1
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Bhadra M, Albert T, Franke A, Josef V, Ivanović-Burmazović I, Swart M, Moënne-Loccoz P, Karlin KD. Reductive Coupling of Nitric Oxide by Cu(I): Stepwise Formation of Mono- and Dinitrosyl Species En Route to a Cupric Hyponitrite Intermediate. J Am Chem Soc 2023; 145:2230-2242. [PMID: 36652374 PMCID: PMC10122266 DOI: 10.1021/jacs.2c09874] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/19/2023]
Abstract
Transition-metal-mediated reductive coupling of nitric oxide (NO(g)) to nitrous oxide (N2O(g)) has significance across the fields of industrial chemistry, biochemistry, medicine, and environmental health. Herein, we elucidate a density functional theory (DFT)-supplemented mechanism of NO(g) reductive coupling at a copper-ion center, [(tmpa)CuI(MeCN)]+ (1) {tmpa = tris(2-pyridylmethyl)amine}. At -110 °C in EtOH (<-90 °C in MeOH), exposing 1 to NO(g) leads to a new binuclear hyponitrite intermediate [{(tmpa)CuII}2(μ-N2O22-)]2+ (2), exhibiting temperature-dependent irreversible isomerization to the previously characterized κ2-O,O'-trans-[(tmpa)2Cu2II(μ-N2O22-)]2+ (OOXray) complex. Complementary stopped-flow kinetic analysis of the reaction in MeOH reveals an initial mononitrosyl species [(tmpa)Cu(NO)]+ (1-(NO)) that binds a second NO molecule, forming a dinitrosyl species [(tmpa)CuII(NO)2] (1-(NO)2). The decay of 1-(NO)2 requires an available starting complex 1 to form a dicopper-dinitrosyl species hypothesized to be [{(tmpa)Cu}2(μ-NO)2]2+ (D) bearing a diamond-core motif, en route to the formation of hyponitrite intermediate 2. In contrast, exposing 1 to NO(g) in 2-MeTHF/THF (v/v 4:1) at <-80 °C leads to the newly observed transient metastable dinitrosyl species [(tmpa)CuII(NO)2] (1-(NO)2) prior to its disproportionation-mediated transformation to the nitrite product [(tmpa)CuII(NO2)]+. Our study furnishes a near-complete profile of NO(g) activation at a reduced Cu site with tripodal tetradentate ligation in two distinctly different solvents, aided by detailed spectroscopic characterization of metastable intermediates, including resonance Raman characterization of the new dinitrosyl and hyponitrite species detected.
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Affiliation(s)
- Mayukh Bhadra
- Department of Chemistry, The Johns Hopkins University, Baltimore, Maryland 21218, United States
| | - Therese Albert
- Department of Chemical Physiology and Biochemistry, Oregon Health & Science University, Portland, Oregon 97239, United States
| | - Alicja Franke
- Department of Chemistry and Pharmacy, Friedrich-Alexander University Erlangen-Nuremberg, 91058 Erlangen, Germany
- Department of Chemistry, Ludwig-Maximilians University, Munich, 81377 Munich, Germany
| | - Verena Josef
- Department of Chemistry and Pharmacy, Friedrich-Alexander University Erlangen-Nuremberg, 91058 Erlangen, Germany
| | - Ivana Ivanović-Burmazović
- Department of Chemistry and Pharmacy, Friedrich-Alexander University Erlangen-Nuremberg, 91058 Erlangen, Germany
- Department of Chemistry, Ludwig-Maximilians University, Munich, 81377 Munich, Germany
| | - Marcel Swart
- IQCC & Departament de Química, Universitat de Girona, Campus Montilivi (Ciencies), 17003 Girona, Spain
- ICREA, Pg. Lluís Companys 23, 08010 Barcelona, Spain
| | - Pierre Moënne-Loccoz
- Department of Chemical Physiology and Biochemistry, Oregon Health & Science University, Portland, Oregon 97239, United States
| | - Kenneth D Karlin
- Department of Chemistry, The Johns Hopkins University, Baltimore, Maryland 21218, United States
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2
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Albert T, Moënne-Loccoz P. Spectroscopic Characterization of a Diferric Mycobacterial Hemerythrin-Like Protein with Unprecedented Reactivity toward Nitric Oxide. J Am Chem Soc 2022; 144:17611-17621. [PMID: 36099449 DOI: 10.1021/jacs.2c07113] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Hemerythrin-like proteins (HLPs) are broadly distributed across taxonomic groups and appear to play highly diverse functional roles in prokaryotes. Mycobacterial HLPs contribute to the survival of these pathogenic bacteria in mammalian macrophages, but their modes of action remain unclear. A recent crystallographic characterization of Mycobacterium kansasii HLP (Mka-HLP) revealed the unexpected presence of a tyrosine sidechain (Tyr54) near the coordination sphere of one of the two iron centers. Here, we show that Tyr54 is a true ligand to the Fe2(III) ion which, in conjunction with the presence of a μ-oxo group bridging the two iron(III), brings unique reactivity toward nitric oxide (NO). Monitoring the titration of Mka-HLP with NO by Fourier-transform infrared and electron paramagnetic resonance spectroscopies shows that both diferric and diferrous forms of Mka-HLP accumulate an uncoupled high-spin and low-spin {FeNO}7 pair. We assign the reactivity of the diferric protein to an initial radical reaction between NO and the μ-oxo bridge to form nitrite and a mixed-valent diiron center that can react further with NO. Amperometric measurements of NO consumption by Mka-HLP confirm that this reactivity can proceed at low micromolar concentrations of NO, before additional NO consumption, supporting a NO scavenging role for mycobacterial HLPs.
