1
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Noodleman L, Götz AW, Han Du WG, Hunsicker-Wang L. Reaction pathways, proton transfer, and proton pumping in ba3 class cytochrome c oxidase: perspectives from DFT quantum chemistry and molecular dynamics. Front Chem 2023; 11:1186022. [PMID: 38188931 PMCID: PMC10766771 DOI: 10.3389/fchem.2023.1186022] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/14/2023] [Accepted: 11/27/2023] [Indexed: 01/09/2024] Open
Abstract
After drawing comparisons between the reaction pathways of cytochrome c oxidase (CcO, Complex 4) and the preceding complex cytochrome bc1 (Complex 3), both being proton pumping complexes along the electron transport chain, we provide an analysis of the reaction pathways in bacterial ba3 class CcO, comparing spectroscopic results and kinetics observations with results from DFT calculations. For an important arc of the catalytic cycle in CcO, we can trace the energy pathways for the chemical protons and show how these pathways drive proton pumping of the vectorial protons. We then explore the proton loading network above the Fe heme a3-CuB catalytic center, showing how protons are loaded in and then released by combining DFT-based reaction energies with molecular dynamics simulations over states of that cycle. We also propose some additional reaction pathways for the chemical and vector protons based on our recent work with spectroscopic support.
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Affiliation(s)
- Louis Noodleman
- Department of Integrative Structural and Computational Biology, The Scripps Research Institute, La Jolla, CA, United States
| | - Andreas W. Götz
- San Diego Supercomputer Center, University of California San Diego, La Jolla, CA, United States
| | - Wen-Ge Han Du
- Department of Integrative Structural and Computational Biology, The Scripps Research Institute, La Jolla, CA, United States
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2
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Kishimoto H, Azai C, Yamamoto T, Mutoh R, Nakaniwa T, Tanaka H, Miyanoiri Y, Kurisu G, Oh-oka H. Soluble domains of cytochrome c-556 and Rieske iron-sulfur protein from Chlorobaculum tepidum: Crystal structures and interaction analysis. Curr Res Struct Biol 2023; 5:100101. [PMID: 37180033 PMCID: PMC10172866 DOI: 10.1016/j.crstbi.2023.100101] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/30/2022] [Revised: 04/04/2023] [Accepted: 04/11/2023] [Indexed: 05/15/2023] Open
Abstract
In photosynthetic green sulfur bacteria, the electron transfer reaction from menaquinol:cytochrome c oxidoreductase to the P840 reaction center (RC) complex occurs directly without any involvement of soluble electron carrier protein(s). X-ray crystallography has determined the three-dimensional structures of the soluble domains of the CT0073 gene product and Rieske iron-sulfur protein (ISP). The former is a mono-heme cytochrome c with an α-absorption peak at 556 nm. The overall fold of the soluble domain of cytochrome c-556 (designated as cyt c-556sol) consists of four α-helices and is very similar to that of water-soluble cyt c-554 that independently functions as an electron donor to the P840 RC complex. However, the latter's remarkably long and flexible loop between the α3 and α4 helices seems to make it impossible to be a substitute for the former. The structure of the soluble domain of the Rieske ISP (Rieskesol protein) shows a typical β-sheets-dominated fold with a small cluster-binding and a large subdomain. The architecture of the Rieskesol protein is bilobal and belongs to those of b6f-type Rieske ISPs. Nuclear magnetic resonance (NMR) measurements revealed weak non-polar but specific interaction sites on Rieskesol protein when mixed with cyt c-556sol. Therefore, menaquinol:cytochrome c oxidoreductase in green sulfur bacteria features a Rieske/cytb complex tightly associated with membrane-anchored cyt c-556.
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Affiliation(s)
- Hiraku Kishimoto
- Department of Biological Sciences, Graduate School of Science, Osaka University, Toyonaka, Osaka, 560-0043, Japan
| | - Chihiro Azai
- Graduate School of Life Sciences, Ritsumeikan University, Kusatsu, Shiga, 525-8577, Japan
| | - Tomoya Yamamoto
- Department of Biological Sciences, Graduate School of Science, Osaka University, Toyonaka, Osaka, 560-0043, Japan
| | - Risa Mutoh
- Institute for Protein Research, Osaka University, Suita, Osaka, 565-0871, Japan
| | - Tetsuko Nakaniwa
- Institute for Protein Research, Osaka University, Suita, Osaka, 565-0871, Japan
| | - Hideaki Tanaka
- Institute for Protein Research, Osaka University, Suita, Osaka, 565-0871, Japan
| | - Yohei Miyanoiri
- Institute for Protein Research, Osaka University, Suita, Osaka, 565-0871, Japan
- Corresponding author.
| | - Genji Kurisu
- Institute for Protein Research, Osaka University, Suita, Osaka, 565-0871, Japan
- Corresponding author.
| | - Hirozo Oh-oka
- Department of Biological Sciences, Graduate School of Science, Osaka University, Toyonaka, Osaka, 560-0043, Japan
- Center for Education in Liberal Arts and Sciences, Osaka University, Toyonaka, Osaka, 560-0043, Japan
- Corresponding author. Department of Biological Sciences, Graduate School of Science, Osaka University, Toyonaka, Osaka, 560-0043, Japan.
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3
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Lindahl PA, Vali SW. Mössbauer-based molecular-level decomposition of the Saccharomyces cerevisiae ironome, and preliminary characterization of isolated nuclei. Metallomics 2022; 14:mfac080. [PMID: 36214417 PMCID: PMC9624242 DOI: 10.1093/mtomcs/mfac080] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/22/2022] [Accepted: 09/23/2022] [Indexed: 11/25/2022]
Abstract
One hundred proteins in Saccharomyces cerevisiae are known to contain iron. These proteins are found mainly in mitochondria, cytosol, nuclei, endoplasmic reticula, and vacuoles. Cells also contain non-proteinaceous low-molecular-mass labile iron pools (LFePs). How each molecular iron species interacts on the cellular or systems' level is underdeveloped as doing so would require considering the entire iron content of the cell-the ironome. In this paper, Mössbauer (MB) spectroscopy was used to probe the ironome of yeast. MB spectra of whole cells and isolated organelles were predicted by summing the spectral contribution of each iron-containing species in the cell. Simulations required input from published proteomics and microscopy data, as well as from previous spectroscopic and redox characterization of individual iron-containing proteins. Composite simulations were compared to experimentally determined spectra. Simulated MB spectra of non-proteinaceous iron pools in the cell were assumed to account for major differences between simulated and experimental spectra of whole cells and isolated mitochondria and vacuoles. Nuclei were predicted to contain ∼30 μM iron, mostly in the form of [Fe4S4] clusters. This was experimentally confirmed by isolating nuclei from 57Fe-enriched cells and obtaining the first MB spectra of the organelle. This study provides the first semi-quantitative estimate of all concentrations of iron-containing proteins and non-proteinaceous species in yeast, as well as a novel approach to spectroscopically characterizing LFePs.
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Affiliation(s)
- Paul A Lindahl
- Department of Chemistry, Texas A&M University, College Station, TX,USA
- Department of Biochemistry and Biophysics, Texas A&M University, College Station TX,USA
| | - Shaik Waseem Vali
- Department of Chemistry, Texas A&M University, College Station, TX,USA
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4
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Valer L, Rossetto D, Parkkila T, Sebastianelli L, Guella G, Hendricks AL, Cowan JA, Sang L, Mansy SS. Histidine Ligated Iron-Sulfur Peptides. Chembiochem 2022; 23:e202200202. [PMID: 35674331 PMCID: PMC9400863 DOI: 10.1002/cbic.202200202] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/08/2022] [Revised: 06/08/2022] [Indexed: 11/17/2022]
Abstract
Iron-sulfur clusters are thought to be ancient cofactors that could have played a role in early protometabolic systems. Thus far, redox active, prebiotically plausible iron-sulfur clusters have always contained cysteine ligands to the cluster. However, extant iron-sulfur proteins can be found to exploit other modes of binding, including ligation by histidine residues, as seen with [2Fe-2S] Rieske and MitoNEET proteins. Here, we investigated the ability of cysteine- and histidine-containing peptides to coordinate a mononuclear Fe2+ center and a [2Fe-2S] cluster and compare their properties with purified iron-sulfur proteins. The iron-sulfur peptides were characterized by UV-vis, circular dichroism, and paramagnetic NMR spectroscopies and cyclic voltammetry. Small (≤6 amino acids) peptides can coordinate [2Fe-2S] clusters through a combination of cysteine and histidine residues with similar reduction potentials as their corresponding proteins. Such complexes may have been important for early cell-like systems.
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Affiliation(s)
- Luca Valer
- D-CIBIOUniversity of Trentovia Sommarive 938123Trento 28123Italy
- Department of ChemistryUniversity of Alberta11227 Saskatchewan DriveEdmontonT6G 2G2AlbertaCanada
| | - Daniele Rossetto
- D-CIBIOUniversity of Trentovia Sommarive 938123Trento 28123Italy
- Department of ChemistryUniversity of Alberta11227 Saskatchewan DriveEdmontonT6G 2G2AlbertaCanada
| | - Taylor Parkkila
- Department of ChemistryUniversity of Alberta11227 Saskatchewan DriveEdmontonT6G 2G2AlbertaCanada
| | - Lorenzo Sebastianelli
- Department of ChemistryUniversity of Alberta11227 Saskatchewan DriveEdmontonT6G 2G2AlbertaCanada
| | - Graziano Guella
- Department of PhysicsUniversity of TrentoVia Sommarive 14Trento38123Italy
| | - Amber L. Hendricks
- Department of Chemistry and BiochemistryThe Ohio State University100 West 18th AveColumbusOH 43210USA
| | - James A. Cowan
- Department of Chemistry and BiochemistryThe Ohio State University100 West 18th AveColumbusOH 43210USA
| | - Lingzi Sang
- Department of ChemistryUniversity of Alberta11227 Saskatchewan DriveEdmontonT6G 2G2AlbertaCanada
| | - Sheref S. Mansy
- D-CIBIOUniversity of Trentovia Sommarive 938123Trento 28123Italy
- Department of ChemistryUniversity of Alberta11227 Saskatchewan DriveEdmontonT6G 2G2AlbertaCanada
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5
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Valer L, Rossetto D, Scintilla S, Hu YJ, Tomar A, Nader S, Betinol IO, Mansy S. Methods to identify and characterize iron-sulfur oligopeptides in water. CAN J CHEM 2022. [DOI: 10.1139/cjc-2021-0237] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Iron-sulfur clusters are ubiquitous cofactors that mediate central biological processes. However, despite their long history, these metallocofactors remain challenging to investigate when coordinated to small (≤ six amino acids) oligopeptides in aqueous solution. In addition to being often unstable in vitro, iron-sulfur clusters can be found in a wide variety of forms with varied characteristics, which makes it difficult to easily discern what is in solution. This difficulty is compounded by the dynamics of iron-sulfur peptides, which frequently coordinate multiple types of clusters simultaneously. To aid investigations of such complex samples, a summary of data from multiple techniques used to characterize both iron-sulfur proteins and peptides is provided. Although not all spectroscopic techniques are equally insightful, it is possible to use several, readily available methods to gain insight into the complex composition of aqueous solutions of iron-sulfur peptides.
