1
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Jafari S, Tavares Santos YA, Bergmann J, Irani M, Ryde U. Benchmark Study of Redox Potential Calculations for Iron-Sulfur Clusters in Proteins. Inorg Chem 2022; 61:5991-6007. [PMID: 35403427 PMCID: PMC9044450 DOI: 10.1021/acs.inorgchem.1c03422] [Citation(s) in RCA: 7] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
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Redox potentials
have been calculated for 12 different iron–sulfur
sites of 6 different types with 1–4 iron ions. Structures were
optimized with combined quantum mechanical and molecular mechanical
(QM/MM) methods, and the redox potentials were calculated using the
QM/MM energies, single-point QM methods in a continuum solvent or
by QM/MM thermodynamic cycle perturbations. We show that the best
results are obtained with a large QM system (∼300 atoms, but
a smaller QM system, ∼150 atoms, can be used for the QM/MM
geometry optimization) and a large value of the dielectric constant
(80). For absolute redox potentials, the B3LYP density functional
method gives better results than TPSS, and the results are improved
with a larger basis set. However, for relative redox potentials, the
opposite is true. The results are insensitive to the force field (charges
of the surroundings) used for the QM/MM calculations or whether the
protein and solvent outside the QM system are relaxed or kept fixed
at the crystal structure. With the best approach for relative potentials,
mean absolute and maximum deviations of 0.17 and 0.44 V, respectively,
are obtained after removing a systematic error of −0.55 V.
Such an approach can be used to identify the correct oxidation states
involved in a certain redox reaction. We
have studied redox potentials of 12 iron−sulfur
sites of 6 types with 1−4 iron ions. Structures were optimized
with combined quantum mechanical and molecular mechanical (QM/MM)
methods, and the redox potentials were calculated with QM/MM, QM calculations
in a continuum solvent or by QM/MM thermodynamic cycle perturbations.
The best results are obtained with the second approach using ∼300
atoms in the QM model and a large dielectric constant.
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Affiliation(s)
- Sonia Jafari
- Department of Chemistry, University of Kurdistan, 66175-416 Sanandaj, Iran.,Department of Theoretical Chemistry, Chemical Centre, Lund University, P.O. Box 124, SE-221 00 Lund, Sweden
| | - Yakini A Tavares Santos
- Department of Theoretical Chemistry, Chemical Centre, Lund University, P.O. Box 124, SE-221 00 Lund, Sweden
| | - Justin Bergmann
- Department of Theoretical Chemistry, Chemical Centre, Lund University, P.O. Box 124, SE-221 00 Lund, Sweden
| | - Mehdi Irani
- Department of Chemistry, University of Kurdistan, 66175-416 Sanandaj, Iran
| | - Ulf Ryde
- Department of Theoretical Chemistry, Chemical Centre, Lund University, P.O. Box 124, SE-221 00 Lund, Sweden
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2
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Li B, Steindel P, Haddad N, Elliott SJ. Maximizing (Electro)catalytic CO 2 Reduction with a Ferredoxin-Based Reduction Potential Gradient. ACS Catal 2021. [DOI: 10.1021/acscatal.1c00092] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/26/2023]
Affiliation(s)
- Bin Li
- Department of Chemistry, Boston University, Boston, Massachusetts 02215, United States
| | - Phillip Steindel
- Department of Chemistry, Boston University, Boston, Massachusetts 02215, United States
| | - Narmien Haddad
- Department of Chemistry, Boston University, Boston, Massachusetts 02215, United States
| | - Sean J. Elliott
- Department of Chemistry, Boston University, Boston, Massachusetts 02215, United States
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3
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Imlay JA, Sethu R, Rohaun SK. Evolutionary adaptations that enable enzymes to tolerate oxidative stress. Free Radic Biol Med 2019; 140:4-13. [PMID: 30735836 PMCID: PMC6684875 DOI: 10.1016/j.freeradbiomed.2019.01.048] [Citation(s) in RCA: 24] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/09/2018] [Accepted: 01/31/2019] [Indexed: 10/27/2022]
Abstract
Biochemical mechanisms emerged and were integrated into the metabolic plan of cellular life long before molecular oxygen accumulated in the biosphere. When oxygen levels finaly rose, they threatened specific types of enzymes: those that use organic radicals as catalysts, and those that depend upon iron centers. Nature has found ways to ensure that such enzymes are still used by contemporary organisms. In some cases they are restricted to microbes that reside in anoxic habitats, but in others they manage to function inside aerobic cells. In the latter case, it is frequently true that the ancestral enzyme has been modified to fend off poisoning. In this review we survey a range of protein adaptations that permit radical-based and low-potential iron chemistry to succeed in oxic environments. In many cases, accessory domains shield the vulnerable radical or metal center from oxygen. In others, the structures of iron cofactors evolved to less oxidizable forms, or alternative metals replaced iron altogether. The overarching view is that some classes of biochemical mechanism are intrinsically incompatible with the presence of oxygen. The structural modification of target enzymes is an under-recognized response to this problem.