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Affiliation(s)
- Therese Albert
- Department of Chemical Physiology and Biochemistry, School of Medicine, Oregon Health & Science University, 3181 SW Sam Jackson Park Road, Portland, Oregon 97239, United States
| | - Pierre Moënne-Loccoz
- Department of Chemical Physiology and Biochemistry, School of Medicine, Oregon Health & Science University, 3181 SW Sam Jackson Park Road, Portland, Oregon 97239, United States
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3
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Matsumura H, Faponle AS, Hagedoorn PL, Tosha T, de Visser SP, Moënne-Loccoz P. Mechanism of substrate inhibition in cytochrome-c dependent NO reductases from denitrifying bacteria (cNORs). J Inorg Biochem 2022; 231:111781. [DOI: 10.1016/j.jinorgbio.2022.111781] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/28/2021] [Revised: 02/21/2022] [Accepted: 02/24/2022] [Indexed: 12/24/2022]
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4
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Lehnert N, Kim E, Dong HT, Harland JB, Hunt AP, Manickas EC, Oakley KM, Pham J, Reed GC, Alfaro VS. The Biologically Relevant Coordination Chemistry of Iron and Nitric Oxide: Electronic Structure and Reactivity. Chem Rev 2021; 121:14682-14905. [PMID: 34902255 DOI: 10.1021/acs.chemrev.1c00253] [Citation(s) in RCA: 92] [Impact Index Per Article: 30.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/14/2023]
Abstract
Nitric oxide (NO) is an important signaling molecule that is involved in a wide range of physiological and pathological events in biology. Metal coordination chemistry, especially with iron, is at the heart of many biological transformations involving NO. A series of heme proteins, nitric oxide synthases (NOS), soluble guanylate cyclase (sGC), and nitrophorins, are responsible for the biosynthesis, sensing, and transport of NO. Alternatively, NO can be generated from nitrite by heme- and copper-containing nitrite reductases (NIRs). The NO-bearing small molecules such as nitrosothiols and dinitrosyl iron complexes (DNICs) can serve as an alternative vehicle for NO storage and transport. Once NO is formed, the rich reaction chemistry of NO leads to a wide variety of biological activities including reduction of NO by heme or non-heme iron-containing NO reductases and protein post-translational modifications by DNICs. Much of our understanding of the reactivity of metal sites in biology with NO and the mechanisms of these transformations has come from the elucidation of the geometric and electronic structures and chemical reactivity of synthetic model systems, in synergy with biochemical and biophysical studies on the relevant proteins themselves. This review focuses on recent advancements from studies on proteins and model complexes that not only have improved our understanding of the biological roles of NO but also have provided foundations for biomedical research and for bio-inspired catalyst design in energy science.
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Affiliation(s)
- Nicolai Lehnert
- Department of Chemistry and Department of Biophysics, University of Michigan, Ann Arbor, Michigan 48109-1055, United States
| | - Eunsuk Kim
- Department of Chemistry, Brown University, Providence, Rhode Island 02912, United States
| | - Hai T Dong
- Department of Chemistry and Department of Biophysics, University of Michigan, Ann Arbor, Michigan 48109-1055, United States
| | - Jill B Harland
- Department of Chemistry and Department of Biophysics, University of Michigan, Ann Arbor, Michigan 48109-1055, United States
| | - Andrew P Hunt
- Department of Chemistry and Department of Biophysics, University of Michigan, Ann Arbor, Michigan 48109-1055, United States
| | - Elizabeth C Manickas
- Department of Chemistry and Department of Biophysics, University of Michigan, Ann Arbor, Michigan 48109-1055, United States
| | - Kady M Oakley
- Department of Chemistry, Brown University, Providence, Rhode Island 02912, United States
| | - John Pham
- Department of Chemistry, Brown University, Providence, Rhode Island 02912, United States
| | - Garrett C Reed
- Department of Chemistry and Department of Biophysics, University of Michigan, Ann Arbor, Michigan 48109-1055, United States
| | - Victor Sosa Alfaro
- Department of Chemistry and Department of Biophysics, University of Michigan, Ann Arbor, Michigan 48109-1055, United States
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5
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Marks WR, Reinheimer EW, Seda T, Zakharov LN, Gilbertson JD. NO Coupling by Nonclassical Dinuclear Dinitrosyliron Complexes to Form N 2O Dictated by Hemilability. Inorg Chem 2021; 60:15901-15909. [PMID: 34514780 DOI: 10.1021/acs.inorgchem.1c02285] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
Selective coupling of NO by a nonclassical dinuclear dinitrosyliron complex (D-DNIC) to form N2O is reported. The coupling is facilitated by the pyridinediimine (PDI) ligand scaffold, which enables the necessary denticity changes to produce mixed-valent, electron-deficient tethered DNICs. One-electron oxidation of the [{Fe(NO)2}]210/10 complex Fe2(PyrrPDI)(NO)4 (4) results in NO coupling to form N2O via the mixed-valent {[Fe(NO)2]2}9/10 species, which possesses an electron-deficient four-coordinate {Fe(NO)2}10 site, crucial in N-N bond formation. The hemilability of the PDI scaffold dictates the selectivity in N-N bond formation because stabilization of the five-coordinate {Fe(NO)2}9 site in the mixed-valent [{Fe(NO)2}]29/10 species, [Fe2(Pyr2PDI)(NO)4][PF6] (6), does not result in an electron-deficient, four-coordinate {Fe(NO)2}10 site, and hence no N-N coupling is observed.
