1
|
Takeda H, Kimura T, Nomura T, Horitani M, Yokota A, Matsubayashi A, Ishii S, Shiro Y, Kubo M, Tosha T. Timing of NO Binding and Protonation in the Catalytic Reaction of Bacterial Nitric Oxide Reductase as Established by Time-Resolved Spectroscopy. BULLETIN OF THE CHEMICAL SOCIETY OF JAPAN 2020. [DOI: 10.1246/bcsj.20200038] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/17/2023]
Affiliation(s)
- Hanae Takeda
- Graduate School of Life Science, University of Hyogo, Hyogo 678-1297, Japan
- RIKEN SPring-8 Center, Hyogo 679-5148, Japan
| | - Tetsunari Kimura
- RIKEN SPring-8 Center, Hyogo 679-5148, Japan
- Department of Chemistry, Graduate School of Science, Kobe University, Kobe 657-8501, Japan
| | - Takashi Nomura
- Graduate School of Life Science, University of Hyogo, Hyogo 678-1297, Japan
- RIKEN SPring-8 Center, Hyogo 679-5148, Japan
| | - Masaki Horitani
- Department of Applied Biochemistry & Food Science, Saga University, Saga 840-8502, Japan
| | - Azusa Yokota
- Graduate School of Life Science, University of Hyogo, Hyogo 678-1297, Japan
| | - Akiko Matsubayashi
- Graduate School of Life Science, University of Hyogo, Hyogo 678-1297, Japan
| | - Shoko Ishii
- Graduate School of Life Science, University of Hyogo, Hyogo 678-1297, Japan
- RIKEN SPring-8 Center, Hyogo 679-5148, Japan
| | - Yoshitsugu Shiro
- Graduate School of Life Science, University of Hyogo, Hyogo 678-1297, Japan
- RIKEN SPring-8 Center, Hyogo 679-5148, Japan
| | - Minoru Kubo
- Graduate School of Life Science, University of Hyogo, Hyogo 678-1297, Japan
- RIKEN SPring-8 Center, Hyogo 679-5148, Japan
| | - Takehiko Tosha
- Graduate School of Life Science, University of Hyogo, Hyogo 678-1297, Japan
- RIKEN SPring-8 Center, Hyogo 679-5148, Japan
| |
Collapse
|
2
|
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.
Collapse
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.
| |
Collapse
|
3
|
Han Du WG, Götz AW, Noodleman L. A Water Dimer Shift Activates a Proton Pumping Pathway in the P R → F Transition of ba 3 Cytochrome c Oxidase. Inorg Chem 2018; 57:1048-1059. [PMID: 29308889 DOI: 10.1021/acs.inorgchem.7b02461] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023]
Abstract
Broken-symmetry density functional calculations have been performed on the [Fea34+,CuB2+] state of the dinuclear center (DNC) for the PR → F part of the catalytic cycle of ba3 cytochrome c oxidase (CcO) from Thermus thermophilus (Tt), using the OLYP-D3-BJ functional. The calculations show that the movement of the H2O molecules in the DNC affects the pKa values of the residue side chains of Tyr237 and His376+, which are crucial for proton transfer/pumping in ba3 CcO from Tt. The calculated lowest energy structure of the DNC in the [Fea34+,CuB2+] state (state F) is of the form Fea34+═O2-···CuB2+, in which the H2O ligand that resulted from protonation of the OH- ligand in the PR state is dissociated from the CuB2+ site. The calculated Fea34+═O2- distance in F (1.68 Å) is 0.03 Å longer than that in PR (1.65 Å), which can explain the different Fea34+═O2- stretching modes in P (804 cm-1) and F (785 cm-1) identified by resonance Raman experiments. In this F state, the CuB2+···O2- (ferryl-oxygen) distance is only around 2.4 Å. Hence, the subsequent OH state [Fea33+-OH--CuB2+] with a μ-hydroxo bridge can be easily formed, as shown by our calculations.
Collapse
Affiliation(s)
- Wen-Ge Han Du
- Department of Integrative Structural and Computational Biology, The Scripps Research Institute , 10550 North Torrey Pines Road, La Jolla, California 92037, United States
| | - Andreas W Götz
- San Diego Supercomputer Center, University of California San Diego , 9500 Gilman Drive MC0505, La Jolla, California 92093, United States
| | - Louis Noodleman
- Department of Integrative Structural and Computational Biology, The Scripps Research Institute , 10550 North Torrey Pines Road, La Jolla, California 92037, United States
| |
Collapse
|
4
|
Han Du WG, Götz AW, Yang L, Walker RC, Noodleman L. A broken-symmetry density functional study of structures, energies, and protonation states along the catalytic O-O bond cleavage pathway in ba3 cytochrome c oxidase from Thermus thermophilus. Phys Chem Chem Phys 2016; 18:21162-71. [PMID: 27094074 DOI: 10.1039/c6cp00349d] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/27/2022]
Abstract
Broken-symmetry density functional calculations have been performed on the [Fea3, CuB] dinuclear center (DNC) of ba3 cytochrome c oxidase from Thermus thermophilus in the states of [Fea3(3+)-(HO2)(-)-CuB(2+), Tyr237(-)] and [Fea3(4+)[double bond, length as m-dash]O(2-), OH(-)-CuB(2+), Tyr237˙], using both PW91-D3 and OLYP-D3 functionals. Tyr237 is a special tyrosine cross-linked to His233, a ligand of CuB. The calculations have shown that the DNC in these states strongly favors the protonation of His376, which is above propionate-A, but not of the carboxylate group of propionate-A. The energies of the structures obtained by constrained geometry optimizations along the O-O bond cleavage pathway between [Fea3(3+)-(O-OH)(-)-CuB(2+), Tyr237(-)] and [Fea3(4+)[double bond, length as m-dash]O(2-)HO(-)-CuB(2+), Tyr237˙] have also been calculated. The transition of [Fea3(3+)-(O-OH)(-)-CuB(2+), Tyr237(-)] → [Fea3(4+)[double bond, length as m-dash]O(2-)HO(-)-CuB(2+), Tyr237˙] shows a very small barrier, which is less than 3.0/2.0 kcal mol(-1) in PW91-D3/OLYP-D3 calculations. The protonation state of His376 does not affect this O-O cleavage barrier. The rate limiting step of the transition from state A (in which O2 binds to Fea3(2+)) to state PM ([Fea3(4+)[double bond, length as m-dash]O(2-), OH(-)-CuB(2+), Tyr237˙], where the O-O bond is cleaved) in the catalytic cycle is, therefore, the proton transfer originating from Tyr237 to O-O to form the hydroperoxo [Fea3(3+)-(O-OH)(-)-CuB(2+), Tyr237(-)] state. The importance of His376 in proton uptake and the function of propionate-A/neutral-Asp372 as a gate to prevent the proton from back-flowing to the DNC are also shown.
Collapse
Affiliation(s)
- Wen-Ge Han Du
- Department of Integrative Structural and Computational Biology, GAC1118, The Scripps Research Institute, 10550 North Torrey Pines Road, La Jolla, CA 92037, USA.
| | | | | | | | | |
Collapse
|
5
|
Szundi I, Kittredge C, Choi SK, McDonald W, Ray J, Gennis RB, Einarsdóttir Ó. Kinetics and Intermediates of the Reaction of Fully Reduced Escherichia coli bo3 Ubiquinol Oxidase with O2. Biochemistry 2014; 53:5393-404. [DOI: 10.1021/bi500567m] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022]
Affiliation(s)
- Istvan Szundi
- Department
of Chemistry and Biochemistry, University of California, Santa Cruz, California 95064, United States
| | - Clive Kittredge
- Department
of Chemistry and Biochemistry, University of California, Santa Cruz, California 95064, United States
| | - Sylvia K. Choi
- Department
of Biochemistry and the Center for Biophysics and Computational Biology, University of Illinois, Urbana-Champaign, Illinois 61801, United States
| | - William McDonald
- Department
of Chemistry and Biochemistry, University of California, Santa Cruz, California 95064, United States
| | - Jayashree Ray
- Department
of Chemistry and Biochemistry, University of California, Santa Cruz, California 95064, United States
| | - Robert B. Gennis
- Department
of Biochemistry and the Center for Biophysics and Computational Biology, University of Illinois, Urbana-Champaign, Illinois 61801, United States
| | - Ólöf Einarsdóttir
- Department
of Chemistry and Biochemistry, University of California, Santa Cruz, California 95064, United States
| |
Collapse
|
6
|
Time-resolved infrared spectroscopic studies of ligand dynamics in the active site from cytochrome c oxidase. BIOCHIMICA ET BIOPHYSICA ACTA-BIOENERGETICS 2014; 1847:79-85. [PMID: 25117435 DOI: 10.1016/j.bbabio.2014.07.018] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/27/2014] [Accepted: 07/29/2014] [Indexed: 10/24/2022]
Abstract
The catalytic site of heme-copper oxidases encompasses two close-lying ligand binding sites: the heme, where oxygen is bound and reduced and the CuB atom, which acts as ligand entry and release port. Diatomic gaseous ligands with a dipole moment, such as the signaling molecules carbon monoxide (CO) and nitric oxide (NO), carry clear infrared spectroscopic signatures in the different states that allow characterization of the dynamics of ligand transfer within, into and out of the active site using time-resolved infrared spectroscopy. We review the nature and diversity of these processes that have in particular been characterized with CO as ligand and which take place on time scales ranging from femtoseconds to milliseconds. These studies have advanced our understanding of the functional ligand pathways and reactivity in enzymes and more globally represent intriguing model systems for mechanisms of ligand motion in a confined protein environment. This article is part of a Special Issue entitled: Vibrational spectroscopies and bioenergetic systems.