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Affiliation(s)
- Luca Valer
- University of Trento, 19034, Trento, Trentino-Alto Adige, Italy
| | | | | | - Yin Juan Hu
- University of Alberta, 3158, Chemistry, Edmonton, Alberta, Canada
| | - Anju Tomar
- University of Trento, 19034, Trento, Trentino-Alto Adige, Italy
| | - Serge Nader
- University of Alberta, 3158, Chemistry, Edmonton, Alberta, Canada
| | | | - Sheref Mansy
- University of Alberta, 3158, Chemistry, Edmonton, Alberta, Canada
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6
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Crofts AR. The modified Q-cycle: A look back at its development and forward to a functional model. BIOCHIMICA ET BIOPHYSICA ACTA-BIOENERGETICS 2021; 1862:148417. [PMID: 33745972 DOI: 10.1016/j.bbabio.2021.148417] [Citation(s) in RCA: 16] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Key Words] [Subscribe] [Scholar Register] [Received: 01/06/2021] [Revised: 02/28/2021] [Accepted: 03/11/2021] [Indexed: 11/25/2022]
Abstract
On looking back at a lifetime of research, it is interesting to see, in the light of current progress, how things came to be, and to speculate on how things might be. I am delighted in the context of the Mitchell prize to have that excuse to present this necessarily personal view of developments in areas of my interests. I have focused on the Q-cycle and a few examples showing wider ramifications, since that had been the main interest of the lab in the 20 years since structures became available, - a watershed event in determining our molecular perspective. I have reviewed the evidence for our model for the mechanism of the first electron transfer of the bifurcated reaction at the Qo-site, which I think is compelling. In reviewing progress in understanding the second electron transfer, I have revisited some controversies to justify important conclusions which appear, from the literature, not to have been taken seriously. I hope this does not come over as nitpicking. The conclusions are important to the final section in which I develop an internally consistent mechanism for turnovers of the complex leading to a state similar to that observed in recent rapid-mix/freeze-quench experiments, reported three years ago. The final model is necessarily speculative but is open to test.
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Affiliation(s)
- Antony R Crofts
- Department of Biochemistry, 417 Roger Adams Laboratory, 600 South Mathews Avenue, Urbana, IL 61801, United States of America
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7
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Sarewicz M, Pintscher S, Pietras R, Borek A, Bujnowicz Ł, Hanke G, Cramer WA, Finazzi G, Osyczka A. Catalytic Reactions and Energy Conservation in the Cytochrome bc1 and b6f Complexes of Energy-Transducing Membranes. Chem Rev 2021; 121:2020-2108. [PMID: 33464892 PMCID: PMC7908018 DOI: 10.1021/acs.chemrev.0c00712] [Citation(s) in RCA: 61] [Impact Index Per Article: 20.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/07/2020] [Indexed: 12/16/2022]
Abstract
This review focuses on key components of respiratory and photosynthetic energy-transduction systems: the cytochrome bc1 and b6f (Cytbc1/b6f) membranous multisubunit homodimeric complexes. These remarkable molecular machines catalyze electron transfer from membranous quinones to water-soluble electron carriers (such as cytochromes c or plastocyanin), coupling electron flow to proton translocation across the energy-transducing membrane and contributing to the generation of a transmembrane electrochemical potential gradient, which powers cellular metabolism in the majority of living organisms. Cytsbc1/b6f share many similarities but also have significant differences. While decades of research have provided extensive knowledge on these enzymes, several important aspects of their molecular mechanisms remain to be elucidated. We summarize a broad range of structural, mechanistic, and physiological aspects required for function of Cytbc1/b6f, combining textbook fundamentals with new intriguing concepts that have emerged from more recent studies. The discussion covers but is not limited to (i) mechanisms of energy-conserving bifurcation of electron pathway and energy-wasting superoxide generation at the quinol oxidation site, (ii) the mechanism by which semiquinone is stabilized at the quinone reduction site, (iii) interactions with substrates and specific inhibitors, (iv) intermonomer electron transfer and the role of a dimeric complex, and (v) higher levels of organization and regulation that involve Cytsbc1/b6f. In addressing these topics, we point out existing uncertainties and controversies, which, as suggested, will drive further research in this field.
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Affiliation(s)
- Marcin Sarewicz
- Department
of Molecular Biophysics, Faculty of Biochemistry, Biophysics and Biotechnology, Jagiellonian University, 30-387 Kraków, Poland
| | - Sebastian Pintscher
- Department
of Molecular Biophysics, Faculty of Biochemistry, Biophysics and Biotechnology, Jagiellonian University, 30-387 Kraków, Poland
| | - Rafał Pietras
- Department
of Molecular Biophysics, Faculty of Biochemistry, Biophysics and Biotechnology, Jagiellonian University, 30-387 Kraków, Poland
| | - Arkadiusz Borek
- Department
of Molecular Biophysics, Faculty of Biochemistry, Biophysics and Biotechnology, Jagiellonian University, 30-387 Kraków, Poland
| | - Łukasz Bujnowicz
- Department
of Molecular Biophysics, Faculty of Biochemistry, Biophysics and Biotechnology, Jagiellonian University, 30-387 Kraków, Poland
| | - Guy Hanke
- School
of Biological and Chemical Sciences, Queen
Mary University of London, London E1 4NS, U.K.
| | - William A. Cramer
- Department
of Biological Sciences, Purdue University, West Lafayette, Indiana 47907 United States
| | - Giovanni Finazzi
- Laboratoire
de Physiologie Cellulaire et Végétale, Université Grenoble Alpes, Centre National Recherche Scientifique,
Commissariat Energie Atomique et Energies Alternatives, Institut National
Recherche l’agriculture, l’alimentation et l’environnement, 38054 Grenoble Cedex 9, France
| | - Artur Osyczka
- Department
of Molecular Biophysics, Faculty of Biochemistry, Biophysics and Biotechnology, Jagiellonian University, 30-387 Kraków, Poland
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8
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Springett R. The proton pumping mechanism of the bc 1 complex. BIOCHIMICA ET BIOPHYSICA ACTA-BIOENERGETICS 2020; 1862:148352. [PMID: 33338489 DOI: 10.1016/j.bbabio.2020.148352] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Subscribe] [Scholar Register] [Received: 03/01/2020] [Revised: 11/17/2020] [Accepted: 12/08/2020] [Indexed: 02/07/2023]
Abstract
The bc1 complex is a proton pump of the mitochondrial electron transport chain which transfers electrons from ubiquinol to cytochrome c. It operates via the modified Q cycle in which the two electrons from oxidation of ubiquinol at the Qo center are bifurcated such that the first electron is passed to Cytc via an iron sulfur center and c1 whereas the second electron is passed across the membrane by bL and bH to reduce ubiquinone at the Qi center. Proton pumping occurs because oxidation of ubiquinol at the Qo center releases protons to the P-side and reduction of ubiquinone at the Qi center takes up protons from the N-side. However, the mechanisms which prevent the thermodynamically more favorable short circuit reactions and so ensure precise bifurcation and proton pumping are not known. Here we use statistical thermodynamics to show that reaction steps that originate from high energy states cannot support high flux even when they have large rate constants. We show how the chemistry of ubiquinol oxidation and the structure of the Qo site can result in free energy profiles that naturally suppress flux through the short circuit pathways while allowing high rates of bifurcation. These predictions are confirmed through in-silico simulations using a Markov state model.
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Affiliation(s)
- Roger Springett
- Cardiovascular Division, King's College London British Heart Foundation Centre of Excellence, London, United Kingdom.