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Affiliation(s)
- Walker R Marks
- Department of Chemistry, Western Washington University, Bellingham, Washington 98225, United States
| | | | - Takele Seda
- Department of Physics, Western Washington University, Bellingham, Washington 98225, United States
| | - Lev N Zakharov
- Department of Chemistry, University of Oregon, Eugene, Oregon 97403, United States
| | - John D Gilbertson
- Department of Chemistry, Western Washington University, Bellingham, Washington 98225, United States
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6
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Takeda H, Kimura T, Nomura T, Horitani M, Yokota A, Matsubayashi A, Ishii S, Shiro Y, Kubo M, Tosha T. Timing of NO Binding and Protonation in the Catalytic Reaction of Bacterial Nitric Oxide Reductase as Established by Time-Resolved Spectroscopy. BULLETIN OF THE CHEMICAL SOCIETY OF JAPAN 2020. [DOI: 10.1246/bcsj.20200038] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/17/2023]
Affiliation(s)
- Hanae Takeda
- Graduate School of Life Science, University of Hyogo, Hyogo 678-1297, Japan
- RIKEN SPring-8 Center, Hyogo 679-5148, Japan
| | - Tetsunari Kimura
- RIKEN SPring-8 Center, Hyogo 679-5148, Japan
- Department of Chemistry, Graduate School of Science, Kobe University, Kobe 657-8501, Japan
| | - Takashi Nomura
- Graduate School of Life Science, University of Hyogo, Hyogo 678-1297, Japan
- RIKEN SPring-8 Center, Hyogo 679-5148, Japan
| | - Masaki Horitani
- Department of Applied Biochemistry & Food Science, Saga University, Saga 840-8502, Japan
| | - Azusa Yokota
- Graduate School of Life Science, University of Hyogo, Hyogo 678-1297, Japan
| | - Akiko Matsubayashi
- Graduate School of Life Science, University of Hyogo, Hyogo 678-1297, Japan
| | - Shoko Ishii
- Graduate School of Life Science, University of Hyogo, Hyogo 678-1297, Japan
- RIKEN SPring-8 Center, Hyogo 679-5148, Japan
| | - Yoshitsugu Shiro
- Graduate School of Life Science, University of Hyogo, Hyogo 678-1297, Japan
- RIKEN SPring-8 Center, Hyogo 679-5148, Japan
| | - Minoru Kubo
- Graduate School of Life Science, University of Hyogo, Hyogo 678-1297, Japan
- RIKEN SPring-8 Center, Hyogo 679-5148, Japan
| | - Takehiko Tosha
- Graduate School of Life Science, University of Hyogo, Hyogo 678-1297, Japan
- RIKEN SPring-8 Center, Hyogo 679-5148, Japan
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7
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Wu W, Liaw W. Nitric oxide reduction forming hyponitrite triggered by metal‐containing complexes. J CHIN CHEM SOC-TAIP 2020. [DOI: 10.1002/jccs.201900473] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022]
Affiliation(s)
- Wun‐Yan Wu
- Department of Chemistry and Frontier Research Center of Fundamental and Applied Science of MattersNational Tsing Hua University Hsinchu, Taiwan Republic of China
| | - Wen‐Feng Liaw
- Department of Chemistry and Frontier Research Center of Fundamental and Applied Science of MattersNational Tsing Hua University Hsinchu, Taiwan Republic of China
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8
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Wu WY, Hsu CN, Hsieh CH, Chiou TW, Tsai ML, Chiang MH, Liaw WF. NO-to-[N2O2]2–-to-N2O Conversion Triggered by {Fe(NO)2}10-{Fe(NO)2}9 Dinuclear Dinitrosyl Iron Complex. Inorg Chem 2019; 58:9586-9591. [DOI: 10.1021/acs.inorgchem.9b01635] [Citation(s) in RCA: 18] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Affiliation(s)
- Wun-Yan Wu
- Department of Chemistry and Frontier Research Center of Fundamental and Applied Science of Matters, National Tsing Hua University, Hsinchu 30013, Taiwan
| | - Chia-Ning Hsu
- Department of Chemistry and Frontier Research Center of Fundamental and Applied Science of Matters, National Tsing Hua University, Hsinchu 30013, Taiwan
| | - Chieh-Hsin Hsieh
- Department of Chemistry and Frontier Research Center of Fundamental and Applied Science of Matters, National Tsing Hua University, Hsinchu 30013, Taiwan
| | - Tzung-Wen Chiou
- Department of Chemistry and Frontier Research Center of Fundamental and Applied Science of Matters, National Tsing Hua University, Hsinchu 30013, Taiwan
| | - Ming-Li Tsai
- Department of Chemistry, National Sun Yat-sen University, Kaohsiung 80424, Taiwan
| | - Ming-Hsi Chiang
- Institute of Chemistry, Academia Sinica, Nankang, Taipei 115, Taiwan
| | - Wen-Feng Liaw
- Department of Chemistry and Frontier Research Center of Fundamental and Applied Science of Matters, National Tsing Hua University, Hsinchu 30013, Taiwan
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9
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Sabuncu S, Reed JH, Lu Y, Moënne-Loccoz P. Nitric Oxide Reductase Activity in Heme-Nonheme Binuclear Engineered Myoglobins through a One-Electron Reduction Cycle. J Am Chem Soc 2018; 140:17389-17393. [PMID: 30512937 DOI: 10.1021/jacs.8b11037] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022]
Abstract
FeBMbs are structural and functional models of native bacterial nitric oxide reductases (NORs) generated through engineering of myoglobin. These biosynthetic models replicate the heme-nonheme diiron site of NORs and allow substitutions of metal centers and heme cofactors. Here, we provide evidence for multiple NOR turnover in monoformyl-heme-containing FeBMb1 proteins loaded with FeII, CoII, or ZnII metal ions at the FeB site (FeII/CoII/ZnII-FeBMb1(MF-heme)). FTIR detection of the ν(NNO) band of N2O at 2231 cm-1 provides a direct quantitative measurement of the product in solution. A maximum number of turnover is observed with FeII-FeBMb1(MF-heme), but the NOR activity is retained when the FeB site is loaded with ZnII. These data support the viability of a one-electron semireduced pathway for the reduction of NO at binuclear centers in reducing conditions.
