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Baserga F, Storm J, Schlesinger R, Heberle J, Stripp ST. The catalytic reaction of cytochrome c oxidase probed by in situ gas titrations and FTIR difference spectroscopy. BIOCHIMICA ET BIOPHYSICA ACTA. BIOENERGETICS 2023; 1864:149000. [PMID: 37516233 DOI: 10.1016/j.bbabio.2023.149000] [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: 12/13/2022] [Revised: 06/22/2023] [Accepted: 07/24/2023] [Indexed: 07/31/2023]
Abstract
Cytochrome c oxidase (CcO) is a transmembrane heme‑copper metalloenzyme that catalyzes the reduction of O2 to H2O at the reducing end of the respiratory electron transport chain. To understand this reaction, we followed the conversion of CcO from Rhodobacter sphaeroides between several active-ready and carbon monoxide-inhibited states via attenuated total reflection Fourier-transform infrared (ATR FTIR) difference spectroscopy. Utilizing a novel gas titration setup, we prepared the mixed-valence, CO-inhibited R2CO state as well as the fully-reduced R4 and R4CO states and induced the "active ready" oxidized state OH. These experiments are performed in the dark yielding FTIR difference spectra exclusively triggered by exposure to O2, the natural substrate of CcO. Our data demonstrate that the presence of CO at heme a3 does not impair the catalytic oxidation of CcO when the cycle starts from the fully-reduced states. Interestingly, when starting from the R2CO state, the release of the CO ligand upon purging with inert gas yield a product that is indistinguishable from photolysis-induced states. The observed changes at heme a3 in the catalytic binuclear center (BNC) result from the loss of CO and are unrelated to electronic excitation upon illumination. Based on our experiments, we re-evaluate the assignment of marker bands that appear in time-resolved photolysis and perfusion-induced experiments on CcO.
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Affiliation(s)
- Federico Baserga
- Freie Universität Berlin, Experimental Molecular Biophysics, Arnimallee 14, D-14195 Berlin, Germany
| | - Julian Storm
- Freie Universität Berlin, Genetic Biophysics, Arnimallee 14, D-14195 Berlin, Germany
| | - Ramona Schlesinger
- Freie Universität Berlin, Genetic Biophysics, Arnimallee 14, D-14195 Berlin, Germany
| | - Joachim Heberle
- Freie Universität Berlin, Experimental Molecular Biophysics, Arnimallee 14, D-14195 Berlin, Germany
| | - Sven T Stripp
- Freie Universität Berlin, Experimental Molecular Biophysics, Arnimallee 14, D-14195 Berlin, Germany; Technische Universität Berlin, Division of Physical Chemistry, Strasse des 17. Juni 115, D-10623 Berlin, Germany.
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2
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An Insight into the Essential Role of Carbohydrate-Binding Modules in Enzymolysis of Xanthan. Int J Mol Sci 2023; 24:ijms24065480. [PMID: 36982553 PMCID: PMC10049358 DOI: 10.3390/ijms24065480] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/20/2023] [Revised: 03/07/2023] [Accepted: 03/10/2023] [Indexed: 03/16/2023] Open
Abstract
To date, due to the low accessibility of enzymes to xanthan substrates, the enzymolysis of xanthan remains deficient, which hinders the industrial production of functional oligoxanthan. To enhance the enzymatic affinity against xanthan, the essential role of two carbohydrate binding modules—MiCBMx and PspCBM84, respectively, derived from Microbacterium sp. XT11 and Paenibacillus sp. 62047—in catalytic properties of endotype xanthanase MiXen were investigated for the first time. Basic characterizations and kinetic parameters of different recombinants revealed that, compared with MiCBMx, PspCBM84 dramatically increased the thermostability of endotype xanthanase, and endowed the enzyme with higher substrate affinity and catalytic efficiency. Notably, the activity of endotype xanthanase was increased by 16 times after being fused with PspCBM84. In addition, the presence of both CBMs obviously enabled endotype xanthanase to produce more oligoxanthan, and xanthan digests prepared by MiXen-CBM84 showed better antioxidant activity due to the higher content of active oligosaccharides. The results of this work lay a foundation for the rational design of endotype xanthanase and the industrial production of oligoxanthan in the future.
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3
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Fedotovskaya O, Albertsson I, Nordlund G, Hong S, Gennis RB, Brzezinski P, Ädelroth P. Identification of a cytochrome bc 1-aa 3 supercomplex in Rhodobacter sphaeroides. BIOCHIMICA ET BIOPHYSICA ACTA-BIOENERGETICS 2021; 1862:148433. [PMID: 33932366 DOI: 10.1016/j.bbabio.2021.148433] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Subscribe] [Scholar Register] [Received: 12/14/2020] [Revised: 04/19/2021] [Accepted: 04/20/2021] [Indexed: 10/21/2022]
Abstract
Respiration is carried out by a series of membrane-bound complexes in the inner mitochondrial membrane or in the cytoplasmic membrane of bacteria. Increasing evidence shows that these complexes organize into larger supercomplexes. In this work, we identified a supercomplex composed of cytochrome (cyt.) bc1 and aa3-type cyt. c oxidase in Rhodobacter sphaeroides. We purified the supercomplex using a His-tag on either of these complexes. The results from activity assays, native and denaturing PAGE, size exclusion chromatography, electron microscopy, optical absorption spectroscopy and kinetic studies on the purified samples support the formation and coupled quinol oxidation:O2 reduction activity of the cyt. bc1-aa3 supercomplex. The potential role of the membrane-anchored cyt. cy as a component in supercomplexes was also investigated.
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Affiliation(s)
- Olga Fedotovskaya
- Department of Biochemistry and Biophysics, The Arrhenius Laboratories for Natural Sciences, Stockholm University, SE-106 91 Stockholm, Sweden
| | - Ingrid Albertsson
- Department of Biochemistry and Biophysics, The Arrhenius Laboratories for Natural Sciences, Stockholm University, SE-106 91 Stockholm, Sweden
| | - Gustav Nordlund
- Department of Biochemistry and Biophysics, The Arrhenius Laboratories for Natural Sciences, Stockholm University, SE-106 91 Stockholm, Sweden
| | - Sangjin Hong
- Department of Biochemistry, University of Illinois at Urbana-Champaign, 600 S. Mathews Avenue, Urbana, IL 61801, USA
| | - Robert B Gennis
- Department of Biochemistry, University of Illinois at Urbana-Champaign, 600 S. Mathews Avenue, Urbana, IL 61801, USA
| | - Peter Brzezinski
- Department of Biochemistry and Biophysics, The Arrhenius Laboratories for Natural Sciences, Stockholm University, SE-106 91 Stockholm, Sweden
| | - Pia Ädelroth
- Department of Biochemistry and Biophysics, The Arrhenius Laboratories for Natural Sciences, Stockholm University, SE-106 91 Stockholm, Sweden.
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4
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Zhao X, Chen Y, Zhang L, Li Z, Wu X, Chen J, Wang F. Molecular cloning and biochemical characterization of a trehalose synthase from Myxococcus sp. strain V11. Protein Expr Purif 2021; 183:105865. [PMID: 33675938 DOI: 10.1016/j.pep.2021.105865] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/01/2020] [Revised: 02/28/2021] [Accepted: 03/01/2021] [Indexed: 11/30/2022]
Abstract
The tresI gene of Myxococcus sp. strain V11 was cloned, and found to encode a trehalose synthase comprising 551 amino acids. The deduced molecular weight of the encoded TreS I protein 64.7 kDa and the isoelectric point (pI) was predicted to be 5.6. The catalytic cleft consists of the Asp202-Glu244-Asp310 catalytic triad and additional conserved residues. The recombinant (His)6-tag enzyme was expressed in Escherichia coli BL21(DE3) and purified by Ni2+-affinity chromatography, resulting in a specific activity of up to 172.7 U/mg. TLC and HPLC results confirmed that rTreS I can convert maltose into trehalose, with a yield of 61%. The KM and Vmax values of recombinant TreS I for maltose were 0.62 mM and 25.5 mM min-1 mg-1 protein, respectively. TreS I was optimally active at 35° and stable at temperatures of <25 °C. TreS I was stable within a narrow range of pH values, from 6.0 to 7.0. The enzymatic activity was slightly stimulated by Mg2+ and strongly inhibited by Fe3+, Co2+ and Cu2+. TreS I was also strongly inhibited by SDS and weakly by EDTA and TritonX-100.
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Affiliation(s)
- Xiaoyan Zhao
- College of Bioscience and Bioengineering, Jiangxi Agricultural University, Nanchang, 330045, PR China
| | - Yunda Chen
- College of Bioscience and Bioengineering, Jiangxi Agricultural University, Nanchang, 330045, PR China
| | - Lixia Zhang
- College of Bioscience and Bioengineering, Jiangxi Agricultural University, Nanchang, 330045, PR China
| | - Zhimin Li
- College of Bioscience and Bioengineering, Jiangxi Agricultural University, Nanchang, 330045, PR China
| | - Xiaoyu Wu
- College of Bioscience and Bioengineering, Jiangxi Agricultural University, Nanchang, 330045, PR China; Collaborative Innovation Center of Postharvest Key Technology and Quality Safety of Fruits and Vegetables in Jiangxi Province, Nanchang, 330045, PR China
| | - Jinyin Chen
- College of Bioscience and Bioengineering, Jiangxi Agricultural University, Nanchang, 330045, PR China; Collaborative Innovation Center of Postharvest Key Technology and Quality Safety of Fruits and Vegetables in Jiangxi Province, Nanchang, 330045, PR China
| | - Fei Wang
- College of Bioscience and Bioengineering, Jiangxi Agricultural University, Nanchang, 330045, PR China; Collaborative Innovation Center of Postharvest Key Technology and Quality Safety of Fruits and Vegetables in Jiangxi Province, Nanchang, 330045, PR China.
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5
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Kruse F, Nguyen AD, Dragelj J, Heberle J, Hildebrandt P, Mroginski MA, Weidinger IM. A Resonance Raman Marker Band Characterizes the Slow and Fast Form of Cytochrome c Oxidase. J Am Chem Soc 2021; 143:2769-2776. [PMID: 33560128 DOI: 10.1021/jacs.0c10767] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/08/2023]
Abstract
Cytochrome c oxidase (CcO) in its as-isolated form is known to exist in a slow and fast form, which differ drastically in their ability to bind oxygen and other ligands. While preparation methods have been established that yield either the fast or the slow form of the protein, the underlying structural differences have not been identified yet. Here, we have performed surface enhanced resonance Raman (SERR) spectroscopy of CcO immobilized on electrodes in both forms. SERR spectra obtained in resonance with the heme a3 metal-to-ligand charge transfer (MLCT) transition at 650 nm displayed a sharp vibrational band at 748 or 750 cm-1 when the protein was in its slow or fast form, respectively. DFT calculations identified the band as a mode of the His-419 ligand that is sensitive to the oxygen ligand and the protonation state of Tyr-288 within the binuclear complex. Potential-dependent SERR spectroscopy showed a redox-induced change of this band around 525 mV versus Ag/AgCl exclusively for the fast form, which coincides with the redox potential of the Tyr-O/Tyr-O- transition. Our data points to a peroxide ligand in the resting state of CcO for both forms. The observed frequencies and redox sensitivities of the Raman marker band suggest that a radical Tyr-288 is present in the fast form and a protonated Tyr-288 in the slow form.