Collapse
|
7
|
McDonald W, Funatogawa C, Li Y, Chen Y, Szundi I, Fee JA, Stout CD, Einarsdóttir O. Conserved glycine 232 in the ligand channel of ba3 cytochrome oxidase from Thermus thermophilus. Biochemistry 2014; 53:4467-75. [PMID: 24937405 PMCID: PMC4216187 DOI: 10.1021/bi500289h] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
Knowing how the protein environment modulates ligand pathways and redox centers in the respiratory heme-copper oxidases is fundamental for understanding the relationship between the structure and function of these enzymes. In this study, we investigated the reactions of O2 and NO with the fully reduced G232V mutant of ba3 cytochrome c oxidase from Thermus thermophilus (Tt ba3) in which a conserved glycine residue in the O2 channel of the enzyme was replaced with a bulkier valine residue. Previous studies of the homologous mutant of Rhodobacter sphaeroides aa3 cytochrome c oxidase suggested that the valine completely blocked the access of O2 to the active site [Salomonsson, L., et al. (2004) Proc. Natl. Acad. Sci. U.S.A. 101, 11617-11621]. Using photolabile O2 and NO carriers, we find by using time-resolved optical absorption spectroscopy that the rates of O2 and NO binding are not significantly affected in the Tt ba3 G232V mutant. Classical molecular dynamics simulations of diffusion of O2 to the active site in the wild-type enzyme and G232V mutant show that the insertion of the larger valine residue in place of the glycine appears to open up other O2 and NO exit/entrance pathways that allow these ligands unhindered access to the active site, thus compensating for the larger valine residue.
Collapse
Affiliation(s)
- William McDonald
- Department of Chemistry and Biochemistry, University of California , Santa Cruz, California 95064, United States
| | | | | | | | | | | | | | | |
Collapse
|
8
|
Einarsdóttir O, McDonald W, Funatogawa C, Szundi I, Woodruff WH, Dyer RB. The pathway of O₂to the active site in heme-copper oxidases. BIOCHIMICA ET BIOPHYSICA ACTA-BIOENERGETICS 2014; 1847:109-18. [PMID: 24998308 DOI: 10.1016/j.bbabio.2014.06.008] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/04/2014] [Accepted: 06/24/2014] [Indexed: 11/16/2022]
Abstract
The route of O₂to and from the high-spin heme in heme-copper oxidases has generally been believed to emulate that of carbon monoxide (CO). Time-resolved and stationary infrared experiments in our laboratories of the fully reduced CO-bound enzymes, as well as transient optical absorption saturation kinetics studies as a function of CO pressure, have provided strong support for CO binding to CuB⁺ on the pathway to and from the high-spin heme. The presence of CO on CuB⁺ suggests that O₂binding may be compromised in CO flow-flash experiments. Time-resolved optical absorption studies show that the rate of O₂and NO binding in the bovine enzyme (1 × 10⁸M⁻¹s⁻¹) is unaffected by the presence of CO, which is consistent with the rapid dissociation (t½ = 1.5μs) of CO from CuB⁺. In contrast, in Thermus thermophilus (Tt) cytochrome ba3 the O₂and NO binding to heme a3 slows by an order of magnitude in the presence of CO (from 1 × 10⁹ to 1 × 10⁸M⁻¹s⁻¹), but is still considerably faster (~10μs at 1atm O₂) than the CO off-rate from CuB in the absence of O₂(milliseconds). These results show that traditional CO flow-flash experiments do not give accurate results for the physiological binding of O₂and NO in Tt ba3, namely, in the absence of CO. They also raise the question whether in CO flow-flash experiments on Tt ba3 the presence of CO on CuB⁺ impedes the binding of O₂to CuB⁺ or, if O₂does not bind to CuB⁺ prior to heme a3, whether the CuB⁺-CO complex sterically restricts access of O₂to the heme. Both possibilities are discussed, and we argue that O₂binds directly to heme a3 in Tt ba3, causing CO to dissociate from CuB⁺ in a concerted manner through steric and/or electronic effects. This would allow CuB⁺ to function as an electron donor during the fast (5μs) breaking of the OO bond. These results suggest that the binding of CO to CuB⁺ on the path to and from heme a3 may not be applicable to O₂and NO in all heme-copper oxidases. This article is part of a Special Issue entitled: Vibrational spectroscopies and bioenergetic systems.
Collapse
Affiliation(s)
- Olöf Einarsdóttir
- Department of Chemistry and Biochemistry, University of California, Santa Cruz, CA 95064, USA.
| | - William McDonald
- Department of Chemistry and Biochemistry, University of California, Santa Cruz, CA 95064, USA
| | - Chie Funatogawa
- Department of Chemistry and Biochemistry, University of California, Santa Cruz, CA 95064, USA
| | - Istvan Szundi
- Department of Chemistry and Biochemistry, University of California, Santa Cruz, CA 95064, USA
| | | | - R Brian Dyer
- Department of Chemistry, Emory University, Atlanta, GA 30322, USA
| |
Collapse
|
9
|
Näsvik Öjemyr L, Maréchal A, Vestin H, Meunier B, Rich PR, Brzezinski P. Reaction of wild-type and Glu243Asp variant yeast cytochrome c oxidase with O2. BIOCHIMICA ET BIOPHYSICA ACTA-BIOENERGETICS 2014; 1837:1012-8. [PMID: 24685432 DOI: 10.1016/j.bbabio.2014.03.012] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/05/2013] [Revised: 03/07/2014] [Accepted: 03/21/2014] [Indexed: 11/29/2022]
Abstract
We have studied internal electron transfer during the reaction of Saccharomyces cerevisiae mitochondrial cytochrome c oxidase with dioxygen. Similar absorbance changes were observed with this yeast oxidase as with the previously studied Rhodobacter sphaeroides and bovine mitochondrial oxidases, which suggests that the reaction proceeds along the same trajectory. However, notable differences were observed in rates and electron-transfer equilibrium constants of specific reaction steps, for example the ferryl (F) to oxidized (O) reaction was faster with the yeast (0.4ms) than with the bovine oxidase (~1ms) and a larger fraction CuA was oxidized with the yeast than with the bovine oxidase in the peroxy (PR) to F reaction. Furthermore, upon replacement of Glu243, located at the end of the so-called D proton pathway, by Asp the PR→F and F→O reactions were slowed by factors of ~3 and ~10, respectively, and electron transfer from CuA to heme a during the PR→F reaction was not observed. These data indicate that during reduction of dioxygen protons are transferred through the D pathway, via Glu243, to the catalytic site in the yeast mitochondrial oxidase. This article is part of a Special Issue entitled: 18th European Bioenergetic Conference.
Collapse
Affiliation(s)
- Linda Näsvik Öjemyr
- Department of Biochemistry and Biophysics, The Arrhenius Laboratories for Natural Sciences, Stockholm University, SE-106 91 Stockholm, Sweden
| | - Amandine Maréchal
- Glynn Laboratory of Bioenergetics, Institute of Structural and Molecular Biology, University College London, Gower Street, London WC1E 6BT, UK
| | - Henrik Vestin
- Department of Biochemistry and Biophysics, The Arrhenius Laboratories for Natural Sciences, Stockholm University, SE-106 91 Stockholm, Sweden
| | - Brigitte Meunier
- Centre de Génétique Moléculaire du CNRS, UPR 3404, avenue de la Terrasse, 91198 Gif-sur-Yvette Cedex, France
| | - Peter R Rich
- Glynn Laboratory of Bioenergetics, Institute of Structural and Molecular Biology, University College London, Gower Street, London WC1E 6BT, UK
| | - Peter Brzezinski
- Department of Biochemistry and Biophysics, The Arrhenius Laboratories for Natural Sciences, Stockholm University, SE-106 91 Stockholm, Sweden.
