1
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Trindade IB, Coelho A, Cantini F, Piccioli M, Louro RO. NMR of paramagnetic metalloproteins in solution: Ubi venire, quo vadis? J Inorg Biochem 2022; 234:111871. [DOI: 10.1016/j.jinorgbio.2022.111871] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/26/2022] [Revised: 05/16/2022] [Accepted: 05/19/2022] [Indexed: 10/18/2022]
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2
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Abstract
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Thanks to recent
improvements in NMR spectrometer hardware and
pulse sequence design, modern 13C NMR has become a useful
tool for biomolecular applications. The complete assignment of a protein
can be accomplished by using 13C detected multinuclear
experiments and it can provide unique information relevant for the
study of a variety of different biomolecules including paramagnetic
proteins and intrinsically disordered proteins. A wide range of NMR
observables can be measured, concurring to the structural and dynamic
characterization of a protein in isolation, as part of a larger complex,
or even inside a living cell. We present the different properties
of 13C with respect to 1H, which provide the
rationale for the experiments developed and their application, the
technical aspects that need to be faced, and the many experimental
variants designed to address different cases. Application areas where
these experiments successfully complement proton NMR are also described.
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Affiliation(s)
- Isabella C Felli
- Department of Chemistry "Ugo Schiff" and Magnetic Resonance Center, University of Florence, Via Luigi Sacconi 6, 50019 Sesto Fiorentino (Florence), Italy
| | - Roberta Pierattelli
- Department of Chemistry "Ugo Schiff" and Magnetic Resonance Center, University of Florence, Via Luigi Sacconi 6, 50019 Sesto Fiorentino (Florence), Italy
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3
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Vilbert AC, Liu Y, Dai H, Lu Y. Recent advances in tuning redox properties of electron transfer centers in metalloenzymes catalyzing oxygen reduction reaction and H 2 oxidation important for fuel cells design. CURRENT OPINION IN ELECTROCHEMISTRY 2021; 30:100780. [PMID: 34435160 PMCID: PMC8382256 DOI: 10.1016/j.coelec.2021.100780] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/13/2023]
Abstract
Current fuel-cell catalysts for oxygen reduction reaction (ORR) and H2 oxidation use precious metals and, for ORR, require high overpotentials. In contrast, metalloenzymes perform their respective reaction at low overpotentials using earth-abundant metals, making metalloenzymes ideal candidates for inspiring electrocatalytic design. Critical to the success of these enzymes are redox-active metal centers surrounding the enzyme active sites that ensure fast electron transfer (ET) to or away from the active site, by tuning the catalytic potential of the reaction as observed in multicopper oxidases but also in dictating the catalytic bias of the reaction as realized in hydrogenases. This review summarizes recent advances in studying these ET centers in multicopper oxidases and heme-copper oxidases that perform ORR and hydrogenases in carrying out H2 oxidation. Insights gained from understanding how the reduction potential of the ET centers effects reactivity at the active site in both the enzymes and their models are provided.
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Affiliation(s)
| | - Yiwei Liu
- Department of Chemistry and Department of Biochemistry, University of Illinois at Urbana-Champaign, Urbana, IL 61801, USA
| | - Huiguang Dai
- Department of Chemistry and Department of Biochemistry, University of Illinois at Urbana-Champaign, Urbana, IL 61801, USA
| | - Yi Lu
- Pacific Northwest National Laboratory, Richland, WA 99352, USA
- Department of Chemistry and Department of Biochemistry, University of Illinois at Urbana-Champaign, Urbana, IL 61801, USA
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4
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Morgada MN, Llases ME, Giannini E, Castro MA, Alzari PM, Murgida DH, Lisa MN, Vila AJ. Unexpected electron spin density on the axial methionine ligand in Cu A suggests its involvement in electron pathways. Chem Commun (Camb) 2020; 56:1223-1226. [PMID: 31897463 DOI: 10.1039/c9cc08883k] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
The CuA center is a paradigm for the study of long-range biological electron transfer. This metal center is an essential cofactor for terminal oxidases like cytochrome c oxidase, the enzymatic complex responsible for cellular respiration in eukaryotes and in most bacteria. CuA acts as an electron hub by transferring electrons from reduced cytochrome c to the catalytic site of the enzyme where dioxygen reduction takes place. Different electron transfer pathways have been proposed involving a weak axial methionine ligand residue, conserved in all CuA sites. This hypothesis has been challenged by theoretical calculations indicating the lack of electron spin density in this ligand. Here we report an NMR study with selectively labeled methionine in a native CuA. NMR spectroscopy discloses the presence of net electron spin density in the methionine axial ligand in the two alternative ground states of this metal center. Similar spin delocalization observed on two second sphere mutants further supports this evidence. These data provide a novel view of the electronic structure of CuA centers and support previously neglected electron transfer pathways.
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Affiliation(s)
- Marcos N Morgada
- Instituto de Biología Molecular y Celular de Rosario (IBR, CONICET-UNR), Ocampo y Esmeralda, Rosario 2000, Argentina.
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5
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Morgada MN, Emiliani F, Chacón KN, Álvarez-Paggi D, Murgida DH, Blackburn NJ, Abriata LA, Vila AJ. pH-Induced Binding of the Axial Ligand in an Engineered Cu A Site Favors the π u State. Inorg Chem 2019; 58:15687-15691. [DOI: 10.1021/acs.inorgchem.9b01868] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Affiliation(s)
- Marcos N. Morgada
- Instituto de Biología Molecular y Celular de Rosario (IBR, CONICET-UNR) and Área Biofísica, Facultad de Ciencias Bioquímicas y Farmacéuticas, Universidad Nacional de Rosario, Ocampo y Esmeralda,
Predio CONICET Rosario, 2000 Rosario, Argentina
| | - Florencia Emiliani
- Instituto de Biología Molecular y Celular de Rosario (IBR, CONICET-UNR) and Área Biofísica, Facultad de Ciencias Bioquímicas y Farmacéuticas, Universidad Nacional de Rosario, Ocampo y Esmeralda,
Predio CONICET Rosario, 2000 Rosario, Argentina
| | - Kelly N. Chacón
- Department of Chemical Physiology and Biochemistry, Oregon Health and Sciences University, Portland, Oregon 97239, United States
| | - Damián Álvarez-Paggi
- INQUIMAE-CONICET, Facultad de Ciencias Exactas y Naturales, Universidad de Buenos Aires, Ciudad Universitaria C1428EHA, Buenos Aires, Argentina
| | - Daniel H. Murgida
- INQUIMAE-CONICET, Facultad de Ciencias Exactas y Naturales, Universidad de Buenos Aires, Ciudad Universitaria C1428EHA, Buenos Aires, Argentina
| | - Ninian J. Blackburn
- Department of Chemical Physiology and Biochemistry, Oregon Health and Sciences University, Portland, Oregon 97239, United States
| | - Luciano A. Abriata
- Instituto de Biología Molecular y Celular de Rosario (IBR, CONICET-UNR) and Área Biofísica, Facultad de Ciencias Bioquímicas y Farmacéuticas, Universidad Nacional de Rosario, Ocampo y Esmeralda,
Predio CONICET Rosario, 2000 Rosario, Argentina
| | - Alejandro J. Vila
- Instituto de Biología Molecular y Celular de Rosario (IBR, CONICET-UNR) and Área Biofísica, Facultad de Ciencias Bioquímicas y Farmacéuticas, Universidad Nacional de Rosario, Ocampo y Esmeralda,
Predio CONICET Rosario, 2000 Rosario, Argentina
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6
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Atsumi M. The 13C nuclear magnetic shielding constants at the singlet excited states in CH2CCH2, CH2O, CH3CHO, CH3NH2, and CO. Chem Phys Lett 2019. [DOI: 10.1016/j.cplett.2019.03.051] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/27/2022]
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7
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Ross MO, Fisher OS, Morgada MN, Krzyaniak MD, Wasielewski MR, Vila AJ, Hoffman BM, Rosenzweig AC. Formation and Electronic Structure of an Atypical Cu A Site. J Am Chem Soc 2019; 141:4678-4686. [PMID: 30807125 PMCID: PMC6953997 DOI: 10.1021/jacs.8b13610] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
PmoD, a recently discovered protein from methane-oxidizing bacteria, forms a homodimer with a dicopper CuA center at the dimer interface. Although the optical and electron paramagnetic resonance (EPR) spectroscopic signatures of the PmoD CuA bear similarities to those of canonical CuA sites, there are also some puzzling differences. Here we have characterized the rapid formation (seconds) and slow decay (hours) of this homodimeric CuA site to two mononuclear Cu2+ sites, as well as its electronic and geometric structure, using stopped-flow optical and advanced paramagnetic resonance spectroscopies. PmoD CuA formation occurs rapidly and involves a short-lived intermediate with a λmax of 360 nm. Unlike other CuA sites, the PmoD CuA is unstable, decaying to two type 2 Cu2+ centers. Surprisingly, NMR data indicate that the PmoD CuA has a pure σu* ground state rather than the typical equilibrium between σu* and πu of all other CuA proteins. EPR, ENDOR, ESEEM, and HYSCORE data indicate the presence of two histidine and two cysteine ligands coordinating the CuA core in a highly symmetrical fashion. This report significantly expands the diversity and understanding of known CuA sites.