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9
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Melin F, Hellwig P. Redox Properties of the Membrane Proteins from the Respiratory Chain. Chem Rev 2020; 120:10244-10297. [DOI: 10.1021/acs.chemrev.0c00249] [Citation(s) in RCA: 22] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022]
Affiliation(s)
- Frederic Melin
- Chimie de la Matière Complexe UMR 7140, Laboratoire de Bioelectrochimie et Spectroscopie, CNRS-Université de Strasbourg, 1 rue Blaise Pascal, 67070 Strasbourg, France
| | - Petra Hellwig
- Chimie de la Matière Complexe UMR 7140, Laboratoire de Bioelectrochimie et Spectroscopie, CNRS-Université de Strasbourg, 1 rue Blaise Pascal, 67070 Strasbourg, France
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10
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Stegmaier K, Blinn CM, Bechtel DF, Greth C, Auerbach H, Müller CS, Jakob V, Reijerse EJ, Netz DJA, Schünemann V, Pierik AJ. Apd1 and Aim32 Are Prototypes of Bishistidinyl-Coordinated Non-Rieske [2Fe–2S] Proteins. J Am Chem Soc 2019; 141:5753-5765. [DOI: 10.1021/jacs.8b13274] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Affiliation(s)
| | | | | | | | | | | | | | - Edward J. Reijerse
- Max-Planck-Institut für Chemische Energiekonversion, Stiftstrasse 34-36, D45470 Mülheim an der Ruhr, Germany
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11
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Vuono DC, Read RW, Hemp J, Sullivan BW, Arnone JA, Neveux I, Blank RR, Loney E, Miceli D, Winkler MKH, Chakraborty R, Stahl DA, Grzymski JJ. Resource Concentration Modulates the Fate of Dissimilated Nitrogen in a Dual-Pathway Actinobacterium. Front Microbiol 2019; 10:3. [PMID: 30723459 PMCID: PMC6349771 DOI: 10.3389/fmicb.2019.00003] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/10/2018] [Accepted: 01/07/2019] [Indexed: 11/30/2022] Open
Abstract
Respiratory ammonification and denitrification are two evolutionarily unrelated dissimilatory nitrogen (N) processes central to the global N cycle, the activity of which is thought to be controlled by carbon (C) to nitrate (NO3 -) ratio. Here we find that Intrasporangium calvum C5, a novel dual-pathway denitrifier/respiratory ammonifier, disproportionately utilizes ammonification rather than denitrification when grown under low C concentrations, even at low C:NO3 - ratios. This finding is in conflict with the paradigm that high C:NO3 - ratios promote ammonification and low C:NO3 - ratios promote denitrification. We find that the protein atomic composition for denitrification modules (NirK) are significantly cost minimized for C and N compared to ammonification modules (NrfA), indicating that limitation for C and N is a major evolutionary selective pressure imprinted in the architecture of these proteins. The evolutionary precedent for these findings suggests ecological importance for microbial activity as evidenced by higher growth rates when I. calvum grows predominantly using its ammonification pathway and by assimilating its end-product (ammonium) for growth under ammonium-free conditions. Genomic analysis of I. calvum further reveals a versatile ecophysiology to cope with nutrient stress and redox conditions. Metabolite and transcriptional profiles during growth indicate that enzyme modules, NrfAH and NirK, are not constitutively expressed but rather induced by nitrite production via NarG. Mechanistically, our results suggest that pathway selection is driven by intracellular redox potential (redox poise), which may be lowered when resource concentrations are low, thereby decreasing catalytic activity of upstream electron transport steps (i.e., the bc1 complex) needed for denitrification enzymes. Our work advances our understanding of the biogeochemical flexibility of N-cycling organisms, pathway evolution, and ecological food-webs.
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Affiliation(s)
- David C. Vuono
- Division of Earth and Ecosystem Sciences, Desert Research Institute, Reno, NV, United States
- Department of Civil and Environmental Engineering, University of Washington, Seattle, WA, United States
| | - Robert W. Read
- Division of Earth and Ecosystem Sciences, Desert Research Institute, Reno, NV, United States
| | - James Hemp
- Division of Geological and Planetary Sciences, California Institute of Technology, Pasadena, CA, United States
| | - Benjamin W. Sullivan
- Department of Natural Resources and Environmental Science, University of Nevada, Reno, Reno, NV, United States
| | - John A. Arnone
- Division of Earth and Ecosystem Sciences, Desert Research Institute, Reno, NV, United States
| | - Iva Neveux
- Division of Earth and Ecosystem Sciences, Desert Research Institute, Reno, NV, United States
| | - Robert R. Blank
- Agricultural Research Service, United States Department of Agriculture, Reno, NV, United States
| | - Evan Loney
- Division of Earth and Ecosystem Sciences, Desert Research Institute, Reno, NV, United States
| | - David Miceli
- Division of Earth and Ecosystem Sciences, Desert Research Institute, Reno, NV, United States
| | - Mari-Karoliina H. Winkler
- Department of Civil and Environmental Engineering, University of Washington, Seattle, WA, United States
| | - Romy Chakraborty
- Earth and Environmental Sciences Area, Lawrence Berkeley National Laboratory, Berkeley, CA, United States
| | - David A. Stahl
- Department of Civil and Environmental Engineering, University of Washington, Seattle, WA, United States
| | - Joseph J. Grzymski
- Division of Earth and Ecosystem Sciences, Desert Research Institute, Reno, NV, United States
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12
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Structure and electrochemistry of proteins harboring iron-sulfur clusters of different nuclearities. Part I. [4Fe-4S] + [2Fe-2S] iron-sulfur proteins. J Struct Biol 2017; 200:1-19. [DOI: 10.1016/j.jsb.2017.05.010] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/12/2017] [Accepted: 05/25/2017] [Indexed: 01/08/2023]
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13
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Hosseinzadeh P, Lu Y. Design and fine-tuning redox potentials of metalloproteins involved in electron transfer in bioenergetics. BIOCHIMICA ET BIOPHYSICA ACTA 2016; 1857:557-581. [PMID: 26301482 PMCID: PMC4761536 DOI: 10.1016/j.bbabio.2015.08.006] [Citation(s) in RCA: 114] [Impact Index Per Article: 14.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/14/2015] [Accepted: 08/20/2015] [Indexed: 12/25/2022]
Abstract
Redox potentials are a major contributor in controlling the electron transfer (ET) rates and thus regulating the ET processes in the bioenergetics. To maximize the efficiency of the ET process, one needs to master the art of tuning the redox potential, especially in metalloproteins, as they represent major classes of ET proteins. In this review, we first describe the importance of tuning the redox potential of ET centers and its role in regulating the ET in bioenergetic processes including photosynthesis and respiration. The main focus of this review is to summarize recent work in designing the ET centers, namely cupredoxins, cytochromes, and iron-sulfur proteins, and examples in design of protein networks involved these ET centers. We then discuss the factors that affect redox potentials of these ET centers including metal ion, the ligands to metal center and interactions beyond the primary ligand, especially non-covalent secondary coordination sphere interactions. We provide examples of strategies to fine-tune the redox potential using both natural and unnatural amino acids and native and nonnative cofactors. Several case studies are used to illustrate recent successes in this area. Outlooks for future endeavors are also provided. This article is part of a Special Issue entitled Biodesign for Bioenergetics--the design and engineering of electronic transfer cofactors, proteins and protein networks, edited by Ronald L. Koder and J.L. Ross Anderson.
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Affiliation(s)
- Parisa Hosseinzadeh
- Department of Chemistry and Department of Biochemistry, University of Illinois at Urbana-Champaign, 600 S. Mathews St., Urbana, IL, 61801, USA
| | - Yi Lu
- Department of Chemistry and Department of Biochemistry, University of Illinois at Urbana-Champaign, 600 S. Mathews St., Urbana, IL, 61801, USA.
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14
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Jagger BR, Koval AM, Wheeler RA. Distinguishing Protonation States of Histidine Ligands to the Oxidized Rieske Iron-Sulfur Cluster through (15) N Vibrational Frequency Shifts. Chemphyschem 2016; 17:216-20. [PMID: 26603967 DOI: 10.1002/cphc.201500838] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/24/2015] [Indexed: 11/07/2022]
Abstract
The Rieske [2Fe-2S] cluster is a vital component of many oxidoreductases, including mitochondrial cytochrome bc1; its chloroplast equivalent, cytochrome b6f; one class of dioxygenases; and arsenite oxidase. The Rieske cluster acts as an electron shuttle and its reduction is believed to couple with protonation of one of the cluster's His ligands. In cytochromes bc1 and b6f, for example, the Rieske cluster acts as the first electron acceptor in a modified Q cycle. The protonation states of the cluster's His ligands determine its ability to accept a proton and possibly an electron through a hydrogen bond to the electron carrier, ubiquinol. Experimental determination of the protonation states of a Rieske cluster's two His ligands by NMR spectroscopy is difficult, due to the close proximity of the two paramagnetic iron atoms of the cluster. Therefore, this work reports density functional calculations and proposes that difference vibrational spectroscopy with (15) N isotopic substitution may be used to assign the protonation states of the His ligands of the oxidized Rieske [2Fe-2S] complex.
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Affiliation(s)
- Benjamin R Jagger
- Department of Chemistry and Biochemistry, Duquesne University, 600 Forbes Avenue, Pittsburgh, PA, 15282, USA
| | - Ashlyn M Koval
- Department of Chemistry and Biochemistry, Duquesne University, 600 Forbes Avenue, Pittsburgh, PA, 15282, USA
| | - Ralph A Wheeler
- Department of Chemistry and Biochemistry, Duquesne University, 600 Forbes Avenue, Pittsburgh, PA, 15282, USA.