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Affiliation(s)
- Fabian Kruse
- Department of Chemistry and Food Chemistry, Technische Universität Dresden, 01069 Dresden, Germany
| | - Anh Duc Nguyen
- Department of Chemistry, Technische Universität Berlin, Strasse des 17. Juni 135, 10623 Berlin, Germany
| | - Jovan Dragelj
- Department of Chemistry, Technische Universität Berlin, Strasse des 17. Juni 135, 10623 Berlin, Germany
| | - Joachim Heberle
- Freie Universität Berlin, Department of Physics, Experimental Molecular Biophysics, Arnimallee 14, 14195 Berlin, Germany
| | - Peter Hildebrandt
- Department of Chemistry, Technische Universität Berlin, Strasse des 17. Juni 135, 10623 Berlin, Germany
| | - Maria Andrea Mroginski
- Department of Chemistry, Technische Universität Berlin, Strasse des 17. Juni 135, 10623 Berlin, Germany
| | - Inez M Weidinger
- Department of Chemistry and Food Chemistry, Technische Universität Dresden, 01069 Dresden, Germany
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6
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Siletsky SA, Gennis RB. Time-Resolved Electrometric Study of the F→O Transition in Cytochrome c Oxidase. The Effect of Zn2+ Ions on the Positive Side of the Membrane. BIOCHEMISTRY (MOSCOW) 2021; 86:105-122. [DOI: 10.1134/s0006297921010107] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/17/2022]
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7
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Zhu X, Aoyama E, Birk AV, Onasanya O, Carr WH, Mourokh L, Minteer SD, Vittadello M. Cytochrome c oxidase oxygen reduction reaction induced by cytochrome c on nickel-coordination surfaces based on graphene oxide in suspension. BIOCHIMICA ET BIOPHYSICA ACTA-BIOENERGETICS 2020; 1861:148262. [PMID: 32673675 DOI: 10.1016/j.bbabio.2020.148262] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/04/2020] [Revised: 07/01/2020] [Accepted: 07/07/2020] [Indexed: 11/25/2022]
Abstract
BACKGROUND The electrochemical and spectroscopic investigation of bacterial electron-transfer proteins stabilized on solid state electrodes has provided an effective approach for functional respiratory enzyme studies. METHODS We assess the biocompatibility of carboxylated graphene oxide (CGO) functionalized with Nickel nitrilotriacetic groups (CGO-NiNTA) ccordinating His-tagged cytochrome c oxidase (CcO) from Rhodobacter sphaeroides. RESULTS Kinetic studies employing UV-visible absorption spectroscopy confirmed that the immobilized CcO oxidized horse-heart cytochrome c (Cyt c) albeit at a slower rate than isolated CcO. The oxygen reduction reaction as catalyzed by immobilized CcO could be clearly distinguished from that arising from CGO-NiNTA in the presence of Cyt c and dithiothreitol (DTT) as a sacrificial reducing agent. Our findings indicate that while the protein content is about 3.7‰ by mass with respect to the support, the contribution to the oxygen consumption activity averaged at 56.3%. CONCLUSIONS The CGO-based support stabilizes the free enzyme which, while capable of Cyt c oxidation, is unable to carry out oxygen consumption in solution on its own under our conditions. The turnover rate for the immobilized CcO was as high as 240 O2 molecules per second per CcO unit. GENERAL SIGNIFICANCE In vitro investigations of electron flow on isolated components of bacterial electron-transfer enzymes immobilized on the surface of CGO in suspension are expected to shed new light on microbial bioenergetic functions, that could ultimately contribute toward the improvement of performance in living organisms.
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Affiliation(s)
- Xiaoping Zhu
- Department of Chemistry and Environmental Science, Medgar Evers College of the City University of New York (CUNY), Brooklyn, NY 11225, USA
| | - Erika Aoyama
- Department of Chemistry, The University of Utah, Salt Lake City, UT 84112, USA
| | - Alexander V Birk
- Department of Chemistry and Environmental Science, Medgar Evers College of the City University of New York (CUNY), Brooklyn, NY 11225, USA; Department of Biology, York College of CUNY, Jamaica, NY 11451, USA
| | - Oladapo Onasanya
- Department of Chemistry and Environmental Science, Medgar Evers College of the City University of New York (CUNY), Brooklyn, NY 11225, USA
| | - William H Carr
- Department of Biology, Medgar Evers College of the City University of New York (CUNY), Brooklyn, NY 11225, USA
| | - Lev Mourokh
- Department of Physics, Queens College of CUNY, Queens, NY 11367, USA; The Graduate Center of CUNY, New York, NY 10016, USA
| | - Shelley D Minteer
- Department of Chemistry, The University of Utah, Salt Lake City, UT 84112, USA
| | - Michele Vittadello
- Department of Chemistry and Environmental Science, Medgar Evers College of the City University of New York (CUNY), Brooklyn, NY 11225, USA; The Graduate Center of CUNY, New York, NY 10016, USA.
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8
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Sun X, Niu H, Song J, Jiang D, Leng J, Zhuang W, Chen Y, Liu D, Ying H. Preparation of a Copper Polyphosphate Kinase Hybrid Nanoflower and Its Application in ADP Regeneration from AMP. ACS OMEGA 2020; 5:9991-9998. [PMID: 32391487 PMCID: PMC7203986 DOI: 10.1021/acsomega.0c00329] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 01/23/2020] [Accepted: 04/07/2020] [Indexed: 06/11/2023]
Abstract
In this research article, we reported a self-assembly approach to prepare a copper polyphosphate kinase 2 hybrid nanoflower and established a cofactor ADP regeneration system from AMP using the nanoflower. First, the structure of the hybrid nanoflower was confirmed by scanning electron microscopy, X-ray diffraction, Fourier transform infrared spectroscopy, and X-ray photoelectron spectroscopy, which indicated the successful loading of the enzyme in the hybrid nanoflower. Moreover, compared to the free enzyme, the hybrid nanoflower exhibited a better performance in ADP production and possessed wider catalytic pH and temperature ranges as well as improved storage stability. The hybrid nanoflower also exhibited well reusability, preserving 71.7% of initial activity after being used for ten cycles. In addition, the phosphorylation of glucose was conducted by utilizing ADP-dependent glucokinase coupled with the ADP regeneration system, in which the hybrid nanoflower was used for regenerating ADP from AMP. It was observed that the ADP regeneration system operated effectively at a very small amount of AMP. Thus, the hybrid nanoflower had great application potential in industrial catalytic processes that were coupled with ADP-dependent enzymes.
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Affiliation(s)
- Xinzeng Sun
- State Key Laboratory
of Materials-Oriented Chemical Engineering, Nanjing Tech University, No. 5, Xinmofan Road, Nanjing 210009, P. R. China
- College
of Biotechnology and Pharmaceutical Engineering, National Engineering
Technique Research Center for Biotechnology, Nanjing Tech University, No. 30, Puzhu South Road, Nanjing 211816, P. R. China
| | - Huanqing Niu
- State Key Laboratory
of Materials-Oriented Chemical Engineering, Nanjing Tech University, No. 5, Xinmofan Road, Nanjing 210009, P. R. China
- College
of Biotechnology and Pharmaceutical Engineering, National Engineering
Technique Research Center for Biotechnology, Nanjing Tech University, No. 30, Puzhu South Road, Nanjing 211816, P. R. China
| | - Jiarui Song
- State Key Laboratory
of Materials-Oriented Chemical Engineering, Nanjing Tech University, No. 5, Xinmofan Road, Nanjing 210009, P. R. China
- College
of Biotechnology and Pharmaceutical Engineering, National Engineering
Technique Research Center for Biotechnology, Nanjing Tech University, No. 30, Puzhu South Road, Nanjing 211816, P. R. China
| | - Dahai Jiang
- State Key Laboratory
of Materials-Oriented Chemical Engineering, Nanjing Tech University, No. 5, Xinmofan Road, Nanjing 210009, P. R. China
- College
of Biotechnology and Pharmaceutical Engineering, National Engineering
Technique Research Center for Biotechnology, Nanjing Tech University, No. 30, Puzhu South Road, Nanjing 211816, P. R. China
| | - Jing Leng
- State Key Laboratory
of Materials-Oriented Chemical Engineering, Nanjing Tech University, No. 5, Xinmofan Road, Nanjing 210009, P. R. China
- College
of Biotechnology and Pharmaceutical Engineering, National Engineering
Technique Research Center for Biotechnology, Nanjing Tech University, No. 30, Puzhu South Road, Nanjing 211816, P. R. China
| | - Wei Zhuang
- State Key Laboratory
of Materials-Oriented Chemical Engineering, Nanjing Tech University, No. 5, Xinmofan Road, Nanjing 210009, P. R. China
- College
of Biotechnology and Pharmaceutical Engineering, National Engineering
Technique Research Center for Biotechnology, Nanjing Tech University, No. 30, Puzhu South Road, Nanjing 211816, P. R. China
| | - Yong Chen
- State Key Laboratory
of Materials-Oriented Chemical Engineering, Nanjing Tech University, No. 5, Xinmofan Road, Nanjing 210009, P. R. China
- College
of Biotechnology and Pharmaceutical Engineering, National Engineering
Technique Research Center for Biotechnology, Nanjing Tech University, No. 30, Puzhu South Road, Nanjing 211816, P. R. China
| | - Dong Liu
- State Key Laboratory
of Materials-Oriented Chemical Engineering, Nanjing Tech University, No. 5, Xinmofan Road, Nanjing 210009, P. R. China
- College
of Biotechnology and Pharmaceutical Engineering, National Engineering
Technique Research Center for Biotechnology, Nanjing Tech University, No. 30, Puzhu South Road, Nanjing 211816, P. R. China
| | - Hanjie Ying
- State Key Laboratory
of Materials-Oriented Chemical Engineering, Nanjing Tech University, No. 5, Xinmofan Road, Nanjing 210009, P. R. China
- College
of Biotechnology and Pharmaceutical Engineering, National Engineering
Technique Research Center for Biotechnology, Nanjing Tech University, No. 30, Puzhu South Road, Nanjing 211816, P. R. China
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9
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Kruse F, Nguyen AD, Dragelj J, Schlesinger R, Heberle J, Mroginski MA, Weidinger IM. Characterisation of the Cyanate Inhibited State of Cytochrome c Oxidase. Sci Rep 2020; 10:3863. [PMID: 32123230 PMCID: PMC7052191 DOI: 10.1038/s41598-020-60801-0] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/22/2019] [Accepted: 02/17/2020] [Indexed: 12/22/2022] Open
Abstract
Heme-copper oxygen reductases are terminal respiratory enzymes, catalyzing the reduction of dioxygen to water and the translocation of protons across the membrane. Oxygen consumption is inhibited by various substances. Here we tested the relatively unknown inhibition of cytochrome c oxidase (CcO) with isocyanate. In contrast to other more common inhibitors like cyanide, inhibition with cyanate was accompanied with the rise of a metal to ligand charge transfer (MLCT) band around 638 nm. Increasing the cyanate concentration furthermore caused selective reduction of heme a. The presence of the CT band allowed for the first time to directly monitor the nature of the ligand via surface-enhanced resonance Raman (SERR) spectroscopy. Analysis of isotope sensitive SERR spectra in comparison with Density Functional Theory (DFT) calculations identified not only the cyanate monomer as an inhibiting ligand but suggested also presence of an uretdion ligand formed upon dimerization of two cyanate ions. It is therefore proposed that under high cyanate concentrations the catalytic site of CcO promotes cyanate dimerization. The two excess electrons that are supplied from the uretdion ligand lead to the observed physiologically inverse electron transfer from heme a3 to heme a.
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Affiliation(s)
- Fabian Kruse
- Technische Universität Dresden, Department of Chemistry and Food Chemistry, 01069, Dresden, Germany
| | - Anh Duc Nguyen
- Technische Universität Berlin, Department of Chemistry, Strasse des 17. Juni 135, 10623, Berlin, Germany
| | - Jovan Dragelj
- Technische Universität Berlin, Department of Chemistry, Strasse des 17. Juni 135, 10623, Berlin, Germany
| | - Ramona Schlesinger
- Freie Universität Berlin, Department of Physics, Arnimallee 14, 14195, Berlin, Germany
| | - Joachim Heberle
- Freie Universität Berlin, Department of Physics, Arnimallee 14, 14195, Berlin, Germany
| | - Maria Andrea Mroginski
- Technische Universität Berlin, Department of Chemistry, Strasse des 17. Juni 135, 10623, Berlin, Germany
| | - Inez M Weidinger
- Technische Universität Dresden, Department of Chemistry and Food Chemistry, 01069, Dresden, Germany.