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Affiliation(s)
- Matthew O. Ross
- Department of Molecular Biosciences, Northwestern University, Evanston, IL, USA
- Department of Chemistry, Northwestern University, Evanston, IL, USA
| | - Oriana S. Fisher
- Department of Molecular Biosciences, Northwestern University, Evanston, IL, USA
- Department of Chemistry, Northwestern University, Evanston, IL, USA
| | - Marcos N. Morgada
- Instituto de Biología Molecular y Celular de Rosario (IBR, CONICET-UNR), Ocampo y Esmeralda, S2002LRK Rosario, Argentina
- Área Biofísica, Facultad de Ciencias Bioquímicas y Farmacéuticas, Universidad Nacional de Rosario, S2002LRK Rosario, Argentina
| | - Matthew D. Krzyaniak
- Department of Chemistry and Institute for Sustainability and Energy at Northwestern, Northwestern University, 2145 Sheridan Rd, Evanston, IL 60208, USA
| | - Michael R. Wasielewski
- Department of Chemistry and Institute for Sustainability and Energy at Northwestern, Northwestern University, 2145 Sheridan Rd, Evanston, IL 60208, USA
| | - Alejandro J. Vila
- Instituto de Biología Molecular y Celular de Rosario (IBR, CONICET-UNR), Ocampo y Esmeralda, S2002LRK Rosario, Argentina
| | - Brian M. Hoffman
- Department of Molecular Biosciences, Northwestern University, Evanston, IL, USA
- Department of Chemistry, Northwestern University, Evanston, IL, USA
| | - Amy C. Rosenzweig
- Department of Molecular Biosciences, Northwestern University, Evanston, IL, USA
- Department of Chemistry, Northwestern University, Evanston, IL, USA
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8
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Dikanov SA, Berry SM, Lu Y. HYSCORE Insights into the Distribution of the Unpaired Spin Density in an Engineered Cu A Site in Azurin and Its His120Gly Variant. Inorg Chem 2019; 58:4437-4445. [PMID: 30869885 DOI: 10.1021/acs.inorgchem.8b03604] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
A comparative study of the 1H and 14N hyperfine interactions between the CuA site in an engineered CuA center in azurin (WT-CuAAz) and its His120Gly variant (H120G-CuAAz) using the two-dimensional ESEEM technique, HYSCORE, is reported. HYSCORE spectroscopy has clarified conflicting results in previous electron paramagnetic resonance (EPR) and electron nuclear double resonance (ENDOR) studies and found clear differences between the two CuA azurins. Specifically, a hyperfine coupling AN⊥ of 15.3 MHz was determined for the first time from the frequencies of double-quantum transitions of 14N histidine nitrogens coordinated to CuA in WT-CuAAz. In contrast, such coupling was not observed in the spectra of H120G-CuAAz, indicating at least a several megahertz increase in AN⊥ for the coordinated nitrogen in this variant. In addition, 14N HYSCORE spectra of WT-CuAAz show interaction with only one type of weakly coupled nitrogen assigned to the remote Nε atom of coordinated imidazole residues based on the quadrupole coupling constant ( e2 Qq/4 h) of ∼0.4 MHz. The spectrum of H120G-CuAAz resolves additional features typical for backbone peptide nitrogens with larger e2 Qq/4 h values of ∼0.7 MHz. Hyperfine couplings with these nitrogens vary between ∼0.4 and 0.7 MHz. In addition, the two resolved cross-peaks from Cβ protons in H120G-CuAAz display only ∼1 MHz shifts relative to the corresponding peaks in WT-CuAAz. These new findings have provided the first experimental evidence of the previous density functional theory analysis that predicted changes in the delocalized electron spin population of ∼0.02-0.03 (i.e., ∼10%) on copper and sulfur atoms of the CuA center in H120 variants relative to WT-CuAAz and resolved contradicting results between EPR and ENDOR studies of the valence distribution in CuAAz and its variants.
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Affiliation(s)
- Sergei A Dikanov
- Department of Veterinary Clinical Medicine , University of Illinois at Urbana-Champaign , Urbana , Illinois 61801 , United States
| | - Steven M Berry
- Department of Chemistry and Biochemistry , University of Minnesota Duluth , Duluth , Minnesota 55812 , United States
| | - Yi Lu
- Department of Chemistry , University of Illinois at Urbana-Champaign , Urbana , Illinois 61801 , United States
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9
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Leguto AJ, Smith MA, Morgada MN, Zitare UA, Murgida DH, Lancaster KM, Vila AJ. Dramatic Electronic Perturbations of Cu A Centers via Subtle Geometric Changes. J Am Chem Soc 2019; 141:1373-1381. [PMID: 30582893 DOI: 10.1021/jacs.8b12335] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
CuA is a binuclear copper site acting as electron entry port in terminal heme-copper oxidases. In the oxidized form, CuA is a mixed valence pair whose electronic structure can be described using a potential energy surface with two minima, σu* and πu, that are variably populated at room temperature. We report that mutations in the first and second coordination spheres of the binuclear metallocofactor can be combined in an additive manner to tune the energy gap and, thus, the relative populations of the two lowest-lying states. A series of designed mutants span σu*/πu energy gaps ranging from 900 to 13 cm-1. The smallest gap corresponds to a variant with an effectively degenerate ground state. All engineered sites preserve the mixed-valence character of this metal center and the electron transfer functionality. An increase of the Cu-Cu distance less than 0.06 Å modifies the σu*/πu energy gap by almost 2 orders of magnitude, with longer distances eliciting a larger population of the πu state. This scenario offers a stark contrast to synthetic systems, as model compounds require a lengthening of 0.5 Å in the Cu-Cu distance to stabilize the πu state. These findings show that the tight control of the protein environment allows drastic perturbations in the electronic structure of CuA sites with minor geometric changes.