| |
Collapse
|
10
|
Prior S, Kim A, Yoshihara T, Tobita S, Takeuchi T, Higuchi M. Mitochondrial respiratory function induces endogenous hypoxia. PLoS One 2014; 9:e88911. [PMID: 24586439 PMCID: PMC3931703 DOI: 10.1371/journal.pone.0088911] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/09/2013] [Accepted: 01/17/2014] [Indexed: 01/26/2023] Open
Abstract
Hypoxia influences many key biological functions. In cancer, it is generally believed that hypoxic condition is generated deep inside the tumor because of the lack of oxygen supply. However, consumption of oxygen by cancer should be one of the key means of regulating oxygen concentration to induce hypoxia but has not been well studied. Here, we provide direct evidence of the mitochondrial role in the induction of intracellular hypoxia. We used Acetylacetonatobis [2-(2′-benzothienyl) pyridinato-kN, kC3’] iridium (III) (BTP), a novel oxygen sensor, to detect intracellular hypoxia in living cells via microscopy. The well-differentiated cancer cell lines, LNCaP and MCF-7, showed intracellular hypoxia without exogenous hypoxia in an open environment. This may be caused by high oxygen consumption, low oxygen diffusion in water, and low oxygen incorporation to the cells. In contrast, the poorly-differentiated cancer cell lines: PC-3 and MDAMB231 exhibited intracellular normoxia by low oxygen consumption. The specific complex I inhibitor, rotenone, and the reduction of mitochondrial DNA (mtDNA) content reduced intracellular hypoxia, indicating that intracellular oxygen concentration is regulated by the consumption of oxygen by mitochondria. HIF-1α was activated in endogenously hypoxic LNCaP and the activation was dependent on mitochondrial respiratory function. Intracellular hypoxic status is regulated by glucose by parabolic dose response. The low concentration of glucose (0.045 mg/ml) induced strongest intracellular hypoxia possibly because of the Crabtree effect. Addition of FCS to the media induced intracellular hypoxia in LNCaP, and this effect was partially mimicked by an androgen analog, R1881, and inhibited by the anti-androgen, flutamide. These results indicate that mitochondrial respiratory function determines intracellular hypoxic status and may regulate oxygen-dependent biological functions.
Collapse
Affiliation(s)
- Sara Prior
- Department of Biochemistry and Molecular Biology, University of Arkansas for Medical Sciences, Little Rock, Arkansas, United States of America
| | - Ara Kim
- Department of Biochemistry and Molecular Biology, University of Arkansas for Medical Sciences, Little Rock, Arkansas, United States of America
| | - Toshitada Yoshihara
- Department of Chemistry and Chemical Biology, Graduate School of Engineering, University of Gunma, Kiryu, Gunma, Japan
| | - Seiji Tobita
- Department of Chemistry and Chemical Biology, Graduate School of Engineering, University of Gunma, Kiryu, Gunma, Japan
| | - Toshiyuki Takeuchi
- Department of Molecular Medicine, Institute for Molecular and Cellular Regulation, University of Gunma, Maebashi, Gunma, Japan
| | - Masahiro Higuchi
- Department of Biochemistry and Molecular Biology, University of Arkansas for Medical Sciences, Little Rock, Arkansas, United States of America
- * E-mail:
| |
Collapse
|
11
|
Maintenance of mitochondrial oxygen homeostasis by cosubstrate compensation. Biophys J 2013; 104:1338-48. [PMID: 23528093 DOI: 10.1016/j.bpj.2013.01.030] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/08/2012] [Revised: 01/15/2013] [Accepted: 01/17/2013] [Indexed: 10/27/2022] Open
Abstract
Mitochondria maintain a constant rate of aerobic respiration over a wide range of oxygen levels. However, the control strategies underlying oxygen homeostasis are still unclear. Using mathematical modeling, we found that the mitochondrial electron transport chain (ETC) responds to oxygen level changes by undergoing compensatory changes in reduced electron carrier levels. This emergent behavior, which we named cosubstrate compensation (CSC), enables the ETC to maintain homeostasis over a wide of oxygen levels. When performing CSC, our ETC models recapitulated a classic scaling relationship discovered by Chance [Chance B (1965) J. Gen. Physiol. 49:163-165] relating the extent of oxygen homeostasis to the kinetics of mitochondrial electron transport. Analysis of an in silico mitochondrial respiratory system further showed evidence that CSC constitutes the dominant control strategy for mitochondrial oxygen homeostasis during active respiration. Our findings indicate that CSC constitutes a robust control strategy for homeostasis and adaptation in cellular biochemical networks.
Collapse
|
12
|
Saen-Oon S, Lucas MF, Guallar V. Electron transfer in proteins: theory, applications and future perspectives. Phys Chem Chem Phys 2013; 15:15271-85. [DOI: 10.1039/c3cp50484k] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022]
|
13
|
Kinetic studies of the reactions of O(2) and NO with reduced Thermus thermophilus ba(3) and bovine aa(3) using photolabile carriers. BIOCHIMICA ET BIOPHYSICA ACTA-BIOENERGETICS 2011; 1817:672-9. [PMID: 22201543 DOI: 10.1016/j.bbabio.2011.12.005] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/11/2011] [Revised: 12/08/2011] [Accepted: 12/08/2011] [Indexed: 11/20/2022]
Abstract
The reactions of molecular oxygen (O(2)) and nitric oxide (NO) with reduced Thermus thermophilus (Tt) ba(3) and bovine heart aa(3) were investigated by time-resolved optical absorption spectroscopy to establish possible relationships between the structural diversity of these enzymes and their reaction dynamics. To determine whether the photodissociated carbon monoxide (CO) in the CO flow-flash experiment affects the ligand binding dynamics, we monitored the reactions in the absence and presence of CO using photolabile O(2) and NO complexes. The binding of O(2)/NO to reduced ba(3) in the absence of CO occurs with a second-order rate constant of 1×10(9)M(-1)s(-1). This rate is 10-times faster than for the mammalian enzyme, and which is attributed to structural differences in the ligand channels of the two enzymes. Moreover, the O(2)/NO binding in ba(3) is 10-times slower in the presence of the photodissociated CO while the rates are the same for the bovine enzyme. This indicates that the photodissociated CO directly or indirectly impedes O(2) and NO access to the active site in Tt ba(3), and that traditional CO flow-flash experiments do not accurately reflect the O(2) and NO binding kinetics in ba(3). We suggest that in ba(3) the binding of O(2) (NO) to heme a(3)(2+) causes rapid dissociation of CO from Cu(B)(+) through steric or electronic effects or, alternatively, that the photodissociated CO does not bind to Cu(B)(+). These findings indicate that structural differences between Tt ba(3) and the bovine aa(3) enzyme are tightly linked to mechanistic differences in the functions of these enzymes. This article is part of a Special Issue entitled: Respiratory Oxidases.
Collapse
|
14
|
Cytochrome c
oxidase: Intermediates of the catalytic cycle and their energy-coupled interconversion. FEBS Lett 2011; 586:630-9. [DOI: 10.1016/j.febslet.2011.08.037] [Citation(s) in RCA: 44] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/02/2011] [Revised: 08/23/2011] [Accepted: 08/24/2011] [Indexed: 11/20/2022]
|
15
|
CO impedes superfast O2 binding in ba3 cytochrome oxidase from Thermus thermophilus. Proc Natl Acad Sci U S A 2010; 107:21010-5. [PMID: 21097703 DOI: 10.1073/pnas.1008603107] [Citation(s) in RCA: 36] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Kinetic studies of heme-copper terminal oxidases using the CO flow-flash method are potentially compromised by the fate of the photodissociated CO. In this time-resolved optical absorption study, we compared the kinetics of dioxygen reduction by ba(3) cytochrome c oxidase from Thermus thermophilus in the absence and presence of CO using a photolabile O(2)-carrier. A novel double-laser excitation is introduced in which dioxygen is generated by photolyzing the O(2)-carrier with a 355 nm laser pulse and the fully reduced CO-bound ba(3) simultaneously with a second 532-nm laser pulse. A kinetic analysis reveals a sequential mechanism in which O(2) binding to heme a(3) at 90 μM O(2) occurs with lifetimes of 9.3 and 110 μs in the absence and presence of CO, respectively, followed by a faster cleavage of the dioxygen bond (4.8 μs), which generates the P intermediate with the concomitant oxidation of heme b. The second-order rate constant of 1 × 10(9) M(-1) s(-1) for O(2) binding to ba(3) in the absence of CO is 10 times greater than observed in the presence of CO as well as for the bovine heart enzyme. The O(2) bond cleavage in ba(3) of 4.8 μs is also approximately 10 times faster than in the bovine enzyme. These results suggest important structural differences between the accessibility of O(2) to the active site in ba(3) and the bovine enzyme, and they demonstrate that the photodissociated CO impedes access of dioxygen to the heme a(3) site in ba(3), making the CO flow-flash method inapplicable.
