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Skeel BA, Suess DLM. Exploiting Molecular Symmetry to Quantitatively Map the Excited-State Landscape of Iron-Sulfur Clusters. J Am Chem Soc 2023; 145:10376-10395. [PMID: 37125463 DOI: 10.1021/jacs.3c02412] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 05/02/2023]
Abstract
Cuboidal [Fe4S4] clusters are ubiquitous cofactors in biological redox chemistry. In the [Fe4S4]1+ state, pairwise spin coupling gives rise to six arrangements of the Fe valences ("valence isomers") among the four Fe centers. Because of the magnetic complexity of these systems, it has been challenging to understand how a protein's active site dictates both the arrangement of the valences in the ground state as well as the population of excited-state valence isomers. Here, we show that the ground-state valence isomer landscape can be simplified from a six-level system in an asymmetric protein environment to a two-level system by studying the problem in synthetic [Fe4S4]1+ clusters with solution C3v symmetry. This simplification allows for the energy differences between valence isomers to be quantified (in some cases with a resolution of <0.1 kcal/mol) by simultaneously fitting the VT NMR and solution magnetic moment data. Using this fitting protocol, we map the excited-state landscape for a range of clusters of the form [(SIMes)3Fe4S4-X/L]n, (SIMes = 1,3-dimesityl-imidazol-4,5-dihydro-2-ylidene; n = 0 for anionic, X-type ligands and n = +1 for neutral, L-type ligands) and find that a single ligand substitution can alter the relative ground-state energies of valence isomers by at least 103 cm-1. On this basis, we suggest that one result of "non-canonical" amino acid ligation in Fe-S proteins is the redistribution of the valence electrons in the manifold of thermally populated excited states.
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Affiliation(s)
- Brighton A Skeel
- Department of Chemistry, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, United States
| | - Daniel L M Suess
- Department of Chemistry, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, United States
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2
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The 1H NMR parameters of magnetically coupled dimers—The Fe2S2 proteins as an example. STRUCTURE AND BONDING 2006. [DOI: 10.1007/bfb0058197] [Citation(s) in RCA: 80] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/03/2022]
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3
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Pattarkine MV, Tanner JJ, Bottoms CA, Lee YH, Wall JD. Desulfovibrio desulfuricans G20 Tetraheme Cytochrome Structure at 1.5Å and Cytochrome Interaction with Metal Complexes. J Mol Biol 2006; 358:1314-27. [PMID: 16580681 DOI: 10.1016/j.jmb.2006.03.010] [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] [Received: 12/07/2005] [Revised: 03/01/2006] [Accepted: 03/04/2006] [Indexed: 11/26/2022]
Abstract
The structure of the type I tetraheme cytochrome c(3) from Desulfovibrio desulfuricans G20 was determined to 1.5 Angstrom by X-ray crystallography. In addition to the oxidized form, the structure of the molybdate-bound form of the protein was determined from oxidized crystals soaked in sodium molybdate. Only small structural shifts were obtained with metal binding, consistent with the remarkable structural stability of this protein. In vitro experiments with pure cytochrome showed that molybdate could oxidize the reduced cytochrome, although not as rapidly as U(VI) present as uranyl acetate. Alterations in the overall conformation and thermostability of the metal-oxidized protein were investigated by circular dichroism studies. Again, only small changes in protein structure were documented. The location of the molybdate ion near heme IV in the crystal structure suggested heme IV as the site of electron exit from the reduced cytochrome and implicated Lys14 and Lys56 in binding. Analysis of structurally conserved water molecules in type I cytochrome c(3) crystal structures identified interactions predicted to be important for protein stability and possibly for intramolecular electron transfer among heme molecules.
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Affiliation(s)
- M V Pattarkine
- Biochemistry Department, University of Missouri-Columbia, Columbia, MO 65211, USA
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Bertini I, Luchinat C, Rosato A. NMR Spectra of Iron-Sulfur Proteins. ADVANCES IN INORGANIC CHEMISTRY 1999. [DOI: 10.1016/s0898-8838(08)60080-x] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/15/2022]
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5
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Macedo A, Moura I, Surerus K, Papaefthymiou V, Liu M, LeGall J, Münck E, Moura J. Thiol/disulfide formation associated with the redox activity of the [Fe3S4] cluster of Desulfovibrio gigas ferredoxin II. 1H NMR and Mössbauer spectroscopic study. J Biol Chem 1994. [DOI: 10.1016/s0021-9258(17)37158-2] [Citation(s) in RCA: 21] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022] Open
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6
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Bertini I, Briganti F, Calzolai L, Messori L, Scozzafava A. Selective interaction of ferricyanide with cluster I of Clostridium pasteurianum 2[Fe4S4] ferredoxin. FEBS Lett 1993; 332:268-72. [PMID: 8405469 DOI: 10.1016/0014-5793(93)80647-d] [Citation(s) in RCA: 19] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/30/2023]
Abstract
Treatment of Clostridium pasteurianum ferredoxin (CpFd) with stoichiometric amounts of potassium ferricyanide results in the specific conversion of cluster I into a Fe3S4+ species while leaving cluster II unaltered. Ferricyanide-treated CpFd derivative has been purified and characterized through biochemical and spectroscopical techniques. The cluster conversion process is reversible and reconstitution of native CpFd has been afforded under appropriate conditions.
