping process, and suggests its identity in the structure. Special emphasis is made on side-reactions that may short-circuit the pump, and the means by which these may be avoided. We will also discuss the most prominent proton pumping mechanisms proposed to date in relation to these data.
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Affiliation(s)
- Mårten Wikström
- Helsinki Bioenergetics Group, Structural Biology and Biophysics Programme, Institute of Biotechnology, University of Helsinki, PB 65 (Viikinkaari 1), FI-00014 University of Helsinki, Finland.
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Namslauer A, Lepp H, Brändén M, Jasaitis A, Verkhovsky MI, Brzezinski P. Plasticity of Proton Pathway Structure and Water Coordination in Cytochrome c Oxidase. J Biol Chem 2007; 282:15148-58. [PMID: 17363369 DOI: 10.1074/jbc.m700348200] [Citation(s) in RCA: 34] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Cytochrome c oxidase (CytcO) is a redox-driven, membrane-bound proton pump. One of the proton transfer pathways of the enzyme, the D pathway, used for the transfer of both substrate and pumped protons, accommodates a network of hydrogen-bonded water molecules that span the distance between an aspartate (Asp(132)), near the protein surface, and glutamate Glu(286), which is an internal proton donor to the catalytic site. To investigate how changes in the environment around Glu(286) affect the mechanism of proton transfer through the pathway, we introduced a non-hydrogen-bonding (Ala) or an acidic residue (Asp) at position Ser(197) (S197A or S197D), located approximately 7 A from Glu(286). Although Ser(197) is hydrogen-bonded to a water molecule that is part of the D pathway "proton wire," replacement of the Ser by an Ala did not affect the proton transfer rate. In contrast, the S197D mutant CytcO displayed a turnover activity of approximately 35% of that of the wild-type CytcO, and the O(2) reduction reaction was not linked to proton pumping. Instead, a fraction of the substrate protons was taken from the positive ("incorrect") side of the membrane. Furthermore, the pH dependence of the proton transfer rate was altered in the mutant CytcO. The results indicate that there is plasticity in the water coordination of the proton pathway, but alteration of the electrostatic potential within the pathway results in uncoupling of the proton translocation machinery.
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Affiliation(s)
- Andreas Namslauer
- Department of Biochemistry and Biophysics, The Arrhenius Laboratories for Natural Sciences, Stockholm University, SE-106 91 Stockholm, Sweden
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Oxygen Activation Mechanism at the Binuclear Site of Heme-Copper Oxidase Superfamily as Revealed by Time-Resolved Resonance Raman Spectroscopy. ACTA ACUST UNITED AC 2007. [DOI: 10.1002/9780470166468.ch6] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 04/05/2023]
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Abstract
A series of metalloprotein complexes embedded in a mitochondrial or bacterial membrane utilize electron transfer reactions to pump protons across the membrane and create an electrochemical potential (DeltamuH+). Current understanding of the principles of electron-driven proton transfer is discussed, mainly with respect to the wealth of knowledge available from studies of cytochrome c oxidase. Structural, experimental, and theoretical evidence supports the model of long-distance proton transfer via hydrogen-bonded water chains in proteins as well as the basic concept that proton uptake and release in a redox-driven pump are driven by charge changes at the membrane-embedded centers. Key elements in the pumping mechanism may include bound water, carboxylates, and the heme propionates, arginines, and associated water above the hemes. There is evidence for an important role of subunit III and proton backflow, but the number and nature of gating mechanisms remain elusive, as does the mechanism of physiological control of efficiency.
