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Da Vela S, Saudino G, Lucarelli F, Banci L, Svergun DI, Ciofi-Baffoni S. Structural plasticity of NFU1 upon interaction with binding partners: insights into the mitochondrial [4Fe-4S] cluster pathway. J Mol Biol 2023:168154. [PMID: 37211204 PMCID: PMC10388178 DOI: 10.1016/j.jmb.2023.168154] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/01/2023] [Revised: 05/12/2023] [Accepted: 05/15/2023] [Indexed: 05/23/2023]
Abstract
In humans, the biosynthesis and trafficking of mitochondrial [4Fe-4S]2+ clusters is a highly coordinated process that requires a complex protein machinery. In a mitochondrial pathway among various proposed to biosynthesize nascent [4Fe-4S]2+ clusters, two [2Fe-2S]2+ clusters are converted into a [4Fe-4S]2+ cluster on a ISCA1-ISCA2 complex. Along this pathway, this cluster is then mobilized from this complex to mitochondrial apo recipient proteins with the assistance of accessory proteins. NFU1 is the accessory protein that first receives the [4Fe-4S]2+ cluster from ISCA1-ISCA2 complex. A structural view of the protein-protein recognition events occurring along the [4Fe-4S]2+ cluster trafficking as well as how the globular N-terminal and C-terminal domains of NFU1 act in such process is, however, still elusive. Here, we applied small-angle X-ray scattering coupled with on-line size-exclusion chromatography and paramagnetic NMR to disclose structural snapshots of ISCA1-, ISCA2- and NFU1-containing apo complexes as well as the coordination of [4Fe-4S]2+ cluster bound to the ISCA1-NFU1 complex, which is the terminal stable species of the [4Fe-4S]2+ cluster transfer pathway involving ISCA1-, ISCA2- and NFU1 proteins. The structural modelling of ISCA1-ISCA2, ISCA1-ISCA2-NFU1 and ISCA1-NFU1 apo complexes, here reported, reveals that the structural plasticity of NFU1 domains is crucial to drive protein partner recognition and modulate [4Fe-4S]2+ cluster transfer from the cluster-assembly site in ISCA1-ISCA2 complex to the cluster-binding site in ISCA1-NFU1 complex. These structures allowed us to provide a first rational for the molecular function of the N-domain of NFU1, which can act as a modulator in the [4Fe-4S]2+ cluster transfer.
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Affiliation(s)
- Stefano Da Vela
- EMBL Hamburg Site, c/o DESY, Notkestrasse 85, 22607 Hamburg, Germany
| | - Giovanni Saudino
- Magnetic Resonance Center CERM, University of Florence, Via Luigi Sacconi 6, 50019 Sesto Fiorentino, Florence Italy
| | - Francesca Lucarelli
- Magnetic Resonance Center CERM, University of Florence, Via Luigi Sacconi 6, 50019 Sesto Fiorentino, Florence Italy; Department of Chemistry, University of Florence, Via della Lastruccia 3, 50019 Sesto Fiorentino, Florence Italy
| | - Lucia Banci
- Magnetic Resonance Center CERM, University of Florence, Via Luigi Sacconi 6, 50019 Sesto Fiorentino, Florence Italy; Department of Chemistry, University of Florence, Via della Lastruccia 3, 50019 Sesto Fiorentino, Florence Italy
| | - Dmitri I Svergun
- EMBL Hamburg Site, c/o DESY, Notkestrasse 85, 22607 Hamburg, Germany
| | - Simone Ciofi-Baffoni
- Magnetic Resonance Center CERM, University of Florence, Via Luigi Sacconi 6, 50019 Sesto Fiorentino, Florence Italy; Department of Chemistry, University of Florence, Via della Lastruccia 3, 50019 Sesto Fiorentino, Florence Italy.