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Affiliation(s)
- I Bertini
- Department of Chemistry, University of Florence, Italy
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7
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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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8
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Belinskii M. Spin coupling model for tetrameric iron clusters in ferredoxins. II. Hyperfine interactions, magnetism, high-spin systems. Chem Phys 1993. [DOI: 10.1016/0301-0104(93)80117-r] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/18/2022]
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11
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Skjeldal L, Westler WM, Markley JL. Detection and characterization of hyperfine-shifted resonances in the proton nuclear magnetic resonance spectrum of Anabaena 7120 ferredoxin at high magnetic fields. Arch Biochem Biophys 1990; 278:482-5. [PMID: 2327800 DOI: 10.1016/0003-9861(90)90289-b] [Citation(s) in RCA: 18] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
Abstract
This paper presents previously unobserved signals in the 1H NMR spectra of oxidized and reduced [2Fe-2S]-ferredoxin from Anabaena 7120 detected at 400, 500, and 600 MHz. The signals shifted to low field exhibited longitudinal relaxation (T1) values in the range of 100-400 microseconds and line widths in the range of 1-10 kHz (at 400 MHz), and the chemical shifts of all signals showed strong temperature dependence. Although the line widths were smaller at lower magnetic fields, the resolution was better at higher magnetic fields. In the oxidized state, a broad signal was detected at 37 ppm, which corresponds to at least 6 protons, and whose chemical shift exhibits positive temperature dependence. This signal also was found in oxidized ferredoxin reconstituted in 2H2O, which excludes the signal as arising from solvent-exchangeable amide protons. In the reduced state, four signals detected between 90 and 140 ppm exhibited negative temperature dependence. These consisted of two pairs of signals, each pair having one component with half the linewidth of the other. On the basis of their chemical shifts, linewidths, longitudinal relaxation properties, and temperature dependence we assigned these resonances to four of the beta hydrogens of the ligated cysteines. Two solvent-exchangeable hyperfine-shifted signals were found in the reduced state; these are located upfield of the diamagnetic region. The low-field hyperfine resonances of half-reduced ferredoxin in the presence of sodium dithionite showed a self electron transfer exchange rate that was slow on the NMR scale as observed earlier (Chan, T., and Markley, J. L. (1983) Biochemistry 22, 5982-5987), but the exchange rate was accelerated in the presence of methyl viologen.
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Affiliation(s)
- L Skjeldal
- Department of Biochemistry, College of Agricultural and Life Sciences, University of Wisconsin-Madison 53706
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12
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Abstract
Proton magnetic resonance spectra at 500 MHz are reported for the oxidized and reduced forms of the 2[4Fe-4S]-ferredoxin from Clostridium pasteurianum. The reduced protein showed additional peaks in the 10-60 ppm region, which were previously unobserved, and there were significant differences between oxidized and reduced states in the whole region. The electron exchange rate in partially reduced ferredoxin is slow on the n.m.r. time scale when reduced with sodium dithionite, but fast when zinc reduced methyl viologen is used as reducing agent. We explain the difference between fast and slow exchange as being due to the different chemical properties of the two reducing agents.