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Affiliation(s)
- Sinan Sabuncu
- Department of Biochemistry & Molecular Biology , Oregon Health & Science University , Portland , Oregon 97239 , United States
| | - Julian H Reed
- Department of Chemistry , University of Illinois at Urbana-Champaign , Urbana , Illinois 61801 , United States
| | - Yi Lu
- Department of Chemistry , University of Illinois at Urbana-Champaign , Urbana , Illinois 61801 , United States
| | - Pierre Moënne-Loccoz
- Department of Biochemistry & Molecular Biology , Oregon Health & Science University , Portland , Oregon 97239 , United States
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10
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Wijeratne GB, Hematian S, Siegler MA, Karlin KD. Copper(I)/NO (g) Reductive Coupling Producing a trans-Hyponitrite Bridged Dicopper(II) Complex: Redox Reversal Giving Copper(I)/NO (g) Disproportionation. J Am Chem Soc 2017; 139:13276-13279. [PMID: 28820592 PMCID: PMC5630263 DOI: 10.1021/jacs.7b07808] [Citation(s) in RCA: 36] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
A copper complex, [CuI(tmpa)(MeCN)]+, effectively reductively couples NO(g) at RT in methanol (MeOH), giving a structurally characterized hyponitrito-dicopper(II) adduct. Hydrogen-bonding from MeOH is critical for the hyponitrite complex formation and stabilization. This complex exhibits the reverse redox process in aprotic solvents, giving CuI + NO(g), leading to CuI-mediated NO(g)-disproportionation. The relationship of this chemistry to biological iron and/or copper mediated NO(g) reductive coupling to give N2O(g) is discussed.
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Affiliation(s)
| | | | - Maxime A. Siegler
- Department of Chemistry, Johns Hopkins University, Baltimore, Maryland 21218, United States
| | - Kenneth D. Karlin
- Department of Chemistry, Johns Hopkins University, Baltimore, Maryland 21218, United States
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11
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Loullis A, Pinakoulaki E. Probing the nitrite and nitric oxide reductase activity of cbb3 oxidase: resonance Raman detection of a six-coordinate ferrous heme-nitrosyl species in the binuclear b3/CuB center. Chem Commun (Camb) 2015; 51:17398-401. [PMID: 26465875 DOI: 10.1039/c5cc06802a] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/04/2023]
Abstract
In this work we report the first spectroscopic evidence demonstrating that cbb3 oxidase catalyzes the reduction of nitrite to nitrous oxide under reducing anaerobic conditions. The reaction proceeds through the formation of a ferrous six-coordinate heme b3-nitrosyl species that has been characterized by resonance Raman spectroscopy.
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Affiliation(s)
- Andreas Loullis
- University of Cyprus, Department of Chemistry, PO Box 20537, 1678 Nicosia, Cyprus.
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12
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Einarsdóttir O, McDonald W, Funatogawa C, Szundi I, Woodruff WH, Dyer RB. The pathway of O₂to the active site in heme-copper oxidases. BIOCHIMICA ET BIOPHYSICA ACTA-BIOENERGETICS 2014; 1847:109-18. [PMID: 24998308 DOI: 10.1016/j.bbabio.2014.06.008] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/04/2014] [Accepted: 06/24/2014] [Indexed: 11/16/2022]
Abstract
The route of O₂to and from the high-spin heme in heme-copper oxidases has generally been believed to emulate that of carbon monoxide (CO). Time-resolved and stationary infrared experiments in our laboratories of the fully reduced CO-bound enzymes, as well as transient optical absorption saturation kinetics studies as a function of CO pressure, have provided strong support for CO binding to CuB⁺ on the pathway to and from the high-spin heme. The presence of CO on CuB⁺ suggests that O₂binding may be compromised in CO flow-flash experiments. Time-resolved optical absorption studies show that the rate of O₂and NO binding in the bovine enzyme (1 × 10⁸M⁻¹s⁻¹) is unaffected by the presence of CO, which is consistent with the rapid dissociation (t½ = 1.5μs) of CO from CuB⁺. In contrast, in Thermus thermophilus (Tt) cytochrome ba3 the O₂and NO binding to heme a3 slows by an order of magnitude in the presence of CO (from 1 × 10⁹ to 1 × 10⁸M⁻¹s⁻¹), but is still considerably faster (~10μs at 1atm O₂) than the CO off-rate from CuB in the absence of O₂(milliseconds). These results show that traditional CO flow-flash experiments do not give accurate results for the physiological binding of O₂and NO in Tt ba3, namely, in the absence of CO. They also raise the question whether in CO flow-flash experiments on Tt ba3 the presence of CO on CuB⁺ impedes the binding of O₂to CuB⁺ or, if O₂does not bind to CuB⁺ prior to heme a3, whether the CuB⁺-CO complex sterically restricts access of O₂to the heme. Both possibilities are discussed, and we argue that O₂binds directly to heme a3 in Tt ba3, causing CO to dissociate from CuB⁺ in a concerted manner through steric and/or electronic effects. This would allow CuB⁺ to function as an electron donor during the fast (5μs) breaking of the OO bond. These results suggest that the binding of CO to CuB⁺ on the path to and from heme a3 may not be applicable to O₂and NO in all heme-copper oxidases. This article is part of a Special Issue entitled: Vibrational spectroscopies and bioenergetic systems.