Collapse
|
16
|
Low Activity and Poor Membrane Tethering for Rabbit Brain Cytochrome c Oxidase in Cholesterol-Copper Alzheimer's Model. J Mol Neurosci 2009; 38:273-9. [DOI: 10.1007/s12031-009-9209-4] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/08/2008] [Accepted: 05/07/2009] [Indexed: 10/20/2022]
|
17
|
Kapetanaki SM, Silkstone G, Husu I, Liebl U, Wilson MT, Vos MH. Interaction of Carbon Monoxide with the Apoptosis-Inducing Cytochrome c−Cardiolipin Complex. Biochemistry 2009; 48:1613-9. [DOI: 10.1021/bi801817v] [Citation(s) in RCA: 66] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/30/2022]
Affiliation(s)
- Sofia M. Kapetanaki
- Laboratoire d’Optique et Biosciences, CNRS, Ecole Polytechnique, and INSERM U696, F-91128 Palaiseau, France, and Department of Biological Sciences, University of Essex, Wivenhoe Park, Colchester CO4 3SQ, United Kingdom
| | - Gary Silkstone
- Laboratoire d’Optique et Biosciences, CNRS, Ecole Polytechnique, and INSERM U696, F-91128 Palaiseau, France, and Department of Biological Sciences, University of Essex, Wivenhoe Park, Colchester CO4 3SQ, United Kingdom
| | - Ivan Husu
- Laboratoire d’Optique et Biosciences, CNRS, Ecole Polytechnique, and INSERM U696, F-91128 Palaiseau, France, and Department of Biological Sciences, University of Essex, Wivenhoe Park, Colchester CO4 3SQ, United Kingdom
| | - Ursula Liebl
- Laboratoire d’Optique et Biosciences, CNRS, Ecole Polytechnique, and INSERM U696, F-91128 Palaiseau, France, and Department of Biological Sciences, University of Essex, Wivenhoe Park, Colchester CO4 3SQ, United Kingdom
| | - Michael T. Wilson
- Laboratoire d’Optique et Biosciences, CNRS, Ecole Polytechnique, and INSERM U696, F-91128 Palaiseau, France, and Department of Biological Sciences, University of Essex, Wivenhoe Park, Colchester CO4 3SQ, United Kingdom
| | - Marten H. Vos
- Laboratoire d’Optique et Biosciences, CNRS, Ecole Polytechnique, and INSERM U696, F-91128 Palaiseau, France, and Department of Biological Sciences, University of Essex, Wivenhoe Park, Colchester CO4 3SQ, United Kingdom
| |
Collapse
|
18
|
Savéant JM. Molecular catalysis of electrochemical reactions. Mechanistic aspects. Chem Rev 2008; 108:2348-78. [PMID: 18620367 DOI: 10.1021/cr068079z] [Citation(s) in RCA: 617] [Impact Index Per Article: 38.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023]
Affiliation(s)
- Jean-Michel Savéant
- Laboratoire d'Electrochimie Moléculaire, Unité Mixte de Recherche Universite-CNRS 7591, Université de Paris 7-Denis Diderot, 2 place Jussieu, 75251 Paris Cedex 05, France.
| |
Collapse
|
19
|
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.
Collapse
Affiliation(s)
- James A Fee
- The Scripps Research Institute, 10550 North Torrey Pines Road, La Jolla, California 92037, USA.
| | | | | |
Collapse
|
20
|
Electron and proton transfer in the ba(3) oxidase from Thermus thermophilus. J Bioenerg Biomembr 2008; 40:281-7. [PMID: 18752061 DOI: 10.1007/s10863-008-9157-7] [Citation(s) in RCA: 33] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/28/2008] [Accepted: 07/30/2008] [Indexed: 10/21/2022]
Abstract
The ba(3)-type cytochrome c oxidase from Thermus thermophilus is phylogenetically very distant from the aa(3)-type cytochrome c oxidases. Nevertheless, both types of oxidases have the same number of redox-active metal sites and the reduction of O(2) to water is catalysed at a haem a(3)-Cu(B) catalytic site. The three-dimensional structure of the ba(3) oxidase reveals three possible proton-conducting pathways showing very low homology compared to those of the mitochondrial, Rhodobacter sphaeroides and Paracoccus denitrificans aa(3) oxidases. In this study we investigated the oxidative part of the catalytic cycle of the ba( 3 )-cytochrome c oxidase using the flow-flash method. After flash-induced dissociation of CO from the fully reduced enzyme in the presence of oxygen we observed rapid oxidation of cytochrome b (k congruent with 6.8 x 10(4) s(-1)) and formation of the peroxy (P(R)) intermediate. In the next step a proton was taken up from solution with a rate constant of approximately 1.7 x 10(4) s(-1), associated with formation of the ferryl (F) intermediate, simultaneous with transient reduction of haem b. Finally, the enzyme was oxidized with a rate constant of approximately 1,100 s(-1), accompanied by additional proton uptake. The total proton uptake stoichiometry in the oxidative part of the catalytic cycle was approximately 1.5 protons per enzyme molecule. The results support the earlier proposal that the P(R) and F intermediate spectra are similar (Siletsky et al. Biochim Biophys Acta 1767:138, 2007) and show that even though the architecture of the proton-conducting pathways is different in the ba(3) oxidases, the proton-uptake reactions occur over the same time scales as in the aa(3)-type oxidases.
Collapse
|
21
|
Ultrafast ligand binding dynamics in the active site of native bacterial nitric oxide reductase. BIOCHIMICA ET BIOPHYSICA ACTA-BIOENERGETICS 2008; 1777:919-24. [DOI: 10.1016/j.bbabio.2008.03.012] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/23/2008] [Revised: 03/03/2008] [Accepted: 03/19/2008] [Indexed: 11/18/2022]
|
22
|
Luna VM, Chen Y, Fee JA, Stout CD. Crystallographic studies of Xe and Kr binding within the large internal cavity of cytochrome ba3 from Thermus thermophilus: structural analysis and role of oxygen transport channels in the heme-Cu oxidases. Biochemistry 2008; 47:4657-65. [PMID: 18376849 DOI: 10.1021/bi800045y] [Citation(s) in RCA: 76] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Cytochrome ba3 is a cytochrome c oxidase from the plasma membrane of Thermus thermophilus and is the preferred terminal enzyme of cellular respiration at low dioxygen tensions. Using cytochrome ba 3 crystals pressurized at varying conditions under Xe or Kr gas, and X-ray data for six crystals, we identify the relative affinities of Xe and Kr atoms for as many as seven distinct binding sites. These sites track a continuous, Y-shaped channel, 18-20 A in length, lined by hydrophobic residues, which leads from the surface of the protein where two entrance holes, representing the top of the Y, connect the bilayer to the a3-CuB center at the base of the Y. Considering the increased affinity of O2 for hydrophobic environments, the hydrophobic nature of the channel, its orientation within the bilayer, its connection to the active site, its uniform diameter, its virtually complete occupation by Xe, and its isomorphous presence in the native enzyme, we infer that the channel is a diffusion pathway for O2 into the dinuclear center of cytochrome ba3. These observations provide a basis for analyzing similar channels in other oxidases of known structure, and these structures are discussed in terms of mechanisms of O2 transport in biological systems, details of CO binding to and egress from the dinuclear center, the bifurcation of the oxygen-in and water-out pathways, and the possible role of the oxygen channel in aerobic thermophily.
Collapse
Affiliation(s)
- V Mitch Luna
- Department of Molecular Biology, The Scripps Research Institute, 10550 North Torrey Pines Road, La Jolla, CA 92037, USA
| | | | | | | |
Collapse
|
23
|
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.
Collapse
Affiliation(s)
- Ilya Belevich
- Helsinki Bioenergetics Group, Program for Structural Biology and Biophysics, Institute of Biotechnology, University of Helsinki, Helsinki, Finland
| | | |
Collapse
|
24
|
Ultrafast dynamics of ligands within heme proteins. BIOCHIMICA ET BIOPHYSICA ACTA-BIOENERGETICS 2007; 1777:15-31. [PMID: 17996720 DOI: 10.1016/j.bbabio.2007.10.004] [Citation(s) in RCA: 71] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/01/2007] [Revised: 10/10/2007] [Accepted: 10/15/2007] [Indexed: 11/21/2022]
Abstract
Physiological bond formation and bond breaking events between proteins and ligands and their immediate consequences are difficult to synchronize and study in general. However, diatomic ligands can be photodissociated from heme, and thus in heme proteins ligand release and rebinding dynamics and trajectories have been studied on timescales of the internal vibrations of the protein that drive many biochemical reactions, and longer. The rapidly expanding number of characterized heme proteins involved in a large variety of functions allows comparative dynamics-structure-function studies. In this review, an overview is given of recent progress in this field, and in particular on initial sensing processes in signaling proteins, and on ligand and electron transfer dynamics in oxidases and cytochromes.