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Affiliation(s)
- Jonathan P. Hosler
- Department of Biochemistry, University of Mississippi Medical Center, Jackson, Mississippi 39216;
| | - Shelagh Ferguson-Miller
- Department of Biochemistry and Molecular Biology, Michigan State University, East Lansing, Michigan 48824; ,
| | - Denise A. Mills
- Department of Biochemistry and Molecular Biology, Michigan State University, East Lansing, Michigan 48824; ,
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Musser SM, Stowell MH, Chan SI. Cytochrome c oxidase: chemistry of a molecular machine. ADVANCES IN ENZYMOLOGY AND RELATED AREAS OF MOLECULAR BIOLOGY 2006; 71:79-208. [PMID: 8644492 DOI: 10.1002/9780470123171.ch3] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/01/2023]
Abstract
The plethora of proposed chemical models attempting to explain the proton pumping reactions catalyzed by the CcO complex, especially the number of recent models, makes it clear that the problem is far from solved. Although we have not discussed all of the models proposed to date, we have described some of the more detailed models in order to illustrate the theoretical concepts introduced at the beginning of this section on proton pumping as well as to illustrate the rich possibilities available for effecting proton pumping. It is clear that proton pumping is effected by conformational changes induced by oxidation/reduction of the various redox centers in the CcO complex. It is for this reason that the CcO complex is called a redox-linked proton pump. The conformational changes of the proton pump cycle are usually envisioned to be some sort of ligand-exchange reaction arising from unstable geometries upon oxidation/reduction of the various redox centers. However, simple geometrical rearrangements, as in the Babcock and Mitchell models are also possible. In any model, however, hydrogen bonds must be broken and reformed due to conformational changes that result from oxidation/reduction of the linkage site during enzyme turnover. Perhaps the most important point emphasized in this discussion, however, is the fact that proton pumping is a directed process and it is electron and proton gating mechanisms that drive the proton pump cycle in the forward direction. Since many of the models discussed above lack effective electron and/or proton gating, it is clear that the major difficulty in developing a viable chemical model is not formulating a cyclic set of protein conformational changes effecting proton pumping (redox linkage) but rather constructing the model with a set of physical constraints so that the proposed cycle proceeds efficiently as postulated. In our discussion of these models, we have not been too concerned about which electron of the catalytic cycle was entering the site of linkage, but merely whether an ET to the binuclear center played a role. However, redox linkage only occurs if ET to the activated binuclear center is coupled to the proton pump. Since all of the models of proton pumping presented here, with the exception of the Rousseau expanded model and the Wikström model, have a maximum stoichiometry of 1 H+/e-, they inadequately explain the 2 H+/e- ratio for the third and fourth electrons of the dioxygen reduction cycle (see Section V.B). One way of interpreting this shortfall of protons is that the remaining protons are pumped by an as yet undefined indirectly coupled mechanism. In this scenario, the site of linkage could be coupled to the pumping of one proton in a direct fashion and one proton in an indirect fashion for a given electron. For a long time, it was assumed that at least some elements of such an indirect mechanism reside in subunit III. While recent evidence argues against the involvement of subunit III in the proton pump, subunit III may still participate in a regulatory and/or structural capacity (Section II.E). Attention has now focused on subunits I and II in the search for residues intimately involved in the proton pump mechanism and/or as part of a proton channel. In particular, the role of some of the highly conserved residues of helix VIII of subunit I are currently being studied by site directed mutagenesis. In our opinion, any model that invokes heme alpha 3 or CuB as the site of linkage must propose a very effective means by which the presumedly fast uncoupling ET to the dioxygen intermediates is prevented. It is difficult to imagine that ET over the short distance from heme alpha 3 or CuB to the dioxygen intermediate requires more than 1 ns. In addition, we expect the conformational changes of the proton pump to require much more than 1 ns (see Section V.B).
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Affiliation(s)
- S M Musser
- Arthur Amos Noyes Laboratory of Chemical Physics, California Institute of Technology, Pasadena 91125, USA
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Edwards JC, Johnson MS, Taylor BL. Differentiation between electron transport sensing and proton motive force sensing by the Aer and Tsr receptors for aerotaxis. Mol Microbiol 2006; 62:823-37. [PMID: 16995896 PMCID: PMC1858650 DOI: 10.1111/j.1365-2958.2006.05411.x] [Citation(s) in RCA: 52] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/01/2022]
Abstract
Aerotaxis (oxygen-seeking) behaviour in Escherichia coli is a response to changes in the electron transport system and not oxygen per se. Because changes in proton motive force (PMF) are coupled to respiratory electron transport, it is difficult to differentiate between PMF, electron transport or redox, all primary candidates for the signal sensed by the aerotaxis receptors, Aer and Tsr. We constructed electron transport mutants that produced different respiratory H+/e- stoichiometries. These strains expressed binary combinations of one NADH dehydrogenase and one quinol oxidase. We then introduced either an aer or tsr mutation into each mutant to create two sets of electron transport mutants. In vivo H+/e- ratios for strains grown in glycerol medium ranged from 1.46+/-0.18-3.04+/-0.47, but rates of respiration and growth were similar. The PMF jump in response to oxygen was proportional to the H+/e- ratio in each set of mutants (r2=0.986-0.996). The length of Tsr-mediated aerotaxis responses increased with the PMF jump (r2=0.988), but Aer-mediated responses did not correlate with either PMF changes (r2=0.297) or the rate of electron transport (r2=0.066). Aer-mediated responses were linked to NADH dehydrogenase I, although there was no absolute requirement. The data indicate that Tsr responds to changes in PMF, but strong Aer responses to oxygen are associated with redox changes in NADH dehydrogenase I.