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Affiliation(s)
- Olöf Einarsdóttir
- Department of Chemistry and Biochemistry, University of California, Santa Cruz, CA 95064, USA.
| | - William McDonald
- Department of Chemistry and Biochemistry, University of California, Santa Cruz, CA 95064, USA
| | - Chie Funatogawa
- Department of Chemistry and Biochemistry, University of California, Santa Cruz, CA 95064, USA
| | - Istvan Szundi
- Department of Chemistry and Biochemistry, University of California, Santa Cruz, CA 95064, USA
| | | | - R Brian Dyer
- Department of Chemistry, Emory University, Atlanta, GA 30322, USA
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13
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Matsumura H, Hayashi T, Chakraborty S, Lu Y, Moënne-Loccoz P. The production of nitrous oxide by the heme/nonheme diiron center of engineered myoglobins (Fe(B)Mbs) proceeds through a trans-iron-nitrosyl dimer. J Am Chem Soc 2014; 136:2420-31. [PMID: 24432820 PMCID: PMC4004238 DOI: 10.1021/ja410542z] [Citation(s) in RCA: 41] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
![]()
Denitrifying NO reductases are transmembrane
protein complexes
that are evolutionarily related to heme/copper terminal oxidases.
They utilize a heme/nonheme diiron center to reduce two NO molecules
to N2O. Engineering a nonheme FeB site within
the heme distal pocket of sperm whale myoglobin has offered well-defined
diiron clusters for the investigation of the mechanism of NO reduction
in these unique active sites. In this study, we use FTIR spectroscopy
to monitor the production of N2O in solution and to show
that the presence of a distal FeBII is not sufficient
to produce the expected product. However, the addition of a glutamate
side chain peripheral to the diiron site allows for 50% of a productive
single-turnover reaction. Unproductive reactions are characterized
by resonance Raman spectroscopy as dinitrosyl complexes, where one
NO molecule is bound to the heme iron to form a five-coordinate low-spin
{FeNO}7 species with ν(FeNO)heme and ν(NO)heme at 522 and 1660 cm–1, and a second NO
molecule is bound to the nonheme FeB site with a ν(NO)FeB at 1755 cm–1. Stopped-flow UV–vis
absorption coupled with rapid-freeze-quench resonance Raman spectroscopy
provide a detailed map of the reaction coordinates leading to the
unproductive iron-nitrosyl dimer. Unexpectedly, NO binding to FeB is kinetically favored and occurs prior to the binding of
a second NO to the heme iron, leading to a (six-coordinate low-spin
heme-nitrosyl/FeB-nitrosyl) transient dinitrosyl complex
with characteristic ν(FeNO)heme at 570 ± 2 cm–1 and ν(NO)FeB at 1755 cm–1. Without the addition of a peripheral glutamate, the dinitrosyl
complex is converted to a dead-end product after the dissociation
of the proximal histidine of the heme iron, but the added peripheral
glutamate side chain in FeBMb2 lowers the rate of dissociation
of the promixal histidine which in turn allows the (six-coordinate
low-spin heme-nitrosyl/FeB-nitrosyl) transient dinitrosyl
complex to decay with production of N2O at a rate of 0.7
s–1 at 4 °C. Taken together, our results support
the proposed trans mechanism of NO reduction in NORs.
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Affiliation(s)
- Hirotoshi Matsumura
- Divison of Environmental & Biomolecular Systems, Institute of Environmental Health, Oregon Health & Science University , 3181 SW Sam Jackson Park Road, Portland, Oregon 97239-3098, United States
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Stern AM, Zhu J. An introduction to nitric oxide sensing and response in bacteria. ADVANCES IN APPLIED MICROBIOLOGY 2014; 87:187-220. [PMID: 24581392 DOI: 10.1016/b978-0-12-800261-2.00005-0] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/19/2022]
Abstract
Nitric oxide (NO) is a radical gas that has been intensively studied for its role as a bacteriostatic agent. NO reacts in complex ways with biological molecules, especially metal centers and other radicals, to generate other bioactive compounds that inhibit enzymes, oxidize macromolecules, and arrest bacterial growth. Bacteria encounter not only NO derived from the host during infection but also NO derived from other bacteria and inorganic sources. The transcriptional responses used by bacteria to respond to NO are diverse but usually involve an iron-containing transcription factor that binds NO and alters its affinity for either DNA or factors involved in transcription, leading to the production of enzymatic tolerance systems. Some of these systems, such as flavohemoglobin and flavorubredoxin, directly remove NO. Some do not but are still important for NO tolerance through other mechanisms. The targets of NO that are protected by these systems include many metabolic pathways such as the tricarboxylic acid cycle and branched chain amino acid synthesis. This chapter discusses these topics and others and serves as a general introduction to microbial NO biology.