Collapse
|
25
|
Affiliation(s)
- Arthur J. Esswein
- Department of Chemistry 6-335, Massachusetts Institute of Technology, 77 Massachusetts Avenue, Cambridge, Massachusetts 02139-4307
| | - Daniel G. Nocera
- Department of Chemistry 6-335, Massachusetts Institute of Technology, 77 Massachusetts Avenue, Cambridge, Massachusetts 02139-4307
| |
Collapse
|
26
|
Treuffet J, Kubarych KJ, Lambry JC, Pilet E, Masson JB, Martin JL, Vos MH, Joffre M, Alexandrou A. Direct observation of ligand transfer and bond formation in cytochrome c oxidase by using mid-infrared chirped-pulse upconversion. Proc Natl Acad Sci U S A 2007; 104:15705-10. [PMID: 17895387 PMCID: PMC2000433 DOI: 10.1073/pnas.0703279104] [Citation(s) in RCA: 31] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/09/2007] [Indexed: 11/18/2022] Open
Abstract
We have implemented the recently demonstrated technique of chirped-pulse upconversion of midinfrared femtosecond pulses into the visible in a visible pump-midinfrared probe experiment for high-resolution, high-sensitivity measurements over a broad spectral range. We have succeeded in time-resolving the CO ligand transfer process from the heme Fe to the neighboring Cu(B) atom in the bimetallic active site of mammalian cytochrome c oxidase, which was known to proceed in <1 ps, using the full CO vibrational signature of Fe-CO bond breaking and Cu(B)-CO bond formation. Our differential transmission results show a delayed onset of the appearance of the Cu(B)-bound species (200 fs), followed by a 450-fs exponential rise. Trajectories calculated by using molecular-dynamics simulations with a Morse potential for the Cu(B)-C interaction display a similar behavior. Both experimental and calculated data strongly suggest a ballistic contribution to the transfer process.
Collapse
Affiliation(s)
- Johanne Treuffet
- Laboratoire d'Optique et Biosciences, Ecole Polytechnique, Centre National de la Recherche Scientifique and Institut National de la Santé et de la Recherche Médicale U696, 91128 Palaiseau, France
| | - Kevin J. Kubarych
- Laboratoire d'Optique et Biosciences, Ecole Polytechnique, Centre National de la Recherche Scientifique and Institut National de la Santé et de la Recherche Médicale U696, 91128 Palaiseau, France
| | - Jean-Christophe Lambry
- Laboratoire d'Optique et Biosciences, Ecole Polytechnique, Centre National de la Recherche Scientifique and Institut National de la Santé et de la Recherche Médicale U696, 91128 Palaiseau, France
| | - Eric Pilet
- Laboratoire d'Optique et Biosciences, Ecole Polytechnique, Centre National de la Recherche Scientifique and Institut National de la Santé et de la Recherche Médicale U696, 91128 Palaiseau, France
| | - Jean-Baptiste Masson
- Laboratoire d'Optique et Biosciences, Ecole Polytechnique, Centre National de la Recherche Scientifique and Institut National de la Santé et de la Recherche Médicale U696, 91128 Palaiseau, France
| | - Jean-Louis Martin
- Laboratoire d'Optique et Biosciences, Ecole Polytechnique, Centre National de la Recherche Scientifique and Institut National de la Santé et de la Recherche Médicale U696, 91128 Palaiseau, France
| | - Marten H. Vos
- Laboratoire d'Optique et Biosciences, Ecole Polytechnique, Centre National de la Recherche Scientifique and Institut National de la Santé et de la Recherche Médicale U696, 91128 Palaiseau, France
| | - Manuel Joffre
- Laboratoire d'Optique et Biosciences, Ecole Polytechnique, Centre National de la Recherche Scientifique and Institut National de la Santé et de la Recherche Médicale U696, 91128 Palaiseau, France
| | - Antigoni Alexandrou
- Laboratoire d'Optique et Biosciences, Ecole Polytechnique, Centre National de la Recherche Scientifique and Institut National de la Santé et de la Recherche Médicale U696, 91128 Palaiseau, France
| |
Collapse
|
27
|
|
28
|
Volkov AG, Volkova-Gugeshashvili MI, Brown-McGauley CL, Osei AJ. Nanodevices in nature: Electrochemical aspects. Electrochim Acta 2007. [DOI: 10.1016/j.electacta.2006.08.062] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/01/2022]
|
29
|
Chen Y, Hunsicker-Wang L, Pacoma RL, Luna E, Fee JA. A homologous expression system for obtaining engineered cytochrome ba3 from Thermus thermophilus HB8. Protein Expr Purif 2005; 40:299-318. [PMID: 15766872 DOI: 10.1016/j.pep.2004.11.014] [Citation(s) in RCA: 28] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/16/2004] [Revised: 11/17/2004] [Indexed: 10/26/2022]
Abstract
Cytochrome ba3 is an integral membrane protein that serves as a terminal oxidase of the respiratory chain in some prokaryotes. We have cloned the complete cba operon of Thermus thermophilus HB8 in an Escherichia coli/T. thermophilus shuttle vector. The ba3-encoding operon, cba, was eliminated from the chromosome of T. thermophilus strain MT111 using the pyrE system of Yamagishi and co-workers. Expression of functional cytochrome ba3 occurred in cells grown at reduced dioxygen levels. A hepta-histidine tag was placed at the N-terminus of subunit I, and a purification method for this form of the enzyme was developed. Growth conditions were investigated for moderate sized cultures (2L) with typical yields of approximately 2 mg of highly pure enzyme per liter of culture medium. The physical properties and enzymatic activities of these recombinant enzymes were compared with those of native enzyme. Recombinant enzyme lacking the histidine tag is spectrally identical to wild-type enzyme. Histidine-tagged cytochrome ba3 shows minor differences from wild-type, and it appears be somewhat less active as a cytochrome c552 oxidase. Exemplary mutants were also produced and compared to native protein. Tyrosine I-237, previously found to be covalently bonded to I-His-233, was changed to phenylalanine (I-Y237F) and to histidine (I-Y237H) in the hepta-histidine tagged cytochrome ba3. The Y to F mutant is devoid of enzyme activity whereas the Y to H mutant possesses approximately 5% wild-type oxidase activity; their properties are compared with those of wild-type enzyme. The above versions of the histidine-tagged enzyme have been crystallized, and our analysis of a 2.3 angstrom resolution electron-density map will be discussed elsewhere.
Collapse
Affiliation(s)
- Ying Chen
- Division of Biology, University of California at San Diego, 9500 Gilman Dr., La Jolla CA 92093-0116, USA
| | | | | | | | | |
Collapse
|
30
|
Fukuzumi S, Okamoto K, Gros CP, Guilard R. Mechanism of Four-Electron Reduction of Dioxygen to Water by Ferrocene Derivatives in the Presence of Perchloric Acid in Benzonitrile, Catalyzed by Cofacial Dicobalt Porphyrins. J Am Chem Soc 2004; 126:10441-9. [PMID: 15315460 DOI: 10.1021/ja048403c] [Citation(s) in RCA: 167] [Impact Index Per Article: 8.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
The selective two-electron reduction of dioxygen occurs in the case of a monocobalt porphyrin [Co(OEP)], whereas the selective four-electron reduction of dioxygen occurs in the case of a cofacial dicobalt porphyrin [Co(2)(DPX)]. The other cofacial dicobalt porphyrins [Co(2)(DPA), Co(2)(DPB), and Co(2)(DPD)] also catalyze the two-electron reduction of dioxygen, but the four-electron reduction is not as efficient as in the case of Co(2)(DPX). The micro-superoxo species of cofacial dicobalt porphyrins were produced by the reactions of cofacial dicobalt(II) porphyrins with dioxygen in the presence of a bulky base and the subsequent one-electron oxidation of the resulting micro-peroxo species by iodine. The superhyperfine structure due to two equivalent cobalt nuclei was observed at room temperature in the ESR spectra of the micro-superoxo species. The superhyperfine coupling constant of the micro-superoxo species of Co(2)(DPX) is the largest among those of cofacial dicobalt porphyrins. This indicates that the efficient catalysis by Co(2)(DPX) for the four-electron reduction of dioxygen by Fe(C(5)H(4)Me)(2) results from the strong binding of the reduced oxygen with Co(2)(DPX) which has a subtle distance between two cobalt nuclei for the oxygen binding. Mechanisms of the catalytic two-electron and four-electron reduction of dioxygen by ferrocene derivatives will be discussed on the basis of detailed kinetics studies on the overall catalytic reactions as well as on each redox reaction in the catalytic cycle. The turnover-determining step in the Co(OEP)-catalyzed two-electron reduction of dioxygen is an electron transfer from ferrocene derivatives to Co(OEP)(+), whereas the turnover-determining step in the Co(2)(DPX)-catalyzed four-electron reduction of dioxygen changes from the electron transfer to the O-O bond cleavage of the peroxo species of Co(2)(DPX), depending on the electron donor ability of ferrocene derivatives.
Collapse
Affiliation(s)
- Shunichi Fukuzumi
- Contribution from the Department of Material and Life Science, Graduate School of Engineering, Osaka University, Suita, Osaka 565-0871, Japan.
| | | | | | | |
Collapse
|
31
|
Affiliation(s)
- Eunsuk Kim
- Department of Chemistry, Johns Hopkins University, Charles and 34th Streets, Baltimore, Maryland 21218, USA
| | | | | | | |
Collapse
|
32
|
Namslauer A, Brzezinski P. Structural elements involved in electron-coupled proton transfer in cytochrome c oxidase. FEBS Lett 2004; 567:103-10. [PMID: 15165901 DOI: 10.1016/j.febslet.2004.04.027] [Citation(s) in RCA: 88] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/05/2004] [Accepted: 04/09/2004] [Indexed: 11/24/2022]
Abstract
Haem-copper oxidases are the last components of the respiratory chains in aerobic organisms. These membrane-bound enzymes energetically couple the electron transfer (eT) reactions associated with reduction of dioxygen to water, to proton pumping across the membrane. Even though the mechanism of proton pumping at the molecular level still remains to be uncovered, recent progress has presented us with the structural features of the pumping machinery and detailed information about the eT and proton-transfer reactions associated with the pumping process.