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10
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Björck ML, Vilhjálmsdóttir J, Hartley AM, Meunier B, Näsvik Öjemyr L, Maréchal A, Brzezinski P. Proton-transfer pathways in the mitochondrial S. cerevisiae cytochrome c oxidase. Sci Rep 2019; 9:20207. [PMID: 31882860 PMCID: PMC6934443 DOI: 10.1038/s41598-019-56648-9] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/21/2019] [Accepted: 12/16/2019] [Indexed: 02/04/2023] Open
Abstract
In cytochrome c oxidase (CytcO) reduction of O2 to water is linked to uptake of eight protons from the negative side of the membrane: four are substrate protons used to form water and four are pumped across the membrane. In bacterial oxidases, the substrate protons are taken up through the K and the D proton pathways, while the pumped protons are transferred through the D pathway. On the basis of studies with CytcO isolated from bovine heart mitochondria, it was suggested that in mitochondrial CytcOs the pumped protons are transferred though a third proton pathway, the H pathway, rather than through the D pathway. Here, we studied these reactions in S. cerevisiae CytcO, which serves as a model of the mammalian counterpart. We analyzed the effect of mutations in the D (Asn99Asp and Ile67Asn) and H pathways (Ser382Ala and Ser458Ala) and investigated the kinetics of electron and proton transfer during the reaction of the reduced CytcO with O2. No effects were observed with the H pathway variants while in the D pathway variants the functional effects were similar to those observed with the R. sphaeroides CytcO. The data indicate that the S. cerevisiae CytcO uses the D pathway for proton uptake and presumably also for proton pumping.
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Affiliation(s)
- Markus L Björck
- Department of Biochemistry and Biophysics, The Arrhenius Laboratories for Natural Sciences, Stockholm University, SE-106 91, Stockholm, Sweden
| | - Jóhanna Vilhjálmsdóttir
- Department of Biochemistry and Biophysics, The Arrhenius Laboratories for Natural Sciences, Stockholm University, SE-106 91, Stockholm, Sweden
| | - Andrew M Hartley
- Department of Biological Sciences, Birkbeck University of London, Malet Street, London, WC1E 7HX, UK
| | - Brigitte Meunier
- Institute for Integrative Biology of the Cell (12BC), CEA, CNRS, Université Paris-Sud, Université Paris-Saclay, 91198, Gif-sur-Yvette, France
| | - Linda Näsvik Öjemyr
- Department of Biochemistry and Biophysics, The Arrhenius Laboratories for Natural Sciences, Stockholm University, SE-106 91, Stockholm, Sweden
| | - Amandine Maréchal
- Department of Biological Sciences, Birkbeck University of London, Malet Street, London, WC1E 7HX, UK. .,Department 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.
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11
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Vilhjálmsdóttir J, Albertsson I, Blomberg MRA, Ädelroth P, Brzezinski P. Proton transfer in uncoupled variants of cytochrome c oxidase. FEBS Lett 2019; 594:813-822. [PMID: 31725900 DOI: 10.1002/1873-3468.13679] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/30/2019] [Revised: 10/31/2019] [Accepted: 11/09/2019] [Indexed: 11/08/2022]
Abstract
Cytochrome c oxidase is a membrane-bound redox-driven proton pump that harbors two proton-transfer pathways, D and K, which are used at different stages of the reaction cycle. Here, we address the question if a D pathway with a modified energy landscape for proton transfer could take over the role of the K pathway when the latter is blocked by a mutation. Our data indicate that structural alterations near the entrance of the D pathway modulate energy barriers that influence proton transfer to the proton-loading site. The data also suggest that during reduction of the catalytic site, its protonation has to occur via the K pathway and that this proton transfer to the catalytic site cannot take place through the D pathway.
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Affiliation(s)
- Jóhanna Vilhjálmsdóttir
- Department of Biochemistry and Biophysics, The Arrhenius Laboratories for Natural Sciences, Stockholm University, Sweden
| | - Ingrid Albertsson
- Department of Biochemistry and Biophysics, The Arrhenius Laboratories for Natural Sciences, Stockholm University, Sweden
| | - Margareta R A Blomberg
- Department of Organic Chemistry, The Arrhenius Laboratories for Natural Sciences, Stockholm University, Sweden
| | - Pia Ädelroth
- Department of Biochemistry and Biophysics, The Arrhenius Laboratories for Natural Sciences, Stockholm University, Sweden
| | - Peter Brzezinski
- Department of Biochemistry and Biophysics, The Arrhenius Laboratories for Natural Sciences, Stockholm University, Sweden
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12
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Kokhan O, Marzolf DR. Detection and quantification of transition metal leaching in metal affinity chromatography with hydroxynaphthol blue. Anal Biochem 2019; 582:113347. [PMID: 31251926 DOI: 10.1016/j.ab.2019.113347] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/29/2019] [Revised: 06/13/2019] [Accepted: 06/24/2019] [Indexed: 11/17/2022]
Abstract
The widespread use of immobilized metal-affinity chromatography (IMAC) for fast and efficient purification of recombinant proteins has brought potentially toxic transition elements into common laboratory usage. However, there are few studies on the leaching of metal from the affinity resin, such as nickel-nitrilotriacetic acid (Ni-NTA), with possible deleterious impact on the biological activity. This is of particular importance when reducing or chelating eluants stronger than imidazole are used. We present a detailed study of hydroxynaphthol blue (HNB) as an indicator of several divalent metal cations, but with emphasis on Ni2+, clarifying and correcting many errors and ambiguities in the older literature on this dye compound. The assay is simple and sensitive and many metals, notably Ni2+, Zn2+, Cu2+, Pb2+, Fe2+, Co2+, and Al3+, can be readily detected and quantified at concentrations down to 15-50 nM (1-5 ppb) at neutral pH and in most commonly used buffers using spectroscopic equipment available in typical biochemistry research labs. Using this method, we show that significant amounts of Ni2+ (up to 20 mM) are co-purified with a target protein (cytochrome bc1 complex) when histidine is used to elute from Ni-NTA resin.
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Affiliation(s)
- Oleksandr Kokhan
- Department of Chemistry and Biochemistry, James Madison University, 901 Carrier Drive, Harrisonburg, VA, 22807, USA.
| | - Daniel R Marzolf
- Department of Chemistry and Biochemistry, James Madison University, 901 Carrier Drive, Harrisonburg, VA, 22807, USA
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13
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Niu H, Ding M, Sun X, Zhuang W, Liu D, Ying H, Zhu C, Chen Y. Immobilization of a polyphosphate kinase 2 by coordinative self-assembly of his-tagged units with metal-organic frameworks and its application in ATP regeneration from AMP. Colloids Surf B Biointerfaces 2019; 181:261-269. [PMID: 31153021 DOI: 10.1016/j.colsurfb.2019.05.054] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/23/2019] [Revised: 05/21/2019] [Accepted: 05/22/2019] [Indexed: 12/11/2022]
Abstract
Self-assembly of the functional units onto the surface of nanoparticles is a powerful approach to generate functional nanosystems. In this work, we first expressed a recombinant class III polyphosphate kinase 2 (ArPPK2) with his-tag. It is able to synthesize ATP from AMP by a single enzyme, simplifying two-step reaction of ATP regeneration from AMP. Then we chose the Fe-based metal-organic frameworks (MOF)s as carriers to produce the enzyme-MOF biocomposite, based on the interaction between the his-tags and coordinatively unsaturated metal sites present on the external surface of MOFs by a self-assembly process. It was found that ArPPK2@MIL-101-NH2@Fe3O4-COOH exhibited better reusability than other candidates during cycle analysis, preserving 70.1% of initial activity after reusing thirteen times, and also retained high storage stability. The optimum pH of the enzyme-MOF biocomposite was increased from 8.0 to 9.0 and the optimum temperature was increased from 30℃ to 45℃. Compared to free ArPPK2, the enzyme-MOF biocomposite showed increased thermal and pH stability. In addition, we successfully constructed an ATP regeneration system from AMP using the enzyme-MOF biocomposite, coupled with amide bond formation catalyzed by the adenylation domain of tyrocidine synthetase A (TycA-A). The immobilized ArPPK2 will provide a promising route for ATP regeneration from AMP in industrial processes. And the generation of the enzyme-MOF biocomposite by the self-assembly approach can be extended to efficiently immobilize other recombinant his-tagged enzymes.
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Affiliation(s)
- Huanqing Niu
- State Key Laboratory of Materials-Oriented Chemical Engineering, Nanjing Tech University, No. 5, Xinmofan Road, Nanjing, 210009, PR China; College of Biotechnology and Pharmaceutical Engineering, National Engineering Technique Research Center for Biotechnology, Nanjing Tech University, No. 30, Puzhu South Road, Nanjing, 211816, PR China
| | - Menglin Ding
- College of Biotechnology and Pharmaceutical Engineering, National Engineering Technique Research Center for Biotechnology, Nanjing Tech University, No. 30, Puzhu South Road, Nanjing, 211816, PR China
| | - Xinzeng Sun
- College of Biotechnology and Pharmaceutical Engineering, National Engineering Technique Research Center for Biotechnology, Nanjing Tech University, No. 30, Puzhu South Road, Nanjing, 211816, PR China
| | - Wei Zhuang
- State Key Laboratory of Materials-Oriented Chemical Engineering, Nanjing Tech University, No. 5, Xinmofan Road, Nanjing, 210009, PR China; College of Biotechnology and Pharmaceutical Engineering, National Engineering Technique Research Center for Biotechnology, Nanjing Tech University, No. 30, Puzhu South Road, Nanjing, 211816, PR China
| | - Dong Liu
- State Key Laboratory of Materials-Oriented Chemical Engineering, Nanjing Tech University, No. 5, Xinmofan Road, Nanjing, 210009, PR China; College of Biotechnology and Pharmaceutical Engineering, National Engineering Technique Research Center for Biotechnology, Nanjing Tech University, No. 30, Puzhu South Road, Nanjing, 211816, PR China
| | - Hanjie Ying
- State Key Laboratory of Materials-Oriented Chemical Engineering, Nanjing Tech University, No. 5, Xinmofan Road, Nanjing, 210009, PR China; College of Biotechnology and Pharmaceutical Engineering, National Engineering Technique Research Center for Biotechnology, Nanjing Tech University, No. 30, Puzhu South Road, Nanjing, 211816, PR China
| | - Chenjie Zhu
- State Key Laboratory of Materials-Oriented Chemical Engineering, Nanjing Tech University, No. 5, Xinmofan Road, Nanjing, 210009, PR China; College of Biotechnology and Pharmaceutical Engineering, National Engineering Technique Research Center for Biotechnology, Nanjing Tech University, No. 30, Puzhu South Road, Nanjing, 211816, PR China.
| | - Yong Chen
- State Key Laboratory of Materials-Oriented Chemical Engineering, Nanjing Tech University, No. 5, Xinmofan Road, Nanjing, 210009, PR China; College of Biotechnology and Pharmaceutical Engineering, National Engineering Technique Research Center for Biotechnology, Nanjing Tech University, No. 30, Puzhu South Road, Nanjing, 211816, PR China.