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15
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Tosha T, Shiro Y. Crystal structures of nitric oxide reductases provide key insights into functional conversion of respiratory enzymes. IUBMB Life 2013; 65:217-26. [DOI: 10.1002/iub.1135] [Citation(s) in RCA: 31] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/11/2012] [Accepted: 12/25/2012] [Indexed: 11/08/2022]
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Hayashi T, Caranto JD, Matsumura H, Kurtz DM, Moënne-Loccoz P. Vibrational analysis of mononitrosyl complexes in hemerythrin and flavodiiron proteins: relevance to detoxifying NO reductase. J Am Chem Soc 2012; 134:6878-84. [PMID: 22449095 PMCID: PMC3335888 DOI: 10.1021/ja301812p] [Citation(s) in RCA: 47] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Flavodiiron proteins (FDPs) play important roles in the microbial nitrosative stress response in low-oxygen environments by reductively scavenging nitric oxide (NO). Recently, we showed that FMN-free diferrous FDP from Thermotoga maritima exposed to 1 equiv NO forms a stable diiron-mononitrosyl complex (deflavo-FDP(NO)) that can react further with NO to form N(2)O [Hayashi, T.; Caranto, J. D.; Wampler, D. A; Kurtz, D. M., Jr.; Moënne-Loccoz, P. Biochemistry 2010, 49, 7040-7049]. Here we report resonance Raman and low-temperature photolysis FTIR data that better define the structure of this diiron-mononitrosyl complex. We first validate this approach using the stable diiron-mononitrosyl complex of hemerythrin, Hr(NO), for which we observe a ν(NO) at 1658 cm(-1), the lowest ν(NO) ever reported for a nonheme {FeNO}(7) species. Both deflavo-FDP(NO) and the mononitrosyl adduct of the flavinated FPD (FDP(NO)) show ν(NO) at 1681 cm(-1), which is also unusually low. These results indicate that, in Hr(NO) and FDP(NO), the coordinated NO is exceptionally electron rich, more closely approaching the Fe(III)(NO(-)) resonance structure. In the case of Hr(NO), this polarization may be promoted by steric enforcement of an unusually small FeNO angle, while in FDP(NO), the Fe(III)(NO(-)) structure may be due to a semibridging electrostatic interaction with the second Fe(II) ion. In Hr(NO), accessibility and steric constraints prevent further reaction of the diiron-mononitrosyl complex with NO, whereas in FDP(NO) the increased nucleophilicity of the nitrosyl group may promote attack by a second NO to produce N(2)O. This latter scenario is supported by theoretical modeling [Blomberg, L. M.; Blomberg, M. R.; Siegbahn, P. E. J. Biol. Inorg. Chem. 2007, 12, 79-89]. Published vibrational data on bioengineered models of denitrifying heme-nonheme NO reductases [Hayashi, T.; Miner, K. D.; Yeung, N.; Lin, Y.-W.; Lu, Y.; Moënne-Loccoz, P. Biochemistry 2011, 50, 5939-5947 ] support a similar mode of activation of a heme {FeNO}(7) species by the nearby nonheme Fe(II).
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Affiliation(s)
- Takahiro Hayashi
- Division of Environmental and Biomolecular Systems, Institute of Environmental Health, Oregon Health and Science University, 20,000 NW Walker Road, Beaverton, Oregon 97006-8921, USA
| | - Jonathan D. Caranto
- Department of Chemistry, University of Texas at San Antonio, San Antonio, Texas 78249, USA
| | - Hirotoshi Matsumura
- Division of Environmental and Biomolecular Systems, Institute of Environmental Health, Oregon Health and Science University, 20,000 NW Walker Road, Beaverton, Oregon 97006-8921, USA
| | - Donald M. Kurtz
- Department of Chemistry, University of Texas at San Antonio, San Antonio, Texas 78249, USA
| | - Pierre Moënne-Loccoz
- Division of Environmental and Biomolecular Systems, Institute of Environmental Health, Oregon Health and Science University, 20,000 NW Walker Road, Beaverton, Oregon 97006-8921, USA
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17
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Shiro Y. Structure and function of bacterial nitric oxide reductases: nitric oxide reductase, anaerobic enzymes. BIOCHIMICA ET BIOPHYSICA ACTA-BIOENERGETICS 2012; 1817:1907-13. [PMID: 22425814 DOI: 10.1016/j.bbabio.2012.03.001] [Citation(s) in RCA: 71] [Impact Index Per Article: 5.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/16/2012] [Revised: 03/01/2012] [Accepted: 03/01/2012] [Indexed: 10/28/2022]
Abstract
The crystal structures of bacterial nitric oxide reductases (NOR) from Pseudomonas aeruginosa and Geobacillus stearothermophilus were reported. The structural characteristics of these enzymes, especially at the catalytic site and on the pathway that catalytic protons are delivered, are compared, and the corresponding regions of aerobic and micro-aerobic cytochrome oxidases, O(2) reducing enzymes, which are evolutionarily related to NOR are discussed. On the basis of these structural comparisons, a mechanism for the reduction of NO to produce N(2)O by NOR, and the possible molecular evolution of the proton pumping ability of the respiratory enzymes is discussed. This article is part of a Special Issue entitled: 17th European Bioenergetics Conference (EBEC 2012).