Collapse
Affiliation(s)
- Andreas Namslauer
- Department of Biochemistry and Biophysics, Stockholm University, SE-106 91 Stockholm, Sweden.
| | | |
Collapse
|
33
|
Adelroth P, Brzezinski P. Surface-mediated proton-transfer reactions in membrane-bound proteins. BIOCHIMICA ET BIOPHYSICA ACTA-BIOENERGETICS 2004; 1655:102-15. [PMID: 15100022 DOI: 10.1016/j.bbabio.2003.10.018] [Citation(s) in RCA: 84] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/22/2003] [Accepted: 10/22/2003] [Indexed: 11/30/2022]
Abstract
As outlined by Peter Mitchell in the chemiosmotic theory, an intermediate in energy conversion in biological systems is a proton electrochemical potential difference ("proton gradient") across a membrane, generated by membrane-bound protein complexes. These protein complexes accommodate proton-transfer pathways through which protons are conducted. In this review, we focus specifically on the role of the protein-membrane surface and the surface-bulk water interface in the dynamics of proton delivery to these proton-transfer pathways. The general mechanisms are illustrated by experimental results from studies of bacterial photosynthetic reaction centres (RCs) and cytochrome c oxidase (CcO).
Collapse
Affiliation(s)
- Pia Adelroth
- Department of Biochemistry and Biophysics, The Arrhenius Laboratories for Natural Sciences, Stockholm University, Svante Arrhenius väg 12, SE-106 91 Stockholm, Sweden.
| | | |
Collapse
|
34
|
Fabian M, Skultety L, Jancura D, Palmer G. Implications of ligand binding studies for the catalytic mechanism of cytochrome c oxidase. BIOCHIMICA ET BIOPHYSICA ACTA-BIOENERGETICS 2004; 1655:298-305. [PMID: 15100045 DOI: 10.1016/j.bbabio.2003.07.008] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/23/2003] [Accepted: 07/17/2003] [Indexed: 11/28/2022]
Abstract
The reaction of oxidized bovine heart cytochrome c oxidase (CcO) with one equivalent of hydrogen peroxide results in the formation of two spectrally distinct species. The yield of these two forms is controlled by the ionization of a group with a pK(a) of 6.6. At basic pH, where this group is deprotonated, an intermediate called P dominates (P, because it was initially believed to be a peroxy compound). At acidic pH where the group is protonated, a different species, called F (ferryl intermediate) is obtained. We previously proposed that the only difference between these two species is the presence of one proton in the catalytic center of F that is absent in P. It is now suggested that the catalytic center of this F form has the same redox and protonation state as a second ferryl intermediate produced at basic pH by two equivalents of hydrogen peroxide; the role of the second equivalent of H(2)O(2) is that of a proton donor in the conversion of P to F. Two chloride-binding sites have been detected in oxidized CcO. One site is located at the binuclear center; the second site was identified from the sensitivity of g=3 signal of cytochrome a to chloride in the EPR spectra of oxidized CcO. Turnover of CcO releases chloride from the catalytic center into the medium probably by one of the hydrophobic channels, proposed for oxygen access, with an orientation parallel to the membrane plane. Chloride in the binuclear center is most likely not involved in CcO catalysis. The influence of the second chloride site upon several reactions of CcO has been assessed. No correlation was found between chloride binding to the second site and the reactions that were examined.
Collapse
Affiliation(s)
- Marian Fabian
- Department of Biochemistry and Cell Biology, Rice University MS 140, P.O. Box 1892, 6100 Main, Houston TX 77005, USA.
| | | | | | | |
Collapse
|
35
|
|
36
|
Kornblatt JA, Hill BC, Marden MC. The influence of temperature and osmolyte on the catalytic cycle of cytochrome c oxidase. EUROPEAN JOURNAL OF BIOCHEMISTRY 2003; 270:253-60. [PMID: 12605676 DOI: 10.1046/j.1432-1033.2003.03381.x] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
The influence of temperature on cytochrome c oxidase (CCO) catalytic activity was studied in the temperature range 240-308 K. Temperatures below 273 K required the inclusion of the osmolyte ethylene glycol. For steady-state activity between 278 and 308 K the activation energy was 12 kcal x mol-1; the molecular activity or turnover number was 12 s-1 at 280 K in the absence of ethylene glycol. CCO activity was studied between 240 and 277 K in the presence of ethylene glycol. The activation energy was 30 kcal x mol-1; the molecular activity was 1 s-1 at 280 K. Ethylene glycol inhibits CCO by lowering the activity of water. The rate limitation in electron transfer (ET) was not associated with ET into the CCO as cytochrome a was predominantly reduced in the aerobic steady state. The activity of CCO in flash-induced oxidation experiments was studied in the low temperature range in the presence of ethylene glycol. Flash photolysis of the reduced CO complex in the presence of oxygen resulted in three discernable processes. At 273 K the rate constants were 1500 s-1, 150 s-1 and 30 s-1 and these dropped to 220 s-1, 27 s-1 and 3 s-1 at 240 K. The activation energies were 5 kcal.mol-1, 7 kcal.mol-1, and 8 kcal.mol-1, respectively. The fastest rate we ascribe to the oxidation of cytochrome a3, the intermediate rate to cytochrome a oxidation and the slowest rate to the re-reduction of cytochrome a followed by its oxidation. There are two comparisons that are important: (a). with vs. without ethylene glycol and (b). steady state vs. flash-induced oxidation. When one makes these two comparisons it is clear that the CCO only senses the presence of osmolyte during the reductive portion of the catalytic cycle. In the present work that would mean after a flash-induced oxidation and the start of the next reduction/oxidation cycle.
Collapse
Affiliation(s)
- Jack A Kornblatt
- Enzyme Research Group, Concordia University, Montreal, Quebec, Canada.
| | | | | |
Collapse
|
37
|
Temperature and pH effects on cytochrome c oxidase immobilized in an electrode-supported lipid bilayer membrane. Electrochim Acta 2000. [DOI: 10.1016/s0013-4686(00)00359-5] [Citation(s) in RCA: 19] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
|
38
|
Ruitenberg M, Kannt A, Bamberg E, Ludwig B, Michel H, Fendler K. Single-electron reduction of the oxidized state is coupled to proton uptake via the K pathway in Paracoccus denitrificans cytochrome c oxidase. Proc Natl Acad Sci U S A 2000; 97:4632-6. [PMID: 10781069 PMCID: PMC18284 DOI: 10.1073/pnas.080079097] [Citation(s) in RCA: 79] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
The reductive part of the catalytic cycle of cytochrome c oxidase from Paracoccus denitrificans was examined by using time-resolved potential measurements on black lipid membranes. Proteoliposomes were adsorbed to the black lipid membranes and Ru(II)(2, 2'-bipyridyl)(3)(2+) was used as photoreductant to measure flash-induced membrane potential generation. Single-electron reduction of the oxidized wild-type cytochrome c oxidase reveals two phases of membrane potential generation (tau(1) approximately 20 micros and tau(2) approximately 175 micros) at pH 7.4. The fast phase is not sensitive to cyanide and is assigned to electron transfer from Cu(A) to heme a. The slower phase is inhibited completely by cyanide and shows a kinetic deuterium isotope effect by a factor of 2-3. Although two enzyme variants mutated in the so-called D pathway of proton transfer (D124N and E278Q) show the same time constants and relative amplitudes as the wild-type enzyme, in the K pathway variant K354M, tau(2) is increased to 900 micros. This result suggests uptake of a proton through the K pathway during the transition from the oxidized to the one-electron reduced state. After the second laser flash under anaerobic conditions, a third electrogenic phase with a time constant of approximately 1 ms appears. The amplitude of this phase grows with increasing flash number. We explain this growth by injection of a second electron into the single-electron reduced enzyme. On multiple flashes, both D pathway mutants behave differently compared with the wild type and two additional slow phases of tau(3) approximately 2 ms and tau(4) approximately 15 ms are observed. These results suggest that the D pathway is involved in proton transfer coupled to the uptake of the second electron.