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Affiliation(s)
- Jessica C Edwards
- Division of Microbiology and Molecular Genetics, Loma Linda University, Loma Linda, CA 92350, USA
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Papa S, Capitanio G, Luca Martino P. Concerted involvement of cooperative proton–electron linkage and water production in the proton pump of cytochrome c oxidase. BIOCHIMICA ET BIOPHYSICA ACTA-BIOENERGETICS 2006; 1757:1133-43. [PMID: 16945321 DOI: 10.1016/j.bbabio.2006.04.009] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/10/2006] [Revised: 04/05/2006] [Accepted: 04/07/2006] [Indexed: 11/25/2022]
Abstract
In cytochrome c oxidase, oxido-reductions of heme a/Cu(A) and heme a3/Cu(B) are cooperatively linked to proton transfer at acid/base groups in the enzyme. H+/e- cooperative linkage at Fe(a3)/Cu(B) is envisaged to be involved in proton pump mechanisms confined to the binuclear center. Models have also been proposed which involve a role in proton pumping of cooperative H+/e- linkage at heme a (and Cu(A)). Observations will be presented on: (i) proton consumption in the reduction of molecular oxygen to H2O in soluble bovine heart cytochrome c oxidase; (ii) proton release/uptake associated with anaerobic oxidation/reduction of heme a/Cu(A) and heme a3/Cu(B) in the soluble oxidase; (iii) H+ release in the external phase (i.e. H+ pumping) associated with the oxidative (R-->O transition), reductive (O-->R transition) and a full catalytic cycle (R-->O-->R transition) of membrane-reconstituted cytochrome c oxidase. A model is presented in which cooperative H+/e- linkage at heme a/Cu(A) and heme a3/Cu(B) with acid/base clusters, C1 and C2 respectively, and protonmotive steps of the reduction of O2 to water are involved in proton pumping.
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Affiliation(s)
- Sergio Papa
- Department of Medical Biochemistry, Biology and Physics, University of Bari, Policlinico, P zza G Cesare, 70124 Bari, Italy.
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Demaurex N, Petheö GL. Electron and proton transport by NADPH oxidases. Philos Trans R Soc Lond B Biol Sci 2006; 360:2315-25. [PMID: 16321802 PMCID: PMC1569595 DOI: 10.1098/rstb.2005.1769] [Citation(s) in RCA: 53] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
Abstract
The NADPH oxidase is the main weapon of phagocytic white blood cells that are the first line of defence of our body against invading pathogens, and patients lacking a functional oxidase suffer from severe and recurrent infections. The oxidase is a multisubunit enzyme complex that transports electrons from cytoplasmic NADPH to molecular oxygen in order to generate superoxide free radicals. Electron transport across the plasma membrane is electrogenic and is associated with the flux of protons through voltage-activated proton channels. Both proton and electron currents can be recorded with the patch-clamp technique, but whether the oxidase is a proton channel or a proton channel modulator remains controversial. Recently, we have used the inside-out configuration of the patch-clamp technique to record proton and electron currents in excised patches. This approach allows us to measure the oxidase activity under very controlled conditions, and has provided new information about the enzymatic activity of the oxidase and its coupling to proton channels. In this chapter I will discuss how the unique characteristics of the electron and proton currents associated with the redox activity of the NADPH oxidase have extended our knowledge about the thermodynamics and the physiological regulation of this remarkable enzyme.
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Affiliation(s)
- Nicolas Demaurex
- University of Geneva Department of Cell Physiology and Metabolism 1 rue Michel-Servet, 1211 Geneva 4, Switzerland.