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Affiliation(s)
- Alcides J Leguto
- Instituto de Biología Molecular y Celular de Rosario (IBR), Departamento de Química Biológica, Facultad de Ciencias Bioquímicas y Farmacéuticas , Universidad Nacional de Rosario and CONICET , 2000 Rosario , Argentina
| | - Meghan A Smith
- Department of Chemistry and Chemical Biology , Cornell University , Ithaca , New York 14853 , United States
| | - Marcos N Morgada
- Instituto de Biología Molecular y Celular de Rosario (IBR), Departamento de Química Biológica, Facultad de Ciencias Bioquímicas y Farmacéuticas , Universidad Nacional de Rosario and CONICET , 2000 Rosario , Argentina
| | - Ulises A Zitare
- Instituto de Química Física de los Materiales, Medio Ambiente y Energía (INQUIMAE), Departamento de Química Inorgánica, Analítica y Química Física, Facultad de Ciencias Exactas y Naturales , Universidad de Buenos Aires and CONICET , 1428 Buenos Aires , Argentina
| | - Daniel H Murgida
- Instituto de Química Física de los Materiales, Medio Ambiente y Energía (INQUIMAE), Departamento de Química Inorgánica, Analítica y Química Física, Facultad de Ciencias Exactas y Naturales , Universidad de Buenos Aires and CONICET , 1428 Buenos Aires , Argentina
| | - Kyle M Lancaster
- Department of Chemistry and Chemical Biology , Cornell University , Ithaca , New York 14853 , United States
| | - Alejandro J Vila
- Instituto de Biología Molecular y Celular de Rosario (IBR), Departamento de Química Biológica, Facultad de Ciencias Bioquímicas y Farmacéuticas , Universidad Nacional de Rosario and CONICET , 2000 Rosario , Argentina
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10
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Espinoza-Cara A, Zitare U, Alvarez-Paggi D, Klinke S, Otero LH, Murgida DH, Vila AJ. Engineering a bifunctional copper site in the cupredoxin fold by loop-directed mutagenesis. Chem Sci 2018; 9:6692-6702. [PMID: 30310603 PMCID: PMC6115626 DOI: 10.1039/c8sc01444b] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/29/2018] [Accepted: 06/27/2018] [Indexed: 12/30/2022] Open
Abstract
Copper sites in proteins are designed to perform either electron transfer or redox catalysis. Type 1 and CuA sites are electron transfer hubs bound to a rigid protein fold that prevents binding of exogenous ligands and side reactions. Here we report the engineering of two Type 1 sites by loop-directed mutagenesis within a CuA scaffold with unique electronic structures and functional features. A copper-thioether axial bond shorter than the copper-thiolate bond is responsible for the electronic structure features, in contrast to all other natural or chimeric sites where the copper thiolate bond is short. These sites display highly unusual features, such as: (1) a high reduction potential despite a strong interaction with the axial ligand, which we attribute to changes in the hydrogen bond network and (2) the ability to bind exogenous ligands such as imidazole and azide. This strategy widens the possibility of using natural protein scaffolds with functional features not present in nature.
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Affiliation(s)
- Andrés Espinoza-Cara
- Instituto de Biología Molecular y Celular de Rosario (IBR, CONICET-UNR) , Rosario , Argentina .
- Área Biofísica , Departamento de Química Biológica , Facultad de Ciencias Bioquímicas y Farmacéuticas , Universidad Nacional de Rosario , Rosario , Argentina
| | - Ulises Zitare
- Departamento de Química Inorgánica , Analítica y Química Física-INQUIMAE , Facultad de Ciencias Exactas y Naturales , Universidad de Buenos Aires-CONICET , Buenos Aires , Argentina
| | - Damián Alvarez-Paggi
- Departamento de Química Inorgánica , Analítica y Química Física-INQUIMAE , Facultad de Ciencias Exactas y Naturales , Universidad de Buenos Aires-CONICET , Buenos Aires , Argentina
- Fundación Instituto Leloir , IIBBA-CONICET , Buenos Aires , Argentina
| | - Sebastián Klinke
- Fundación Instituto Leloir , IIBBA-CONICET , Buenos Aires , Argentina
- Plataforma Argentina de Biología Estructural y Metabolómica PLABEM. , Buenos Aires , Argentina
| | - Lisandro H Otero
- Fundación Instituto Leloir , IIBBA-CONICET , Buenos Aires , Argentina
- Plataforma Argentina de Biología Estructural y Metabolómica PLABEM. , Buenos Aires , Argentina
| | - Daniel H Murgida
- Departamento de Química Inorgánica , Analítica y Química Física-INQUIMAE , Facultad de Ciencias Exactas y Naturales , Universidad de Buenos Aires-CONICET , Buenos Aires , Argentina
| | - Alejandro J Vila
- Instituto de Biología Molecular y Celular de Rosario (IBR, CONICET-UNR) , Rosario , Argentina .
- Área Biofísica , Departamento de Química Biológica , Facultad de Ciencias Bioquímicas y Farmacéuticas , Universidad Nacional de Rosario , Rosario , Argentina
- Plataforma Argentina de Biología Estructural y Metabolómica PLABEM. , Buenos Aires , Argentina
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11
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Kroneck PMH. Walking the seven lines: binuclear copper A in cytochrome c oxidase and nitrous oxide reductase. J Biol Inorg Chem 2017; 23:27-39. [PMID: 29218634 DOI: 10.1007/s00775-017-1510-z] [Citation(s) in RCA: 22] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/14/2017] [Accepted: 10/20/2017] [Indexed: 01/19/2023]
Abstract
The enzymes nitrous oxide reductase (N2OR) and cytochrome c oxidase (COX) are constituents of important biological processes. N2OR is the terminal reductase in a respiratory chain converting N2O to N2 in denitrifying bacteria; COX is the terminal oxidase of the aerobic respiratory chain of certain bacteria and eukaryotic organisms transforming O2 to H2O accompanied by proton pumping. Different spectroscopies including magnetic resonance techniques, were applied to show that N2OR has a mixed-valent Cys-bridged [Cu1.5+(CyS)2Cu1.5+] copper site, and that such a binuclear center, called CuA, does also exist in COX. A sequence motif shared between the CuA center of N2OR and the subunit II of COX raises the issue of a putative evolutionary relationship of the two enzymes. The suggestion of a binuclear CuA in COX, with one unpaired electron delocalized between two equivalent Cu nuclei, was difficult to accept originally, even though regarded as a clever solution to many experimental observations. This minireview in honor of Helmut Sigel traces several of the critical steps forward in understanding the nature of CuA in N2OR and COX, and discusses its unique electronic features to some extent including the contributions made by the development of methodology and the discovery of a novel multi-copper enzyme. Left: X-band (9.130 GHz) and C-band (4.530 GHz, 1st harmonic display of experimental spectrum) EPR spectra of bovine heart cytochrome c oxidase, recorded at 20K. Right: Ribbon presentation of the CuA domain in cytochrome c oxidase and nitrous oxide reductase.