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Affiliation(s)
- James A Imlay
- Department of Microbiology, University of Illinois, 601 S. Goodwin Ave, Urbana, IL, 61801, USA.
| | - Ramakrishnan Sethu
- Department of Microbiology, University of Illinois, 601 S. Goodwin Ave, Urbana, IL, 61801, USA
| | - Sanjay Kumar Rohaun
- Department of Microbiology, University of Illinois, 601 S. Goodwin Ave, Urbana, IL, 61801, USA
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4
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Witt A, Pozzi R, Diesch S, Hädicke O, Grammel H. New light on ancient enzymes –
in vitro
CO
2
Fixation by Pyruvate Synthase of
Desulfovibrio africanus
and
Sulfolobus acidocaldarius. FEBS J 2019; 286:4494-4508. [DOI: 10.1111/febs.14981] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/03/2019] [Revised: 05/13/2019] [Accepted: 07/02/2019] [Indexed: 01/09/2023]
Affiliation(s)
- Andreas Witt
- Hochschule Biberach University of Applied Science Biberach Germany
| | - Roberta Pozzi
- Hochschule Biberach University of Applied Science Biberach Germany
| | - Stephan Diesch
- Hochschule Biberach University of Applied Science Biberach Germany
| | - Oliver Hädicke
- Max Planck Institute for Dynamics of Complex Technical Systems Magdeburg Germany
| | - Hartmut Grammel
- Hochschule Biberach University of Applied Science Biberach Germany
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5
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Kpebe A, Benvenuti M, Guendon C, Rebai A, Fernandez V, Le Laz S, Etienne E, Guigliarelli B, García-Molina G, de Lacey AL, Baffert C, Brugna M. A new mechanistic model for an O 2-protected electron-bifurcating hydrogenase, Hnd from Desulfovibrio fructosovorans. BIOCHIMICA ET BIOPHYSICA ACTA-BIOENERGETICS 2018; 1859:1302-1312. [PMID: 30463674 DOI: 10.1016/j.bbabio.2018.09.364] [Citation(s) in RCA: 27] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Key Words] [Subscribe] [Scholar Register] [Received: 07/18/2018] [Revised: 08/22/2018] [Accepted: 09/16/2018] [Indexed: 10/28/2022]
Abstract
The genome of the sulfate-reducing and anaerobic bacterium Desulfovibrio fructosovorans encodes different hydrogenases. Among them is Hnd, a tetrameric cytoplasmic [FeFe] hydrogenase that has previously been described as an NADP-specific enzyme (Malki et al., 1995). In this study, we purified and characterized a recombinant Strep-tagged form of Hnd and demonstrated that it is an electron-bifurcating enzyme. Flavin-based electron-bifurcation is a mechanism that couples an exergonic redox reaction to an endergonic one allowing energy conservation in anaerobic microorganisms. One of the three ferredoxins of the bacterium, that was named FdxB, was also purified and characterized. It contains a low-potential (Em = -450 mV) [4Fe4S] cluster. We found that Hnd was not able to reduce NADP+, and that it catalyzes the simultaneous reduction of FdxB and NAD+. Moreover, Hnd is the first electron-bifurcating hydrogenase that retains activity when purified aerobically due to formation of an inactive state of its catalytic site protecting against O2 damage (Hinact). Hnd is highly active with the artificial redox partner (methyl viologen) and can perform the electron-bifurcation reaction to oxidize H2 with a specific activity of 10 μmol of NADH/min/mg of enzyme. Surprisingly, the ratio between NADH and reduced FdxB varies over the reaction with a decreasing amount of FdxB reduced per NADH produced, indicating a more complex mechanism than previously described. We proposed a new mechanistic model in which the ferredoxin is recycled at the hydrogenase catalytic subunit.
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Affiliation(s)
- Arlette Kpebe
- Aix Marseille Univ, CNRS, BIP, 31 Chemin Joseph Aiguier, 13402, Marseille Cedex 09, France.
| | - Martino Benvenuti
- Aix Marseille Univ, CNRS, BIP, 31 Chemin Joseph Aiguier, 13402, Marseille Cedex 09, France.
| | - Chloé Guendon
- Aix Marseille Univ, CNRS, BIP, 31 Chemin Joseph Aiguier, 13402, Marseille Cedex 09, France.
| | - Amani Rebai
- Aix Marseille Univ, CNRS, BIP, 31 Chemin Joseph Aiguier, 13402, Marseille Cedex 09, France
| | - Victoria Fernandez
- Aix Marseille Univ, CNRS, BIP, 31 Chemin Joseph Aiguier, 13402, Marseille Cedex 09, France
| | - Sébastien Le Laz
- Aix Marseille Univ, CNRS, BIP, 31 Chemin Joseph Aiguier, 13402, Marseille Cedex 09, France
| | - Emilien Etienne
- Aix Marseille Univ, CNRS, BIP, 31 Chemin Joseph Aiguier, 13402, Marseille Cedex 09, France.
| | - Bruno Guigliarelli
- Aix Marseille Univ, CNRS, BIP, 31 Chemin Joseph Aiguier, 13402, Marseille Cedex 09, France.
| | | | - Antonio L de Lacey
- Instituto de Catálisis y Petroleoquímica, CSIC, c/ Marie Curie 2, Madrid, Spain.
| | - Carole Baffert
- Aix Marseille Univ, CNRS, BIP, 31 Chemin Joseph Aiguier, 13402, Marseille Cedex 09, France.
| | - Myriam Brugna
- Aix Marseille Univ, CNRS, BIP, 31 Chemin Joseph Aiguier, 13402, Marseille Cedex 09, France.