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15
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The competition between chemistry and biology in assembling iron–sulfur derivatives. Molecular structures and electrochemistry. Part III. {[Fe2S2](Cys)3(X)} (X=Asp, Arg, His) and {[Fe2S2](Cys)2(His)2} proteins. Coord Chem Rev 2016. [DOI: 10.1016/j.ccr.2015.07.015] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
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16
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Structural analysis of atovaquone-inhibited cytochrome bc1 complex reveals the molecular basis of antimalarial drug action. Nat Commun 2014; 5:4029. [DOI: 10.1038/ncomms5029] [Citation(s) in RCA: 119] [Impact Index Per Article: 11.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/02/2013] [Accepted: 05/02/2014] [Indexed: 11/08/2022] Open
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17
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Liu J, Chakraborty S, Hosseinzadeh P, Yu Y, Tian S, Petrik I, Bhagi A, Lu Y. Metalloproteins containing cytochrome, iron-sulfur, or copper redox centers. Chem Rev 2014; 114:4366-469. [PMID: 24758379 PMCID: PMC4002152 DOI: 10.1021/cr400479b] [Citation(s) in RCA: 560] [Impact Index Per Article: 56.0] [Reference Citation Analysis] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/02/2013] [Indexed: 02/07/2023]
Affiliation(s)
- Jing Liu
- Department of Chemistry, Department of Biochemistry, and Center for Biophysics
and Computational
Biology, University of Illinois at Urbana-Champaign, Urbana, Illinois 61801, United States
| | - Saumen Chakraborty
- Department of Chemistry, Department of Biochemistry, and Center for Biophysics
and Computational
Biology, University of Illinois at Urbana-Champaign, Urbana, Illinois 61801, United States
| | - Parisa Hosseinzadeh
- Department of Chemistry, Department of Biochemistry, and Center for Biophysics
and Computational
Biology, University of Illinois at Urbana-Champaign, Urbana, Illinois 61801, United States
| | - Yang Yu
- Department of Chemistry, Department of Biochemistry, and Center for Biophysics
and Computational
Biology, University of Illinois at Urbana-Champaign, Urbana, Illinois 61801, United States
| | - Shiliang Tian
- Department of Chemistry, Department of Biochemistry, and Center for Biophysics
and Computational
Biology, University of Illinois at Urbana-Champaign, Urbana, Illinois 61801, United States
| | - Igor Petrik
- Department of Chemistry, Department of Biochemistry, and Center for Biophysics
and Computational
Biology, University of Illinois at Urbana-Champaign, Urbana, Illinois 61801, United States
| | - Ambika Bhagi
- Department of Chemistry, Department of Biochemistry, and Center for Biophysics
and Computational
Biology, University of Illinois at Urbana-Champaign, Urbana, Illinois 61801, United States
| | - Yi Lu
- Department of Chemistry, Department of Biochemistry, and Center for Biophysics
and Computational
Biology, University of Illinois at Urbana-Champaign, Urbana, Illinois 61801, United States
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18
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Analysis of the kinetics and bistability of ubiquinol:cytochrome c oxidoreductase. Biophys J 2014; 105:343-55. [PMID: 23870256 DOI: 10.1016/j.bpj.2013.05.033] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/27/2012] [Revised: 03/28/2013] [Accepted: 05/13/2013] [Indexed: 11/21/2022] Open
Abstract
Ubiquinol:cytochrome c oxidoreductase, bc1 complex, is the enzyme in the respiratory chain of mitochondria responsible for the transfer reducing potential from ubiquinol to cytochrome c coupled to the movement of charge against the electrostatic potential across the mitochondrial inner membrane. The complex is also implicated in the generation of reactive oxygen species under certain conditions and is thus a contributor to cellular oxidative stress. Here, a biophysically detailed, thermodynamically consistent model of the bc1 complex for mammalian mitochondria is developed. The model incorporates the major redox centers near the Qo- and Qi-site of the enzyme, includes the pH-dependent redox reactions, accounts for the effect of the proton-motive force of the reaction rate, and simulates superoxide production at the Qo-site. The model consists of six distinct states characterized by the mobile electron distribution in the enzyme. Within each state, substates that correspond to various electron localizations exist in a rapid equilibrium distribution. The steady-state equation for the six-state system is parameterized using five independent data sets and validated in comparison to additional experimental data. Model analysis suggests that the pH-dependence on turnover is primarily due to the pKa values of cytochrome bH and Rieske iron sulfur protein. A previously proposed kinetic scheme at the Qi-site where ubiquinone binds to only the reduced enzyme and ubiquinol binds to only the oxidized enzyme is shown to be thermodynamically infeasible. Moreover, the model is able to reproduce the bistability phenomenon where at a given overall flux through the enzyme, different rates of superoxide production are attained when the enzyme is differentially reduced.
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19
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Kallas T. Cytochrome b 6 f Complex at the Heart of Energy Transduction and Redox Signaling. PHOTOSYNTHESIS 2012. [DOI: 10.1007/978-94-007-1579-0_21] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/21/2022]
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20
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Valetti F, Fantuzzi A, Sadeghi SJ, Gilardi G. Iron-based redox centres of reductase and oxygenase components of phenol hydroxylase from A. radioresistens: a redox chain working at highly positive redox potentials. Metallomics 2011; 4:72-7. [PMID: 21984271 DOI: 10.1039/c1mt00136a] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
This is the first report of the direct electrochemistry of the reductase (PHR) and oxygenase (PHO) components of phenol hydroxylase from Acinetobacter radioresistens S13 studied by cyclic and differential pulse voltammetry. The PHR contains one 2Fe2S cluster and one FAD that mediate the transfer of electrons from NAD(P)H to the non-heme diiron cluster of PHO. Cyclic and differential pulse voltammetry (CV and DPV) on glassy carbon showed two redox pairs with midpoint potentials at +131.5 ± 13 mV and -234 ± 3 mV versus normal hydrogen electrode (NHE). The first redox couple is attributed to the FeS centre, while the second one corresponds to free FAD released by the protein. DPV scans on native and guanidinium chloride treated PHR highlighted the presence of a split signal (ΔE ≈ 100 mV) attributed to heterogeneous properties of the 2Fe2S cluster interacting with the electrode, possibly due to the presence of two protein conformers and consistently with the large peak-to-peak separation and the peak broadening observed in CV. DPV experiments on gold electrodes performed on PHO confirm a consistently higher reduction potential at +396 mV vs. NHE. The positive redox potentials measured by direct electrochemistry for the FeS cluster in PHR and for the non-heme diiron cluster of PHO show that the entire phenol hydroxylase system works at higher potentials than those reported for structurally similar enzymes, for example methane monooxygenases.
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Affiliation(s)
- Francesca Valetti
- Department of Human and Animal Biology, University of Torino, via Accademia Albertina 13, 10123, Torino, Italy
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21
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Selivanov VA, Votyakova TV, Zeak JA, Trucco M, Roca J, Cascante M. Bistability of mitochondrial respiration underlies paradoxical reactive oxygen species generation induced by anoxia. PLoS Comput Biol 2009; 5:e1000619. [PMID: 20041200 PMCID: PMC2789320 DOI: 10.1371/journal.pcbi.1000619] [Citation(s) in RCA: 46] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/15/2009] [Accepted: 11/17/2009] [Indexed: 11/18/2022] Open
Abstract
Increased production of reactive oxygen species (ROS) in mitochondria underlies major systemic diseases, and this clinical problem stimulates a great scientific interest in the mechanism of ROS generation. However, the mechanism of hypoxia-induced change in ROS production is not fully understood. To mathematically analyze this mechanism in details, taking into consideration all the possible redox states formed in the process of electron transport, even for respiratory complex III, a system of hundreds of differential equations must be constructed. Aimed to facilitate such tasks, we developed a new methodology of modeling, which resides in the automated construction of large sets of differential equations. The detailed modeling of electron transport in mitochondria allowed for the identification of two steady state modes of operation (bistability) of respiratory complex III at the same microenvironmental conditions. Various perturbations could induce the transition of respiratory chain from one steady state to another. While normally complex III is in a low ROS producing mode, temporal anoxia could switch it to a high ROS producing state, which persists after the return to normal oxygen supply. This prediction, which we qualitatively validated experimentally, explains the mechanism of anoxia-induced cell damage. Recognition of bistability of complex III operation may enable novel therapeutic strategies for oxidative stress and our method of modeling could be widely used in systems biology studies. The levels of reactive oxygen species (ROS) that are generated as a side product of mitochondrial respiratory electron transport largely define the extent of oxidative stress in living cells. Free radicals formed in electron transport, such as ubisemiquinone, could pass their non-paired electron directly to oxygen, thus producing superoxide radical that gives rise to a variety of ROS. It is well known in clinical practice that upon recommencing oxygen supply after anoxia a tissue produces much more ROS than before the anoxia, and the state of high ROS production is stable. The mechanism of switching from low to high ROS production by temporal anoxia was unknown, in part because of the lack of detailed mathematical description of hundreds of redox states of respiratory complexes, which are formed in the process of electron transport. A new methodology of automated construction of large systems of differential equations allowed us to describe the system in detail and predicts that the mechanism of paradoxical effect of anoxia-reoxygenation could be defined by the properties of complex III of mitochondrial respiratory chain. Our experiments confirmed that the effect of hypoxia-reoxygenation is confined by intramitochondrial processes since it is observed in isolated mitochondria.
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Affiliation(s)
- Vitaly A. Selivanov
- Departament de Bioquimica i Biologia Molecular, Facultat de Biologia, Institut de Biomedicina at Universitat de Barcelona IBUB and IDIBAPS Hospital Clinic, Barcelona, Catalunya, Spain
- Hospital Clínic, IDIBAPS, CIBERES; Universitat de Barcelona, Barcelona, Catalunya, Spain
- A.N.Belozersky Institute of Physico-Chemical Biology, Moscow State University, Moscow, Russia
| | - Tatyana V. Votyakova
- Department of Pediatrics, The University of Pittsburgh School of Medicine and The Children's Hospital of Pittsburgh, Diabetes Institute, Pittsburgh, Pennsylvania, United States of America
- * E-mail: (TVV); (MC)
| | - Jennifer A. Zeak
- Department of Pediatrics, The University of Pittsburgh School of Medicine and The Children's Hospital of Pittsburgh, Diabetes Institute, Pittsburgh, Pennsylvania, United States of America
| | - Massimo Trucco
- Department of Pediatrics, The University of Pittsburgh School of Medicine and The Children's Hospital of Pittsburgh, Diabetes Institute, Pittsburgh, Pennsylvania, United States of America
| | - Josep Roca
- Hospital Clínic, IDIBAPS, CIBERES; Universitat de Barcelona, Barcelona, Catalunya, Spain
| | - Marta Cascante
- Departament de Bioquimica i Biologia Molecular, Facultat de Biologia, Institut de Biomedicina at Universitat de Barcelona IBUB and IDIBAPS Hospital Clinic, Barcelona, Catalunya, Spain
- * E-mail: (TVV); (MC)
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22
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Lhee S, Kolling DRJ, Nair SK, Dikanov SA, Crofts AR. Modifications of protein environment of the [2Fe-2S] cluster of the bc1 complex: effects on the biophysical properties of the rieske iron-sulfur protein and on the kinetics of the complex. J Biol Chem 2009; 285:9233-48. [PMID: 20023300 DOI: 10.1074/jbc.m109.043505] [Citation(s) in RCA: 32] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
The rate-determining step in the overall turnover of the bc(1) complex is electron transfer from ubiquinol to the Rieske iron-sulfur protein (ISP) at the Q(o)-site. Structures of the ISP from Rhodobacter sphaeroides show that serine 154 and tyrosine 156 form H-bonds to S-1 of the [2Fe-2S] cluster and to the sulfur atom of the cysteine liganding Fe-1 of the cluster, respectively. These are responsible in part for the high potential (E(m)(,7) approximately 300 mV) and low pK(a) (7.6) of the ISP, which determine the overall reaction rate of the bc(1) complex. We have made site-directed mutations at these residues, measured thermodynamic properties using protein film voltammetry to evaluate the E(m) and pK(a) values of ISPs, explored the local proton environment through two-dimensional electron spin echo envelope modulation, and characterized function in strains S154T, S154C, S154A, Y156F, and Y156W. Alterations in reaction rate were investigated under conditions in which concentration of one substrate (ubiquinol or ISP(ox)) was saturating and the other was varied, allowing calculation of kinetic terms and relative affinities. These studies confirm that H-bonds to the cluster or its ligands are important determinants of the electrochemical characteristics of the ISP, likely through electron affinity of the interacting atom and the geometry of the H-bonding neighborhood. The calculated parameters were used in a detailed Marcus-Brønsted analysis of the dependence of rate on driving force and pH. The proton-first-then-electron model proposed accounts naturally for the effects of mutation on the overall reaction.