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Affiliation(s)
- Peter M H Kroneck
- Department of Biology, University of Konstanz, Universitätsstrasse 10, 78457, Konstanz, Germany.
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12
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Alvarez-Paggi D, Hannibal L, Castro MA, Oviedo-Rouco S, Demicheli V, Tórtora V, Tomasina F, Radi R, Murgida DH. Multifunctional Cytochrome c: Learning New Tricks from an Old Dog. Chem Rev 2017; 117:13382-13460. [DOI: 10.1021/acs.chemrev.7b00257] [Citation(s) in RCA: 135] [Impact Index Per Article: 19.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022]
Affiliation(s)
- Damián Alvarez-Paggi
- Departamento
de Química Inorgánica, Analítica y Química
Física and INQUIMAE (CONICET-UBA), Facultad de Ciencias Exactas
y Naturales, Universidad de Buenos Aires, Ciudad Universitaria, Pab. 2, piso 1, Buenos Aires C1428EHA, Argentina
| | - Luciana Hannibal
- Department
of Pediatrics, Universitätsklinikum Freiburg, Mathildenstrasse 1, Freiburg 79106, Germany
- Departamento
de Bioquímica and Center for Free Radical and Biomedical Research,
Facultad de Medicina, Universidad de la República, Av.
Gral. Flores 2125, Montevideo 11800, Uruguay
| | - María A. Castro
- Departamento
de Química Inorgánica, Analítica y Química
Física and INQUIMAE (CONICET-UBA), Facultad de Ciencias Exactas
y Naturales, Universidad de Buenos Aires, Ciudad Universitaria, Pab. 2, piso 1, Buenos Aires C1428EHA, Argentina
| | - Santiago Oviedo-Rouco
- Departamento
de Química Inorgánica, Analítica y Química
Física and INQUIMAE (CONICET-UBA), Facultad de Ciencias Exactas
y Naturales, Universidad de Buenos Aires, Ciudad Universitaria, Pab. 2, piso 1, Buenos Aires C1428EHA, Argentina
| | - Veronica Demicheli
- Departamento
de Bioquímica and Center for Free Radical and Biomedical Research,
Facultad de Medicina, Universidad de la República, Av.
Gral. Flores 2125, Montevideo 11800, Uruguay
| | - Veronica Tórtora
- Departamento
de Bioquímica and Center for Free Radical and Biomedical Research,
Facultad de Medicina, Universidad de la República, Av.
Gral. Flores 2125, Montevideo 11800, Uruguay
| | - Florencia Tomasina
- Departamento
de Bioquímica and Center for Free Radical and Biomedical Research,
Facultad de Medicina, Universidad de la República, Av.
Gral. Flores 2125, Montevideo 11800, Uruguay
| | - Rafael Radi
- Departamento
de Bioquímica and Center for Free Radical and Biomedical Research,
Facultad de Medicina, Universidad de la República, Av.
Gral. Flores 2125, Montevideo 11800, Uruguay
| | - Daniel H. Murgida
- Departamento
de Química Inorgánica, Analítica y Química
Física and INQUIMAE (CONICET-UBA), Facultad de Ciencias Exactas
y Naturales, Universidad de Buenos Aires, Ciudad Universitaria, Pab. 2, piso 1, Buenos Aires C1428EHA, Argentina
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13
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Alvarez-Paggi D, Zitare UA, Szuster J, Morgada MN, Leguto AJ, Vila AJ, Murgida DH. Tuning of Enthalpic/Entropic Parameters of a Protein Redox Center through Manipulation of the Electronic Partition Function. J Am Chem Soc 2017; 139:9803-9806. [PMID: 28662578 DOI: 10.1021/jacs.7b05199] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
Manipulation of the partition function (Q) of the redox center CuA from cytochrome c oxidase is attained by tuning the accessibility of a low lying alternative electronic ground state and by perturbation of the electrostatic potential through point mutations, loop engineering and pH variation. We report clear correlations of the entropic and enthalpic contributions to redox potentials with Q and with the identity and hydrophobicity of the weak axial ligand, respectively.
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Affiliation(s)
- Damian Alvarez-Paggi
- Instituto de Química Física de los Materiales, Medio Ambiente y Energía (INQUIMAE), Departamento de Química Inorgánica, Analítica y Química Física, Facultad de Ciencias Exactas y Naturales, Universidad de Buenos Aires and CONICET ,1428 Buenos Aires, Argentina
| | - Ulises A Zitare
- Instituto de Química Física de los Materiales, Medio Ambiente y Energía (INQUIMAE), Departamento de Química Inorgánica, Analítica y Química Física, Facultad de Ciencias Exactas y Naturales, Universidad de Buenos Aires and CONICET ,1428 Buenos Aires, Argentina
| | - Jonathan Szuster
- Instituto de Química Física de los Materiales, Medio Ambiente y Energía (INQUIMAE), Departamento de Química Inorgánica, Analítica y Química Física, Facultad de Ciencias Exactas y Naturales, Universidad de Buenos Aires and CONICET ,1428 Buenos Aires, Argentina
| | - Marcos N Morgada
- Instituto de Biología Molecular y Celular de Rosario (IBR), Departamento de Química Biológica, Facultad de Ciencias Bioquímicas y Farmacéuticas, Universidad Nacional de Rosario and CONICET , 2000 Rosario, Argentina
| | - Alcides J Leguto
- Instituto de Biología Molecular y Celular de Rosario (IBR), Departamento de Química Biológica, Facultad de Ciencias Bioquímicas y Farmacéuticas, Universidad Nacional de Rosario and CONICET , 2000 Rosario, Argentina
| | - Alejandro J Vila
- Instituto de Biología Molecular y Celular de Rosario (IBR), Departamento de Química Biológica, Facultad de Ciencias Bioquímicas y Farmacéuticas, Universidad Nacional de Rosario and CONICET , 2000 Rosario, Argentina
| | - Daniel H Murgida
- Instituto de Química Física de los Materiales, Medio Ambiente y Energía (INQUIMAE), Departamento de Química Inorgánica, Analítica y Química Física, Facultad de Ciencias Exactas y Naturales, Universidad de Buenos Aires and CONICET ,1428 Buenos Aires, Argentina
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Zitare U, Alvarez-Paggi D, Morgada MN, Abriata LA, Vila AJ, Murgida DH. Reversible Switching of Redox-Active Molecular Orbitals and Electron Transfer Pathways in CuASites of Cytochrome cOxidase. Angew Chem Int Ed Engl 2015. [DOI: 10.1002/ange.201504188] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
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15
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Zitare U, Alvarez-Paggi D, Morgada MN, Abriata LA, Vila AJ, Murgida DH. Reversible Switching of Redox-Active Molecular Orbitals and Electron Transfer Pathways in Cu(A) Sites of Cytochrome c Oxidase. Angew Chem Int Ed Engl 2015; 54:9555-9. [PMID: 26118421 DOI: 10.1002/anie.201504188] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/07/2015] [Indexed: 11/06/2022]
Abstract
The Cu(A) site of cytochrome c oxidase is a redox hub that participates in rapid electron transfer at low driving forces with two redox cofactors in nearly perpendicular orientations. Spectroscopic and electrochemical characterizations performed on first and second-sphere mutants have allowed us to experimentally detect the reversible switching between two alternative electronic states that confer different directionalities to the redox reaction. Specifically, the M160H variant of a native Cu(A) shows a reversible pH transition that allows to functionally probe both states in the same protein species. Alternation between states exerts a dramatic impact on the kinetic redox parameters, thereby suggesting this effect as the mechanism underlying the efficiency and directionality of Cu(A) electron transfer in vivo. These findings may also prove useful for the development of molecular electronics.