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6
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Zanello P. The competition between chemistry and biology in assembling iron–sulfur derivatives. Molecular structures and electrochemistry. Part V. {[Fe4S4](SCysγ)4} proteins. Coord Chem Rev 2017. [DOI: 10.1016/j.ccr.2016.10.003] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/04/2023]
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7
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Li B, Elliott SJ. The Catalytic Bias of 2-Oxoacid:ferredoxin Oxidoreductase in CO2: evolution and reduction through a ferredoxin-mediated electrocatalytic assay. Electrochim Acta 2016. [DOI: 10.1016/j.electacta.2016.02.119] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/22/2022]
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8
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Bhave DP, Han WG, Pazicni S, Penner-Hahn JE, Carroll KS, Noodleman L. Geometric and electrostatic study of the [4Fe-4S] cluster of adenosine-5'-phosphosulfate reductase from broken symmetry density functional calculations and extended X-ray absorption fine structure spectroscopy. Inorg Chem 2011; 50:6610-25. [PMID: 21678934 DOI: 10.1021/ic200446c] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
Abstract
Adenosine-5'-phosphosulfate reductase (APSR) is an iron-sulfur protein that catalyzes the reduction of adenosine-5'-phosphosulfate (APS) to sulfite. APSR coordinates to a [4Fe-4S] cluster via a conserved CC-X(~80)-CXXC motif, and the cluster is essential for catalysis. Despite extensive functional, structural, and spectroscopic studies, the exact role of the iron-sulfur cluster in APS reduction remains unknown. To gain an understanding into the role of the cluster, density functional theory (DFT) analysis and extended X-ray fine structure spectroscopy (EXAFS) have been performed to reveal insights into the coordination, geometry, and electrostatics of the [4Fe-4S] cluster. X-ray absorption near-edge structure (XANES) data confirms that the cluster is in the [4Fe-4S](2+) state in both native and substrate-bound APSR while EXAFS data recorded at ~0.1 Å resolution indicates that there is no significant change in the structure of the [4Fe-4S] cluster between the native and substrate-bound forms of the protein. On the other hand, DFT calculations provide an insight into the subtle differences between the geometry of the cluster in the native and APS-bound forms of APSR. A comparison between models with and without the tandem cysteine pair coordination of the cluster suggests a role for the unique coordination in facilitating a compact geometric structure and "fine-tuning" the electronic structure to prevent reduction of the cluster. Further, calculations using models in which residue Lys144 is mutated to Ala confirm the finding that Lys144 serves as a crucial link in the interactions involving the [4Fe-4S] cluster and APS.
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Affiliation(s)
- Devayani P Bhave
- Chemical Biology Graduate Program, University of Michigan, Ann Arbor, Michigan 48109-2216, USA
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9
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Crystal structures of the all-cysteinyl-coordinated D14C variant of Pyrococcus furiosus ferredoxin: [4Fe–4S] ↔ [3Fe–4S] cluster conversion. J Biol Inorg Chem 2011; 16:763-75. [DOI: 10.1007/s00775-011-0778-7] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/07/2010] [Accepted: 03/25/2011] [Indexed: 10/18/2022]
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10
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Pieulle L, Nouailler M, Morelli X, Cavazza C, Gallice P, Blanchet S, Bianco P, Guerlesquin F, Hatchikian EC. Multiple orientations in a physiological complex: the pyruvate-ferredoxin oxidoreductase-ferredoxin system. Biochemistry 2005; 43:15480-93. [PMID: 15581360 DOI: 10.1021/bi0485878] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Ferredoxin I from Desulfovibrio africanus (Da FdI) is a small acidic [4Fe-4S] cluster protein that exchanges electrons with pyruvate-ferredoxin oxidoreductase (PFOR), a key enzyme in the energy metabolism of anaerobes. The thermodynamic properties and the electron transfer between PFOR and either native or mutated FdI have been investigated by microcalorimetry and steady-state kinetics, respectively. The association constant of the PFOR-FdI complex is 3.85 x 10(5) M(-1), and the binding affinity has been found to be highly sensitive to ionic strength, suggesting the involvement of electrostatic forces in formation of the complex. Surprisingly, the punctual or combined neutralizations of carboxylate residues surrounding the [4Fe-4S] cluster slightly affect the PFOR-FdI interaction. Furthermore, hydrophobic residues around the cluster do not seem to be crucial for the PFOR-FdI system activity; however, some of them play an important role in the stability of the FeS cluster. NMR restrained docking associated with site-directed mutagenesis studies suggested the presence of various interacting sites on Da FdI. The modification of additional acidic residues at the interacting interface, generating a FdI pentamutant, evidenced at least two distinct FdI binding sites facing the distal [4Fe-4S] cluster of the PFOR. We also used a set of various small acidic partners to investigate the specificity of PFOR toward redox partners. The remarkable flexibility of the PFOR-FdI system supports the idea that the specificity of the physiological complex has probably been "sacrificed" to improve the turnover rate and thus the efficiency of bacterial electron transfer.