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Yoshikawa S, Muramoto K, Shinzawa-Itoh K, Aoyama H, Tsukihara T, Ogura T, Shimokata K, Katayama Y, Shimada H. Reaction mechanism of bovine heart cytochrome c oxidase. BIOCHIMICA ET BIOPHYSICA ACTA-BIOENERGETICS 2006; 1757:395-400. [PMID: 16829226 DOI: 10.1016/j.bbabio.2006.04.028] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/31/2006] [Revised: 04/21/2006] [Accepted: 04/28/2006] [Indexed: 10/24/2022]
Abstract
The 1.9 A resolution X-ray structure of the O2 reduction site of bovine heart cytochrome c oxidase in the fully reduced state indicates trigonal planar coordination of CuB by three histidine residues. One of the three histidine residues has a covalent link to a tyrosine residue to ensure retention of the tyrosine at the O2 reduction site. These moieties facilitate a four electron reduction of O2, and prevent formation of active oxygen species. The combination of a redox-coupled conformational change of an aspartate residue (Asp51) located near the intermembrane surface of the enzyme molecule and the existence of a hydrogen bond network connecting Asp51 to the matrix surface suggest that the proton-pumping process is mediated at Asp51. Mutation analyses using a gene expression system of the Asp51-containing enzyme subunit yield results in support of the proposal that Asp51 plays a critical role in the proton pumping process.
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Affiliation(s)
- Shinya Yoshikawa
- Department of Life Science, University of Hyogo, Kamigohri Akoh, Hyogo 678-1297, Japan.
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Mulkidjanian AY, Heberle J, Cherepanov DA. Protons @ interfaces: implications for biological energy conversion. BIOCHIMICA ET BIOPHYSICA ACTA-BIOENERGETICS 2006; 1757:913-30. [PMID: 16624250 DOI: 10.1016/j.bbabio.2006.02.015] [Citation(s) in RCA: 142] [Impact Index Per Article: 7.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/31/2005] [Revised: 02/09/2006] [Accepted: 02/16/2006] [Indexed: 12/01/2022]
Abstract
The review focuses on the anisotropy of proton transfer at the surface of biological membranes. We consider (i) the data from "pulsed" experiments, where light-triggered enzymes capture or eject protons at the membrane surface, (ii) the electrostatic properties of water at charged interfaces, and (iii) the specific structural attributes of proton-translocating enzymes. The pulsed experiments revealed that proton exchange between the membrane surface and the bulk aqueous phase takes as much as about 1 ms, but could be accelerated by added mobile pH-buffers. Since the accelerating capacity of the latter decreased with the increase in their electric charge, it was concluded that the membrane surface is separated from the bulk aqueous phase by a barrier of electrostatic nature. The barrier could arise owing to the water polarization at the negatively charged membrane surface. The barrier height depends linearly on the charge of penetrating ions; for protons, it has been estimated as about 0.12 eV. While the proton exchange between the surface and the bulk aqueous phase is retarded by the interfacial barrier, the proton diffusion along the membrane, between neighboring enzymes, takes only microseconds. The proton spreading over the membrane is facilitated by the hydrogen-bonded networks at the surface. The membrane-buried layers of these networks can eventually serve as a storage/buffer for protons (proton sponges). As the proton equilibration between the surface and the bulk aqueous phase is slower than the lateral proton diffusion between the "sources" and "sinks", the proton activity at the membrane surface, as sensed by the energy transducing enzymes at steady state, might deviate from that measured in the adjoining water phase. This trait should increase the driving force for ATP synthesis, especially in the case of alkaliphilic bacteria.
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Affiliation(s)
- Armen Y Mulkidjanian
- AN Belozersky Institute of Physico-Chemical Biology, Moscow State University, Moscow, Russia.
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Ji H, Yeh SR, Rousseau DL. Structural characterization of the PCO/O2compound of cytochromecoxidase. FEBS Lett 2005; 579:6361-4. [PMID: 16263119 DOI: 10.1016/j.febslet.2005.10.018] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/21/2005] [Revised: 10/10/2005] [Accepted: 10/12/2005] [Indexed: 10/25/2022]
Abstract
The structural properties of a key transient oxygen intermediate of cytochrome c oxidase, P(R), remain an enigma, although inferences have been drawn from its equilibrium analogues, [Pco/o(2)] , P(H) and P(M). With resonance Raman spectroscopy, an oxygen isotope-sensitive band at 806 cm(-1) was observed in [Pco/o(2)] produced by adding CO and O(2) to the resting enzyme. The vibrational band shifted to 771 cm(-1) upon isotopic substitution of (16)O(2) with (18)O(2). The same modes at 806 and 771 cm(-1) were present simultaneously when the mixed isotope, (18)O(16)O, was employed, indicating that in [Pco/o(2)] the O-O bond is cleaved, resulting in a Fe(4+)O(2-) structure. This result unifies the nature of the three equilibrium analogues of the P(R) intermediate.