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Affiliation(s)
- L Skjeldal
- Department of Chemistry, University of Trondheim, Dragvoll, Norway
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13
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Comparative nuclear magnetic resonance studies of high potential iron-sulfur proteins from Chromatium vinosum and Rhodopseudomonas gelatinosa. Additional hyperfine shifted resonances and pH-dependent structural perturbations. J Biol Chem 1983. [DOI: 10.1016/s0021-9258(20)82054-7] [Citation(s) in RCA: 28] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022] Open
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14
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Gayda J, Bertrand P, Theodule F, Moura JJG. Three‐iron clusters in iron–sulfur proteins: An EPR study of the exchange interactions. J Chem Phys 1982. [DOI: 10.1063/1.444281] [Citation(s) in RCA: 25] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
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15
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Proton magnetic resonance studies of Azotobacter vinelandii ferredoxin I. Evidence for a difference in coordination of the 3Fe centers in azotobacter vinelandii ferredoxin I and desulfovibrio gigas ferredoxin II. J Biol Chem 1981. [DOI: 10.1016/s0021-9258(18)43257-7] [Citation(s) in RCA: 21] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022] Open
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16
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Gayda JP, Bertrand P, More C, Le Gall J, Cammack RC. Energy of the low-lying excited levels for some reduced [4Fe-4S] ferredoxins, from the relaxation broadening of the E.P.R. signals. Biochem Biophys Res Commun 1981; 99:1265-70. [PMID: 6266417 DOI: 10.1016/0006-291x(81)90756-7] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/19/2023]
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17
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Moura I, Moura JJ, Bruschi M, Le Gall J. Flavodoxin and rubredoxin from Desulphovibrio salexigens. BIOCHIMICA ET BIOPHYSICA ACTA 1980; 591:1-8. [PMID: 7388008 DOI: 10.1016/0005-2728(80)90215-7] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/25/2023]
Abstract
A flavodoxin and a rubredoxin have been isolated from the sulfate-reducing bacterium Desulphovibrio salexigens (strain British Guiana, NICB 8403). Their amino acid composition and spectral characteristics did not differ markedly from the homologous proteins presented in other Desulphovibrio spp. Flavodoxin was shown to be active in the electron transport of the sulfite reductase system.
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Bruschi M, Couchoud P. Amino acid sequence of Desulfovibrio gigas ferredoxin: revisions. Biochem Biophys Res Commun 1979; 91:623-8. [PMID: 518659 DOI: 10.1016/0006-291x(79)91567-5] [Citation(s) in RCA: 63] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022]
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Adman ET. A comparison of the structures of electron transfer proteins. BIOCHIMICA ET BIOPHYSICA ACTA 1979; 549:107-44. [PMID: 224921 DOI: 10.1016/0304-4173(79)90012-0] [Citation(s) in RCA: 75] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
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LEGALL JEAN, DER VARTANIAN DANIELV, PECK HARRYD. Flavoproteins, Iron Proteins, and Hemoproteins as Electron-Transfer Components of the Sulfate-Reducing Bacteria. ACTA ACUST UNITED AC 1979. [DOI: 10.1016/b978-0-12-152509-5.50013-0] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 03/09/2023]
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Abstract
The sulphate-reducing bacteria have a complex electron transfer system which leads to the reduction of sulphate by oxidation of either organic substrates or molecular hydrogen. These bacteria can either produce or consume molecular hydrogen. The central part of this electron pathway for Desulovibrio gigas is constituted by hydrogenase (3 X (4Fe-4S)). cytochrome c3 (4 haems with different redox potentials) and a one (4Fe-4S) cluster ferredoxin. This ferredoxin is isolated in different oligomeric forms, which stabilize different oxidation states and have different physiological roles; the trimer FdI being involved in the production of H2 and the tetramer FdII being more efficient for the consumption of H2. The presence of intrinsic probes (the iron ions) in these proteins is particularly helpful for structural studies using NMR spectroscopy. These studies allowed a characterization of the oxidation states used by the different oligomers of the ferredoxin and obtaintion of structural information on multi-haem cytochromes (c3 and c7). NMR is also suitable to study protein-protein interaction. The study of the complex formed between FdII and cytochrome c3 has shown that there is an alteration of the kinetics of electron transfer upon complexation.
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Moura JJ, Xavier AV, Hatchikian EC, Le Gall J. Structural control of the redox potentials and of the physiological activity by oligomerization of ferredoxin. FEBS Lett 1978; 89:177-9. [PMID: 658398 DOI: 10.1016/0014-5793(78)80549-3] [Citation(s) in RCA: 51] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/23/2022]
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23
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Moura JJ, Xavier AV, Cookson DJ, Moore GR, Williams RJ. Redox states of cytochrome c3 in the absence and presence of ferredoxin. FEBS Lett 1977; 81:275-80. [PMID: 200473 DOI: 10.1016/0014-5793(77)80534-6] [Citation(s) in RCA: 39] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
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24
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Moura I, Bruschi M, Le Gall J, Moura JJ, Xavier AV. Isolation and characterization of desulforedoxin, a new type of non-heme iron protein from Desulfovibrio gigas. Biochem Biophys Res Commun 1977; 75:1037-44. [PMID: 861023 DOI: 10.1016/0006-291x(77)91486-3] [Citation(s) in RCA: 70] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/24/2022]
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