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Affiliation(s)
- Ulises Zitare
- Instituto de Química Física de los Materiales, Medio Ambiente y Energía, Departamento de Química Inorgánica, Analítica y Química Física, Facultad de Ciencias Exactas y Naturales, Universidad de Buenos Aires and CONICET (Argentina)
| | - Damián Alvarez-Paggi
- Instituto de Química Física de los Materiales, Medio Ambiente y Energía, Departamento de Química Inorgánica, Analítica y Química Física, Facultad de Ciencias Exactas y Naturales, Universidad de Buenos Aires and CONICET (Argentina)
| | - Marcos N Morgada
- Instituto de Biología Molecular y Celular de Rosario (IBR), Departamento de Química Biológica, Facultad de Ciencias Bioquímicas y Farmacéuticas, Universidad Nacional de Rosario and CONICET (Argentina)
| | - Luciano A Abriata
- Instituto de Biología Molecular y Celular de Rosario (IBR), Departamento de Química Biológica, Facultad de Ciencias Bioquímicas y Farmacéuticas, Universidad Nacional de Rosario and CONICET (Argentina)
| | - Alejandro J Vila
- Instituto de Biología Molecular y Celular de Rosario (IBR), Departamento de Química Biológica, Facultad de Ciencias Bioquímicas y Farmacéuticas, Universidad Nacional de Rosario and CONICET (Argentina)
| | - Daniel H Murgida
- Instituto de Química Física de los Materiales, Medio Ambiente y Energía, Departamento de Química Inorgánica, Analítica y Química Física, Facultad de Ciencias Exactas y Naturales, Universidad de Buenos Aires and CONICET (Argentina).
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16
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Felli IC, Pierattelli R. Spin-state-selective methods in solution- and solid-state biomolecular 13C NMR. PROGRESS IN NUCLEAR MAGNETIC RESONANCE SPECTROSCOPY 2015; 84-85:1-13. [PMID: 25669738 DOI: 10.1016/j.pnmrs.2014.10.001] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/14/2014] [Accepted: 10/26/2014] [Indexed: 06/04/2023]
Abstract
Spin-state-selective methods to achieve homonuclear decoupling in the direct acquisition dimension of (13)C detected NMR experiments have been one of the key contributors to converting (13)C detected NMR experiments into really useful tools for studying biomolecules. We discuss here in detail the various methods that have been proposed, summarize the large array of new experiments that have been developed and present applications to different kinds of proteins in different aggregation states.
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Affiliation(s)
- Isabella C Felli
- Magnetic Resonance Center (CERM) and Department of Chemistry "Ugo Schiff", University of Florence, Via L. Sacconi 6, 50019 Sesto Fiorentino, Italy.
| | - Roberta Pierattelli
- Magnetic Resonance Center (CERM) and Department of Chemistry "Ugo Schiff", University of Florence, Via L. Sacconi 6, 50019 Sesto Fiorentino, Italy.
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17
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Morgada MN, Abriata LA, Zitare U, Alvarez-Paggi D, Murgida DH, Vila AJ. Control of the Electronic Ground State on an Electron-Transfer Copper Site by Second-Sphere Perturbations. Angew Chem Int Ed Engl 2014; 53:6188-92. [DOI: 10.1002/anie.201402083] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/04/2014] [Revised: 02/24/2014] [Indexed: 01/07/2023]
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18
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Morgada MN, Abriata LA, Zitare U, Alvarez-Paggi D, Murgida DH, Vila AJ. Control of the Electronic Ground State on an Electron-Transfer Copper Site by Second-Sphere Perturbations. Angew Chem Int Ed Engl 2014. [DOI: 10.1002/ange.201402083] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/09/2023]
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19
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Alvarez-Paggi D, Zitare U, Murgida DH. The role of protein dynamics and thermal fluctuations in regulating cytochrome c/cytochrome c oxidase electron transfer. BIOCHIMICA ET BIOPHYSICA ACTA-BIOENERGETICS 2014; 1837:1196-207. [PMID: 24502917 DOI: 10.1016/j.bbabio.2014.01.019] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/22/2013] [Revised: 01/22/2014] [Accepted: 01/28/2014] [Indexed: 01/06/2023]
Abstract
In this overview we present recent combined electrochemical, spectroelectrochemical, spectroscopic and computational studies from our group on the electron transfer reactions of cytochrome c and of the primary electron acceptor of cytochrome c oxidase, the CuA site, in biomimetic complexes. Based on these results, we discuss how protein dynamics and thermal fluctuations may impact on protein ET reactions, comment on the possible physiological relevance of these results, and finally propose a regulatory mechanism that may operate in the Cyt/CcO electron transfer reaction in vivo. This article is part of a Special Issue entitled: 18th European Bioenergetic Conference.
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Affiliation(s)
- Damian Alvarez-Paggi
- INQUIMAE-CONICET, Departamento de Química Inorgánica, Analítica y Química Física, Facultad de Ciencias Exactas y Naturales, Universidad de Buenos Aires, Ciudad Universitaria, pab. 2, piso 3, C1428EHA Buenos Aires, Argentina
| | - Ulises Zitare
- INQUIMAE-CONICET, Departamento de Química Inorgánica, Analítica y Química Física, Facultad de Ciencias Exactas y Naturales, Universidad de Buenos Aires, Ciudad Universitaria, pab. 2, piso 3, C1428EHA Buenos Aires, Argentina
| | - Daniel H Murgida
- INQUIMAE-CONICET, Departamento de Química Inorgánica, Analítica y Química Física, Facultad de Ciencias Exactas y Naturales, Universidad de Buenos Aires, Ciudad Universitaria, pab. 2, piso 3, C1428EHA Buenos Aires, Argentina.
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20
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Ciofi-Baffoni S, Gallo A, Muzzioli R, Piccioli M. The IR-¹⁵N-HSQC-AP experiment: a new tool for NMR spectroscopy of paramagnetic molecules. JOURNAL OF BIOMOLECULAR NMR 2014; 58:123-8. [PMID: 24414179 DOI: 10.1007/s10858-013-9810-2] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/29/2013] [Accepted: 12/27/2013] [Indexed: 05/22/2023]
Abstract
A crucial factor for the understanding of structure-function relationships in metalloproteins is the identification of NMR signals from residues surrounding the metal cofactor. When the latter is paramagnetic, the NMR information in the proximity of the metal center may be scarce, because fast nuclear relaxation quenches signal intensity and coherence transfer efficiency. To identify residues at a short distance from a paramagnetic center, we developed a modified version of the ¹⁵N-HSQC experiment where (1) an inversion recovery filter is added prior to HSQC, (2) the INEPT period has been optimized according to fast relaxation of interested spins, (3) the inverse INEPT has been eliminated and signals acquired as antiphase doublets. The experiment has been successfully tested on a human [Fe₂S₂] protein which is involved in the biogenesis of iron-sulfur proteins. Thirteen HN resonances, unobserved with conventional HSQC experiments, could be identified. The structural arrangement of the protein scaffold in the proximity of the Fe/S cluster is fundamental to comprehend the molecular processes responsible for the transfer of Fe/S groups in the iron-sulfur protein assembly machineries.