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Affiliation(s)
- Hong Ji
- Department of Physiology and Biophysics, Albert Einstein College of Medicine of Yeshiva University, Bronx, NY 10461, USA
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Shikama K. Nature of the FeO2 bonding in myoglobin and hemoglobin: A new molecular paradigm. PROGRESS IN BIOPHYSICS AND MOLECULAR BIOLOGY 2005; 91:83-162. [PMID: 16005052 DOI: 10.1016/j.pbiomolbio.2005.04.001] [Citation(s) in RCA: 60] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/24/2022]
Abstract
The iron(II)-dioxygen bond in myoglobin and hemoglobin is a subject of wide interest. Studies range from examinations of physical-chemical properties dependent on its electronic structure, to investigations of the stability as a function of oxygen supply. Among these, stability properties are of particular importance in vivo. Like all known dioxygen carriers synthesized so far with transition metals, the oxygenated forms of myoglobin and hemoglobin are known to be oxidized easily to their ferric met-forms, which cannot bind molecular oxygen and are therefore physiologically inactive. The mechanistic details of this autoxidation reaction, which are of clinical, as well as of physical-chemical, interest, have long been investigated by a number of authors, but a full understanding of the heme oxidation has not been reached so far. Recent kinetic and thermodynamic studies of the stability of oxymyoglobin (MbO2) and oxyhemoglobin (HbO2) have revealed new features in the FeO2 bonding. In vivo, the iron center is always subject to a nucleophilic attack of the water molecule or hydroxyl ion, which can enter the heme pocket from the surrounding solvent and thereby irreversibly displace the bound dioxygen from MbO2 or HbO2 in the form of O2- so that the iron is converted to the ferric met-form. Since the autoxidation reaction of MbO2 or HbO2 proceeds through a nucleophilic displacement following one-electron transfer from iron(II) to the bound O2, this reaction may be viewed as a meeting point of the stabilization and the activation of molecular oxygen performed by hemoproteins. Along with these lines of evidence, we finally discuss the stability property of human HbO2 and provide with the most recent state of hemoglobin research. The HbA molecule contains two types of alphabeta contacts and seems to differentiate them quite properly for its functional properties. The alpha1beta2 or alpha2beta1 contact is associated with the cooperative oxygen binding, whereas the alpha1beta1 or alpha2beta2 contact is used for controlling the stability of the bound O2. We can thus form a unified picture for hemoglobin function by closely integrating the cooperative and the stable binding of molecular oxygen with iron(II) in aqueous solvent. These new views on the nature of FeO2 bonding and the possible role of globin moiety in stabilizing MbO2 and HbO2 are of primary importance, not only for a full understanding of various hemoprotein reactions with O2, but also for planning new molecular designs for synthetic oxygen carriers which may be able to function in aqueous solvent and at physiological temperature.
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Affiliation(s)
- Keiji Shikama
- Biological Institute, Graduate School of Life Sciences, Tohoku University, Sendai, Japan.
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47
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Bertrand P. Application of electron transfer theories to biological systems. STRUCTURE AND BONDING 2005. [DOI: 10.1007/3-540-53260-9_1] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 03/08/2023]
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Abstract
Cytochrome c oxidase (CcO) is the terminal transmembrane enzyme of the respiratory electron transport chain in aerobic cells. It catalyzes the reduction of oxygen to water and utilizes the free energy of the reduction reaction for proton pumping, a process which results in a membrane electrochemical proton gradient. Although the structure of the enzyme has been solved for several organisms, the molecular mechanism of proton pumping and proton exit pathways remain unknown. In our previous work, the continuum electrostatic calculations were employed to evaluate the electrostatic potential, energies, and protonation state of bovine cytochrome c oxidase for different redox states of the enzyme. A possible mechanism of oxygen reduction and proton pumping via His291 was proposed. In this paper, using electrostatic calculations, we examine the proton exit pathways in the enzyme. By monitoring the changes of the protonation states, proton affinities, and energies of electrostatic interactions between the titratable groups in different redox states of CcO, we identified the clusters of strongly interacting residues. Using these data, we detected four possible proton exit points on the periplasmic side of the membrane (Lys171B/Asp173B, His24B/Asp25B, Asp51, and Asp300). We then were able to trace the proton exit pathways and to evaluate the energy profiles along the paths. On the basis of energetic considerations and the conservation of the residues in a protein sequence, the most likely exit pathway is one via the Lys171B/Asp173B site. The obtained results are fully consistent with our His291 model of proton pumping, and provide a rationale for the absence of proton leaking in CcO between the pumping strokes.