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Affiliation(s)
- Sangmoon Lhee
- Center for Biophysics and Computational Biology, University of Illinois, Urbana, Illinois 61801, USA
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23
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A structural perspective on mechanism and function of the cytochrome bc (1) complex. Results Probl Cell Differ 2007; 45:253-78. [PMID: 18038116 DOI: 10.1007/400_2007_042] [Citation(s) in RCA: 30] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
Abstract
The cytochrome bc (1) complex is a fundamental component of the energy conversion machinery of respiratory and photosynthetic electron transfer chains. The multi-subunit membrane protein complex couples electron transfer from hydroquinone to cytochrome c to the translocation of protons across the membrane, thereby substantially contributing to the proton motive force that is used for ATP synthesis. Considerable progress has been made with structural and functional studies towards complete elucidation of the Q cycle mechanism, which was originally proposed by Mitchell 30 years ago. Yet, open questions regarding key steps of the mechanism still remain. The role of the complex as a major source of reactive oxygen species and its implication in pathophysiological conditions has recently gained interest.
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24
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Hudder BN, Morales JG, Stubna A, Münck E, Hendrich MP, Lindahl PA. Electron paramagnetic resonance and Mössbauer spectroscopy of intact mitochondria from respiring Saccharomyces cerevisiae. J Biol Inorg Chem 2007; 12:1029-53. [PMID: 17665226 DOI: 10.1007/s00775-007-0275-1] [Citation(s) in RCA: 35] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/05/2007] [Accepted: 06/27/2007] [Indexed: 11/30/2022]
Abstract
Mitochondria from respiring cells were isolated under anaerobic conditions. Microscopic images were largely devoid of contaminants, and samples consumed O(2) in an NADH-dependent manner. Protein and metal concentrations of packed mitochondria were determined, as was the percentage of external void volume. Samples were similarly packed into electron paramagnetic resonance tubes, either in the as-isolated state or after exposure to various reagents. Analyses revealed two signals originating from species that could be removed by chelation, including rhombic Fe(3+) (g = 4.3) and aqueous Mn(2+) ions (g = 2.00 with Mn-based hyperfine). Three S = 5/2 signals from Fe(3+) hemes were observed, probably arising from cytochrome c peroxidase and the a(3):Cu(b) site of cytochrome c oxidase. Three Fe/S-based signals were observed, with averaged g values of 1.94, 1.90 and 2.01. These probably arise, respectively, from the [Fe(2)S(2)](+) cluster of succinate dehydrogenase, the [Fe(2)S(2)](+) cluster of the Rieske protein of cytochrome bc (1), and the [Fe(3)S(4)](+) cluster of aconitase, homoaconitase or succinate dehydrogenase. Also observed was a low-intensity isotropic g = 2.00 signal arising from organic-based radicals, and a broad signal with g (ave) = 2.02. Mössbauer spectra of intact mitochondria were dominated by signals from Fe(4)S(4) clusters (60-85% of Fe). The major feature in as-isolated samples, and in samples treated with ethylenebis(oxyethylenenitrilo)tetraacetic acid, dithionite or O(2), was a quadrupole doublet with DeltaE (Q) = 1.15 mm/s and delta = 0.45 mm/s, assigned to [Fe(4)S(4)](2+) clusters. Substantial high-spin non-heme Fe(2+) (up to 20%) and Fe(3+) (up to 15%) species were observed. The distribution of Fe was qualitatively similar to that suggested by the mitochondrial proteome.
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Affiliation(s)
- Brandon N Hudder
- Department of Chemistry, Texas A&M University, College Station, TX 77843-3255, USA
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25
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Abstract
Crystal structures and their implications for function are described for the energy transducing hetero-oligomeric dimeric cytochrome b6f complex of oxygenic photosynthesis from the thermophilic cyanobacterium, Mastigocladus laminosus, and the green alga, Chlamydomonas reinhardtii. The complex has a cytochrome b core and a central quinone exchange cavity, defined by the two monomers that are very similar to those in the respiratory cytochrome bc1 complex. The pathway of quinol/quinone (Q/QH2) transfer emphasizes the labyrinthine internal structure of the complex, including an 11x12 A portal through which Q/QH2, containing a 45-carbon isoprenoid chain, must pass. Three prosthetic groups are present in the b6f complex that are not found in the related bc1 complex: a chlorophyll (Chl) a, a beta-carotene, and a structurally unique covalently bound heme that does not possess amino acid side chains as axial ligands. It is hypothesized that this heme, exposed to the cavity and a neighboring plastoquinone and close to the positive surface potential of the complex, can function in cyclic electron transport via anionic ferredoxin.
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Affiliation(s)
- William A Cramer
- Department of Biological Sciences, Purdue University, West Lafayette, Indiana 47907-2054, USA.
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26
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Noodleman L, Han WG. Structure, redox, pK a, spin. A golden tetrad for understanding metalloenzyme energetics and reaction pathways. J Biol Inorg Chem 2006; 11:674-94. [PMID: 16830148 DOI: 10.1007/s00775-006-0136-3] [Citation(s) in RCA: 74] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/14/2006] [Accepted: 06/14/2006] [Indexed: 10/24/2022]
Abstract
After a review of the current status of density functional theory (DFT) for spin-polarized and spin-coupled systems, we focus on the resting states and intermediates of redox-active metalloenzymes and electron transfer proteins, showing how comparisons of DFT-calculated spectroscopic parameters with experiment and evaluation of related energies and geometries provide important information. The topics we examine include (1) models for the active-site structure of methane monooxygenase intermediate Q and ribonucleotide reductase intermediate X; (2) the coupling of electron transfer to proton transfer in manganese superoxide dismutase, with implications for reaction kinetics; (3) redox, pK(a), and electronic structure issues in the Rieske iron-sulfur protein, including their connection to coupled electron/proton transfer, and an analysis of how partial electron delocalization strongly alters the electron paramagnetic resonance spectrum; (4) the connection between protein-induced structural distortion and the electronic structure of oxidized high-potential 4Fe4S proteins with implications for cluster reactivity; (5) an analysis of cluster assembly and central-atom insertion into the FeMo cofactor center of nitrogenase based on DFT structural and redox potential calculations.
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Affiliation(s)
- Louis Noodleman
- Department of Molecular Biology, TPC15, The Scripps Research Institute, La Jolla, CA 92037, USA.
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27
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Schneider D, Schmidt CL. Multiple Rieske proteins in prokaryotes: where and why? BIOCHIMICA ET BIOPHYSICA ACTA-BIOENERGETICS 2005; 1710:1-12. [PMID: 16271700 DOI: 10.1016/j.bbabio.2005.09.003] [Citation(s) in RCA: 44] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/16/2004] [Revised: 09/19/2005] [Accepted: 09/20/2005] [Indexed: 11/28/2022]
Abstract
Many microbial genomes have been sequenced in the recent years. Multiple genes encoding Rieske iron-sulfur proteins, which are subunits of cytochrome bc-type complexes or oxygenases, have been detected in many pro- and eukaryotic genomes. The diversity of substrates, co-substrates and reactions offers obvious explanations for the diversity of the low potential Rieske proteins associated with oxygenases, but the physiological significance of the multiple genes encoding high potential Rieske proteins associated with the cytochrome bc-type complexes remains elusive. For some organisms, investigations into the function of the later group of genes have been initiated. Here, we summarize recent finding on the characteristics and physiological functions of multiple high potential Rieske proteins in prokaryotes. We suggest that the existence of multiple high potential Rieske proteins in prokaryotes could be one way of allowing an organism to adapt their electron transfer chains to changing environmental conditions.
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Affiliation(s)
- Dirk Schneider
- Albert-Ludwigs-University Freiburg, Institut für Biochemie und Molekularbiologie, Stefan-Meier-Strasse 19, 79104 Freiburg, Germany.
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28
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Cramer WA, Yan J, Zhang H, Kurisu G, Smith JL. Structure of the cytochrome b6f complex: new prosthetic groups, Q-space, and the 'hors d'oeuvres hypothesis' for assembly of the complex. PHOTOSYNTHESIS RESEARCH 2005; 85:133-43. [PMID: 15977064 DOI: 10.1007/s11120-004-2149-5] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/03/2004] [Accepted: 08/13/2004] [Indexed: 05/03/2023]
Abstract
3-A crystal structures of the cytochrome b6f complex have provided a structural framework for the photosynthetic electron transport chain. The structures of the 220,000 molecular weight dimeric cytochrome b6f complex from the thermophilic cyanobacterium, Mastigocladis laminosus (Kurisu et al. 2003, Science 302: 1009-1014), and the green alga, Chlamydomonas reinhardtii (Stroebel et al. 2003, Nature 426: 413-418), are very similar. The latter is the first structure of a integral membrane photosynthetic electron transport complex from a eukaryotic source. The M. laminosus and C. reinhardtii structures have provided structural information and experimental insights to the properties and functions of three native and novel prosthetic groups, a chlorophyll a, a beta-carotene, and a unique heme x, one copy of which is found in each monomer of the cytochrome b6f complex, but not the cytochrome bc1 complex from the mitochondrial respiratory chain of animals and yeast. Several functional insights have emerged from the structures including the function of the dimer; the properties of heme x; the function of the inter-monomer quinone-exchange cavity; a quinone diffusion pathway through relatively narrow crevices or portals; a modified reaction scheme for n-side quinone redox reactions; a necessarily novel mechanism for quenching of the bound chlorophyll triplet state; a possible role for the bound chlorophyll a in activation of the LHC kinase; and a structural and assembly role for the four small PetG, L, M, and N subunits. An 'hors d'oeuvres hypothesis' for assembly of the complex is proposed for the small 'hydrophobic stick' or 'picket fence' polypeptides at the periphery of the complex, based on the cis-positive orientation of the small hydrophobic subunits and the 'toothpick' binding mode of the beta-carotene.