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Affiliation(s)
- Simone Ciofi-Baffoni
- Magnetic Resonance Center and Department of Chemistry, University of Florence, Via Luigi Sacconi 6, 50019, Sesto Fiorentino, Florence, Italy
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21
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Abriata LA, Vila AJ, Dal Peraro M. Molecular dynamics simulations of apocupredoxins: insights into the formation and stabilization of copper sites under entatic control. J Biol Inorg Chem 2014; 19:565-75. [PMID: 24477946 DOI: 10.1007/s00775-014-1108-7] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/15/2013] [Accepted: 12/30/2013] [Indexed: 10/25/2022]
Abstract
Cupredoxins perform copper-mediated long-range electron transfer (ET) in biological systems. Their copper-binding sites have evolved to force copper ions into ET-competent systems with decreased reorganization energy, increased reduction potential, and a distinct electronic structure compared with those of non-ET-competent copper complexes. The entatic or rack-induced state hypothesis explains these special properties in terms of the strain that the protein matrix exerts on the metal ions. This idea is supported by X-ray structures of apocupredoxins displaying "closed" arrangements of the copper ligands like those observed in the holoproteins; however, it implies completely buried copper-binding atoms, conflicting with the notion that they must be exposed for copper loading. On the other hand, a recent work based on NMR showed that the copper-binding regions of apocupredoxins are flexible in solution. We have explored five cupredoxins in their "closed" apo forms through molecular dynamics simulations. We observed that prearranged ligand conformations are not stable as the X-ray data suggest, although they do form part of the dynamic landscape of the apoproteins. This translates into variable flexibility of the copper-binding regions within a rigid fold, accompanied by fluctuations of the hydrogen bonds around the copper ligands. Major conformations with solvent-exposed copper-binding atoms could allow initial binding of the copper ions. An eventual subsequent incursion to the closed state would result in binding of the remaining ligands, trapping the closed conformation thanks to the additional binding energy and the fastening of noncovalent interactions that make up the rack.
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Affiliation(s)
- Luciano A Abriata
- Laboratory of Biomolecular Modeling, School of Life Sciences, École Polytechnique Fédérale de Lausanne, Lausanne, Switzerland,
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22
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Alvarez-Paggi D, Abriata LA, Murgida DH, Vila AJ. Native Cu(A) redox sites are largely resilient to pH variations within a physiological range. Chem Commun (Camb) 2013; 49:5381-3. [PMID: 23652317 DOI: 10.1039/c3cc40457a] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Previous studies on engineered CuA centres have shown that one of the histidine ligands is protonated and dissociated from the metal site at physiological pH values, thus suggesting a role in regulating proton-coupled electron transfer of cytochrome c oxidases in vivo. Here we report that for native CuA such protonation does not take place at physiologically relevant pH values and, furthermore, no significant changes in the spectroscopic and redox properties of the metal site occur at low pH.
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Affiliation(s)
- Damián Alvarez-Paggi
- INQUIMAE-CONICET and Departamento de Química Inorgánica, Analítica y Química Física, Facultad de Ciencias Exactas y Naturales, Universidad de Buenos Aires, Ciudad Universitaria Pab. 2, C1428EHA Buenos Aires, Argentina
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23
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Reger DL, Pascui AE, Pellechia PJ, Ozarowski A. NMR Investigations of Dinuclear, Single-Anion Bridged Copper(II) Metallacycles: Structure and Antiferromagnetic Behavior in Solution. Inorg Chem 2013; 52:12741-8. [DOI: 10.1021/ic402016m] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/02/2023]
Affiliation(s)
- Daniel L. Reger
- Department of Chemistry and Biochemistry, University of South Carolina, Columbia, South Carolina 29208, United States
| | - Andrea E. Pascui
- Department of Chemistry and Biochemistry, University of South Carolina, Columbia, South Carolina 29208, United States
| | - Perry J. Pellechia
- Department of Chemistry and Biochemistry, University of South Carolina, Columbia, South Carolina 29208, United States
| | - Andrew Ozarowski
- National
High Magnetic Field Laboratory, Florida State University, Tallahassee, Florida 32310, United States
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24
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Abriata LA, Vila AJ. Redox-state sensing by hydrogen bonds in the CuA center of cytochrome c oxidase. J Inorg Biochem 2013; 132:18-20. [PMID: 24012017 DOI: 10.1016/j.jinorgbio.2013.07.032] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/23/2013] [Revised: 07/18/2013] [Accepted: 07/23/2013] [Indexed: 11/25/2022]
Abstract
Cytochrome c oxidases (CcO) couple electron transfer to active proton translocation through a gated mechanism that minimizes energy losses by preventing protons from flowing backwards or leaking. Such a complex mechanism requires that information about the redox and protonation states of the different centers be transmitted between different parts of the oxidase. Here we report a network of residues located around the electron entry point of CcO, the CuA site in subunit II, that experience collective pH equilibria around neutral pH. This network starts at the occluded side of the CuA site and extends to the interface between subunits I and II of the CcO, where the proton exit is located and through which electrons flow into subunit I. One of the residues in this network is directly involved in a hydrogen bond to one of the CuA ligands, whose strength is highly sensitive to the redox state of the metal center. We propose that this interaction mediates the transmission of redox changes from ET centers to other functional regions of the oxidase, and possibly also in other similar machineries, as part of their gating and regulatory mechanisms.
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Affiliation(s)
- Luciano A Abriata
- Instituto de Biología Molecular y Celular de Rosario (IBR, CONICET-UNR) and Área Biofísica, Facultad de Ciencias Bioquímicas y Farmacéuticas, Universidad Nacional de Rosario, Rosario, Argentina
| | - Alejandro J Vila
- Instituto de Biología Molecular y Celular de Rosario (IBR, CONICET-UNR) and Área Biofísica, Facultad de Ciencias Bioquímicas y Farmacéuticas, Universidad Nacional de Rosario, Rosario, Argentina.
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25
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Cacciatore S, Piccioli M, Turano P. Electron self-exchange of cytochrome c measured via13C detected protonless NMR. J PORPHYR PHTHALOCYA 2013. [DOI: 10.1142/s1088424612501404] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
Abstract
The use of protonless 13C′–13C′ EXSY (COCO-EXSY) is proposed here to measure electron self-exchange rates. The experiment is compared to the commonly employed 1H and 15N EXSY experiments using as a reference system human cytochrome c. In COCO-EXSY, the exchange peaks are stronger than in the other experiments with respect to the self peaks and their intensity is less dependent on the choice of the EXSY mixing time. The use of 13C directed detection may be essential for all those cases where T2 relaxation is detrimental, as in the case of proteins containing highly paramagnetic metal centers, or rotating slowly in solution, or where the amide signals are difficult to detect due to chemical or conformational exchange. The proposed experiment has a general applicability and can be used to monitor exchange phenomena different from electron self-exchange.