Collapse
Affiliation(s)
- M Ruitenberg
- Max-Planck-Institute of Biophysics, Department of Biophysical Chemistry, Kennedyallee 70, 60596 Frankfurt/Main, Germany
| | | | | | | | | | | |
Collapse
|
39
|
Vos MH, Borisov VB, Liebl U, Martin JL, Konstantinov AA. Femtosecond resolution of ligand-heme interactions in the high-affinity quinol oxidase bd: A di-heme active site? Proc Natl Acad Sci U S A 2000; 97:1554-9. [PMID: 10660685 PMCID: PMC26473 DOI: 10.1073/pnas.030528197] [Citation(s) in RCA: 48] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/25/1999] [Accepted: 12/06/1999] [Indexed: 11/18/2022] Open
Abstract
Interaction of the two high-spin hemes in the oxygen reduction site of the bd-type quinol oxidase from Escherichia coli has been studied by femtosecond multicolor transient absorption spectroscopy. The previously unidentified Soret band of ferrous heme b(595) was determined to be centered around 440 nm by selective excitation of the fully reduced unliganded or CO-bound cytochrome bd in the alpha-band of heme b(595). The redox state of the b-type hemes strongly affects both the line shape and the kinetics of the absorption changes induced by photodissociation of CO from heme d. In the reduced enzyme, CO photodissociation from heme d perturbs the spectrum of ferrous cytochrome b(595) within a few ps, pointing to a direct interaction between hemes b(595) and d. Whereas in the reduced enzyme no heme d-CO geminate recombination is observed, in the mixed-valence CO-liganded complex with heme b(595) initially oxidized, a significant part of photodissociated CO does not leave the protein and recombines with heme d within a few hundred ps. This caging effect may indicate that ferrous heme b(595) provides a transient binding site for carbon monoxide within one of the routes by which the dissociated ligand leaves the protein. Taken together, the data indicate physical proximity of the hemes d and b(595) and corroborate the possibility of a functional cooperation between the two hemes in the dioxygen-reducing center of cytochrome bd.
Collapse
Affiliation(s)
- M H Vos
- Institut National de la Santé et de la Recherche Médicale U451, Laboratoire d'Optique Appliquée, Ecole Polytechnique-Ecole Nationale Supérieure des Techniques Avancées, 91761 Palaiseau Cedex, France.
| | | | | | | | | |
Collapse
|
40
|
Affiliation(s)
- M H Vos
- INSERM U451, Laboratoire d'Optique Appliquée, Ecole Polytechnique-ENSTA, 91761, Palaiseau Cedex, France.
| | | |
Collapse
|
41
|
Vamvouka M, Müller W, Ludwig B, Varotsis C. Fourier Transform Infrared and Resonance Raman Studies of the Interaction of Azide with Cytochrome c Oxidase from Paracoccus denitrificans. J Phys Chem B 1999. [DOI: 10.1021/jp984589o] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
- Magdalini Vamvouka
- Department of Chemistry, University of Crete, 71409 Iraklion, Crete, Greece, and Institut für Biochemie, Molekulare Genetik, Johann Wolfgang Goethe-Universität, Biozentrum N200, Marie-Curie-Strasse 9, D-60439 Frankfurt/M., Germany
| | - Werner Müller
- Department of Chemistry, University of Crete, 71409 Iraklion, Crete, Greece, and Institut für Biochemie, Molekulare Genetik, Johann Wolfgang Goethe-Universität, Biozentrum N200, Marie-Curie-Strasse 9, D-60439 Frankfurt/M., Germany
| | - Bernd Ludwig
- Department of Chemistry, University of Crete, 71409 Iraklion, Crete, Greece, and Institut für Biochemie, Molekulare Genetik, Johann Wolfgang Goethe-Universität, Biozentrum N200, Marie-Curie-Strasse 9, D-60439 Frankfurt/M., Germany
| | - Constantinos Varotsis
- Department of Chemistry, University of Crete, 71409 Iraklion, Crete, Greece, and Institut für Biochemie, Molekulare Genetik, Johann Wolfgang Goethe-Universität, Biozentrum N200, Marie-Curie-Strasse 9, D-60439 Frankfurt/M., Germany
| |
Collapse
|
42
|
Giuffrè A, Watmough NJ, Giannini S, Brunori M, Konings WN, Greenwood C. Electron transfer kinetics of caa3 oxidase from Bacillus stearothermophilus: a hypothesis for thermophilicity. Biophys J 1999; 76:438-42. [PMID: 9876155 PMCID: PMC1302532 DOI: 10.1016/s0006-3495(99)77210-3] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022] Open
Abstract
The O2 reaction and the reverse electron transfer of the thermophilic caa3 terminal oxidase of Bacillus stearothermophilus have been studied by laser flash-photolysis. The results show that both reactions, although studied at a temperature of 20 degreesC, far from the optimal temperature of > 60 degreesC for caa3, follow a kinetic behavior essentially identical to that observed with the electrostatic complex between mammalian cyt c and cyt c oxidase. In the O2 reaction cyt a and cyt a3 are very quickly oxidized; cyt a is then re-reduced via CuA, whereas cyt c oxidation is apparently rate-limited by the oxidation of CuA. Upon photodissociation of the mixed valence-CO caa3, reverse electron transfer from the binuclear center to cyt a3+ (tau1 = 3 micros) and CuA2+ (tau2 = 64 micros) is observed, while cyt c is not reduced by any detectable level. These results seem to rule out accounting for enzymatic thermophilicity by altered kinetics of intramolecular electron transfer involving the cyt center in the reduced configuration, which is very fast. On the basis of these results and previous data, we propose that thermophilicity involves an increased activation barrier for the reduction of cyt a3-CuB in the configuration typical of the oxidized site.
Collapse
Affiliation(s)
- A Giuffrè
- Department of Biochemical Sciences and CNR Center of Molecular Biology, University of Rome "La Sapienza", Rome, Italy
| | | | | | | | | | | |
Collapse
|
43
|
Abstract
Cytochrome c oxidase couples electron transfer to proton transfer from inside the mitochondrion to the cytosol. Protons pass through a channel; it is closed except when protons are pumped. Electron transfer is also coupled to a water cycle. Water moves into and out of the oxidase during electron transfer, presumably through a channel. The three processes are coupled because of the common dependence on electron transfer. If water and protons had to pass through the same channel for the proton to pass, it might be possible to block the pore by entraining small molecules in the flow. The data in this report indicate that there is a correlation between the ability of a compound to inhibit the oxidase and its size. Formamide and formaldehyde are potent inhibitors. Larger and smaller molecules are poor inhibitors. Formamide introduces an internal block in electron transfer. It is a slow-onset, reversible inhibitor, dependent on turnover to manifest its effects. Vesicular oxidase is less influenced by formamide than is soluble oxidase; formamide must pass a permeability barrier to act. The data are consistent with a proton channel with constrictions at both ends that open to yield a pore of approximately 4 A.
Collapse
Affiliation(s)
- J A Kornblatt
- Enzyme Research Group, Department of Biology, Concordia University, Montréal, Québec H3G 1M8, Canada.
| |
Collapse
|
44
|
Karpefors M, Adelroth P, Zhen Y, Ferguson-Miller S, Brzezinski P. Proton uptake controls electron transfer in cytochrome c oxidase. Proc Natl Acad Sci U S A 1998; 95:13606-11. [PMID: 9811847 PMCID: PMC24866 DOI: 10.1073/pnas.95.23.13606] [Citation(s) in RCA: 55] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/17/1998] [Accepted: 09/14/1998] [Indexed: 11/18/2022] Open
Abstract
In cytochrome c oxidase, a requirement for proton pumping is a tight coupling between electron and proton transfer, which could be accomplished if internal electron-transfer rates were controlled by uptake of protons. During reaction of the fully reduced enzyme with oxygen, concomitant with the "peroxy" to "oxoferryl" transition, internal transfer of the fourth electron from CuA to heme a has the same rate as proton uptake from the bulk solution (8,000 s-1). The question was therefore raised whether the proton uptake controls electron transfer or vice versa. To resolve this question, we have studied a site-specific mutant of the Rhodobacter sphaeroides enzyme in which methionine 263 (SU II), a CuA ligand, was replaced by leucine, which resulted in an increased redox potential of CuA. During reaction of the reduced mutant enzyme with O2, a proton was taken up at the same rate as in the wild-type enzyme (8,000 s-1), whereas electron transfer from CuA to heme a was impaired. Together with results from studies of the EQ(I-286) mutant enzyme, in which both proton uptake and electron transfer from CuA to heme a were blocked, the results from this study show that the CuA --> heme a electron transfer is controlled by the proton uptake and not vice versa. This mechanism prevents further electron transfer to heme a3-CuB before a proton is taken up, which assures a tight coupling of electron transfer to proton pumping.