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Affiliation(s)
- Laetitia Pieulle
- Unité de Bioénergétique et Ingéniérie des Protéines, Institut de Biologie Structurale et Microbiologie, CNRS, 31 Chemin Joseph-Aiguier, 13402 Marseille Cedex 20, France
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11
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McDevitt CA, Hanson GR, Noble CJ, Cheesman MR, McEwan AG. Characterization of the redox centers in dimethyl sulfide dehydrogenase from Rhodovulum sulfidophilum. Biochemistry 2002; 41:15234-44. [PMID: 12484761 DOI: 10.1021/bi026221u] [Citation(s) in RCA: 39] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Dimethyl sulfide dehydrogenase from the purple phototrophic bacterium Rhodovulum sulfidophilum catalyzes the oxidation of dimethyl sulfide to dimethyl sulfoxide. Recent DNA sequence analysis of the ddh operon, encoding dimethyl sulfide dehydrogenase (ddhABC), and biochemical analysis (1) have revealed that it is a member of the DMSO reductase family of molybdenum enzymes and is closely related to respiratory nitrate reductase (NarGHI). Variable temperature X-band EPR spectra (120-122 K) of purified heterotrimeric dimethyl sulfide dehydrogenase showed resonances arising from multiple redox centers, Mo(V), [3Fe-4S](+), [4Fe-4S](+), and a b-type heme. A pH-dependent EPR study of the Mo(V) center in (1)H(2)O and (2)H(2)O revealed the presence of three Mo(V) species in equilibrium, Mo(V)-OH(2), Mo(V)-anion, and Mo(V)-OH. Above pH 8.2 the dominant species was Mo(V)-OH. The maximum specific activity occurred at pH 9.27. Comparison of the rhombicity and anisotropy parameters for the Mo(V) species in DMS dehydrogenase with other molybdenum enzymes of the DMSO reductase family showed that it was most similar to the low-pH nitrite spectrum of Escherichia coli nitrate reductase (NarGHI), consistent with previous sequence analysis of DdhA and NarG. A sequence comparison of DdhB and NarH has predicted the presence of four [Fe-S] clusters in DdhB. A [3Fe-4S](+) cluster was identified in dimethyl sulfide dehydrogenase whose properties resembled those of center 2 of NarH. A [4Fe-4S](+) cluster was also identified with unusual spin Hamiltonian parameters, suggesting that one of the iron atoms may have a fifth non-sulfur ligand. The g matrix for this cluster is very similar to that found for the minor conformation of center 1 in NarH [Guigliarelli, B., Asso, M., More, C., Augher, V., Blasco, F., Pommier, J., Giodano, G., and Bertrand, P. (1992) Eur. J. Biochem. 307, 63-68]. Analysis of a ddhC mutant showed that this gene encodes the b-type cytochrome in dimethyl sulfide dehydrogenase. Magnetic circular dichroism studies revealed that the axial ligands to the iron in this cytochrome are a histidine and methionine, consistent with predictions from protein sequence analysis. Redox potentiometry showed that the b-type cytochrome has a high midpoint redox potential (E degrees = +315 mV, pH 8).
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Affiliation(s)
- Christopher A McDevitt
- Department of Microbiology and Parasitology, School of Molecular and Microbial Sciences, Centre for Magnetic Resonance, and Centre for Metals in Biology, The University of Queensland, St. Lucia 4072, Australia
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12
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Pieulle L, Charon MH, Bianco P, Bonicel J, Pétillot Y, Hatchikian EC. Structural and kinetic studies of the pyruvate-ferredoxin oxidoreductase/ferredoxin complex from Desulfovibrio africanus. EUROPEAN JOURNAL OF BIOCHEMISTRY 1999; 264:500-8. [PMID: 10491097 DOI: 10.1046/j.1432-1327.1999.00648.x] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
The pyruvate-ferredoxin oxidoreductase (PFOR)/ferredoxin (Fd) system of Desulfovibrio africanus has been investigated with the aim of understanding more fully protein-protein interaction and the kinetic characteristics of electron transfer between the two redox partners. D. africanus contains three Fds (Fd I, Fd II and Fd III) able to function as electron acceptors for PFOR. The complete amino acid sequence of Fd II was determined by automatic Edman degradation. It revealed a striking similarity to that of Fd I. The protein consists of 64 residues and its amino acid sequence is in agreement with a molecular mass of 6822.5 Da as measured by electrospray MS. Fd II contains five cysteine residues of which the first four (Cys11, Cys14, Cys17 and Cys54) are likely ligands for the single [4Fe-4S] cluster. A covalently cross-linked complex between PFOR and Fd I or Fd II was obtained by using a water soluble carbodiimide. This complex exhibited a stoichiometry of one ferredoxin for one PFOR subunit and is dependent on the ionic strength. The second-order rate constants for electron transfer between PFOR and Fds determined electrochemically using cyclic voltammetry are 7 x 107 M-1.s-1 for Fd I and 2 x 107 M-1.s-1 for Fd II and Fd III. The Km values of PFOR for Fd I and Fd II measured both by the electrochemical and the spectrophotometric method have been found to be 3 microM and 5 microM, respectively. The three-dimensional modelling of Fd II and surface analysis of Fd I, Fd II and PFOR suggest that a protein-protein complex is likely to be formed between aspartic acid/glutamic acid invariant residues of Fds and lysine residues surrounding the distal [4Fe-4S] cluster of PFOR. All of these studies are indicative of the involvement of electrostatic interactions between the two redox partners.