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14
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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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15
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Vygodina TV, Kaminskaya OP, Konstantinov AA, Ptushenko VV. Effect of Ca 2+ on the redox potential of heme a in cytochrome c oxidase. Biochimie 2018; 149:71-78. [PMID: 29635042 DOI: 10.1016/j.biochi.2018.04.005] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/30/2017] [Accepted: 04/04/2018] [Indexed: 11/19/2022]
Abstract
Subunit I of cytochrome c oxidase (CcO) from mitochondria and many bacteria contains a cation binding site (CBS) located at the outer positively charged aqueous phase not far from heme a. Binding of Ca2+ with the CBS in bovine CcO inhibits activity of the enzyme 2-3 -fold [Vygodina, T., Kirichenko, A. & Konstantinov A.A. (2013) Direct Regulation of Cytochrome c Oxidase by Calcium Ions, PLoS One.8 e74436]. Here we show that binding of Ca2+ at CBS of bovine CcO shifts Em of heme a to the positive by 15-20 mV. Na+ ions that bind to the same site and compete with Ca2+ do not affect Em of heme a and also prevent and reverse the effect of Ca2+. No effect of Ca2+ or EGTA is observed on Em of heme a with the wild type bacterial oxidases from R.sphaeroides or P.denitrificans that contain tightly-bound calcium at the site. In the D477A mutant CcO from P. denitrificans that binds Ca2+ reversibly like the mitochondrial CcO, calcium shifts redox titration curve of heme a to the positive by ∼35-50 mV that is in good agreement with the results of electrostatic calculations; however, as shown earlier, it does not inhibit CcO activity of the mutant enzyme. Therefore the data do not support the proposal that the inhibitory effect of Ca2+ on CcO activity may be explained by the Ca2+-induced shift of Em of heme a. Rather, Ca2+ retards electron transfer by inhibition of charge dislocation in the exit part of the proton channel H in mammalian CcO, that is absent in the bacterial oxidases.
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Affiliation(s)
- Tatiana V Vygodina
- A.N.Belozersky Institute of Physico-Chemical Biology, Moscow State University, Moscow, Russia
| | - Olga P Kaminskaya
- Institute of Basic Biological Problems, Russian Academy of Sciences, Pushchino, Moscow Region, 142290, Russia
| | | | - Vasily V Ptushenko
- A.N.Belozersky Institute of Physico-Chemical Biology, Moscow State University, Moscow, Russia; N.M.Emanuel Institute of Biochemical Physics, Russian Academy of Sciences, Moscow, Russia.
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16
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Mohrmann H, Dragelj J, Baserga F, Knapp EW, Stripp ST, Heberle J. The reductive phase of Rhodobacter sphaeroides cytochrome c oxidase disentangled by CO ligation. Phys Chem Chem Phys 2017. [PMID: 29067359 DOI: 10.1039/c7cp06480b] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Cytochrome c oxidase (CcO) is a membrane protein of the respiratory chain that catalytically reduces molecular oxygen (O2) to water while translocating protons across the membrane. The enzyme hosts two copper and two heme iron moieties (heme a/heme a3). The atomic details of the sequential steps that go along with this redox-driven proton translocation are a matter of debate. Particularly for the reductive phase of CcO that precedes oxygen binding experimental data are scarce. Here, we use CcO under anaerobic conditions where carbon monoxide (CO) is bound to heme a3 which in tandem with CuB forms the binuclear center (BNC). Fourier-transform infrared (FTIR) absorption spectroscopy is combined with electro-chemistry to probe different redox and protonation states populated by variation of the external electrostatic potential. With this approach, the redox behavior of heme a and the BNC could be separated and the corresponding redox potentials were determined. We also infer the protonation of one of the propionate side chains of heme a3 to correlate with the oxidation of heme a. Experimental changes in the local electric field surrounding CO bound to heme a3 are determined by their vibrational Stark effect and agree well with electrostatic computations. The comparison of experimental and computational results indicates that changes of the heme a3/CuB redox state are coupled to proton transfer towards heme a3. The latter supports the role of the heme a3 propionate D as proton loading site.
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Affiliation(s)
- Hendrik Mohrmann
- Experimental Molecular Biophysics, Freie Universität Berlin, Arnimallee 14, 14195 Berlin, Germany.
| | - Jovan Dragelj
- Institute of Chemistry and Biochemistry, Freie Universität Berlin, Fabeckstraße 36A, 14195 Berlin, Germany
| | - Federico Baserga
- Experimental Molecular Biophysics, Freie Universität Berlin, Arnimallee 14, 14195 Berlin, Germany.
| | - Ernst-Walter Knapp
- Institute of Chemistry and Biochemistry, Freie Universität Berlin, Fabeckstraße 36A, 14195 Berlin, Germany
| | - Sven T Stripp
- Experimental Molecular Biophysics, Freie Universität Berlin, Arnimallee 14, 14195 Berlin, Germany.
| | - Joachim Heberle
- Experimental Molecular Biophysics, Freie Universität Berlin, Arnimallee 14, 14195 Berlin, Germany.
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17
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Xu L, Öjemyr LN, Bergstrand J, Brzezinski P, Widengren J. Protonation Dynamics on Lipid Nanodiscs: Influence of the Membrane Surface Area and External Buffers. Biophys J 2017; 110:1993-2003. [PMID: 27166807 PMCID: PMC4939474 DOI: 10.1016/j.bpj.2016.03.035] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/21/2015] [Revised: 02/11/2016] [Accepted: 03/07/2016] [Indexed: 11/29/2022] Open
Abstract
Lipid membrane surfaces can act as proton-collecting antennae, accelerating proton uptake by membrane-bound proton transporters. We investigated this phenomenon in lipid nanodiscs (NDs) at equilibrium on a local scale, analyzing fluorescence fluctuations of individual pH-sensitive fluorophores at the membrane surface by fluorescence correlation spectroscopy (FCS). The protonation rate of the fluorophores was ∼100-fold higher when located at 9- and 12-nm diameter NDs, compared to when in solution, indicating that the proton-collecting antenna effect is maximal already for a membrane area of ∼60 nm2. Fluorophore-labeled cytochrome c oxidase displayed a similar increase when reconstituted in 12 nm NDs, but not in 9 nm NDs, i.e., an acceleration of the protonation rate at the surface of cytochrome c oxidase is found when the lipid area surrounding the protein is larger than 80 nm2, but not when below 30 nm2. We also investigated the effect of external buffers on the fluorophore proton exchange rates at the ND membrane-water interfaces. With increasing buffer concentrations, the proton exchange rates were found to first decrease and then, at millimolar buffer concentrations, to increase. Monte Carlo simulations, based on a simple kinetic model of the proton exchange at the membrane-water interface, and using rate parameter values determined in our FCS experiments, could reconstruct both the observed membrane-size and the external buffer dependence. The FCS data in combination with the simulations indicate that the local proton diffusion coefficient along a membrane is ∼100 times slower than that observed over submillimeter distances by proton-pulse experiments (Ds ∼ 10−5cm2/s), and support recent theoretical studies showing that proton diffusion along membrane surfaces is time- and length-scale dependent.
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Affiliation(s)
- Lei Xu
- Experimental Biomolecular Physics, Department of Applied Physics, KTH-Royal Institute of Technology, AlbaNova University Center, Stockholm, Sweden
| | - Linda Näsvik Öjemyr
- Department of Biochemistry and Biophysics, Arrhenius Laboratories for Natural Sciences, Stockholm University, Stockholm, Sweden
| | - Jan Bergstrand
- Experimental Biomolecular Physics, Department of Applied Physics, KTH-Royal Institute of Technology, AlbaNova University Center, Stockholm, Sweden
| | - Peter Brzezinski
- Department of Biochemistry and Biophysics, Arrhenius Laboratories for Natural Sciences, Stockholm University, Stockholm, Sweden
| | - Jerker Widengren
- Experimental Biomolecular Physics, Department of Applied Physics, KTH-Royal Institute of Technology, AlbaNova University Center, Stockholm, Sweden.
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18
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Redox induced protonation of heme propionates in cytochrome c oxidase: Insights from surface enhanced resonance Raman spectroscopy and QM/MM calculations. BIOCHIMICA ET BIOPHYSICA ACTA-BIOENERGETICS 2016; 1858:103-108. [PMID: 27810193 DOI: 10.1016/j.bbabio.2016.10.009] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/22/2016] [Revised: 10/18/2016] [Accepted: 10/28/2016] [Indexed: 12/16/2022]
Abstract
Understanding the coupling between heme reduction and proton translocation in cytochrome c oxidase (CcO) is still an open problem. The propionic acids of heme a3 have been proposed to act as a proton loading site (PLS) in the proton pumping pathway, yet this proposal could not be verified by experimental data so far. We have set up an experiment where the redox states of the two hemes in CcO can be controlled via external electrical potential. Surface enhanced resonance Raman (SERR) spectroscopy was applied to simultaneously monitor the redox state of the hemes and the protonation state of the heme propionates. Simulated spectra based on QM/MM calculations were used to assign the resonant enhanced CH2 twisting modes of the propionates to the protonation state of the individual heme a and heme a3 propionates respectively. The comparison between calculated and measured H2OD2O difference spectra allowed a sound band assignment. In the fully reduced enzyme at least three of the four heme propionates were found to be protonated whereas in the presence of a reduced heme a and an oxidized heme a3 only protonation of one heme a3 propionates was observed. Our data supports the postulated scenario where the heme a3 propionates are involved in the proton pathway.
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19
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Cassano JA, Choi SK, McDonald W, Szundi I, Villa Gawboy TR, Gennis RB, Einarsdóttir Ó. The CO Photodissociation and Recombination Dynamics of the W172Y/F282T Ligand Channel Mutant of Rhodobacter sphaeroides aa3 Cytochrome c Oxidase. Photochem Photobiol 2016; 92:410-9. [PMID: 27029379 DOI: 10.1111/php.12587] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/31/2015] [Accepted: 02/25/2016] [Indexed: 12/26/2022]
Abstract
In the ligand channel of the cytochrome c oxidase from Rhodobacter sphaeroides (Rs aa3 ) W172 and F282 have been proposed to generate a constriction that may slow ligand access to and from the active site. To explore this issue, the tryptophan and phenylalanine residues in Rs aa3 were mutated to the less bulky tyrosine and threonine residues, respectively, which occupy these sites in Thermus thermophilus (Tt) ba3 cytochrome oxidase. The CO photolysis and recombination dynamics of the reduced wild-type Rs aa3 and the W172Y/F282T mutant were investigated using time-resolved optical absorption spectroscopy. The spectral changes associated with the multiple processes are attributed to different conformers. The major CO recombination process (44 μs) in the W172Y/F282T mutant is ~500 times faster than the predominant CO recombination process in the wild-type enzyme (~23 ms). Classical dynamic simulations of the wild-type enzyme and double mutant showed significant structural changes at the active site in the mutant, including movement of the heme a3 ring-D propionate toward CuB and reduced binuclear center cavity volume. These structural changes effectively close the ligand exit pathway from the binuclear center, providing a basis for the faster CO recombination in the double mutant.