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2
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Suraci D, Saudino G, Nasta V, Ciofi-Baffoni S, Banci L. ISCA1 Orchestrates ISCA2 and NFU1 in the Maturation of Human Mitochondrial [4Fe-4S] Proteins. J Mol Biol 2021; 433:166924. [PMID: 33711344 DOI: 10.1016/j.jmb.2021.166924] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/10/2020] [Revised: 02/12/2021] [Accepted: 03/01/2021] [Indexed: 10/21/2022]
Abstract
The late-acting steps of the pathway responsible for the maturation of mitochondrial [4Fe-4S] proteins are still elusive. Three proteins ISCA1, ISCA2 and NFU1 were shown to be implicated in the assembly of [4Fe-4S] clusters and their transfer into mitochondrial apo proteins. We present here a NMR-based study showing a detailed molecular model of the succession of events performed in a coordinated manner by ISCA1, ISCA2 and NFU1 to make [4Fe-4S] clusters available to mitochondrial apo proteins. We show that ISCA1 is the key player of the [4Fe-4S] protein maturation process because of its ability to interact with both NFU1 and ISCA2, which, instead do not interact each other. ISCA1 works as the promoter of the interaction between ISCA2 and NFU1 being able to determine the formation of a transient ISCA1-ISCA2-NFU1 ternary complex. We also show that ISCA1, thanks to its specific interaction with the C-terminal cluster-binding domain of NFU1, drives [4Fe-4S] cluster transfer from the site where the cluster is assembled on the ISCA1-ISCA2 complex to a cluster binding site formed by ISCA1 and NFU1 in the ternary ISCA1-ISCA2-NFU1 complex. Such mechanism guarantees that the [4Fe-4S] cluster can be safely moved from where it is assembled on the ISCA1-ISCA2 complex to NFU1, thereby resulting the [4Fe-4S] cluster available for the mitochondrial apo proteins specifically requiring NFU1 for their maturation.
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Affiliation(s)
- Dafne Suraci
- Magnetic Resonance Center CERM, University of Florence, Via Luigi Sacconi 6, 50019 Sesto Fiorentino, Florence, Italy; Department of Chemistry, University of Florence, Via della Lastruccia 3, 50019 Sesto Fiorentino, Florence, Italy
| | - Giovanni Saudino
- Magnetic Resonance Center CERM, University of Florence, Via Luigi Sacconi 6, 50019 Sesto Fiorentino, Florence, Italy; Department of Chemistry, University of Florence, Via della Lastruccia 3, 50019 Sesto Fiorentino, Florence, Italy
| | - Veronica Nasta
- Magnetic Resonance Center CERM, University of Florence, Via Luigi Sacconi 6, 50019 Sesto Fiorentino, Florence, Italy; Department of Chemistry, University of Florence, Via della Lastruccia 3, 50019 Sesto Fiorentino, Florence, Italy
| | - Simone Ciofi-Baffoni
- Magnetic Resonance Center CERM, University of Florence, Via Luigi Sacconi 6, 50019 Sesto Fiorentino, Florence, Italy; Department of Chemistry, University of Florence, Via della Lastruccia 3, 50019 Sesto Fiorentino, Florence, Italy.
| | - Lucia Banci
- Magnetic Resonance Center CERM, University of Florence, Via Luigi Sacconi 6, 50019 Sesto Fiorentino, Florence, Italy; Department of Chemistry, University of Florence, Via della Lastruccia 3, 50019 Sesto Fiorentino, Florence, Italy.
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3
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Camponeschi F, Muzzioli R, Ciofi-Baffoni S, Piccioli M, Banci L. Paramagnetic 1H NMR Spectroscopy to Investigate the Catalytic Mechanism of Radical S-Adenosylmethionine Enzymes. J Mol Biol 2019; 431:4514-4522. [PMID: 31493409 DOI: 10.1016/j.jmb.2019.08.018] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/09/2019] [Revised: 08/30/2019] [Accepted: 08/30/2019] [Indexed: 10/26/2022]
Abstract
Iron-sulfur clusters in radical S-adenosylmethionine (SAM) enzymes catalyze an astonishing array of complex and chemically challenging reactions across all domains of life. Here we showed that 1H NMR spectroscopy experiments tailored to reveal hyperfine-shifted signals of metal-ligands is a powerful tool to monitor the binding of SAM and of the octanoyl-peptide substrate to the two [4Fe-4S] clusters of human lipoyl synthase. The paramagnetically shifted signals of the iron-ligands were specifically assigned to each of the two bound [4Fe-4S] clusters, and then used to examine the interaction of SAM and substrate molecules with each of the two [4Fe-4S] clusters of human lipoyl synthase. 1H NMR spectroscopy can therefore contribute to the description of the catalityc mechanism of radical SAM enzymes.