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Affiliation(s)
- L Pieulle
- Unité de Bioénergétique et Ingéniérie des Protéines, Institut de Biologie Structurale et Microbiologie, CNRS, Marseille, France
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13
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Guigliarelli B, Bertrand P. Application of EPR Spectroscopy to the Structural and Functional Study of Iron-Sulfur Proteins. ADVANCES IN INORGANIC CHEMISTRY 1999. [DOI: 10.1016/s0898-8838(08)60084-7] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 10/22/2022]
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14
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Davy SL, Osborne MJ, Moore GR. Determination of the structure of oxidised Desulfovibrio africanus ferredoxin I by 1H NMR spectroscopy and comparison of its solution structure with its crystal structure. J Mol Biol 1998; 277:683-706. [PMID: 9533888 DOI: 10.1006/jmbi.1998.1631] [Citation(s) in RCA: 17] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
The solution structure of the 64 amino acid Fe4S4 ferredoxin I from Desulfovibrio africanus has been determined using two-dimensional 1H NMR spectroscopy. Sequence-specific assignments were obtained for 59 amino acid residues and the structure determined with the program DIANA on the basis of 549 nuclear Overhauser enhancement (NOE) upper distance limits, and four dihedral angle and 52 distance constraints for the Fe4S4 cluster. The NMR structure was refined using the simulated annealing and energy minimisation protocols of the program X-PLOR to yield a final family of 19 structures selected on the basis of good covalent geometry and minimal restraint violations. The r.m.s.d. values to the average structure for this family are 0.49(+/-0.07) A and 0.94(+/-0.09) A for the backbone and heavy-atoms of residues 3 to 62, respectively. The NMR structure has been compared to the previously reported X-ray structures for the two molecules within the asymmetric unit of the crystal, which have a network of seven hydrogen bonds between them. This intermolecular interface, involving residues 38, 40 to 43 and 46, has the same conformation in the solution structures showing that the crystal packing does not perturb the structure. There are three regions in which the NMR and X-ray structures differ: around the cluster, a turn involving residues 8 to 10, and a loop involving residues 29 to 32. In the family of solution structures the backbone of the loop region incorporating residues 29 to 32 is well-defined whilst in both of the X-ray molecules it is ill-defined. The small differences between the X-ray and NMR structures for the cluster environment and the turn between residues 8 to 10 probably reflects a lack of NMR constraints. The observation of relatively rapid amide NH hydrogen exchange of NH groups close to the cluster, together with rapid flipping for Phe25, which is also close to the cluster, indicates that the cluster environment is more dynamic than the corresponding regions of related Fe/S proteins.
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Affiliation(s)
- S L Davy
- School of Chemical Sciences, University of East Anglia, Norwich, NR4 7TJ, U.K
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15
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Bianco P, Lattuca C. Membrane-assembly of carbon microelectrodes for the electrochemical study of redox proteins. Anal Chim Acta 1997. [DOI: 10.1016/s0003-2670(97)00384-x] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/27/2022]
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16
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Stephens PJ, Jollie DR, Warshel A. Protein Control of Redox Potentials of Ironminus signSulfur Proteins. Chem Rev 1996; 96:2491-2514. [PMID: 11848834 DOI: 10.1021/cr950045w] [Citation(s) in RCA: 312] [Impact Index Per Article: 11.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
- P. J. Stephens
- Department of Chemistry, University of Southern California, Los Angeles, California 90089-0482
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17
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Pieulle L, Haladjian J, Bonicel J, Hatchikian EC. Biochemical studies of the c-type cytochromes of the sulfate reducer Desulfovibrio africanus. Characterization of two tetraheme cytochromes c3 with different specificity. BIOCHIMICA ET BIOPHYSICA ACTA 1996; 1273:51-61. [PMID: 8573595 DOI: 10.1016/0005-2728(95)00129-8] [Citation(s) in RCA: 35] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/31/2023]
Abstract
Three c-type cytochromes were isolated and characterized from the sulfate reducer Desulfovibrio africanus. A basic tetraheme cytochrome c3 of molecular mass 16 kDa was previously described and we have extended its characterization. Two other c3-type cytochromes, not previously observed, have also been characterized. These include an acidic tetraheme cytochrome c3 of molecular mass 15 kDa and an octaheme dimeric cytochrome c3 with a native size of 35 kDa. This is the first report of the presence of two distinct tetraheme cytochromes c3 in a Desulfovibrio species. The physico-chemical properties of the three cytochromes, including optical properties, iron content, cysteine and histidine content, N-terminal amino sequence and redox properties, are characteristic of cytochrome c3 family. The acidic tetraheme cytochrome c3 exhibited similar midpoint potential values for all four hemes (Em1 = -210 mV; Em2 = -240 mV; Em3 = -260 mV; Em4 = -270 mV), whereas in the basic tetraheme cytochrome c3 one heme had a much more positive potential than the others (Em1 = -90 mV; Em2 = -260 mV; Em3 = -280 mV; Em4 = -290 mV). The acidic tetraheme cytochrome c3 exhibited unique properties including amino-acid composition and poor reactivity towards hydrogenase. However, it is readily reduced by this enzyme in the presence of the basic cytochrome c3. The weak reactivity of the acidic tetraheme cytochrome c3 towards hydrogenase has been correlated with its low content of basic residues.