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Affiliation(s)
- Dragan M Popović
- Department of Chemistry, University of California, One Shields Avenue, Davis, California 95616, USA
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49
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Papa S, Capitanio N, Capitanio G, Palese LL. Protonmotive cooperativity in cytochrome c oxidase. BIOCHIMICA ET BIOPHYSICA ACTA-BIOENERGETICS 2004; 1658:95-105. [PMID: 15282180 DOI: 10.1016/j.bbabio.2004.04.014] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/09/2004] [Revised: 04/21/2004] [Accepted: 04/23/2004] [Indexed: 10/26/2022]
Abstract
Cooperative linkage of solute binding at separate binding sites in allosteric proteins is an important functional attribute of soluble and membrane bound hemoproteins. Analysis of proton/electron coupling at the four redox centers, i.e. Cu(A), heme a, heme a(3) and Cu(B), in the purified bovine cytochrome c oxidase in the unliganded, CO-liganded and CN-liganded states is presented. These studies are based on direct measurement of scalar proton translocation associated with oxido-reduction of the metal centers and pH dependence of the midpoint potential of the redox centers. Heme a (and Cu(A)) exhibits a cooperative proton/electron linkage (Bohr effect). Bohr effect seems also to be associated with the oxygen-reduction chemistry at the heme a(3)-Cu(B) binuclear center. Data on electron transfer in cytochrome c oxidase are also presented, which, together with structural data, provide evidence showing the occurrence of direct electron transfer from Cu(A) to the binuclear center in addition to electron transfer via heme a. A survey of structural and functional data showing the essential role of cooperative proton/electron linkage at heme a in the proton pump of cytochrome c oxidase is presented. On the basis of this and related functional and structural information, variants for cooperative mechanisms in the proton pump of the oxidase are examined.
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Affiliation(s)
- Sergio Papa
- Department of Biomedical Science, Faculty of Medicine, University of Foggia, Foggia, Italy.
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50
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Siletsky SA, Pawate AS, Weiss K, Gennis RB, Konstantinov AA. Transmembrane Charge Separation during the Ferryl-oxo → Oxidized Transition in a Nonpumping Mutant of Cytochrome c Oxidase. J Biol Chem 2004; 279:52558-65. [PMID: 15385565 DOI: 10.1074/jbc.m407549200] [Citation(s) in RCA: 71] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
The N139D mutant of cytochrome c oxidase from Rhodobacter sphaeroides retains full steady state oxidase activity but completely lacks proton translocation coupled to turnover in reconstituted liposomes (Pawate, A. S., Morgan, J., Namslauer, A., Mills, D., Brzezinski, P., Ferguson-Miller, S., and Gennis, R. B. (2002) Biochemistry 41, 13417-13423). Here, time-resolved electron transfer and vectorial charge translocation in the ferryl-oxo --> oxidized transition (transfer of the 4th electron in the catalytic cycle) have been studied with the N139D mutant using ruthenium(II)-tris-bipyridyl complex as a photoactive single-electron donor. With the wild type oxidase, the flash-induced generation of Deltaphi in the ferryl-oxo --> oxidized transition begins with rapid vectorial electron transfer from CuA to heme a (tau approximately 15 micros), followed by two protonic phases, referred to as the intermediate (0.4 ms) and slow electrogenic phases (1.5 ms). In the N139D mutant, only a single protonic phase (tau approximately 0.6 ms) is observed, which was associated with electron transfer from heme a to the heme a3/CuB site and decelerates approximately 4-fold in D2O. With the wild type oxidase, such a high H2O/D2O solvent isotope effect is characteristic of only the slow (1.5 ms) phase. Presumably, the 0.6-ms electrogenic phase in the N139D mutant reports proton transfer from the inner aqueous phase to Glu-286, replacing the "chemical" proton transferred from Glu-286 to the heme a3/CuB site. The transfer occurs through the D-channel, because it is observed also in the N139D/K362M double mutant in which the K-channel is blocked. It is concluded that the intermediate electrogenic phase observed in the wild type enzyme is missing in the N139D mutant and is because of translocation of the "pumped" proton from Glu-286 to the D-ring propionate of heme a3 or to release of this proton to the outer aqueous phase. Significantly, with the wild type oxidase, the protonic electrogenic phase associated with proton pumping (approximately 0.4 ms) precedes the electrogenic phase associated with the oxygen chemistry (approximately 1.5 ms).
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Affiliation(s)
- Sergey A Siletsky
- AN Belozersky Institute of Physico-Chemical Biology, Moscow State University, Moscow 119 992, Russia
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