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Affiliation(s)
- William A Cramer
- Department of Biological Sciences, Lilly Hall of Life Sciences, Purdue University, 915 West State Street, West Lafayette, IN 47907-2054, USA
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29
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Quenneville J, Popović DM, Stuchebrukhov AA. Redox-Dependent pKa of CuB Histidine Ligand in Cytochrome c Oxidase. J Phys Chem B 2004. [DOI: 10.1021/jp0467797] [Citation(s) in RCA: 33] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
- Jason Quenneville
- Department of Chemistry, University of California, One Shields Avenue, Davis, California 95616
| | - Dragan M. Popović
- Department of Chemistry, University of California, One Shields Avenue, Davis, California 95616
| | - Alexei A. Stuchebrukhov
- Department of Chemistry, University of California, One Shields Avenue, Davis, California 95616
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30
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Covian R, Gutierrez-Cirlos EB, Trumpower BL. Anti-cooperative Oxidation of Ubiquinol by the Yeast Cytochrome bc1 Complex. J Biol Chem 2004; 279:15040-9. [PMID: 14761953 DOI: 10.1074/jbc.m400193200] [Citation(s) in RCA: 52] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
We have investigated the interaction between monomers of the dimeric yeast cytochrome bc(1) complex by analyzing the pre-steady and steady state activities of the isolated enzyme in the presence of antimycin under conditions that allow the first turnover of ubiquinol oxidation to be observable in cytochrome c(1) reduction. At pH 8.8, where the redox potential of the iron-sulfur protein is approximately 200 mV and in a bc(1) complex with a mutated iron-sulfur protein of equally low redox potential, the amount of cytochrome c(1) reduced by several equivalents of decyl-ubiquinol in the presence of antimycin corresponded to only half of that present in the bc(1) complex. Similar experiments in the presence of several equivalents of cytochrome c also showed only half of the bc(1) complex participating in quinol oxidation. The extent of cytochrome b reduced corresponded to two b(H) hemes undergoing reduction through one center P per dimer, indicating electron transfer between the two cytochrome b subunits. Antimycin stimulated the ubiquinol-cytochrome c reductase activity of the bc(1) complex at low inhibitor/enzyme ratios. This stimulation could only be fitted to a model in which half of the bc(1) dimer is inactive when both center N sites are free, becoming active upon binding of one center N inhibitor molecule per dimer, and there is electron transfer between the cytochrome b subunits of the dimer. These results are consistent with an alternating half-of-the-sites mechanism of ubiquinol oxidation in the bc(1) complex dimer.
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Affiliation(s)
- Raul Covian
- Department of Biochemistry, Dartmouth Medical School, Hanover, New Hampshire 03755, USA
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31
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Kounosu A, Li Z, Cosper NJ, Shokes JE, Scott RA, Imai T, Urushiyama A, Iwasaki T. Engineering a three-cysteine, one-histidine ligand environment into a new hyperthermophilic archaeal Rieske-type [2Fe-2S] ferredoxin from Sulfolobus solfataricus. J Biol Chem 2004; 279:12519-28. [PMID: 14726526 DOI: 10.1074/jbc.m305923200] [Citation(s) in RCA: 49] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
We heterologously overproduced a hyperthermostable archaeal low potential (E(m) = -62 mV) Rieske-type ferredoxin (ARF) from Sulfolobus solfataricus strain P-1 and its variants in Escherichia coli to examine the influence of ligand substitutions on the properties of the [2Fe-2S] cluster. While two cysteine ligand residues (Cys(42) and Cys(61)) are essential for the cluster assembly and/or stability, the contributions of the two histidine ligands to the cluster assembly in the archaeal Rieske-type ferredoxin appear to be inequivalent as indicated by much higher stability of the His(64) --> Cys variant (H64C) than the His(44) --> Cys variant (H44C). The x-ray absorption and resonance Raman spectra of the H64C variant firmly established the formation of a novel, oxidized [2Fe-2S] cluster with one histidine and three cysteine ligands in the archaeal Rieske-type protein moiety. Comparative resonance Raman features of the wild-type, natural abundance and uniformly (15)N-labeled ARF and its H64C variant showed significant mixing of the Fe-S and Fe-N stretching characters for an oxidized biological [2Fe-2S] cluster with partial histidine ligation.
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Affiliation(s)
- Asako Kounosu
- Department of Biochemistry and Molecular Biology, Nippon Medical School, Sendagi, Bunkyo-ku, Tokyo 113-8602, Japan
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Palsdottir H, Lojero CG, Trumpower BL, Hunte C. Structure of the yeast cytochrome bc1 complex with a hydroxyquinone anion Qo site inhibitor bound. J Biol Chem 2003; 278:31303-11. [PMID: 12782631 DOI: 10.1074/jbc.m302195200] [Citation(s) in RCA: 160] [Impact Index Per Article: 7.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Bifurcated electron transfer during ubiquinol oxidation is the key reaction of cytochrome bc1 complex catalysis. Binding of the competitive inhibitor 5-n-heptyl-6-hydroxy-4,7-dioxobenzothiazole to the Qo site of the cytochrome bc1 complex from Saccharomyces cerevisiae was analyzed by x-ray crystallography. This alkylhydroxydioxobenzothiazole is bound in its ionized form as evident from the crystal structure and confirmed by spectroscopic analysis, consistent with a measured pKa = 6.1 of the hydroxy group in detergent micelles. Stabilizing forces for the hydroxyquinone anion inhibitor include a polarized hydrogen bond to the iron-sulfur cluster ligand His181 and on-edge interactions via weak hydrogen bonds with cytochrome b residue Tyr279. The hydroxy group of the latter contributes to stabilization of the Rieske protein in the b-position by donating a hydrogen bond. The reported pH dependence of inhibition with lower efficacy at alkaline pH is attributed to the protonation state of His181 with a pKa of 7.5. Glu272, a proposed primary ligand and proton acceptor of ubiquinol, is not bound to the carbonyl group of the hydroxydioxobenzothiazole ring but is rotated out of the binding pocket toward the heme bL propionate A, to which it is hydrogen-bonded via a single water molecule. The observed hydrogen bonding pattern provides experimental evidence for the previously proposed proton exit pathway involving the heme propionate and a chain of water molecules. Binding of the alkyl-6-hydroxy-4,7-dioxobenzothiazole is discussed as resembling an intermediate step of ubiquinol oxidation, supporting a single occupancy model at the Qo site.
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Affiliation(s)
- Hildur Palsdottir
- Abt. Molekulare Membranbiologie, Max-Planck-Institut für Biophysik, Marie-Curie-Strasse 15, D-60439 Frankfurt, Germany
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Abstract
The cytochrome bc(1) complex catalyzes electron transfer from ubiquinol to cytochrome c by a protonmotive Q cycle mechanism in which electron transfer is linked to proton translocation across the inner mitochondrial membrane. In the Q cycle mechanism proton translocation is the net result of topographically segregated reduction of quinone and reoxidation of quinol on opposite sides of the membrane, with protons being carried across the membrane as hydrogens on the quinol. The linkage of proton chemistry to electron transfer during quinol oxidation and quinone reduction requires pathways for moving protons to and from the aqueous phase and the hydrophobic environment in which the quinol and quinone redox reactions occur. Crystal structures of the mitochondrial cytochrome bc(1) complexes in various conformations allow insight into possible proton conduction pathways. In this review we discuss pathways for proton conduction linked to ubiquinone redox reactions with particular reference to recently determined structures of the yeast bc(1) complex.
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Affiliation(s)
- Carola Hunte
- Department Molecular Membrane Biology, Max-Planck-Institute Biophysics, D-60439 Frankfurt am Main, Germany.
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Cosper NJ, Eby DM, Kounosu A, Kurosawa N, Neidle EL, Kurtz DM, Iwasaki T, Scott RA. Redox-dependent structural changes in archaeal and bacterial Rieske-type [2Fe-2S] clusters. Protein Sci 2002; 11:2969-73. [PMID: 12441394 PMCID: PMC2373747 DOI: 10.1110/ps.0222402] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/27/2022]
Abstract
Proteins containing Rieske-type [2Fe-2S] clusters play important roles in many biological electron transfer reactions. Typically, [2Fe-2S] clusters are not directly involved in the catalytic transformation of substrate, but rather supply electrons to the active site. We report herein X-ray absorption spectroscopic (XAS) data that directly demonstrate an average increase in the iron-histidine bond length of at least 0.1 A upon reduction of two distantly related Rieske-type clusters in archaeal Rieske ferredoxin from Sulfolobus solfataricus strain P-1 and bacterial anthranilate dioxygenases from Acinetobacter sp. strain ADP1. This localized redox-dependent structural change may fine tune the protein-protein interaction (in the case of ARF) or the interdomain interaction (in AntDO) to facilitate rapid electron transfer between a lower potential Rieske-type cluster and its redox partners, thereby regulating overall oxygenase reactions in the cells.
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Affiliation(s)
- Nathaniel J Cosper
- Center for Metalloenzyme Studies, University of Georgia, Athens 30602, USA.