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Affiliation(s)
- L Pieulle
- Unité de Bioénergétique et Ingénierie des Protéines, CNRS, Marseille, France
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18
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Bennett B, Gruer MJ, Guest JR, Thomson AJ. Spectroscopic characterisation of an aconitase (AcnA) of Escherichia coli. EUROPEAN JOURNAL OF BIOCHEMISTRY 1995; 233:317-26. [PMID: 7588761 DOI: 10.1111/j.1432-1033.1995.317_1.x] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/26/2023]
Abstract
A spectroscopic study of an aconitase, AcnA, from Escherichia coli is presented. The amino acid sequence of AcnA has 53% identity with mammalian cytosolic aconitase (c-aconitase) which is the translational regulator known as iron regulatory factor (IRF). In the [3Fe-4S](+)-containing, inactive state, AcnA displays an EPR signal which is not unlike the corresponding signal from mammalian mitochondrial aconitase (m-aconitase) but is even more similar to the signal from c-aconitase. This is perhaps related to the greater similarity of the AcnA amino acid sequence with c-aconitase. Magnetic circular dichroism (MCD) spectroscopy has revealed that the electronic structure of the [3Fe-4S] cluster of AcnA must be similar to, but not identical to that of m-aconitase. Whilst the [Fe-4S] clusters from both of these enzymes display some features in their MCD spectra common to [3Fe-4S] clusters in general, their spectra overall are unique and indicate that the Fea atom of the [4Fe-4S] form is not the only unusual feature of the [Fe-S] clusters of aconitases. Active [4Fe-4S]-containing AcnA can be reduced to yield an EPR signal due to a [4Fe-4S]+ cluster which is indistinguishable from the signals from the [4Fe-4S]+ cluster in the mammalian enzymes. However, in contrast to the mammalian enzymes, the EPR signals of the cluster in AcnA are not significantly perturbed upon the addition of substrate. Furthermore, the catalytic activity of [Fe-4S](2+)-containing AcnA is fivefold higher than that of m-aconitase. The mechanistic implications of these data are discussed. A novel S = 1/2 EPR signal with g approximately 2 was observed in AcnA upon treatment with EDTA. The species giving rise to this signal is proposed to be an intermediate in cluster deconstruction.
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Affiliation(s)
- B Bennett
- School of Chemical Sciences, University of East Anglia, Norwich, UK
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Pieulle L, Guigliarelli B, Asso M, Dole F, Bernadac A, Hatchikian EC. Isolation and characterization of the pyruvate-ferredoxin oxidoreductase from the sulfate-reducing bacterium Desulfovibrio africanus. BIOCHIMICA ET BIOPHYSICA ACTA 1995; 1250:49-59. [PMID: 7612653 DOI: 10.1016/0167-4838(95)00029-t] [Citation(s) in RCA: 84] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/26/2023]
Abstract
We report the first purification and characterization of a pyruvate-ferredoxin oxidoreductase (POR) from a sulfate-reducing bacterium, Desulfovibrio africanus. The enzyme as isolated is highly stable in the presence of oxygen and exhibits a specific activity of 14 U/mg. D. africanus POR is a 256 kDa homodimer which contains thiamine pyrophosphate (TPP) and iron-sulfur clusters. EPR spectroscopic study of the enzyme indicates the presence of three [4Fe-4S]2+/1- centers/subunits. The midpoint potentials of the three centers are -390 mV, -515 mV and -540 mV. The catalytic mechanism of POR involves a free radical intermediate which disappears when coenzyme A is added. This behaviour is discussed in terms of an electron-transport chain from TPP to the acceptor. The enzyme activated by dithioerythritol shows an exceptionally high activity compared with other mesophile PORs and becomes very sensitive to oxygen in contrast to the enzyme before activation. The comparison of EPR spectra given by the as isolated and activated enzymes shows that neither the nature, nor the arrangement of FeS centers are affected by the activation process. D. africanus ferredoxins I and II are involved as the physiological electron carriers of the enzyme. POR was shown to be located in the cytoplasm by immunogold labelling.