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Affiliation(s)
- Jennifer A Cassano
- Department of Chemistry and Biochemistry, University of California, Santa Cruz, CA
| | - Sylvia K Choi
- Center for Biophysics and Computational Biology, Department of Chemistry, University of Illinois at Urbana-Champaign, Urbana, IL
| | - William McDonald
- Department of Chemistry and Biochemistry, University of California, Santa Cruz, CA
| | - Istvan Szundi
- Department of Chemistry and Biochemistry, University of California, Santa Cruz, CA
| | - Terra R Villa Gawboy
- Department of Chemistry and Biochemistry, University of California, Santa Cruz, CA
| | - Robert B Gennis
- Center for Biophysics and Computational Biology, Department of Chemistry, University of Illinois at Urbana-Champaign, Urbana, IL
| | - Ólöf Einarsdóttir
- Department of Chemistry and Biochemistry, University of California, Santa Cruz, CA
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20
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von Ballmoos C, Biner O, Nilsson T, Brzezinski P. Mimicking respiratory phosphorylation using purified enzymes. BIOCHIMICA ET BIOPHYSICA ACTA-BIOENERGETICS 2015; 1857:321-31. [PMID: 26707617 DOI: 10.1016/j.bbabio.2015.12.007] [Citation(s) in RCA: 37] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Key Words] [Subscribe] [Scholar Register] [Received: 08/17/2015] [Revised: 11/17/2015] [Accepted: 12/16/2015] [Indexed: 11/26/2022]
Abstract
The enzymes of oxidative phosphorylation is a striking example of the functional association of multiple enzyme complexes, working together to form ATP from cellular reducing equivalents. These complexes, such as cytochrome c oxidase or the ATP synthase, are typically investigated individually and therefore, their functional interplay is not well understood. Here, we present methodology that allows the co-reconstitution of purified terminal oxidases and ATP synthases in synthetic liposomes. The enzymes are functionally coupled via proton translocation where upon addition of reducing equivalents the oxidase creates and maintains a transmembrane electrochemical proton gradient that energizes the synthesis of ATP by the F1F0 ATP synthase. The method has been tested with the ATP synthases from Escherichia coli and spinach chloroplasts, and with the quinol and cytochrome c oxidases from E. coli and Rhodobacter sphaeroides, respectively. Unlike in experiments with the ATP synthase reconstituted alone, the setup allows in vitro ATP synthesis under steady state conditions, with rates up to 90 ATP×s(-1)×enzyme(-1). We have also used the novel system to study the phenomenon of "mild uncoupling" as observed in mitochondria upon addition of low concentrations of ionophores (e.g. FCCP, SF6847) and the recoupling effect of 6-ketocholestanol. While we could reproduce the described effects, our data with the in vitro system does not support the idea of a direct interaction between a mitochondrial protein and the uncoupling agents as proposed earlier.
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Affiliation(s)
- Christoph von Ballmoos
- Department of Chemistry and Biochemistry, University of Bern, Freiestrasse 3, 3012 Bern, Switzerland.
| | - Olivier Biner
- Department of Chemistry and Biochemistry, University of Bern, Freiestrasse 3, 3012 Bern, Switzerland
| | - Tobias Nilsson
- Department of Biochemistry and Biophysics, The Arrhenius Laboratories for Natural Sciences, Stockholm University, SE-106 91 Stockholm, Sweden
| | - Peter Brzezinski
- Department of Biochemistry and Biophysics, The Arrhenius Laboratories for Natural Sciences, Stockholm University, SE-106 91 Stockholm, Sweden
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21
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Vilhjálmsdóttir J, Johansson AL, Brzezinski P. Structural Changes and Proton Transfer in Cytochrome c Oxidase. Sci Rep 2015; 5:12047. [PMID: 26310633 PMCID: PMC4550891 DOI: 10.1038/srep12047] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/30/2015] [Accepted: 06/16/2015] [Indexed: 01/28/2023] Open
Abstract
In cytochrome c oxidase electron transfer from cytochrome c to O2 is linked to transmembrane proton pumping, which contributes to maintaining a proton electrochemical gradient across the membrane. The mechanism by which cytochrome c oxidase couples the exergonic electron transfer to the endergonic proton translocation is not known, but it presumably involves local structural changes that control the alternating proton access to the two sides of the membrane. Such redox-induced structural changes have been observed in X-ray crystallographic studies at residues 423-425 (in the R. sphaeroides oxidase), located near heme a. The aim of the present study is to investigate the functional effects of these structural changes on reaction steps associated with proton pumping. Residue Ser425 was modified using site-directed mutagenesis and time-resolved spectroscopy was used to investigate coupled electron-proton transfer upon reaction of the oxidase with O2. The data indicate that the structural change at position 425 propagates to the D proton pathway, which suggests a link between redox changes at heme a and modulation of intramolecular proton-transfer rates.
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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
| | - Ann-Louise Johansson
- Department of Biochemistry and Biophysics, The Arrhenius Laboratories for Natural Sciences, Stockholm University, SE-106 91 Stockholm, Sweden
| | - Peter Brzezinski
- Department of Biochemistry and Biophysics, The Arrhenius Laboratories for Natural Sciences, Stockholm University, SE-106 91 Stockholm, Sweden
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22
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Sezer M, Kielb P, Kuhlmann U, Mohrmann H, Schulz C, Heinrich D, Schlesinger R, Heberle J, Weidinger IM. Surface Enhanced Resonance Raman Spectroscopy Reveals Potential Induced Redox and Conformational Changes of Cytochrome c Oxidase on Electrodes. J Phys Chem B 2015; 119:9586-91. [PMID: 26135359 DOI: 10.1021/acs.jpcb.5b03206] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
Immobilization of Cytochrome c oxidase (CcO) on electrodes makes voltage-driven reduction of oxygen to water possible. Efficient catalytic turnover in CcO/electrode systems is, however, often observed at large overpotentials that cannot be rationalized by the redox properties of the enzyme itself. To understand the structural basis for this observation, CcO was electrostatically adsorbed on amino-functionalized Ag electrodes, and the redox transitions of heme a and a3 were monitored via surface enhanced resonance Raman spectroscopy (SERRS) as a function of applied potential. Under completely anaerobic conditions, the reduction of heme a3 could be seen at potentials close to those measured in solution indicating an intact catalytic center. However, in the immobilized state, a new non-native heme species was observed that exhibited a redox potential much more negative than measured for the native hemes. Analysis of the high and low frequency SERR spectra indicated that this new species is formed from heme a upon axial loss of one histidine ligand. It is concluded that the formation of the non-native heme a species alters the potential-dependent electron supply to the catalytic reaction and, thus, can have a impact on the applicability of this enzyme in biofuel cells.
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Affiliation(s)
- Murat Sezer
- †Institut für Chemie PC 14, Technische Universität Berlin, Strasse des 17. Juni 135, 10623 Berlin, Germany
| | - Patrycja Kielb
- †Institut für Chemie PC 14, Technische Universität Berlin, Strasse des 17. Juni 135, 10623 Berlin, Germany
| | - Uwe Kuhlmann
- †Institut für Chemie PC 14, Technische Universität Berlin, Strasse des 17. Juni 135, 10623 Berlin, Germany
| | - Hendrik Mohrmann
- ‡Institut für Experimentalphysik, Freie Universität Berlin, Arnimallee 14, 14195 Berlin, Germany
| | - Claudia Schulz
- †Institut für Chemie PC 14, Technische Universität Berlin, Strasse des 17. Juni 135, 10623 Berlin, Germany
| | - Dorothea Heinrich
- ‡Institut für Experimentalphysik, Freie Universität Berlin, Arnimallee 14, 14195 Berlin, Germany
| | - Ramona Schlesinger
- ‡Institut für Experimentalphysik, Freie Universität Berlin, Arnimallee 14, 14195 Berlin, Germany
| | - Joachim Heberle
- ‡Institut für Experimentalphysik, Freie Universität Berlin, Arnimallee 14, 14195 Berlin, Germany
| | - Inez M Weidinger
- †Institut für Chemie PC 14, Technische Universität Berlin, Strasse des 17. Juni 135, 10623 Berlin, Germany
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23
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Nordlund G, Brzezinski P, von Ballmoos C. SNARE-fusion mediated insertion of membrane proteins into native and artificial membranes. Nat Commun 2014; 5:4303. [DOI: 10.1038/ncomms5303] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/01/2014] [Accepted: 06/04/2014] [Indexed: 11/09/2022] Open
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24
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Svahn E, Faxén K, Gennis RB, Brzezinski P. Proton pumping by an inactive structural variant of cytochrome c oxidase. J Inorg Biochem 2014; 140:6-11. [PMID: 25042731 DOI: 10.1016/j.jinorgbio.2014.06.016] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/16/2014] [Revised: 06/23/2014] [Accepted: 06/23/2014] [Indexed: 12/12/2022]
Abstract
The aa3-type cytochrome c oxidases (CytcOs) from e.g. Rhodobacter sphaeroides and Paracoccus denitrificans harbor two proton-transfer pathways. The K pathway is used for proton uptake upon reduction of the CytcO, while the D pathway is used after binding of O2 to the catalytic site. The aim of the present study was to determine whether or not CytcO in which the K pathway is blocked (by e.g. the Lys362Met replacement) is capable of pumping protons. The process can not be studied using conventional assays because the O2-reduction activity is too low when the K pathway is blocked. Consequently, proton pumping with a blocked K pathway has not been demonstrated directly. Here, the Lys362Met and Ser299Glu structural variants were reconstituted in liposomes and allowed to (slowly) become completely reduced. Then, the reaction with O2 was studied with μs time resolution after flash photolysis of a blocking CO ligand bound to heme a3. The data show that with both the inactive Lys362Met and partly active Ser299Glu variants proton release occurred with the same time constants as with the wild-type oxidase, i.e. ~200μs and ~3ms, corresponding in time to formation of the ferryl and oxidized states, respectively. Thus, the data show that the K pathway is not required for proton pumping, suggesting that D and K pathways operate independently of each other after binding of O2 to the catalytic site.
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Affiliation(s)
- Emelie Svahn
- Department of Biochemistry and Biophysics, The Arrhenius Laboratories for Natural Sciences, Stockholm University, SE-106 91 Stockholm, Sweden
| | - Kristina Faxén
- 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, IL 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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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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26
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Vygodina T, Kirichenko A, Konstantinov AA. Direct regulation of cytochrome c oxidase by calcium ions. PLoS One 2013; 8:e74436. [PMID: 24058566 PMCID: PMC3769247 DOI: 10.1371/journal.pone.0074436] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/03/2013] [Accepted: 08/01/2013] [Indexed: 12/16/2022] Open
Abstract
Cytochrome c oxidase from bovine heart binds Ca2+ reversibly at a specific Cation Binding Site located near the outer face of the mitochondrial membrane. Ca2+ shifts the absorption spectrum of heme a, which allowed previously to determine the kinetics and equilibrium characteristics of the binding. However, no effect of Ca2+ on the functional characteristics of cytochrome oxidase was revealed earlier. Here we report that Ca2+ inhibits cytochrome oxidase activity of isolated bovine heart enzyme by 50–60% with Ki of ∼1 µM, close to Kd of calcium binding with the oxidase determined spectrophotometrically. The inhibition is observed only at low, but physiologically relevant, turnover rates of the enzyme (∼10 s−1 or less). No inhibitory effect of Ca2+ is observed under conventional conditions of cytochrome c oxidase activity assays (turnover number >100 s−1 at pH 8), which may explain why the effect was not noticed earlier. The inhibition is specific for Ca2+ and is reversed by EGTA. Na+ ions that compete with Ca2+ for binding with the Cation Binding Site, do not affect significantly activity of the enzyme but counteract the inhibitory effect of Ca2+. The Ca2+-induced inhibition of cytochrome c oxidase is observed also with the uncoupled mitochondria from several rat tissues. At the same time, calcium ions do not inhibit activity of the homologous bacterial cytochrome oxidases. Possible mechanisms of the inhibition are discussed as well as potential physiological role of Ca2+ binding with cytochrome oxidase. Ca2+- binding at the Cation Binding Site is proposed to inhibit proton-transfer through the exit part of the proton conducting pathway H in the mammalian oxidases.