Collapse
Affiliation(s)
- M Karpefors
- Department of Biochemistry and Biophysics, Göteborg University, (Medicinaregatan 9C) P.O. Box 462, SE-405 30 Göteborg, Sweden
| | | | | | | | | |
Collapse
|
45
|
Malatesta F, Nicoletti F, Zickermann V, Ludwig B, Brunori M. Electron entry in a CuA mutant of cytochrome c oxidase from Paracoccus denitrificans. Conclusive evidence on the initial electron entry metal center. FEBS Lett 1998; 434:322-4. [PMID: 9742947 DOI: 10.1016/s0014-5793(98)01006-0] [Citation(s) in RCA: 20] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/08/2023]
Abstract
A cytochrome c oxidase subunit II C216S mutant from Paracoccus denitrificans in which the CuA site was changed by site-directed mutagenesis to a mononuclear copper site [Zickermann, V., Wittershagen, A., Kolbesen, B.O. and Ludwig, B. Biochemistry 36 (1997) 3232-3236] was investigated by stopped-flow spectroscopy. Contrary to the behavior of the wild type enzyme, in this mutant cytochrome a cannot be reduced by excess cytochrome c in the millisecond time scale in which cytochrome c oxidation is observed. The results conclusively identify and establish CuA as the initial electron entry site in cytochrome c oxidase. Partial rapid reduction (ca. 20%) of the modified CuA site suggests that the mononuclear copper ion has a redox potential ca. 100 mV lower than the wild type, and that internal electron transfer to cytochrome a is > or = 10(3)-fold slower than with the wild type enzyme.
Collapse
Affiliation(s)
- F Malatesta
- Department of Biochemical Sciences A. Rossi Fanelli and CNR Centre of Molecular Biology, University of Rome La Sapienza, Italy.
| | | | | | | | | |
Collapse
|
46
|
Larsen RW, Osborne J, Langley T, Gennis RB. Volume Changes Associated with CO Photodissociation from Fully Reduced Cytochrome bo3 from Escherichia coli. J Am Chem Soc 1998. [DOI: 10.1021/ja981143c] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
- Randy W. Larsen
- Department of Chemistry, University of Hawaii at Manoa Honolulu, Hawaii 96822 School of Chemical Sciences, University of Illinois Urbana, Illinois 61801
| | - Jeffrey Osborne
- Department of Chemistry, University of Hawaii at Manoa Honolulu, Hawaii 96822 School of Chemical Sciences, University of Illinois Urbana, Illinois 61801
| | - Tana Langley
- Department of Chemistry, University of Hawaii at Manoa Honolulu, Hawaii 96822 School of Chemical Sciences, University of Illinois Urbana, Illinois 61801
| | - Robert B. Gennis
- Department of Chemistry, University of Hawaii at Manoa Honolulu, Hawaii 96822 School of Chemical Sciences, University of Illinois Urbana, Illinois 61801
| |
Collapse
|
47
|
Duranteau J, Chandel NS, Kulisz A, Shao Z, Schumacker PT. Intracellular signaling by reactive oxygen species during hypoxia in cardiomyocytes. J Biol Chem 1998; 273:11619-24. [PMID: 9565580 DOI: 10.1074/jbc.273.19.11619] [Citation(s) in RCA: 497] [Impact Index Per Article: 19.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/10/2023] Open
Abstract
Cardiomyocytes suppress contraction and O2 consumption during hypoxia. Cytochrome oxidase undergoes a decrease in Vmax during hypoxia, which could alter mitochondrial redox and increase generation of reactive oxygen species (ROS). We therefore tested whether ROS generated by mitochondria act as second messengers in the signaling pathway linking the detection of O2 with the functional response. Contracting cardiomyocytes were superfused under controlled O2 conditions while fluorescence imaging of 2, 7-dichlorofluorescein (DCF) was used to assess ROS generation. Compared with normoxia (PO2 approximately 107 torr, 15% O2), graded increases in DCF fluorescence were seen during hypoxia, with responses at PO2 = 7 torr > 20 torr > 35 torr. The antioxidants 2-mercaptopropionyl glycine and 1,10-phenanthroline attenuated these increases and abolished the inhibition of contraction. Superfusion of normoxic cells with H2O2 (25 microM) for >60 min mimicked the effects of hypoxia by eliciting decreases in contraction that were reversible after washout of H2O2. To test the role of cytochrome oxidase, sodium azide (0.75-2 microM) was added during normoxia to reduce the Vmax of the enzyme. Azide produced graded increases in ROS signaling, accompanied by graded decreases in contraction that were reversible. These results demonstrate that mitochondria respond to graded hypoxia by increasing the generation of ROS and suggest that cytochrome oxidase may contribute to this O2 sensing.
Collapse
Affiliation(s)
- J Duranteau
- Pulmonary and Critical Care Medicine, The University of Chicago, Chicago, Illinois 60637, USA
| | | | | | | | | |
Collapse
|
48
|
Ferrocyanide-peroxidase activity of cytochrome c oxidase. BIOCHIMICA ET BIOPHYSICA ACTA 1998; 1363:11-23. [PMID: 9526032 DOI: 10.1016/s0005-2728(97)00087-x] [Citation(s) in RCA: 17] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
Abstract
Redox interaction of mitochondrial cytochrome c oxidase (COX) with ferrocyanide/ferricyanide couple is greatly accelerated by polycations, such as poly-l-lysine [Musatov et al. (1991) Biological Membranes 8, 229-234]. This has allowed us to study ferrocyanide oxidation by COX at very high redox potentials of the ferrocyanide/ferricyanide couple either following spectrophotometrically ferricyanide accumulation or measuring proton uptake associated with water formation in the reaction. At low [ferrocyanide]/[ferricyanide] ratios (Eh values around 500 mV) and ambient oxygen concentration, the ferrocyanide-oxidase activity of COX becomes negligibly small as compared to the reaction rate observed with pure ferrocyanide. Oxidation of ferrocyanide under these conditions, is greatly stimulated by H2O2 or ethylhydroperoxide indicating peroxidatic reaction involved. The ferrocyanide-peroxidase activity of COX is strictly polylysine-dependent and is inhibited by heme a3 ligands such as KCN and NaN3. Apparently the reaction involves normal electron pathway, i.e. electron donation through CuA and oxidation via heme a3. The peroxidase reaction shows a pH-dependence similar to that of the cytochrome c oxidase activity of COX. When COX is preequilibrated with excess H2O2, addition of ferrocyanide shifts the initial steady-state concentrations of the Ferryl-Oxo and Peroxy compounds towards approximately 2:1 ratio of the two intermediates. It is suggested that in the peroxidase cycleferrocyanide donates electrons to both P and F intermediates with a comparable efficiency. Isolation of a partial redox activity of COX opens a possibility to study separately proton translocation coupled to the peroxidase half-reaction of the COX reaction cycle. Copyright 1998
Collapse
|
49
|
Giuffrè A, Gomes CM, Antonini G, D'Itri E, Teixeira M, Brunori M. Functional properties of the quinol oxidase from Acidianus ambivalens and the possible catalytic role of its electron donor--studies on the membrane-integrated and purified enzyme. EUROPEAN JOURNAL OF BIOCHEMISTRY 1997; 250:383-8. [PMID: 9428688 DOI: 10.1111/j.1432-1033.1997.0383a.x] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/05/2023]
Abstract
The aa3 quinol oxidase has been purified from the thermoacidophilic archaea Acidianus ambivalens as a three-redox-centers enzyme. The functional properties of this oxidase both as purified and in its most integral form (i.e. in native membranes and in intact cells) were investigated by stopped-flow spectrophotometry. The results suggest that the enzyme interacts in vivo with a redox-active molecule, which favours the electron entry via heme a and provides the fourth electron demanded for catalysis. We observe that the purified enzyme has two hemes with apparent redox potentials 215 +/- 20 mV and 415 +/- 20 mV at pH 5.4, showing redox-Bohr effect, and a heme a3-CuB center with an affinity for carbon monoxide (Ka = 5.7 x 10(4) M(-1) at 35 degrees C) much lower than that reported for the mammalian enzyme (Ka = 4 x 10(6) M(-1) at 20 degrees C). The reduction by dithionite is fast and monophasic when the quinol oxidase is in the native membranes, whereas it is slow and biphasic in the purified enzyme (with heme a3 being reduced faster than heme a). The oxygen reaction of the reduced purified enzyme is fast (few milliseconds), but yields an intermediate (likely ferryl) clearly different from the fully oxidized enzyme. In contrast, the same reaction performed in intact cells leads to the fully oxidized enzyme. We postulate that caldariella quinol, the physiological electron donor, is in vivo tightly bound to the enzyme, providing the fourth redox active center lacking in the purified enzyme.
Collapse
Affiliation(s)
- A Giuffrè
- Department of Biochemical Sciences and CNR Center of Molecular Biology, University of Rome La Sapienza, Italy
| | | | | | | | | | | |
Collapse
|
50
|
Salamon Z, Macleod HA, Tollin G. Surface plasmon resonance spectroscopy as a tool for investigating the biochemical and biophysical properties of membrane protein systems. II: Applications to biological systems. BIOCHIMICA ET BIOPHYSICA ACTA 1997; 1331:131-52. [PMID: 9325439 DOI: 10.1016/s0304-4157(97)00003-8] [Citation(s) in RCA: 110] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/05/2023]
Affiliation(s)
- Z Salamon
- Department of Biochemistry, University of Arizona, Tucson 85721, USA
| | | | | |
Collapse
|