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Affiliation(s)
- Francesca Camponeschi
- Magnetic Resonance Center CERM, University of Florence, Via Luigi Sacconi 6, 50019, Sesto Fiorentino, Florence, Italy; Department of Chemistry, University of Florence, Via della Lastruccia 3, 50019 Sesto Fiorentino, Florence, Italy
| | - Riccardo Muzzioli
- Magnetic Resonance Center CERM, University of Florence, Via Luigi Sacconi 6, 50019, Sesto Fiorentino, Florence, Italy; Department of Chemistry, University of Florence, Via della Lastruccia 3, 50019 Sesto Fiorentino, Florence, Italy
| | - Simone Ciofi-Baffoni
- Magnetic Resonance Center CERM, University of Florence, Via Luigi Sacconi 6, 50019, Sesto Fiorentino, Florence, Italy; Department of Chemistry, University of Florence, Via della Lastruccia 3, 50019 Sesto Fiorentino, Florence, Italy
| | - Mario Piccioli
- Magnetic Resonance Center CERM, University of Florence, Via Luigi Sacconi 6, 50019, Sesto Fiorentino, Florence, Italy; Department of Chemistry, University of Florence, Via della Lastruccia 3, 50019 Sesto Fiorentino, Florence, Italy
| | - Lucia Banci
- Magnetic Resonance Center CERM, University of Florence, Via Luigi Sacconi 6, 50019, Sesto Fiorentino, Florence, Italy; Department of Chemistry, University of Florence, Via della Lastruccia 3, 50019 Sesto Fiorentino, Florence, Italy.
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4
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Banci L, Camponeschi F, Ciofi-Baffoni S, Piccioli M. The NMR contribution to protein-protein networking in Fe-S protein maturation. J Biol Inorg Chem 2018; 23:665-685. [PMID: 29569085 PMCID: PMC6006191 DOI: 10.1007/s00775-018-1552-x] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/30/2018] [Accepted: 03/12/2018] [Indexed: 12/12/2022]
Abstract
Iron–sulfur proteins were among the first class of metalloproteins that were actively studied using NMR spectroscopy tailored to paramagnetic systems. The hyperfine shifts, their temperature dependencies and the relaxation rates of nuclei of cluster-bound residues are an efficient fingerprint of the nature and the oxidation state of the Fe–S cluster. NMR significantly contributed to the analysis of the magnetic coupling patterns and to the understanding of the electronic structure occurring in [2Fe–2S], [3Fe–4S] and [4Fe–4S] clusters bound to proteins. After the first NMR structure of a paramagnetic protein was obtained for the reduced E. halophila HiPIP I, many NMR structures were determined for several Fe–S proteins in different oxidation states. It was found that differences in chemical shifts, in patterns of unobserved residues, in internal mobility and in thermodynamic stability are suitable data to map subtle changes between the two different oxidation states of the protein. Recently, the interaction networks responsible for maturing human mitochondrial and cytosolic Fe–S proteins have been largely characterized by combining solution NMR standard experiments with those tailored to paramagnetic systems. We show here the contribution of solution NMR in providing a detailed molecular view of “Fe–S interactomics”. This contribution was particularly effective when protein–protein interactions are weak and transient, and thus difficult to be characterized at high resolution with other methodologies.
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Affiliation(s)
- Lucia Banci
- Magnetic Resonance Center CERM, University of Florence, Via Luigi Sacconi 6, Sesto Fiorentino, 50019, Florence, Italy. .,Department of Chemistry, University of Florence, Via della Lastruccia 3, Sesto Fiorentino, 50019, Florence, Italy.
| | - Francesca Camponeschi
- Magnetic Resonance Center CERM, University of Florence, Via Luigi Sacconi 6, Sesto Fiorentino, 50019, Florence, Italy.,Department of Chemistry, University of Florence, Via della Lastruccia 3, Sesto Fiorentino, 50019, Florence, Italy
| | - Simone Ciofi-Baffoni
- Magnetic Resonance Center CERM, University of Florence, Via Luigi Sacconi 6, Sesto Fiorentino, 50019, Florence, Italy.,Department of Chemistry, University of Florence, Via della Lastruccia 3, Sesto Fiorentino, 50019, Florence, Italy
| | - Mario Piccioli
- Magnetic Resonance Center CERM, University of Florence, Via Luigi Sacconi 6, Sesto Fiorentino, 50019, Florence, Italy. .,Department of Chemistry, University of Florence, Via della Lastruccia 3, Sesto Fiorentino, 50019, Florence, Italy.