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Affiliation(s)
- Tatiana Vygodina
- A. N. Belozersky Institute of Physico-Chemical Biology, M. V. Lomonosov Moscow State University, Moscow, Russia
| | - Anna Kirichenko
- A. N. Belozersky Institute of Physico-Chemical Biology, M. V. Lomonosov Moscow State University, Moscow, Russia
| | - Alexander A. Konstantinov
- A. N. Belozersky Institute of Physico-Chemical Biology, M. V. Lomonosov Moscow State University, Moscow, Russia
- * E-mail:
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Role of aspartate 132 at the orifice of a proton pathway in cytochrome c oxidase. Proc Natl Acad Sci U S A 2013; 110:8912-7. [PMID: 23674679 DOI: 10.1073/pnas.1303954110] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022] Open
Abstract
Proton transfer across biological membranes underpins central processes in biological systems, such as energy conservation and transport of ions and molecules. In the membrane proteins involved in these processes, proton transfer takes place through specific pathways connecting the two sides of the membrane via control elements within the protein. It is commonly believed that acidic residues are required near the orifice of such proton pathways to facilitate proton uptake. In cytochrome c oxidase, one such pathway starts near a conserved Asp-132 residue. Results from earlier studies have shown that replacement of Asp-132 by, e.g., Asn, slows proton uptake by a factor of ∼5,000. Here, we show that proton uptake at full speed (∼10(4) s(-1)) can be restored in the Asp-132-Asn oxidase upon introduction of a second structural modification further inside the pathway (Asn-139-Thr) without compensating for the loss of the negative charge. This proton-uptake rate was insensitive to Zn(2+) addition, which in the wild-type cytochrome c oxidase slows the reaction, indicating that Asp-132 is required for Zn(2+) binding. Furthermore, in the absence of Asp-132 and with Thr at position 139, at high pH (>9), proton uptake was significantly accelerated. Thus, the data indicate that Asp-132 is not strictly required for maintaining rapid proton uptake. Furthermore, despite the rapid proton uptake in the Asn-139-Thr/Asp-132-Asn mutant cytochrome c oxidase, proton pumping was impaired, which indicates that the segment around these residues is functionally linked to pumping.
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Johansson AL, Carlsson J, Högbom M, Hosler JP, Gennis RB, Brzezinski P. Proton uptake and pKa changes in the uncoupled Asn139Cys variant of cytochrome c oxidase. Biochemistry 2013; 52:827-36. [PMID: 23305515 DOI: 10.1021/bi301597a] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022]
Abstract
Cytochrome c oxidase (CytcO) is a membrane-bound enzyme that links electron transfer from cytochrome c to O(2) to proton pumping across the membrane. Protons are transferred through specific pathways that connect the protein surface with the catalytic site as well as the proton input with the proton output sides. Results from earlier studies have shown that one site within the so-called D proton pathway, Asn139, located ~10 Å from the protein surface, is particularly sensitive to mutations that uncouple the O(2) reduction reaction from the proton pumping activity. For example, none of the Asn139Asp (charged) or Asn139Thr (neutral) mutant CytcOs pump protons, although the proton-uptake rates are unaffected. Here, we have investigated the Asn139Cys and Asn139Cys/Asp132Asn mutant CytcOs. In contrast to other structural variants investigated to date, the Cys side chain may be either neutral or negatively charged in the experimentally accessible pH range. The data show that the Asn139Cys and Asn139Asp mutations result in the same changes of the kinetic and thermodynamic parameters associated with the proton transfer. The similarity is not due to introduction of charge at position 139, but rather introduction of a protonatable group that modulates the proton connectivity around this position. These results illuminate the mechanism by which CytcO couples electron transfer to proton pumping.
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Affiliation(s)
- Ann-Louise Johansson
- Department of Biochemistry and Biophysics, The Arrhenius Laboratories for Natural Sciences, Stockholm University, Stockholm, Sweden
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Vygodina TV, Dyuba AV, Konstantinov AA. Effect of calcium ions on electron transfer between hemes a and a 3 in cytochrome c oxidase. BIOCHEMISTRY (MOSCOW) 2012; 77:901-9. [DOI: 10.1134/s0006297912080111] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
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30
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Öjemyr LN, von Ballmoos C, Faxén K, Svahn E, Brzezinski P. The membrane modulates internal proton transfer in cytochrome c oxidase. Biochemistry 2012; 51:1092-100. [PMID: 22257086 DOI: 10.1021/bi201795c] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
The functionality of membrane proteins is often modulated by the surrounding membrane. Here, we investigated the effect of membrane reconstitution of purified cytochrome c oxidase (CytcO) on the kinetics and thermodynamics of internal electron and proton-transfer reactions during O(2) reduction. Reconstitution of the detergent-solubilized enzyme in small unilamellar soybean phosphatidylcholine vesicles resulted in a lowering of the pK(a) in the pH dependence profile of the proton-uptake rate. This pK(a) change resulted in decreased proton-uptake rates in the pH range of ~6.5-9.5, which is explained in terms of lowering of the pK(a) of an internal proton donor within CytcO. At pH 7.5, the rate decreased to the same extent when vesicles were prepared from the pure zwitterionic lipid 1,2-dioleoyl-sn-glycero-3-phosphocholine (DOPC) or the anionic lipid 1,2-dioleoyl-sn-glycero-3-phospho(1-rac-glycerol) (DOPG). In addition, a small change in the internal Cu(A)-heme a electron equilibrium constant was observed. This effect was lipid-dependent and explained in terms of a lower electrostatic potential within the membrane-spanning part of the protein with the anionic DOPG lipids than with the zwitterionic DOPC lipids. In conclusion, the data show that the membrane significantly modulates internal charge-transfer reactions and thereby the function of the membrane-bound enzyme.
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Affiliation(s)
- Linda Näsvik Öjemyr
- Department of Biochemistry and Biophysics, The Arrhenius Laboratories for Natural Sciences, Stockholm University, SE-106 91 Stockholm, Sweden
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Näsvik Öjemyr L, von Ballmoos C, Gennis RB, Sligar SG, Brzezinski P. Reconstitution of respiratory oxidases in membrane nanodiscs for investigation of proton-coupled electron transfer. FEBS Lett 2011; 586:640-5. [PMID: 22209982 DOI: 10.1016/j.febslet.2011.12.023] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/25/2011] [Revised: 12/19/2011] [Accepted: 12/21/2011] [Indexed: 12/31/2022]
Abstract
The function of membrane-bound transporters is commonly affected by the milieu of the hydrophobic, membrane-spanning part of the transmembrane protein. Consequently, functional studies of these proteins often involve incorporation into a native-like bilayer where the lipid components of the membrane can be controlled. The classical approach is to reconstitute the purified protein into liposomes. Even though the use of such liposomes is essential for studies of transmembrane transport processes in general, functional studies of the transporters themselves in liposomes suffer from several disadvantages. For example, transmembrane proteins can adopt two different orientations when reconstituted into liposomes, and one of these populations may be inaccessible to ligands, to changes in pH or ion concentration in the external solution. Furthermore, optical studies of proteins reconstituted in liposomes suffer from significant light scattering, which diminishes the signal-to-noise value of the measurements. One attractive approach to circumvent these problems is to use nanodiscs, which are phospholipid bilayers encircled by a stabilizing amphipathic helical membrane scaffold protein. These membrane nanodiscs are stable, soluble in aqueous solution without detergent and do not scatter light significantly. In the present study, we have developed a protocol for reconstitution of the aa(3)- and ba(3)-type cytochrome c oxidases into nanodiscs. Furthermore, we studied proton-coupled electron-transfer reactions in these enzymes with microsecond time resolution. The data show that the nanodisc membrane environment accelerates proton uptake in both oxidases.
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Affiliation(s)
- Linda Näsvik Öjemyr
- Department of Biochemistry and Biophysics, The Arrhenius Laboratories for Natural Sciences, Stockholm University, SE-106 91 Stockholm, Sweden
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32
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Egawa T, Ganesan K, Lin MT, Yu MA, Hosler JP, Yeh SR, Rousseau DL, Gennis RB. Differential effects of glutamate-286 mutations in the aa(3)-type cytochrome c oxidase from Rhodobacter sphaeroides and the cytochrome bo(3) ubiquinol oxidase from Escherichia coli. BIOCHIMICA ET BIOPHYSICA ACTA 2011; 1807:1342-8. [PMID: 21684251 PMCID: PMC3155654 DOI: 10.1016/j.bbabio.2011.06.001] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/14/2011] [Revised: 05/28/2011] [Accepted: 06/01/2011] [Indexed: 11/26/2022]
Abstract
Both the aa(3)-type cytochrome c oxidase from Rhodobacter sphaeroides (RsCcO(aa3)) and the closely related bo(3)-type ubiquinol oxidase from Escherichia coli (EcQO(bo3)) possess a proton-conducting D-channel that terminates at a glutamic acid, E286, which is critical for controlling proton transfer to the active site for oxygen chemistry and to a proton loading site for proton pumping. E286 mutations in each enzyme block proton flux and, therefore, inhibit oxidase function. In the current work, resonance Raman spectroscopy was used to show that the E286A and E286C mutations in RsCcO(aa3) result in long range conformational changes that influence the protein interactions with both heme a and heme a(3). Therefore, the severe reduction of the steady-state activity of the E286 mutants in RsCcO(aa3) to ~0.05% is not simply a result of the direct blockage of the D-channel, but it is also a consequence of the conformational changes induced by the mutations to heme a and to the heme a(3)-Cu(B) active site. In contrast, the E286C mutation of EcQO(bo3) exhibits no evidence of conformational changes at the two heme sites, indicating that its reduced activity (3%) is exclusively a result of the inhibition of proton transfer from the D-channel. We propose that in RsCcO(aa3), the E286 mutations severely perturb the active site through a close interaction with F282, which lies between E286 and the heme-copper active site. The local structure around E286 in EcQO(bo3) is different, providing a rationale for the very different effects of E286 mutations in the two enzymes. This article is part of a Special Issue entitled: Allosteric cooperativity in respiratory proteins.
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Affiliation(s)
- Tsuyoshi Egawa
- Department of Physiology and Biophysics, Albert Einstein College of Medicine, Bronx, New York 10461
| | - Krithika Ganesan
- Center for Biophysics and Computational Biology, University of Illinois at Urbana-Champaign, Urbana, Illinois 61801
| | - Myat T. Lin
- Center for Biophysics and Computational Biology, University of Illinois at Urbana-Champaign, Urbana, Illinois 61801
| | - Michelle A. Yu
- Department of Physiology and Biophysics, Albert Einstein College of Medicine, Bronx, New York 10461
| | - Jonathan P. Hosler
- Department of Biochemistry, University of Mississippi Medical Center, Jackson, Mississippi 39216
| | - Syun-Ru Yeh
- Department of Physiology and Biophysics, Albert Einstein College of Medicine, Bronx, New York 10461
| | - Denis L. Rousseau
- Department of Physiology and Biophysics, Albert Einstein College of Medicine, Bronx, New York 10461
| | - Robert B. Gennis
- Center for Biophysics and Computational Biology, University of Illinois at Urbana-Champaign, Urbana, Illinois 61801
- Department of Biochemistry, University of Illinois at Urbana-Champaign, Urbana, Illinois 61801
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Johansson AL, Chakrabarty S, Berthold CL, Högbom M, Warshel A, Brzezinski P. Proton-transport mechanisms in cytochrome c oxidase revealed by studies of kinetic isotope effects. BIOCHIMICA ET BIOPHYSICA ACTA-BIOENERGETICS 2011; 1807:1083-94. [PMID: 21463601 DOI: 10.1016/j.bbabio.2011.03.012] [Citation(s) in RCA: 30] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/09/2011] [Revised: 03/25/2011] [Accepted: 03/28/2011] [Indexed: 10/18/2022]
Abstract
Cytochrome c oxidase (CytcO) is a membrane-bound enzyme, which catalyzes the reduction of di-oxygen to water and uses a major part of the free energy released in this reaction to pump protons across the membrane. In the Rhodobacter sphaeroides aa₃ CytcO all protons that are pumped across the membrane, as well as one half of the protons that are used for O₂ reduction, are transferred through one specific intraprotein proton pathway, which holds a highly conserved Glu286 residue. Key questions that need to be addressed in order to understand the function of CytcO at a molecular level are related to the timing of proton transfers from Glu286 to a "pump site" and the catalytic site, respectively. Here, we have investigated the temperature dependencies of the H/D kinetic-isotope effects of intramolecular proton-transfer reactions in the wild-type CytcO as well as in two structural CytcO variants, one in which proton uptake from solution is delayed and one in which proton pumping is uncoupled from O₂ reduction. These processes were studied for two specific reaction steps linked to transmembrane proton pumping, one that involves only proton transfer (peroxy-ferryl, P→F, transition) and one in which the same sequence of proton transfers is also linked to electron transfer to the catalytic site (ferryl-oxidized, F→O, transition). An analysis of these reactions in the framework of theory indicates that that the simpler, P→F reaction is rate-limited by proton transfer from Glu286 to the catalytic site. When the same proton-transfer events are also linked to electron transfer to the catalytic site (F→O), the proton-transfer reactions might well be gated by a protein structural change, which presumably ensures that the proton-pumping stoichiometry is maintained also in the presence of a transmembrane electrochemical gradient. Furthermore, the present study indicates that a careful analysis of the temperature dependence of the isotope effect should help us in gaining mechanistic insights about CytcO.