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Matsumoto Y, Tosha T, Pisliakov AV, Hino T, Sugimoto H, Nagano S, Sugita Y, Shiro Y. Crystal structure of quinol-dependent nitric oxide reductase from Geobacillus stearothermophilus. Nat Struct Mol Biol 2012; 19:238-45. [PMID: 22266822 DOI: 10.1038/nsmb.2213] [Citation(s) in RCA: 81] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/17/2011] [Accepted: 11/22/2011] [Indexed: 11/09/2022]
Abstract
The structure of quinol-dependent nitric oxide reductase (qNOR) from G. stearothermophilus, which catalyzes the reduction of NO to produce the major ozone-depleting gas N(2)O, has been characterized at 2.5 Å resolution. The overall fold of qNOR is similar to that of cytochrome c-dependent NOR (cNOR), and some structural features that are characteristic of cNOR, such as the calcium binding site and hydrophilic cytochrome c domain, are observed in qNOR, even though it harbors no heme c. In contrast to cNOR, structure-based mutagenesis and molecular dynamics simulation studies of qNOR suggest that a water channel from the cytoplasm can serve as a proton transfer pathway for the catalytic reaction. Further structural comparison of qNOR with cNOR and aerobic and microaerobic respiratory oxidases elucidates their evolutionary relationship and possible functional conversions.
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Affiliation(s)
- Yushi Matsumoto
- Biometal Science Laboratory, RIKEN SPring-8 Center, Sayo, Hyogo, Japan
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19
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Kinetic studies of the reactions of O(2) and NO with reduced Thermus thermophilus ba(3) and bovine aa(3) using photolabile carriers. BIOCHIMICA ET BIOPHYSICA ACTA-BIOENERGETICS 2011; 1817:672-9. [PMID: 22201543 DOI: 10.1016/j.bbabio.2011.12.005] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/11/2011] [Revised: 12/08/2011] [Accepted: 12/08/2011] [Indexed: 11/20/2022]
Abstract
The reactions of molecular oxygen (O(2)) and nitric oxide (NO) with reduced Thermus thermophilus (Tt) ba(3) and bovine heart aa(3) were investigated by time-resolved optical absorption spectroscopy to establish possible relationships between the structural diversity of these enzymes and their reaction dynamics. To determine whether the photodissociated carbon monoxide (CO) in the CO flow-flash experiment affects the ligand binding dynamics, we monitored the reactions in the absence and presence of CO using photolabile O(2) and NO complexes. The binding of O(2)/NO to reduced ba(3) in the absence of CO occurs with a second-order rate constant of 1×10(9)M(-1)s(-1). This rate is 10-times faster than for the mammalian enzyme, and which is attributed to structural differences in the ligand channels of the two enzymes. Moreover, the O(2)/NO binding in ba(3) is 10-times slower in the presence of the photodissociated CO while the rates are the same for the bovine enzyme. This indicates that the photodissociated CO directly or indirectly impedes O(2) and NO access to the active site in Tt ba(3), and that traditional CO flow-flash experiments do not accurately reflect the O(2) and NO binding kinetics in ba(3). We suggest that in ba(3) the binding of O(2) (NO) to heme a(3)(2+) causes rapid dissociation of CO from Cu(B)(+) through steric or electronic effects or, alternatively, that the photodissociated CO does not bind to Cu(B)(+). These findings indicate that structural differences between Tt ba(3) and the bovine aa(3) enzyme are tightly linked to mechanistic differences in the functions of these enzymes. This article is part of a Special Issue entitled: Respiratory Oxidases.
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20
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Giuffrè A, Borisov VB, Mastronicola D, Sarti P, Forte E. Cytochromebdoxidase and nitric oxide: From reaction mechanisms to bacterial physiology. FEBS Lett 2011; 586:622-9. [DOI: 10.1016/j.febslet.2011.07.035] [Citation(s) in RCA: 65] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/24/2011] [Revised: 07/20/2011] [Accepted: 07/26/2011] [Indexed: 11/27/2022]
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21
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Hayashi T, Miner KD, Yeung N, Lin YW, Lu Y, Moënne-Loccoz P. Spectroscopic characterization of mononitrosyl complexes in heme--nonheme diiron centers within the myoglobin scaffold (Fe(B)Mbs): relevance to denitrifying NO reductase. Biochemistry 2011; 50:5939-47. [PMID: 21634416 DOI: 10.1021/bi200409a] [Citation(s) in RCA: 31] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
Denitrifying NO reductases are evolutionarily related to the superfamily of heme--copper terminal oxidases. These transmembrane protein complexes utilize a heme-nonheme diiron center to reduce two NO molecules to N(2)O. To understand this reaction, the diiron site has been modeled using sperm whale myoglobin as a scaffold and mutating distal residues Leu-29 and Phe-43 to histidines and Val-68 to a glutamic acid to create a nonheme Fe(B) site. The impact of incorporation of metal ions at this engineered site on the reaction of the ferrous heme with one NO was examined by UV-vis absorption, EPR, resonance Raman, and FTIR spectroscopies. UV--vis absorption and resonance Raman spectra demonstrate that the first NO molecule binds to the ferrous heme, but while the apoproteins and Cu(I)- or Zn(II)-loaded proteins show characteristic EPR signatures of S = 1/2 six-coordinate heme {FeNO}(7) species that can be observed at liquid nitrogen temperature, the Fe(II)-loaded proteins are EPR silent at ≥30 K. Vibrational modes from the heme [Fe-N-O] unit are identified in the RR and FTIR spectra using (15)NO and (15)N(18)O. The apo and Cu(I)-bound proteins exhibit ν(FeNO) and ν(NO) that are only marginally distinct from those reported for native myoglobin. However, binding of Fe(II) at the Fe(B) site shifts the heme ν(FeNO) by 17 cm(-1) and the ν(NO) by -50 cm(-1) to 1549 cm(-1). This low ν(NO) is without precedent for a six-coordinate heme {FeNO}(7) species and suggests that the NO group adopts a strong nitroxyl character stabilized by electrostatic interaction with the nearby nonheme Fe(II). Detection of a similarly low ν(NO) in the Zn(II)-loaded protein supports this interpretation.