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5
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Bertarello A, Schubeis T, Fuccio C, Ravera E, Fragai M, Parigi G, Emsley L, Pintacuda G, Luchinat C. Paramagnetic Properties of a Crystalline Iron–Sulfur Protein by Magic-Angle Spinning NMR Spectroscopy. Inorg Chem 2017; 56:6624-6629. [DOI: 10.1021/acs.inorgchem.7b00674] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/27/2022]
Affiliation(s)
- Andrea Bertarello
- Centre de RMN à
Très Hauts Champs, Institut des Sciences Analytiques (CNRS,
ENS Lyon, UCB Lyon 1), Université de Lyon, 69100 Villeurbanne, France
| | - Tobias Schubeis
- Centre de RMN à
Très Hauts Champs, Institut des Sciences Analytiques (CNRS,
ENS Lyon, UCB Lyon 1), Université de Lyon, 69100 Villeurbanne, France
- Giotto Biotech S.R.L., Via Madonna
del Piano 6, 50019 Sesto Fiorentino, Italy
| | - Carmelo Fuccio
- Magnetic Resonance Center (CERM) and Interuniversity Consortium for Magnetic Resonance of Metallo Proteins (CIRMMP), Via L. Sacconi 6, 50019 Sesto Fiorentino, Italy
| | - Enrico Ravera
- Magnetic Resonance Center (CERM) and Interuniversity Consortium for Magnetic Resonance of Metallo Proteins (CIRMMP), Via L. Sacconi 6, 50019 Sesto Fiorentino, Italy
| | - Marco Fragai
- Magnetic Resonance Center (CERM) and Interuniversity Consortium for Magnetic Resonance of Metallo Proteins (CIRMMP), Via L. Sacconi 6, 50019 Sesto Fiorentino, Italy
- Department
of Chemistry “Ugo Schiff”, University of Florence, Via della Lastruccia 3, 50019 Sesto Fiorentino, Italy
| | - Giacomo Parigi
- Magnetic Resonance Center (CERM) and Interuniversity Consortium for Magnetic Resonance of Metallo Proteins (CIRMMP), Via L. Sacconi 6, 50019 Sesto Fiorentino, Italy
- Department
of Chemistry “Ugo Schiff”, University of Florence, Via della Lastruccia 3, 50019 Sesto Fiorentino, Italy
| | - Lyndon Emsley
- Institut
des Sciences et Ingénierie Chimiques, Ecole Polytechnique Fédérale de Lausanne (EPFL), CH-1015 Lausanne, Switzerland
| | - Guido Pintacuda
- Centre de RMN à
Très Hauts Champs, Institut des Sciences Analytiques (CNRS,
ENS Lyon, UCB Lyon 1), Université de Lyon, 69100 Villeurbanne, France
| | - Claudio Luchinat
- Giotto Biotech S.R.L., Via Madonna
del Piano 6, 50019 Sesto Fiorentino, Italy
- Magnetic Resonance Center (CERM) and Interuniversity Consortium for Magnetic Resonance of Metallo Proteins (CIRMMP), Via L. Sacconi 6, 50019 Sesto Fiorentino, Italy
- Department
of Chemistry “Ugo Schiff”, University of Florence, Via della Lastruccia 3, 50019 Sesto Fiorentino, Italy
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6
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Piccioli M, Turano P. Transient iron coordination sites in proteins: Exploiting the dual nature of paramagnetic NMR. Coord Chem Rev 2015. [DOI: 10.1016/j.ccr.2014.05.007] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/25/2022]
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7
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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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8
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Orio M, Mouesca JM. Variation of average g values and effective exchange coupling constants among [2Fe-2S] clusters: a density functional theory study of the impact of localization (trapping forces) versus delocalization (double-exchange) as competing factors. Inorg Chem 2008; 47:5394-416. [PMID: 18491857 DOI: 10.1021/ic701730h] [Citation(s) in RCA: 35] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
A phenomenological model aimed at rationalizing variations in both average g-tensor values (gav identical with 1/3Sigmaigi ) and effective exchange coupling constants Jeff (defined as two-thirds of the energy difference between the S = 3/2 and S = 1/2 spin states) has been derived in order to describe the great variety of magnetic properties exhibited by reduced [2Fe-2S] clusters in proteins. The key quantity in the present analysis is the ratio Delta E/B computed from two competing terms. Delta Ecomprises various effects that result in trapping-site asymmetries: vibronic coupling and the chemical nature (S/N/O) and conformations of the ligands on the one hand and solvation terms, the hydrogen bonding network, etc., on the other. All of these additive terms (in a "bottom-up" approach) favor valence localization of the reducing electron onto one of the two iron sites. In contrast, the B term is the double-exchange term, which favors electronic delocalization. Both gav and Jeff can be expressed as functions of Delta E/ B. We have also shown that electronic localization generally favors small gav and large Jeff values (while the opposite is true for electronic delocalization) in a comparative study of the spectroscopic features of plant-type ferredoxins (Fd's) and Rieske centers (and related mutants). Two other types of problems were particularly challenging. The first of these involved deprotonated Rieske centers and the xanthine oxidase clusters II, which are characterized by very small Jeff values (40-45 cm (-1) with a J S A. S B model) correlated with unusually large gav values (in the range 1.97-2.01) as a result of an antisymmetric exchange coupling mechanism. The second concerned the analogous Fd's from Clostridium pasteurianum (Cp) and Aquifex aeolicus (Aa). Detailed Mössbauer studies of the C56S mutant of the Cp system revealed a mixture of clusters with valence-localized S = 1/2 and valence-delocalized S = 9/2 ground states. We relied on crystallographic structures of wild-type and mutant Aa Fd's in order to explain such a distribution of spin states.