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Affiliation(s)
- Ann-Louise Johansson
- Department of Biochemistry and Biophysics, The Arrhenius Laboratories for Natural Sciences, Stockholm University, Sweden
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Namslauer I, Dietz MS, Brzezinski P. Functional effects of mutations in cytochrome c oxidase related to prostate cancer. BIOCHIMICA ET BIOPHYSICA ACTA-BIOENERGETICS 2011; 1807:1336-41. [PMID: 21334999 DOI: 10.1016/j.bbabio.2011.02.005] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/20/2010] [Revised: 02/08/2011] [Accepted: 02/09/2011] [Indexed: 01/26/2023]
Abstract
A number of missense mutations in subunit I of cytochrome c oxidase (CytcO) have previously been linked to prostate cancer (Petros et al., 2005). To investigate the effects of these mutations at the molecular level, in the present study we prepared four different structural variants of the bacterial Rhodobacter sphaeroides CytcO (cytochrome aa(3)), each carrying one amino-acid residue replacement corresponding to the following substitutions identified in the above-mentioned study: Asn11Ser, Ala122Thr, Ala341Ser and Val380Ile (residues Asn25, Ser168, Ala384 and Val423 in the R. sphaeroides oxidase). This bacterial CytcO displays essentially the same structural and functional characteristics as those of the mitochondrial counterpart. We investigated the overall activity, proton pumping and internal electron- and proton-transfer reactions in the structural variants. The results show that the turnover activities of the mutant CytcOs were reduced by at most a factor of two. All variants pumped protons, but in Ser168Thr, Ala384Ser and Val423Ile we observed slight internal proton leaks. In all structural variants the internal electron equilibrium was slightly shifted away from the catalytic site at high pH (10), resulting in a slower observed ferryl to oxidized transition. Even though the effects of the mutations were relatively modest, the results suggest that they destabilize the proton-gating machinery. Such effects could be manifested in the presence of a transmembrane electrochemical gradient resulting in less efficient energy conservation. This article is part of a Special Issue entitled: Allosteric cooperativity in respiratory proteins.
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Affiliation(s)
- Ida Namslauer
- Department of Biochemistry and Biophysics, Stockholm University, Stockholm, Sweden
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Wang W, Wang DIC, Li Z. Facile fabrication of recyclable and active nanobiocatalyst: purification and immobilization of enzyme in one pot with Ni-NTA functionalized magnetic nanoparticle. Chem Commun (Camb) 2011; 47:8115-7. [DOI: 10.1039/c1cc12685g] [Citation(s) in RCA: 43] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
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36
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Bolshakov IA, Vygodina TV, Gennis R, Karyakin AA, Konstantinov AA. Catalase Activity of Cytochrome c Oxidase Assayed with Hydrogen Peroxide-Sensitive Electrode Microsensor. BIOCHEMISTRY (MOSCOW) 2010; 75:1352-60. [DOI: 10.1134/s0006297910110064] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
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Lee HJ, Svahn E, Swanson JMJ, Lepp H, Voth GA, Brzezinski P, Gennis RB. Intricate role of water in proton transport through cytochrome c oxidase. J Am Chem Soc 2010; 132:16225-39. [PMID: 20964330 DOI: 10.1021/ja107244g] [Citation(s) in RCA: 45] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Cytochrome c oxidase (CytcO), the final electron acceptor in the respiratory chain, catalyzes the reduction of O(2) to H(2)O while simultaneously pumping protons across the inner mitochondrial or bacterial membrane to maintain a transmembrane electrochemical gradient that drives, for example, ATP synthesis. In this work mutations that were predicted to alter proton translocation and enzyme activity in preliminary computational studies are characterized with extensive experimental and computational analysis. The mutations were introduced in the D pathway, one of two proton-uptake pathways, in CytcO from Rhodobacter sphaeroides . Serine residues 200 and 201, which are hydrogen-bonded to crystallographically resolved water molecules halfway up the D pathway, were replaced by more bulky hydrophobic residues (Ser200Ile, Ser200Val/Ser201Val, and Ser200Val/Ser201Tyr) to query the effects of changing the local structure on enzyme activity as well as proton uptake, release, and intermediate transitions. In addition, the effects of these mutations on internal proton transfer were investigated by blocking proton uptake at the pathway entrance (Asp132Asn replacement in addition to the above-mentioned mutations). Even though the overall activities of all mutant CytcO's were lowered, both the Ser200Ile and Ser200Val/Ser201Val variants maintained the ability to pump protons. The lowered activities were shown to be due to slowed oxidation kinetics during the P(R) → F and F → O transitions (P(R) is the "peroxy" intermediate formed at the catalytic site upon reaction of the four-electron-reduced CytcO with O(2), F is the oxoferryl intermediate, and O is the fully oxidized CytcO). Furthermore, the P(R) → F transition is shown to be essentially pH independent up to pH 12 (i.e., the apparent pK(a) of Glu286 is increased from 9.4 by at least 3 pK(a) units) in the Ser200Val/Ser201Val mutant. Explicit simulations of proton transport in the mutated enzymes revealed that the solvation dynamics can cause intriguing energetic consequences and hence provide mechanistic insights that would never be detected in static structures or simulations of the system with fixed protonation states (i.e., lacking explicit proton transport). The results are discussed in terms of the proton-pumping mechanism of CytcO.
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Affiliation(s)
- Hyun Ju Lee
- Department of Biochemistry and Biophysics, The Arrhenius Laboratories for Natural Sciences, Stockholm University, SE-106 91 Stockholm, Sweden
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Functional interactions between membrane-bound transporters and membranes. Proc Natl Acad Sci U S A 2010; 107:15763-7. [PMID: 20798065 DOI: 10.1073/pnas.1006109107] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
One key role of many cellular membranes is to hold a transmembrane electrochemical ion gradient that stores free energy, which is used, for example, to generate ATP or to drive transmembrane transport processes. In mitochondria and many bacteria, the gradient is maintained by proton-transport proteins that are part of the respiratory (electron-transport) chain. Even though our understanding of the structure and function of these proteins has increased significantly, very little is known about the specific role of functional protein-membrane and membrane-mediated protein-protein interactions. Here, we have investigated the effect of membrane incorporation on proton-transfer reactions within the membrane-bound proton pump cytochrome c oxidase. The results show that the membrane acts to accelerate proton transfer into the enzyme's catalytic site and indicate that the intramolecular proton pathway is wired via specific amino acid residues to the two-dimensional space defined by the membrane surface. We conclude that the membrane not only acts as a passive barrier insulating the interior of the cell from the exterior solution, but also as a component of the energy-conversion machinery.
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Siletsky SA, Zhu J, Gennis RB, Konstantinov AA. Partial steps of charge translocation in the nonpumping N139L mutant of Rhodobacter sphaeroides cytochrome c oxidase with a blocked D-channel. Biochemistry 2010; 49:3060-73. [PMID: 20192226 DOI: 10.1021/bi901719e] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
The N139L substitution in the D-channel of cytochrome oxidase from Rhodobacter sphaeroides results in an approximately 15-fold decrease in the turnover number and a loss of proton pumping. Time-resolved absorption and electrometric assays of the F --> O transition in the N139L mutant oxidase result in three major findings. (1) Oxidation of the reduced enzyme by O(2) shows approximately 200-fold inhibition of the F --> O step (k approximately 2 s(-1) at pH 8) which is not compatible with enzyme turnover ( approximately 30 s(-1)). Presumably, an abnormal intermediate F(deprotonated) is formed under these conditions, one proton-deficient relative to a normal F state. In contrast, the F --> O transition in N139L oxidase induced by single-electron photoreduction of intermediate F, generated by reaction of the oxidized enzyme with H(2)O(2), decelerates to an extent compatible with enzyme turnover. (2) In the N139L mutant, the protonic phase of Deltapsi generation coupled to the flash-induced F --> O transition greatly decreases in rate and magnitude and can be assigned to the movement of a proton from E286 to the binuclear site, required for reduction of heme a(3) from the Fe(4+) horizontal lineO(2-) state to the Fe(3+)-OH(-) state. Electrogenic reprotonation of E286 from the inner aqueous phase is missing from the F --> O step in the mutant. (3) In the N139L mutant, the KCN-insensitive rapid electrogenic phase may be composed of two components with lifetimes of approximately 10 and approximately 40 mus and a magnitude ratio of approximately 3:2. The 10 mus phase matches vectorial electron transfer from Cu(A) to heme a, whereas the 40 mus component is assigned to intraprotein proton displacement across approximately 20% of the membrane dielectric thickness. This proton displacement might be triggered by rotation of the charged K362 side chain coupled to heme a reduction. The two components of the rapid electrogenic phase have been resolved subsequently with other D-channel mutants as well as with cyanide-inhibited wild-type oxidase. The finding helps to reconcile the unusually high relative contribution of the microsecond electrogenic phase in the bacterial enzyme ( approximately 30%) with the net electrogenicity of the F --> O transition coupled to transmembrane transfer of two charges per electron.
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Affiliation(s)
- Sergey A Siletsky
- A. N. Belozersky Institute of Physico-Chemical Biology, Moscow State University, Moscow 119991, Russia
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40
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Cell-free synthesis of cytochrome c oxidase, a multicomponent membrane protein. J Bioenerg Biomembr 2010; 42:235-40. [DOI: 10.1007/s10863-010-9285-8] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/28/2009] [Accepted: 02/26/2010] [Indexed: 11/26/2022]
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Ganesan K, Gennis RB. Blocking the K-pathway still allows rapid one-electron reduction of the binuclear center during the anaerobic reduction of the aa3-type cytochrome c oxidase from Rhodobacter sphaeroides. BIOCHIMICA ET BIOPHYSICA ACTA-BIOENERGETICS 2010; 1797:619-24. [PMID: 20307488 DOI: 10.1016/j.bbabio.2010.03.012] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/15/2010] [Revised: 03/08/2010] [Accepted: 03/10/2010] [Indexed: 11/15/2022]
Abstract
The K-pathway is one of the two proton-input channels required for function of cytochrome c oxidase. In the Rhodobacter sphaeroides cytochrome c oxidase, the K-channel starts at Glu101 in subunit II, which is at the surface of the protein exposed to the cytoplasm, and runs to Tyr288 at the heme a3/CuB active site. Mutations of conserved, polar residues within the K-channel block or inhibit steady state oxidase activity. A large body of research has demonstrated that the K-channel is required to fully reduce the heme/Cu binuclear center, prior to the reaction with O2, presumably by providing protons to stabilize the reduced metals (ferrous heme a3 and cuprous CuB). However, there are conflicting reports which raise questions about whether blocking the K-channel blocks both electrons or only one electron from reaching the heme/Cu center. In the current work, the rate and extent of the anaerobic reduction of the heme/Cu center were monitored by optical and EPR spectroscopies, comparing the wild type and mutants that block the K-channel. The new data show that when the K-channel is blocked, one electron will still readily enter the binuclear center. The one-electron reduction of the resting oxidized ("O") heme/Cu center of the K362M mutant, results in a partially reduced binuclear center in which the electron is distributed about evenly between heme a3 and CuB in the R. sphaeroides oxidase. Complete reduction of the heme/Cu center requires the uptake of two protons which must be delivered through the K-channel.