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35
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Soriano GM, Guo LW, De Vitry C, Kallas T, Cramer WA. Electron transfer from the Rieske iron-sulfur protein (ISP) to cytochrome f in vitro. Is a guided trajectory of the ISP necessary for competent docking? J Biol Chem 2002; 277:41865-71. [PMID: 12207018 DOI: 10.1074/jbc.m205772200] [Citation(s) in RCA: 17] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
The time course of electron transfer in vitro between soluble domains of the Rieske iron-sulfur protein (ISP) and cytochrome f subunits of the cytochrome b(6)f complex of oxygenic photosynthesis was measured by stopped-flow mixing. The domains were derived from Chlamydomonas reinhardtii and expressed in Escherichia coli. The expressed 142-residue soluble ISP apoprotein was reconstituted with the [2Fe-2S] cluster. The second-order rate constant, k(2)((ISP-f)) = 1.5 x 10(6) m(-1) s(-1), for ISP to cytochrome f electron transfer was <10(-2) of the rate constant at low ionic strength, k(2)((f-PC))(> 200 x 10(6) m(-1) s(-1)), for the reduction of plastocyanin by cytochrome f, and approximately 1/30 of k(2)((f-PC)) at the ionic strength estimated for the thylakoid interior. In contrast to k(2)((f-PC)), k(2)((ISP-f)) was independent of pH and ionic strength, implying no significant role of electrostatic interactions. Effective pK values of 6.2 and 8.3, respectively, of oxidized and reduced ISP were derived from the pH dependence of the amplitude of cytochrome f reduction. The first-order rate constant, k(1)((ISP-f)), predicted from k(2)((ISP-f)) is approximately 10 and approximately 150 times smaller than the millisecond and microsecond phases of cytochrome f reduction observed in vivo. It is proposed that in the absence of electrostatic guidance, a productive docking geometry for fast electron transfer is imposed by the guided trajectory of the ISP extrinsic domain. The requirement of a specific electrically neutral docking configuration for ISP electron transfer is consistent with structure data for the related cytochrome bc(1) complex.
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Affiliation(s)
- Glenda M Soriano
- Department of Biological Sciences and Program in Biochemistry/Molecular Biology, Purdue University, West Lafayette, Indiana 47907-1392, USA
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36
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Trumpower BL. A concerted, alternating sites mechanism of ubiquinol oxidation by the dimeric cytochrome bc(1) complex. BIOCHIMICA ET BIOPHYSICA ACTA 2002; 1555:166-73. [PMID: 12206910 DOI: 10.1016/s0005-2728(02)00273-6] [Citation(s) in RCA: 80] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 10/27/2022]
Abstract
A refinement of the protonmotive Q cycle mechanism is proposed in which oxidation of ubiquinol is a concerted reaction and occurs by an alternating, half-of-the-sites mechanism. A concerted mechanism of ubiquinol oxidation is inferred from the finding that there is reciprocal control between the high potential and low potential redox components involved in ubiquinol oxidation. The potential of the Rieske iron-sulfur protein controls the rate of reduction of the b cytochromes, and the potential of the b cytochromes controls the rate of reduction of the Rieske protein and cytochrome c(1). A concerted mechanism of ubiquinol oxidation reconciles the findings that the ubiquinol-cytochrome c reductase kinetics of the bc(1) complex include both a pH dependence and a dependence on Rieske iron-sulfur protein midpoint potential.An alternating, half-of-the-sites mechanism for ubiquinol oxidation is inferred from the finding that some inhibitory analogs of ubiquinol that block ubiquinol oxidation by binding to the ubiquinol oxidation site in the bc(1) complex inhibit the yeast enzyme with a stoichiometry of 0.5 per bc(1) complex. One molecule of inhibitor is sufficient to fully inhibit the dimeric enzyme, and the binding is anti-cooperative, in that a second molecule of inhibitor binds with much lower affinity to a dimer in which an inhibitor molecule is already bound. An alternating, half-of-the-sites mechanism implies that, at least under some conditions, only half of the sites in the dimeric enzyme are reactive at any one time. This provides a raison d'être for the dimeric structure of the enzyme, in that bc(1) activity may be regulated and capable of switching between a half-of-the-sites active and a fully active enzyme.
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Affiliation(s)
- Bernard L Trumpower
- Department of Biochemistry, Dartmouth Medical School, Hanover, NH 03755-3844, USA.
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Bönisch H, Schmidt CL, Schäfer G, Ladenstein R. The structure of the soluble domain of an archaeal Rieske iron-sulfur protein at 1.1 A resolution. J Mol Biol 2002; 319:791-805. [PMID: 12054871 DOI: 10.1016/s0022-2836(02)00323-6] [Citation(s) in RCA: 60] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/27/2022]
Abstract
The first crystal structure of an archaeal Rieske iron-sulfur protein, the soluble domain of Rieske iron-sulfur protein II (soxF) from the hyperthermo-acidophile Sulfolobus acidocaldarius, has been solved by multiple wavelength anomalous dispersion (MAD) and has been refined to 1.1 A resolution. SoxF is a subunit of the terminal oxidase supercomplex SoxM in the plasma membrane of S. acidocaldarius that combines features of a cytochrome bc(1) complex and a cytochrome c oxidase. The [2Fe-2S] cluster of soxF is most likely the primary electron acceptor during the oxidation of caldariella quinone by the cytochrome a(587)/Rieske subcomplex. The geometry of the [2Fe-2S] cluster and the structure of the cluster-binding site are almost identical in soxF and the Rieske proteins from eucaryal cytochrome bc(1) and b(6)f complexes, suggesting a strict conservation of the catalytic mechanism. The main domain of soxF and part of the cluster-binding domain, though structurally related, show a significantly divergent structure with respect to topology, non-covalent interactions and surface charges. The divergent structure of soxF reflects a different topology of the soxM complex compared to eucaryal bc complexes and the adaptation of the protein to the extreme ambient conditions on the outer membrane surface of a hyperthermo-acidophilic organism.
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Affiliation(s)
- Heiko Bönisch
- Department of Biosciences at NOVUM, Center for Structural Biochemistry, Karolinska Institutet, Hälsovägen 7-9, S-14157 Huddinge, Sweden
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Covián R, Moreno-Sánchez R. Role of protonatable groups of bovine heart bc(1) complex in ubiquinol binding and oxidation. EUROPEAN JOURNAL OF BIOCHEMISTRY 2001; 268:5783-90. [PMID: 11722564 DOI: 10.1046/j.0014-2956.2001.02521.x] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
The pH dependence of the initial reaction rate catalyzed by the isolated bovine heart ubiquinol-cytochrome c reductase (bc1 complex) varying decylbenzoquinol (DBH) and decylbenzoquinone (DB) concentrations was determined. The affinity for DBH was increased threefold by the protonation of a group with pKa = 5.7 +/- 0.2, while the inhibition constant (Ki) for DB decreased 22 and 2.8 times when groups with pKa = 5.2 +/- 0.6 and 7.7 +/- 0.2, respectively, were protonated. This suggests stabilization of the protonated form of the acidic group by DBH binding. Initial rates were best fitted to a kinetic model involving three protonatable groups. The protonation of the pKa approximately 5.7 group blocked catalysis, indicating its role in proton transfer. The kinetic model assumed that the deprotonation of two groups (pKa values of 7.5 +/- 0.03 and approximately 9.2) decreases the catalytic rate by diminishing the redox potential of the iron-sulfur (Fe-S) cluster. The protonation of the pKa approximately 7.5 group also decreased the reaction rate by 80-86%, suggesting its role as acceptor of a proton from ubiquinol. The lack of effect on the Km for DBH when the pKa 7.5-7.7 group is deprotonated suggests that hydrogen bonding to this residue is not the main factor that determines substrate binding to the Qo site. The possible relationship of the pKa 5.2-5.7 and pKa 7.5-7.7 groups with Glu272 of cytochrome b and His161 of the Fe-S protein is discussed.
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Affiliation(s)
- R Covián
- Departamento de Bioquímica, Instituto Nacional de Cardiología, México.
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39
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Janssen S, Trincão J, Teixeira M, Schäfer G, Anemüller S. Ferredoxins from the archaeon Acidianus ambivalens: overexpression and characterization of the non-zinc-containing ferredoxin FdB. Biol Chem 2001; 382:1501-7. [PMID: 11727834 DOI: 10.1515/bc.2001.184] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022]
Abstract
Two ferredoxin genes, fdA and fdB, from the extremely thermoacidophilic crenarchaeon Acidianus ambivalens have been sequenced; the sequences share 86% similarity. Whereas the deduced protein sequence of the ferredoxin FdA clearly contains a zinc-binding motif, the corresponding sequence of the FdB is devoid of this motif. Thus far, only the zinc-containing ferredoxin, FdA, from A. ambivalens has been chemically and functionally characterized from its native source. Using RT-PCR and Northern blot analysis, we show that both ferredoxins are expressed by A. ambivalens under either anaerobic or aerobic growth conditions. The zinc-free ferredoxin, FdB, was overexpressed in E. coli and purified to homogeneity. Using EPR spectroscopy, we could demonstrate that FdB contains one [3Fe-4S](1+/0) and one [4Fe-4S](2+/1+) cluster. The reduction potential of the [3Fe-4S](1+/0) cluster was determined as -235+/-10 mV, at pH 6.5, by EPR-monitored redox titration. The high melting temperature of 108+/-2 degrees C of FdB determined by CD spectroscopy reveals that it is not the binding of the Zn2+ that induces the extreme thermostability of these ferredoxins.