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Affiliation(s)
- L Pieulle
- Unité de Bioénergétique et Ingénierie des Protéines, CNRS, Marseille, France
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Davy SL, Breton J, Osborne MJ, Thomson AJ, Thurgood AP, Lian LY, Pétillot Y, Hatchikian C, Moore GR. MCD and 1H-NMR spectroscopic studies of Desulfovibrio africanus ferredoxin I: revised amino-acid sequence and identification of secondary structure. BIOCHIMICA ET BIOPHYSICA ACTA 1994; 1209:33-9. [PMID: 7947979 DOI: 10.1016/0167-4838(94)90133-3] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/28/2023]
Abstract
Desulfovibrio africanus ferredoxin I was studied by magnetic circular dichroism and 1H-NMR spectroscopies. These showed the presence of histidine and tryptophan, in contrast to the previously reported amino-acid sequence (Bruschi and Hatchikian (1982) Biochimie 64, 503-507). This was redetermined and the revised sequence shown to contain both histidine and tryptophan, as well as four other corrections (Sery et al. (1994) Biochemistry, submitted). Electrospray mass spectrometry confirmed the mass of the ferredoxin was that given by the revised amino-acid sequence. The secondary structure of the ferredoxin I was investigated with two-dimensional 1H-NMR experiments and both alpha-helix and beta-sheet structure detected. The influence of the paramagnetism of the Fe4 S4 cluster on the NMR properties of the ferredoxin protons was investigated, by temperature-dependent experiments, and it was concluded that there is only a negligible dipolar contribution to resonance chemical shifts from this source. The significance of this for the determination of the three-dimensional structure of the ferredoxin by NMR is discussed.
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Affiliation(s)
- S L Davy
- Centre for Metalloprotein Spectroscopy and Biology, School of Chemical Sciences, University of East Anglia, Norwich, UK
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Onate YA, Finnegan MG, Hales BJ, Johnson MK. Variable temperature magnetic circular dichroism studies of reduced nitrogenase iron proteins and [4Fe-4S]+ synthetic analog clusters. BIOCHIMICA ET BIOPHYSICA ACTA 1993; 1164:113-23. [PMID: 8329442 DOI: 10.1016/0167-4838(93)90237-l] [Citation(s) in RCA: 43] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/29/2023]
Abstract
Variable temperature magnetic circular dichroism (VTMCD) and EPR spectroscopies have been used to investigate the ground and excited-state properties of [4Fe-4S]+ clusters in Mo- and V-nitrogenase Fe-proteins from Azotobacter vinelandii and two synthetic analog clusters, [Fe4S4(SEt)4]3- and [Fe4S4(SC6H11)4]3-. The results indicate similar [4Fe-4S]+ clusters with analogous S = 1/2 and S = 3/2 ground states in both Fe-proteins. However, the Fe-proteins do differ in terms of the medium effects on the S = 1/2 and S = 3/2 spin mixtures in frozen solution. By utilizing medium effects in both Fe-proteins, the VTMCD characteristics of both the S = 1/2 and S = 3/2 forms of the [4Fe-4S]+ have been determined. Together with the VTMCD studies of [Fe4S4(SEt)4]3- and [Fe4S4(SC6H11)4]3-, which are shown to be predominantly S = 1/2 and 3/2, respectively, in frozen DMF/toluene solutions, the results demonstrate that the form of the VTMCD spectra provides a means of identifying and distinguishing S = 1/2 and S = 3/2 [4Fe-4S]+ clusters. Ground state zero-field splitting parameters for the S = 3/2 clusters are determined for both Fe-proteins. In addition to spin state heterogeneity, samples of the Mo-nitrogenase Fe-protein in the presence of 50% (v/v) ethylene glycol were found to exhibit heterogeneity in the S = 1/2 resonance. A rapidly relaxing axial resonance, g perpendicular = 1.94 and g parallel = 1.82, was observed in addition to the characteristic rhombic resonance, g = 2.05, 1.94 and 1.87. The origin of the heterogeneity exhibited by [4Fe-4S]+ clusters in frozen solution is discussed in light of these results.
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Affiliation(s)
- Y A Onate
- Department of Chemistry, University of Georgia, Athens 30602
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22
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Belinskii M. Spin coupling model for tetrameric iron clusters in ferredoxins. I. Theory, exchange levels, g-factors. Chem Phys 1993. [DOI: 10.1016/0301-0104(93)80116-q] [Citation(s) in RCA: 21] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/17/2022]
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23
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Heisenberg exchange model for [Fe3(II)Fe(III)] clusters of ferredoxins. A generalized solution of the exchange problem. Chem Phys Lett 1993. [DOI: 10.1016/0009-2614(93)85586-d] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
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24
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Shergill JK, Cammack R, Weiner JH. Electron spin-echo envelope modulation studies of the [3Fe–4S] cluster of Escherichia coli fumarate reductase. ACTA ACUST UNITED AC 1993. [DOI: 10.1039/ft9938903685] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
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25
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Guigliarelli B, Asso M, More C, Augier V, Blasco F, Pommier J, Giordano G, Bertrand P. EPR and redox characterization of iron-sulfur centers in nitrate reductases A and Z from Escherichia coli. Evidence for a high-potential and a low-potential class and their relevance in the electron-transfer mechanism. EUROPEAN JOURNAL OF BIOCHEMISTRY 1992; 207:61-8. [PMID: 1321049 DOI: 10.1111/j.1432-1033.1992.tb17020.x] [Citation(s) in RCA: 86] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/26/2022]
Abstract
The redox properties of the iron-sulfur centers of the two nitrate reductases from Escherichia coli have been investigated by EPR spectroscopy. A detailed study of nitrate reductase A performed in the range +200 mV to -500 mV shows that the four iron-sulfur centers of the enzyme belong to two classes with markedly different redox potentials. The high-potential group comprises a [3Fe-4S] and a [4Fe-4S] cluster whose midpoint potentials are +60 mV and +80 mV, respectively. Although these centers are magnetically isolated, they are coupled by a significant anticooperative redox interaction of about 50 mV. The [4Fe-4S]1+ center occurs in two different conformations as shown by its composite EPR spectrum. The low-potential group contains two [4Fe-4S] clusters with more typical redox potentials (-200 mV and -400 mV). In the fully reduced state, the three [4Fe-4S]1+ centers are magnetically coupled, leading to a broad featureless spectrum. The redox behaviour of the high-pH EPR signal given by the molybdenum cofactor was also studied. The iron-sulfur centers of the second nitrate reductase of E. coli, nitrate reductase Z, exhibit essentially the same characteristics than those of nitrate reductase A, except that the midpoint potentials of the high-potential centers appear negatively shifted by about 100 mV. From the comparison between the redox centers of nitrate reductase and of dimethylsulfoxide reductase, a correspondence between the high-potential iron-sulfur clusters of the two enzymes can be proposed.