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Affiliation(s)
- Stefano Cacciatore
- Magnetic Resonance Center (CERM) and Department of Chemistry, University of Florence, Via L. Sacconi 6, Sesto, Fiorentino 50019, Italy
| | - Mario Piccioli
- Magnetic Resonance Center (CERM) and Department of Chemistry, University of Florence, Via L. Sacconi 6, Sesto, Fiorentino 50019, Italy
| | - Paola Turano
- Magnetic Resonance Center (CERM) and Department of Chemistry, University of Florence, Via L. Sacconi 6, Sesto, Fiorentino 50019, Italy
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26
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Abriata LA, Zaballa ME, Berry RE, Yang F, Zhang H, Walker FA, Vila AJ. Electron spin density on the axial His ligand of high-spin and low-spin nitrophorin 2 probed by heteronuclear NMR spectroscopy. Inorg Chem 2013; 52:1285-95. [PMID: 23327568 PMCID: PMC3594510 DOI: 10.1021/ic301805y] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
The electronic structure of heme proteins is exquisitely tuned by the interaction of the iron center with the axial ligands. NMR studies of paramagnetic heme systems have been focused on the heme signals, but signals from the axial ligands have been rather difficult to detect and assign. We report an extensive assignment of the (1)H, (13)C and (15)N resonances of the axial His ligand in the NO-carrying protein nitrophorin 2 (NP2) in the paramagnetic high-spin and low-spin forms, as well as in the diamagnetic NO complex. We find that the high-spin protein has σ spin delocalization to all atoms in the axial His57, which decreases in size as the number of bonds between Fe(III) and the atom in question increases, except that within the His57 imidazole ring the contact shifts are a balance between positive σ and negative π contributions. In contrast, the low-spin protein has π spin delocalization to all atoms of the imidazole ring. Our strategy, adequately combined with a selective residue labeling scheme, represents a straightforward characterization of the electron spin density in heme axial ligands.
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Affiliation(s)
- Luciano A Abriata
- Instituto de Biología Molecular y Celular de Rosario (IBR-CONICET), Facultad de Ciencias Bioquímicas y Farmacéuticas, Universidad Nacional de Rosario, Ocampo y Esmeralda, Predio CONICET Rosario, Rosario 2000, Santa Fe, Argentina
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27
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Alternative ground states enable pathway switching in biological electron transfer. Proc Natl Acad Sci U S A 2012; 109:17348-53. [PMID: 23054836 DOI: 10.1073/pnas.1204251109] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Electron transfer is the simplest chemical reaction and constitutes the basis of a large variety of biological processes, such as photosynthesis and cellular respiration. Nature has evolved specific proteins and cofactors for these functions. The mechanisms optimizing biological electron transfer have been matter of intense debate, such as the role of the protein milieu between donor and acceptor sites. Here we propose a mechanism regulating long-range electron transfer in proteins. Specifically, we report a spectroscopic, electrochemical, and theoretical study on WT and single-mutant Cu(A) redox centers from Thermus thermophilus, which shows that thermal fluctuations may populate two alternative ground-state electronic wave functions optimized for electron entry and exit, respectively, through two different and nearly perpendicular pathways. These findings suggest a unique role for alternative or "invisible" electronic ground states in directional electron transfer. Moreover, it is shown that this energy gap and, therefore, the equilibrium between ground states can be fine-tuned by minor perturbations, suggesting alternative ways through which protein-protein interactions and membrane potential may optimize and regulate electron-proton energy transduction.
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28
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Abriata LA. Analysis of copper-ligand bond lengths in X-ray structures of different types of copper sites in proteins. ACTA CRYSTALLOGRAPHICA SECTION D: BIOLOGICAL CRYSTALLOGRAPHY 2012; 68:1223-31. [PMID: 22948924 DOI: 10.1107/s0907444912026054] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/27/2012] [Accepted: 06/08/2012] [Indexed: 11/10/2022]
Abstract
An updated picture of the ligand sets and copper-ligand atom bond lengths in proteins is presented which takes advantage of (i) the approximately twofold increase in the number of entries for copper-containing proteins in the PDB since the last study of this kind, especially benefiting from the recent incorporation of the structures of proteins involved in copper homeostasis, and (ii) a preliminary classification of copper sites based on their structural, electronic and functional features. This classification allowed the calculation of reliable target copper-ligand distances for several bonds that were not available in previous work and that are in good agreement with EXAFS data and the known chemistry of these sites. The analysis presented here further disclosed an artifactual dependence of the average of the reported Cu-NHis bond lengths on structure resolution, highlighting the importance of taking this into account when computing target distances even from high-resolution structures. Finally, a relationship between the two Cu-O distances in bidentate carboxylates is disclosed, similar to that reported previously for other metal ions.
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Affiliation(s)
- Luciano A Abriata
- Instituto de Biología Molecular y Celular de Rosario (IBR-CONICET), Facultad de Ciencias Bioquímicas y Farmacéuticas, Universidad Nacional de Rosario, Rosario, Argentina.
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29
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Chiarella GM, Melgarejo DY, Fackler JP. Synthesis, Characterization and Properties of a Novel Cationic Hexanuclear Cyclic Guanidinate Copper(I) Cluster of High Solubility in Non-polar Solvents. J CLUST SCI 2012. [DOI: 10.1007/s10876-012-0498-3] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/28/2022]
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30
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Wilson TD, Savelieff MG, Nilges MJ, Marshall NM, Lu Y. Kinetics of Copper Incorporation into a Biosynthetic Purple CuA Azurin: Characterization of Red, Blue, and a New Intermediate Species. J Am Chem Soc 2011; 133:20778-92. [DOI: 10.1021/ja205281t] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/23/2023]
Affiliation(s)
- Tiffany D. Wilson
- Department of Chemistry, University of Illinois at Urbana—Champaign, 600 South Mathews Avenue, Urbana, Illinois 61801, United States
| | - Masha G. Savelieff
- Department of Chemistry, University of Illinois at Urbana—Champaign, 600 South Mathews Avenue, Urbana, Illinois 61801, United States
| | - Mark J. Nilges
- Department of Chemistry, University of Illinois at Urbana—Champaign, 600 South Mathews Avenue, Urbana, Illinois 61801, United States
| | - Nicholas M. Marshall
- Department of Chemistry, University of Illinois at Urbana—Champaign, 600 South Mathews Avenue, Urbana, Illinois 61801, United States
| | - Yi Lu
- Department of Chemistry, University of Illinois at Urbana—Champaign, 600 South Mathews Avenue, Urbana, Illinois 61801, United States
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A theoretical investigation of the functional role of the axial methionine ligand of the Cu(A) site in cytochrome c oxidase. BIOCHIMICA ET BIOPHYSICA ACTA-BIOENERGETICS 2011; 1807:1314-27. [PMID: 21745457 DOI: 10.1016/j.bbabio.2011.06.014] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/07/2011] [Revised: 05/29/2011] [Accepted: 06/22/2011] [Indexed: 11/20/2022]
Abstract
The functional roles of the amino acid residues of the Cu(A) site in bovine cytochrome c oxidase (CcO) were investigated by utilizing hybrid quantum mechanics (QM)/molecular mechanics (MM) calculations. The energy levels of the molecular orbitals (MOs) involving Cu d(zx) orbitals unexpectedly increased, as compared with those found previously with a simplified model system lacking the axial Met residue (i.e., Cu(2)S(2)N(2)). This elevation of MO energies stemmed from the formation of the anti-bonding orbitals, which are generated by hybridization between the d(zx) orbitals of Cu ions and the p-orbitals of the S and O atoms of the axial ligands. To clarify the roles of the axial Met ligand, the inner-sphere reorganization energies of the Cu(A) site were computed, with the Met residue assigned to either the QM or MM region. The reorganization energy slightly increased when the Met residue was excluded from the QM region. The existing experimental data and the present structural modeling study also suggested that the axial Met residue moderately increased the redox potential of the Cu(A) site. Thus, the role of the Met may be to regulate the electron transfer rate through the fine modulation of the electronic structure of the Cu(A) "platform", created by two Cys/His residues coordinated to the Cu ions. This regulation would provide the optimum redox potential/reorganization energy of the Cu(A) site, and thereby facilitate the subsequent cooperative reactions, such as the proton pump and the enzymatic activity, of CcO. This article is part of a Special Issue entitled: Allosteric cooperativity in respiratory proteins.