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Affiliation(s)
- Krithika Ganesan
- Biophysics and Computational Biology, Department of Biochemistry, University of Illinois, Urbana, IL 61801, USA
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42
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Nowak C, Schach D, Gebert J, Grosserueschkamp M, Gennis RB, Ferguson-Miller S, Knoll W, Walz D, Naumann RLC. Oriented immobilization and electron transfer to the cytochrome c oxidase. J Solid State Electrochem 2010. [DOI: 10.1007/s10008-010-1032-x] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/19/2022]
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43
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Namslauer I, Lee HJ, Gennis RB, Brzezinski P. A pathogenic mutation in cytochrome c oxidase results in impaired proton pumping while retaining O(2)-reduction activity. BIOCHIMICA ET BIOPHYSICA ACTA-BIOENERGETICS 2010; 1797:550-6. [PMID: 20117076 DOI: 10.1016/j.bbabio.2010.01.027] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/22/2009] [Revised: 01/21/2010] [Accepted: 01/25/2010] [Indexed: 10/19/2022]
Abstract
In this work we have investigated the effect of a pathogenic mitochondrial DNA mutation found in human colon cells, at a functional-molecular level. The mutation results in the amino-acid substitution Tyr19His in subunit I of the human CytcO and it is associated with respiratory deficiency. It was introduced into Rhodobacter sphaeroides, which carries a cytochrome c oxidase (cytochrome aa(3)) that serves as a model of the mitochondrial counterpart. The residue is situated in the middle of a pathway that is used to transfer substrate protons as well as protons that are pumped across the membrane. The Tyr33His (equivalent residue in the bacterial CytcO) structural variant of the enzyme was purified and its function was investigated. The results show that in the structurally altered CytcO the activity decreased due to slowed proton transfer; proton transfer from an internal proton donor, the highly-conserved Glu286, to the catalytic site was slowed by a factor of approximately 5, while reprotonation of the Glu from solution was slowed by a factor of approximately 40. In addition, in the structural variant proton pumping was completely impaired. These results are explained in terms of introduction of a barrier for proton transfer through the D pathway and changes in the coordination of water molecules surrounding the Glu286 residue. The study offers an explanation, at the molecular level, to the link between a specific amino-acid substitution and a pathogenic phenotype identified in human colon cells.
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Affiliation(s)
- Ida Namslauer
- Department of Biochemistry and Biophysics, The Arrhenius Laboratories for Natural Sciences, Stockholm University, Stockholm, Sweden
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Ojemyr L, Sandén T, Widengren J, Brzezinski P. Lateral proton transfer between the membrane and a membrane protein. Biochemistry 2009; 48:2173-9. [PMID: 19166299 DOI: 10.1021/bi8022152] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Proton transport across biological membranes is a key step of the energy conservation machinery in living organisms, and it has been proposed that the membrane itself plays an important role in this process. In the present study we have investigated the effect of incorporation of a proton transporter, cytochrome c oxidase, into a membrane on the protonation kinetics of a fluorescent pH-sensitive probe attached at the surface of the protein. The results show that proton transfer to the probe was slightly accelerated upon attachment at the protein surface (approximately 7 x 1010 s(-1) M(-1), compared to the expected value of (1-2) x 10(10) s(-1) M(-1)), which is presumably due to the presence of acidic/His groups in the vicinity. Upon incorporation of the protein into small unilamellar phospholipid vesicles the rate increased by more than a factor of 400 to approximately 3 x 10(13) s(-1) M(-1), which indicates that the protein-attached probe is in rapid protonic contact with the membrane surface. The results indicate that the membrane acts to accelerate proton uptake by the membrane-bound proton transporter.
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Affiliation(s)
- Linda Ojemyr
- Department of Biochemistry and Biophysics, The Arrhenius Laboratories for Natural Sciences, Stockholm University, Sweden
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Lee HJ, Ojemyr L, Vakkasoglu A, Brzezinski P, Gennis RB. Properties of Arg481 mutants of the aa3-type cytochrome c oxidase from Rhodobacter sphaeroides suggest that neither R481 nor the nearby D-propionate of heme a3 is likely to be the proton loading site of the proton pump. Biochemistry 2009; 48:7123-31. [PMID: 19575527 DOI: 10.1021/bi901015d] [Citation(s) in RCA: 32] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Cytochrome c oxidase utilizes the energy from electron transfer and reduction of oxygen to water and pumps protons across the membrane, generating a proton motive force. A large body of biochemical work has shown that all the pumped protons enter the enzyme through the D-channel, which is apparent in X-ray structures as a chain of water molecules connecting D132 at the cytoplasmic surface of the enzyme to E286, near the enzyme active site. The exit pathway utilized by pumped protons beyond this point and leading to the bacterial periplasm is not known. Also not known is the proton loading site (or sites) which undergoes changes in pKa in response to the chemistry at the enzyme active site and drives the proton pump mechanism. In this paper, we examine the role of R481, a highly conserved arginine that forms an ion pair with the D-propionate of heme a3. The R481H, R481N, R481Q, and R481L mutants were examined. The R481H mutant oxidase is approximately 18% active and pumps protons with approximately 40% of the stoichiometry of the wild type. The R481N, R481Q, and R481L mutants each retain only approximately 5% of the steady-state activity, and this is shown to be due to inhibition of steps in the reaction of O(2) with the reduced enzyme. Neither the R481N mutant nor the R481Q mutant oxidases pump protons, but remarkably, the R481L mutant does pump protons with the same efficiency as the R481H mutant. Since the proton pump is clearly operating in the R481L mutant, these results rule out an essential role in the proton pump mechanism for R481 or its hydrogen bond partner, the D-propionate of heme a3.
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Affiliation(s)
- Hyun Ju Lee
- Department of Biochemistry, University of Illinois, Urbana, Illinois 61801, USA
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Nordlund G, Sing Ng JB, Bergström L, Brzezinski P. A membrane-reconstituted multisubunit functional proton pump on mesoporous silica particles. ACS NANO 2009; 3:2639-2646. [PMID: 19653679 DOI: 10.1021/nn9005413] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/28/2023]
Abstract
We have investigated formation of a proteolipid membrane surrounding mesoporous silica particles with a diameter of 550 nm and pore sizes of 3.0 nm. A multisubunit redox-driven proton pump, cytochrome c oxidase, was incorporated into the membrane, and we show that the enzyme is functional, both with respect to catalysis of O(2) reduction to water, and charge separation across the membrane. The orientation of cytochrome c oxidase in the membrane was found to be the same ( approximately 70%) in the lipid vesicles and in the silica-particle-supported lipid membrane, which provides information on the mechanism by which the vesicles adsorb to the surface. Furthermore, cytochrome c oxidase could maintain a proton electrochemical gradient across the supported proteomembrane, that is, the membrane system was proton tight, defining an interior particle compartment that is separated from the surrounding aqueous media. Such a biofunctional cellular interface, supported onto a colloid that has a connected interior cytoskeleton-like pore structure, provides a basis for functional studies of membrane-bound transport proteins, and also for applications within pharmaceutical drug delivery.
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Affiliation(s)
- Gustav Nordlund
- Department of Biochemistry and Biophysics, Centre for Biomembrane Research, Stockholm University, SE-10691 Stockholm, Sweden
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47
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Internal charge transfer in cytochrome c oxidase at a limited proton supply: Proton pumping ceases at high pH. Biochim Biophys Acta Gen Subj 2009; 1790:552-7. [DOI: 10.1016/j.bbagen.2009.03.023] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/29/2008] [Revised: 03/18/2009] [Accepted: 03/24/2009] [Indexed: 11/19/2022]
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48
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Vygodina TV, Zakirzianova W, Konstantinov AA. Inhibition of membrane-bound cytochromecoxidase by zinc ions: High-affinity Zn2+-binding site at the P-side of the membrane. FEBS Lett 2008; 582:4158-62. [DOI: 10.1016/j.febslet.2008.11.018] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/07/2008] [Revised: 11/13/2008] [Accepted: 11/14/2008] [Indexed: 10/21/2022]
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49
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Mills DA, Xu S, Geren L, Hiser C, Qin L, Sharpe MA, McCracken J, Durham B, Millett F, Ferguson-Miller S. Proton-dependent electron transfer from CuA to heme a and altered EPR spectra in mutants close to heme a of cytochrome oxidase. Biochemistry 2008; 47:11499-509. [PMID: 18847227 PMCID: PMC2659347 DOI: 10.1021/bi801156s] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
Eukaryotic cytochrome c oxidase (CcO) and homologous prokaryotic forms of Rhodobacter and Paraccocus differ in the EPR spectrum of heme a. It was noted that a histidine ligand of heme a (H102) is hydrogen bonded to serine in Rhodobacter (S44) and Paraccocus CcOs, in contrast to glycine in the bovine enzyme. Mutation of S44 to glycine shifts the heme a EPR signal from g(z) = 2.82 to 2.86, closer to bovine heme a at 3.03, without modifying other properties. Mutation to aspartate, however, results in an oppositely shifted and split heme a EPR signal of g(z) = 2.72/2.78, accompanied by lower activity and drastically inhibited intrinsic electron transfer from CuA to heme a. This intrinsic rate is biphasic; the proportion that is slow is pH dependent, as is the relative intensity of the two EPR signal components. At pH 8, the heme a EPR signal at 2.72 is most intense, and the electron transfer rate (CuA to heme a) is 10-130 s(-1), compared to wild-type at 90,000 s(-1). At pH 5.5, the signal at 2.78 is intensified, and a biphasic rate is observed, 50% fast (approximately wild type) and 50% slow (90 s(-1)). The data support the prediction that the hydrogen-bonding partner of the histidine ligand of heme a is one determinant of the EPR spectral difference between bovine and bacterial CcO. We further demonstrate that the heme a redox potential can be dramatically altered by a nearby carboxyl, whose protonation leads to a proton-coupled electron transfer process.
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Affiliation(s)
- Denise A. Mills
- Department of Biochemistry and Molecular Biology, Michigan State University, East Lansing, Michigan 48824
| | - Shujuan Xu
- Department of Chemistry, Michigan State University, East Lansing, Michigan 48824
| | - Lois Geren
- Department of Chemistry and Biochemistry, University of Arkansas, Fayetteville, Arkansas 72701
| | - Carrie Hiser
- Department of Biochemistry and Molecular Biology, Michigan State University, East Lansing, Michigan 48824
| | - Ling Qin
- Department of Biochemistry and Molecular Biology, Michigan State University, East Lansing, Michigan 48824
| | - Martyn A. Sharpe
- Department of Biochemistry and Molecular Biology, Michigan State University, East Lansing, Michigan 48824
| | - John McCracken
- Department of Chemistry, Michigan State University, East Lansing, Michigan 48824
| | - Bill Durham
- Department of Chemistry and Biochemistry, University of Arkansas, Fayetteville, Arkansas 72701
| | - Francis Millett
- Department of Chemistry and Biochemistry, University of Arkansas, Fayetteville, Arkansas 72701
| | - Shelagh Ferguson-Miller
- Department of Biochemistry and Molecular Biology, Michigan State University, East Lansing, Michigan 48824
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50
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Protein tethered lipid bilayer: An alternative mimic of the biological membrane (Mini Review). Biointerphases 2008; 3:FA101. [DOI: 10.1116/1.2936939] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022] Open
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