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Affiliation(s)
- S Janssen
- Institut für Biochemie, Medizinische Universität zu Lübeck, Germany
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40
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Affiliation(s)
- T Iwasaki
- Department of Biochemistry and Molecular Biology, Nippon Medical School, Tokyo 113-8602, Japan
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41
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Colbert CL, Couture MM, Eltis LD, Bolin JT. A cluster exposed: structure of the Rieske ferredoxin from biphenyl dioxygenase and the redox properties of Rieske Fe-S proteins. Structure 2000; 8:1267-78. [PMID: 11188691 DOI: 10.1016/s0969-2126(00)00536-0] [Citation(s) in RCA: 91] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022]
Abstract
BACKGROUND Ring-hydroxylating dioxygenases are multicomponent systems that initiate biodegradation of aromatic compounds. Many dioxygenase systems include Rieske-type ferredoxins with amino acid sequences and redox properties remarkably different from the Rieske proteins of proton-translocating respiratory and photosynthetic complexes. In the latter, the [Fe2S2] clusters lie near the protein surface, operate at potentials above +300 mV at pH 7, and express pH- and ionic strength-dependent redox behavior. The reduction potentials of the dioxygenase ferredoxins are approximately 150 mV and are pH-independent. These distinctions were predicted to arise from differences in the exposure of the cluster and/or interactions of the histidine ligands. RESULTS The crystal structure of BphF, the Rieske-type ferredoxin associated with biphenyl dioxygenase, was determined by multiwavelength anomalous diffraction and refined at 1.6 A resolution. The structure of BphF was compared with other Rieske proteins at several levels. BphF has the same two-domain fold as other Rieske proteins, but it lacks all insertions that give the others unique structural features. The BphF Fe-S cluster and its histidine ligands are exposed. However, the cluster has a significantly different environment in that five fewer polar groups interact strongly with the cluster sulfide or the cysteinyl ligands. CONCLUSIONS BphF has structural features consistent with a minimal and perhaps archetypical Rieske protein. Variations in redox potentials among Rieske clusters appear to be largely the result of local electrostatic interactions with protein partial charges. Moreover, it appears that the redox-linked ionizations of the Rieske proteins from proton-translocating complexes are also promoted by these electrostatic interactions.
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Affiliation(s)
- C L Colbert
- Department of Biological Sciences, Purdue University, West Lafayette, Indiana 47907, USA
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42
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Hewitson KS, Baldwin JE, Shaw NM, Roach PL. Mutagenesis of the proposed iron-sulfur cluster binding ligands in Escherichia coli biotin synthase. FEBS Lett 2000; 466:372-6. [PMID: 10682863 DOI: 10.1016/s0014-5793(00)01101-7] [Citation(s) in RCA: 30] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
Abstract
Biotin synthase (BioB) is a member of a family of enzymes that includes anaerobic ribonucleotide reductase and pyruvate formate lyase activating enzyme. These enzymes all use S-adenosylmethionine during turnover and contain three highly conserved cysteine residues that may act as ligands to an iron-sulfur cluster required for activity. Three mutant enzymes of BioB have been made, each with one cysteine residue (C53, 57, 60) mutated to alanine. All three mutant enzymes were inactive, but they still exhibited the characteristic UV-visible spectrum of a [2Fe-2S]2+ cluster similar to that of the wild-type enzyme.
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Affiliation(s)
- K S Hewitson
- Dyson Perrins Laboratory, University of Oxford, UK
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43
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Brugna M, Nitschke W, Asso M, Guigliarelli B, Lemesle-Meunier D, Schmidt C. Redox components of cytochrome bc-type enzymes in acidophilic prokaryotes. II. The Rieske protein of phylogenetically distant acidophilic organisms. J Biol Chem 1999; 274:16766-72. [PMID: 10358018 DOI: 10.1074/jbc.274.24.16766] [Citation(s) in RCA: 40] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
The Rieske proteins of two phylogenetically distant acidophilic organisms, i.e. the proteobacterium Thiobacillus ferrooxidans and the crenarchaeon Sulfolobus acidocaldarius, were studied by EPR. Redox titrations at a range of pH values showed that the Rieske centers of both organisms are characterized by redox midpoint potential-versus-pH curves featuring a common pK value of 6.2. This pK value is significantly more acidic (by almost 2 pH units) than that of Rieske proteins in neutrophilic species. The orientations of the Rieske center's g tensors with respect to the plane of the membrane were studied between pH 4 and 8 using partially ordered samples. At pH 4, the Sulfolobus Rieske cluster was found in the "typical" orientation of chemically reduced Rieske centers, whereas this orientation changed significantly on going toward high pH values. The Thiobacillus protein, by contrast, appeared to be in the "standard" orientation at both low and high pH values. The results are discussed with respect to the molecular parameters conveying acid resistance and in light of the recently demonstrated long-range conformational movement of the Rieske protein during enzyme turnover in cytochrome bc1 complexes.
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Affiliation(s)
- M Brugna
- Laboratoire de Bioénergétique et Ingénierie des Protéines (UPR 9036), CNRS, Institut de Biologie Structurale et Microbiologie, 31 chemin Joseph Aiguier, 13402 Marseille Cedex 20, France
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44
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Schoepp B, Brugna M, Riedel A, Nitschke W, Kramer DM. The Qo-site inhibitor DBMIB favours the proximal position of the chloroplast Rieske protein and induces a pK-shift of the redox-linked proton. FEBS Lett 1999; 450:245-50. [PMID: 10359083 DOI: 10.1016/s0014-5793(99)00511-6] [Citation(s) in RCA: 48] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/18/2022]
Abstract
The interaction of the inhibitor 2,5-dibromo-3-methyl-6-isopropylbenzoquinone (DBMIB) with the Rieske protein of the chloroplast b6f complex has been studied by EPR. All three redox states of DBMIB were found to interact with the iron-sulphur cluster. The presence of the oxidised form of DBMIB altered the equilibrium distribution of the Rieske protein's conformational substates, strongly favouring the proximal position close to heme bL. In addition to this conformational effect, DBMIB shifted the pK-value of the redox-linked proton involved in the iron-sulphur cluster's redox transition by about 1.5 pH units towards more acidic values. The implications of these results with respect to the interaction of the native quinone substrate and the Rieske cluster in cytochrome bc complexes are discussed.
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Affiliation(s)
- B Schoepp
- Laboratoire de Bioénergétique et Ingénierie des Protéines (UPR 9036), Institut de Biologie Structurale et Microbiologie, Marseille, France
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Kozlov AV, Gille L, Staniek K, Nohl H. Dihydrolipoic acid maintains ubiquinone in the antioxidant active form by two-electron reduction of ubiquinone and one-electron reduction of ubisemiquinone. Arch Biochem Biophys 1999; 363:148-54. [PMID: 10049509 DOI: 10.1006/abbi.1998.1064] [Citation(s) in RCA: 78] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Dihydrolipoic acid (DHLA) is a constituent of cellular energy metabolism, where it cycles between the oxidized and reduced form. The two thiol residues of DHLA make this biomolecule susceptible to most radical species and prevent Fenton-type reactions by chelating free iron. In this study we present a novel mode of action by which DHLA exerts antioxidant function in combination with coenzyme Q (ubiquinone). DHLA was found to reduce ubiquinone to ubiquinol by the transfer of a pair of electrons, thereby increasing the antioxidant capacity of coenzyme Q in biomembranes. In addition, ubisemiquinone, which was earlier shown to be an active oxygen radical source when existing in the anionic form, is removed from equilibrium by the addition of a single electron from DHLA. The high reactivity of DHLA with this potentially deleterious ubisemiquinone species not only prevents the formation of prooxidants, it also keeps ubiquinone in its antioxidant active form. Experimental data of this study demonstrate a superadditive effect of ubiquinone in combination with DHLA in preventing peroxidation of biomembranes.
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Affiliation(s)
- A V Kozlov
- Institute of Pharmacology and Toxicology, Veterinary University of Vienna, Veterinärplatz 1, Vienna, A-1210, Austria
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46
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Schoepp B, Brugna M, Lebrun E, Nitschke W. Iron-Sulfur Centers Involved in Photosynthetic Light Reactions. ADVANCES IN INORGANIC CHEMISTRY 1999. [DOI: 10.1016/s0898-8838(08)60082-3] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
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47
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48
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Ugulava NB, Crofts AR. CD-monitored redox titration of the Rieske Fe-S protein of Rhodobacter sphaeroides: pH dependence of the midpoint potential in isolated bc1 complex and in membranes. FEBS Lett 1998; 440:409-13. [PMID: 9872412 DOI: 10.1016/s0014-5793(98)01493-8] [Citation(s) in RCA: 61] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/17/2022]
Abstract
The redox potential of the Rieske Fe-S protein has been investigated using circular dichroism (CD)-spectroscopy. The CD features characteristic of the purified bc1 complex and membranes of Rhodobacter sphaeroides were found in the region between 450 and 550 nm. The difference between reduced and oxidized CD-spectra shows a negative band at about 500 nm with a half of width 30 nm that corresponds to the specific dichroic absorption of the reduced Rieske protein (Fee, J.A. et al. (1984) J. Biol. Chem. 259, 124-133; Degli Esposti, M. et al. (1987) Biochem. J. 241, 285-290; Rich, P.R. and Wiggins, T.E. (1992) Biochem. Soc. Trans. 20, 241S). It was found that the redox potential at pH 7.0 for the Rieske center in the isolated bc1 complex and in chromatophore membranes from the R-26 strain of Rh. sphaeroides is 300 +/- 5 mV. In chromatophores from the BC17C strain of Rh. sphaeroides, the Em value measured for the Rieske iron-sulfur protein (ISP) was higher (315 +/- 5 mV), but the presence of carotenoids made measurement less accurate. The Em varied with pH in the range above pH 7, and the pH dependence was well fit either by one pK at approximately 7.5 in the range of titration, or by two pK values, pK1 = 7.6 and pK2 = 9.8. Similar titrations and pK values were found for the Rieske Fe-S protein in the isolated bc1 complex and membranes from the R-26 strain of Rb. sphaeroides. The results are discussed in the context of the mechanism of quinol oxidation by the bc1 complex, and the role of the iron sulfur protein in formation of a reaction complex at the Qo-site.
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Affiliation(s)
- N B Ugulava
- Department of Microbiology, University of Illinois at Urbana-Champaign, Urbana 61801, USA.
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49
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Limson J, Nyokong T. Voltammetric Studies of Spinach Ferredoxin on a Glassy Carbon Electrode Modified with Cobalt(II) Tetrasulfophthalocyanine. ELECTROANAL 1998. [DOI: 10.1002/(sici)1521-4109(199810)10:14<988::aid-elan988>3.0.co;2-p] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
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50
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de Vries S, Cherepanov A, Berg A, Canters G. Spectroscopic investigations on the water-soluble fragment of the Rieske [2Fe2S] protein from Paracoccus denitrificans. Inorganica Chim Acta 1998. [DOI: 10.1016/s0020-1693(98)00113-3] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/18/2022]
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