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32
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Zaballa ME, Ziegler L, Kosman DJ, Vila AJ. NMR study of the exchange coupling in the trinuclear cluster of the multicopper oxidase Fet3p. J Am Chem Soc 2010; 132:11191-6. [PMID: 20698686 DOI: 10.1021/ja1037148] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022]
Abstract
Fet3p from Saccharomyces cerevisiae is a multicopper oxidase (MCO) which oxidizes Fe(2+) to Fe(3+). The electronic structure of the different copper centers in this family of enzymes has been extensively studied and discussed for years with a particular focus on the exchange coupling regime in the trinuclear cluster (TNC). Using NMR spectroscopy we have quantified the exchange coupling constant in the type 3 center in a fully metalated oxidase; this value in Fet3p is significantly higher than that reported for proteins containing isolated type 3 centers as tyrosinase. We also provide evidence of exchange coupling between the type 2 and the type 3 Cu(2+) ions, which supports the crystallographic evidence of dioxygen binding to the TNC. This work provides the foundation for the application of NMR to these complex systems.
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Affiliation(s)
- María-Eugenia Zaballa
- IBR (Instituto de Biología Molecular y Celular de Rosario), CONICET, Facultad de Ciencias Bioquímicas y Farmacéuticas, Universidad Nacional de Rosario, Suipacha 531, (S2002LRK), Rosario, Argentina
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Clark KM, Yu Y, Marshall NM, Sieracki NA, Nilges MJ, Blackburn NJ, van der Donk WA, Lu Y. Transforming a blue copper into a red copper protein: engineering cysteine and homocysteine into the axial position of azurin using site-directed mutagenesis and expressed protein ligation. J Am Chem Soc 2010; 132:10093-101. [PMID: 20608676 DOI: 10.1021/ja102632p] [Citation(s) in RCA: 53] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/08/2023]
Abstract
Interactions of the axial ligand with its blue copper center are known to be important in tuning spectroscopic and redox properties of cupredoxins. While conversion of the blue copper center with a weak axial ligand to a green copper center containing a medium strength axial ligand has been demonstrated in cupredoxins, converting the blue copper center to a red copper center with a strong axial ligand has not been reported. Here we show that replacing Met121 in azurin from Pseudomonas aeruginosa with Cys caused an increased ratio (R(L)) of absorption at 447 nm over that at 621 nm. Whereas no axial Cu-S(Cys121) interaction in Met121Cys was detectable by extended X-ray absorption fine structure (EXAFS) spectroscopy at pH 5, similar to what was observed in native azurin with Met121 as the axial ligand, the Cu-S(Cys121) interaction at 2.74 A is clearly visible at higher pH. Despite the higher R(L) and stronger axial Cys121 interaction with Cu(II) ion, the Met121Cys variant remains largely a type 1 copper protein at low pH (with hyperfine coupling constant A( parallel) = 54 x 10(-4) cm(-1) at pH 4 and 5), or distorted type 1 or green copper protein at high pH (A(parallel) = 87 x 10(-4) cm(-1) at pH 8 and 9), attributable to the relatively long distance between the axial ligand and copper and the constraint placed by the protein scaffold. To shorten the distance between axial ligand and copper, we replaced Met121 with a nonproteinogenic amino acid homocysteine that contains an extra methylene group, resulting in a variant whose spectra (R(L)= 1.5, and A(parallel) = 180 x 10(-4) cm(-1)) and Cu-S(Cys) distance (2.22 A) are very similar to those of the red copper protein nitrosocyanin. Replacing Met121 with Cys or homocysteine resulted in lowering of the reduction potential from 222 mV in the native azurin to 95 +/- 3 mV for Met121Cys azurin and 113 +/- 6 mV for Met121Hcy azurin at pH 7. The results strongly support the "coupled distortion" model that helps explain axial ligand tuning of spectroscopic properties in cupredoxins, and demonstrate the power of using unnatural amino acids to address critical chemical biological questions.
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Affiliation(s)
- Kevin M Clark
- Department of Biochemistry, University of Illinois at Urbana-Champaign, 600 South Mathews Avenue, Urbana, Illinois 61801, USA
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Chiarella GM, Melgarejo DY, Prosvirin AV, Dunbar KR, Fackler JP. Tetranuclear, Oxygen Centered Copper(II) Clusters Linked Together with Guanidine-Guanidinate Ligands. J CLUST SCI 2010. [DOI: 10.1007/s10876-010-0342-6] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
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Savelieff MG, Lu Y. CuA centers and their biosynthetic models in azurin. J Biol Inorg Chem 2010; 15:461-83. [DOI: 10.1007/s00775-010-0625-2] [Citation(s) in RCA: 40] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/03/2009] [Accepted: 01/20/2010] [Indexed: 11/28/2022]
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Bermel W, Bertini I, Felli IC, Pierattelli R. Speeding up (13)C direct detection biomolecular NMR spectroscopy. J Am Chem Soc 2010; 131:15339-45. [PMID: 19795864 DOI: 10.1021/ja9058525] [Citation(s) in RCA: 71] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
After the exploitation of (1)H polarization as a starting source for (13)C direct detection experiments, pulse sequences are designed which exploit the accelerated (1)H longitudinal relaxation to expedite (13)C direct detection experiments. We show here that 2D experiments based on (13)C direct detection on a 0.5 mM water sample of ubiquitin can be recorded in a few minutes and 3D experiments in a few hours. We also show that fast methods like nonuniform sampling can be easily implemented. As overall experimental time has always been a counter indication for the use of (13)C direct detection experiments, this research opens new avenues for the application of (13)C NMR to biological molecules.
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Affiliation(s)
- Wolfgang Bermel
- Bruker BioSpin GmbH, Silberstreifen, 76287 Rheinstetten, Germany
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Bermel W, Bertini I, Felli IC, Peruzzini R, Pierattelli R. Exclusively Heteronuclear NMR Experiments to Obtain Structural and Dynamic Information on Proteins. Chemphyschem 2010; 11:689-95. [DOI: 10.1002/cphc.200900772] [Citation(s) in RCA: 33] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
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