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Affiliation(s)
- B Guigliarelli
- Laboratoire d'Electronique des Milieux Condensés, URA CNRS 784, Université de Provence, Marseille, France
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Armstrong FA. Dynamic Electrochemistry of Iron—Sulfur Proteins. ADVANCES IN INORGANIC CHEMISTRY 1992. [DOI: 10.1016/s0898-8838(08)60063-x] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 10/22/2022]
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Zambrano IC, Kowal AT, Mortenson LE, Adams MW, Johnson MK. Magnetic Circular Dichroism and Electron Paramagnetic Resonance Studies of Hydrogenases I and II from Clostridium pasteurianum. J Biol Chem 1989. [DOI: 10.1016/s0021-9258(19)30032-8] [Citation(s) in RCA: 54] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022] Open
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29
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Spectroscopic characterization of the iron-sulfur cluster in Bacillus subtilis glutamine phosphoribosylpyrophosphate amidotransferase. J Biol Chem 1989. [DOI: 10.1016/s0021-9258(18)51476-9] [Citation(s) in RCA: 33] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
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30
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Bovier-Lapierre G, Bruschi M, Bonicel J, Hatchikian E. Amino-acid sequence of Desulfovibrio africanus ferredoxin III: a unique structural feature for accommodating iron-sulfur clusters. ACTA ACUST UNITED AC 1987. [DOI: 10.1016/0167-4838(87)90227-5] [Citation(s) in RCA: 37] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
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Johnson MK, Bennett DE, Fee JA, Sweeney WV. Spectroscopic studies of the seven-iron-containing ferredoxins from Azotobacter vinelandii and Thermus thermophilus. BIOCHIMICA ET BIOPHYSICA ACTA 1987; 911:81-94. [PMID: 3024733 DOI: 10.1016/0167-4838(87)90273-1] [Citation(s) in RCA: 52] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/03/2023]
Abstract
The seven-iron-containing ferredoxins from Azotobacter vinelandii and Thermus thermophilus have been investigated by low-temperature magnetic circular dichroism (MCD) and electron paramagnetic resonance (EPR) spectroscopies and room temperature ultraviolet-visible absorption spectroscopy. The results confirm the presence of one trinuclear and one tetranuclear iron-sulfur cluster in both ferredoxins and facilitate comparison of the electronic and magnetic properties of the oxidized and reduced [3Fe-xS] clusters. MCD magnetization data are consistent with an S = 2 ground state for both reduced [3Fe-xS] clusters, but indicate differences in the rhombicity of the zero-field splittings. The data permit rationalization of the absence of a delta M = 4 EPR transition for the reduced [3Fe-xS] cluster in A. vinelandii ferredoxin I. Spectroscopic studies of anaerobically isolated A. vinelandii ferredoxin I do not support the hypothesis that the [3Fe-xS] cluster arises as a result of aerial oxidative damage to a [4Fe-4S] cluster during isolation. The possibility that two distinct forms of [3Fe-xS] clusters can exist in A. vinelandii ferredoxin I was investigated by spectroscopic studies as a function of pH. The results reveal two distinct and interconvertible forms of the reduced [3Fe-xS] cluster, but do not permit rationalization of the inconsistencies in the structural data that have been reported for the oxidized clusters.
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Spectroscopic characterization of the number and type of iron-sulfur clusters in NADH:ubiquinone oxidoreductase. J Biol Chem 1986. [DOI: 10.1016/s0021-9258(18)67645-8] [Citation(s) in RCA: 38] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022] Open
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Maguire JJ, Johnson MK, Morningstar JE, Ackrell BA, Kearney EB. Electron paramagnetic resonance studies of mammalian succinate dehydrogenase. Detection of the tetranuclear cluster S2. J Biol Chem 1985. [DOI: 10.1016/s0021-9258(17)39119-6] [Citation(s) in RCA: 19] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/22/2022] Open
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Dooley DM, Dawson JH. Bioinorganic applications of magnetic circular dichroism spectroscopy: Copper, rare-earth ions, cobalt and non-heme iron systems. Coord Chem Rev 1984. [DOI: 10.1016/0010-8545(84)85061-4] [Citation(s) in RCA: 27] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
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