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Affiliation(s)
- Maylis Orio
- Laboratory of Inorganic and Biological Chemistry, Grenoble cedex, France
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9
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Torrens F. Calculation of organic solvent–water partition coefficients of iron–sulfur protein models. Polyhedron 2002. [DOI: 10.1016/s0277-5387(02)00956-7] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
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10
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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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11
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Coordination sphere versus protein environment as determinants of electronic and functional properties of iron-sulfur proteins. STRUCTURE AND BONDING 1998. [DOI: 10.1007/3-540-62888-6_5] [Citation(s) in RCA: 37] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/24/2022]
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12
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Cowan J, Lui SM. Structure-Function Correlations in High-Potential IRON Proteins. ADVANCES IN INORGANIC CHEMISTRY 1998. [DOI: 10.1016/s0898-8838(08)60028-8] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
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13
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Ciurli S, Cremonini MA, Kofod P, Luchinat C. 1H NMR of high-potential iron-sulfur protein from the purple non-sulfurbacterium Rhodoferax fermentans. EUROPEAN JOURNAL OF BIOCHEMISTRY 1996; 236:405-11. [PMID: 8612609 DOI: 10.1111/j.1432-1033.1996.00405.x] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/31/2023]
Abstract
Oxidized and reduced forms of high-potential iron-sulfur protein (HiPIP) from the purple non-sulfur photosynthetic bacterium Rhodoferax fermentans have been characterized using 1H-NMR spectroscopy. Pairwise and sequence-specific assignments of hyperfine-shifted 1H-NMR signals to protons of cysteine residues bound to the [4Fe-4S]3+/2+ cluster have been performed using one-dimensional NOE and exchange spectroscopy experiments. 1H-NMR hyperfine shifts and relaxation rates of cluster-bound Cys beta-CH2 protons indicate that in the [4Fe-4S]3+ cluster one iron ion can be formally described as Fe(III), while electron density corresponding to one electron is unevenly delocalized onto the remaining three iron ions. This delocalization is effected by means of two different electronic distributions interconverting rapidly on the NMR time scale. The mechanism of paramagnetic proton relaxation, studied by analyzing longitudinal relaxation rates of Cys beta-CH2 protons in HiPIPs from six different sources as a function of the Fe-S-C beta-C alpha dihedral angle, indicate that the major contribution is due to a dipolar metal-centered mechanism, with a non-negligible contribution from a ligand-centered dipolar mechanism which involves the 3p orbital of the Cys sulfur atom. A semi-quantitative tool for extracting structural information from relaxation time measurements is proposed.
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Affiliation(s)
- S Ciurli
- Institute of Agricultural Chemistry, University of Bologna, Italy
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14
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Babini E, Bertini I, Borsari M, Capozzi F, Dikiy A, Eltis LD, Luchinat C. A Serine → Cysteine Ligand Mutation in the High Potential Iron−Sulfur Protein fromChromatium vinosumProvides Insight into the Electronic Structure of the [4Fe−4S] Cluster. J Am Chem Soc 1996. [DOI: 10.1021/ja952636+] [Citation(s) in RCA: 52] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
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15
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The electronic structure of FeS centers in proteins and models a contribution to the understanding of their electron transfer properties. STRUCTURE AND BONDING 1995. [DOI: 10.1007/3-540-59105-2_1] [Citation(s) in RCA: 79] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/15/2022]
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16
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Bertini I, Felli IC, Kastrau DH, Luchinat C, Piccioli M, Viezzoli MS. Sequence-specific assignment of the 1H and 15N nuclear magnetic resonance spectra of the reduced recombinant high-potential iron-sulfur protein I from Ectothiorhodospira halophila. EUROPEAN JOURNAL OF BIOCHEMISTRY 1994; 225:703-14. [PMID: 7957186 DOI: 10.1111/j.1432-1033.1994.00703.x] [Citation(s) in RCA: 23] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/28/2023]
Abstract
A 1H and 15N NMR investigation through two-dimensional and three-dimensional spectroscopy has been performed on the reduced form ([Fe4S4]2+) of the recombinant high-potential iron-sulfur protein (HiPIP) I from Ectothiorhodospira halophila expressed in Escherichia coli. [Fe4S4]2+ clusters in proteins are paramagnetic with a relatively low mu eff of about 0.8 mu B/iron ion, but the paramagnetic effects on nuclear relaxation are so strong as to yield T1 values of a few milliseconds and linewidths of hundreds of hertz for the nuclei closet to the paramagnetic center. Despite these features, 71 out of 73 residues were identified, most of which were assigned completely as far as proton resonances are concerned; as many as 68 residues could be assigned without any reference to the existing X-ray structure. A total of 88% of all protein protons and 58 out of 69 peptide HN nitrogen signals were assigned. To the best of our knowledge, this is the most extensive 1H assignment of a paramagnetic protein to date. Protons sensitive to the proximity of the cluster were assigned through suitable NOE spectroscopy experiments. Three out of the four coordinated cysteines were assigned, and two residues have been identified whose peptide HN protons give rise to H bonds with coordinated sulfur atoms. The inter-residue NOE cross peaks are in qualitative agreement with the secondary and tertiary structure as obtained from the available X-ray crystallographic analysis of the wild-type protein at 250-pm resolution. It is therefore shown that the expressed protein is properly folded and that it is a reliable model for the wild-type protein. These data are meaningful for the detection of structural differences among mutants in future studies.
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Affiliation(s)
- I Bertini
- Department of Chemistry, University of Florence, Italy
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17
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Banci L, Bertini I, Eltis LD, Felli IC, Kastrau DH, Luchinat C, Piccioli M, Pierattelli R, Smith M. The three-dimensional structure in solution of the paramagnetic high-potential iron-sulfur protein I from Ectothiorhodospira halophila through nuclear magnetic resonance. EUROPEAN JOURNAL OF BIOCHEMISTRY 1994; 225:715-25. [PMID: 7957187 DOI: 10.1111/j.1432-1033.1994.00715.x] [Citation(s) in RCA: 92] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/28/2023]
Abstract
The three-dimensional structure in solution of reduced recombinant high-potential iron-sulfur protein iso-I from Ectothiorhodospira halophila was determined using 948 relevant interproton NOEs out of the 1246 observed NOEs. The determination was accomplished using the XEASY program for spectral analysis and the distance geometry (DG) program DIANA for generation of the structure as described by Wüthrich [Wüthrich, K. (1989) Acc. Chem. Res. 22, 36-44]. The FeS cluster was simulated using an amino acid residue constructed for the present work from a cysteinyl residue with an iron and a sulfur atom attached to the terminal thiol. The family of structures obtained from distance geometry were subjected to energy minimization and molecular dynamics simulations using previously defined force field parameters. The quality of these structures at each stage of the refinement process is discussed with respect to the dihedral angle order parameter and the root-mean-square deviation of the atomic coordinates. The latter values for the backbone atoms vary from 67 pm for the distance-geometry structures to 60 pm for the energy-minimized structures to 51 pm for the structures subjected to restrained molecular dynamics. Finally, the structure in best agreement with the NOE constraints has been further treated with extensive restrained molecular dynamics in water. The solution structure is well defined and is very similar to the available X-ray structure. We do not know of any previous determination of the structure of a paramagnetic protein in solution by NMR. The effect of paramagnetism on the quality of the structure determination is discussed.
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Affiliation(s)
- L Banci
- Department of Chemistry, University of Florence, Italy
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Banci L, Bertini I, Luchinat C. Two-dimensional nuclear magnetic resonance spectra of paramagnetic systems. Methods Enzymol 1994; 239:485-514. [PMID: 7830596 DOI: 10.1016/s0076-6879(94)39019-3] [Citation(s) in RCA: 28] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/27/2023]
Affiliation(s)
- L Banci
- Department of Chemistry, University of Florence, Italy
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