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Affiliation(s)
- Takahiro Hayashi
- Division of Environmental and Biomolecular Systems, Oregon Health and Science University, Beaverton, Oregon 97006, United States
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22
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Schopfer MP, Wang J, Karlin KD. Bioinspired heme, heme/nonheme diiron, heme/copper, and inorganic NOx chemistry: *NO((g)) oxidation, peroxynitrite-metal chemistry, and *NO((g)) reductive coupling. Inorg Chem 2010; 49:6267-82. [PMID: 20666386 DOI: 10.1021/ic100033y] [Citation(s) in RCA: 88] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022]
Abstract
The focus of this Forum Article highlights work from our own laboratories and those of others in the area of biochemical and biologically inspired inorganic chemistry dealing with nitric oxide [nitrogen monoxide, *NO((g))] and its biological roles and reactions. The latter focus is on (i) oxidation of *NO((g)) to nitrate by nitric oxide dioxygenases (NODs) and (ii) reductive coupling of two molecules of *NO((g)) to give N(2)O(g). In the former case, NODs are described, and the highlighting of possible peroxynitrite/heme intermediates and the consequences of this are given by a discussion of recent works with myoglobin and a synthetic heme model system for NOD action. Summaries of recent copper complex chemistries with *NO((g)) and O(2)(g), leading to peroxynitrite species, are given. The coverage of biological reductive coupling of *NO((g)) deals with bacterial nitric oxide reductases (NORs) with heme/nonheme diiron active sites and on heme/copper oxidases such as cytochrome c oxidase, which can mediate the same chemistry. Recently designed protein and synthetic model compounds (heme/nonheme/diiron or heme/copper) as functional mimics are discussed in some detail. We also highlight examples from the chemical literature, not necessarily involving biologically relevant metal ions, that describe the oxidation of *NO((g)) to nitrate (or nitrite) and possible peroxynitrite intermediates or reductive coupling of *NO((g)) to give nitrous oxide.
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Affiliation(s)
- Mark P Schopfer
- Department of Chemistry, The Johns Hopkins University, Baltimore, Maryland 21218, USA
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23
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Hayashi T, Caranto JD, Wampler DA, Kurtz DM, Moënne-Loccoz P. Insights into the nitric oxide reductase mechanism of flavodiiron proteins from a flavin-free enzyme. Biochemistry 2010; 49:7040-9. [PMID: 20669924 PMCID: PMC2923256 DOI: 10.1021/bi100788y] [Citation(s) in RCA: 71] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
Flavodiiron proteins (FDPs) catalyze reductive scavenging of dioxygen and nitric oxide in air-sensitive microorganisms. FDPs contain a distinctive non-heme diiron/flavin mononucleotide (FMN) active site. Alternative mechanisms for the nitric oxide reductase (NOR) activity consisting of either protonation of a diiron-bridging hyponitrite or "super-reduction" of a diferrous-dinitrosyl by the proximal FMNH(2) in the rate-determining step have been proposed. To test these alternative mechanisms, we examined a deflavinated FDP (deflavo-FDP) from Thermotoga maritima. The deflavo-FDP retains an intact diiron site but does not exhibit multiturnover NOR or O(2) reductase (O(2)R) activity. Reactions of the reduced (diferrous) deflavo-FDP with nitric oxide were examined by UV-vis absorption, EPR, resonance Raman, and FTIR spectroscopies. Anaerobic addition of nitric oxide up to one NO per diferrous deflavo-FDP results in formation of a diiron-mononitrosyl complex characterized by a broad S = (1)/(2 )EPR signal arising from antiferromagnetic coupling of an S = (3)/(2) {FeNO}(7) with an S = 2 Fe(II). Further addition of NO results in two reaction pathways, one of which produces N(2)O and the diferric site and the other of which produces a stable diiron-dinitrosyl complex. Both NO-treated and as-isolated deflavo-FDPs regain full NOR and O(2)R activities upon simple addition of FMN. The production of N(2)O upon addition of NO to the mononitrosyl deflavo-FDP supports the hyponitrite mechanism, but the concomitant formation of a stable diiron-dinitrosyl complex in the deflavo-FDP is consistent with a super-reduction pathway in the flavinated enzyme. We conclude that a diiron-mononitrosyl complex is an intermediate in the NOR catalytic cycle of FDPs.
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Affiliation(s)
- Takahiro Hayashi
- Department of Science & Engineering, School of Medicine, Oregon Health & Science University, 20,000 NW Walker Road, Beaverton, Oregon 97006, USA
| | - Jonathan D. Caranto
- Department of Chemistry, University of Texas at San Antonio, San Antonio, Texas 78249, USA
| | - David A. Wampler
- Department of Chemistry, University of Texas at San Antonio, San Antonio, Texas 78249, USA
| | - Donald M. Kurtz
- Department of Chemistry, University of Texas at San Antonio, San Antonio, Texas 78249, USA
| | - Pierre Moënne-Loccoz
- Department of Science & Engineering, School of Medicine, Oregon Health & Science University, 20,000 NW Walker Road, Beaverton, Oregon 97006, USA
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24
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Vincent KA. Triggered infrared spectroscopy for investigating metalloprotein chemistry. PHILOSOPHICAL TRANSACTIONS. SERIES A, MATHEMATICAL, PHYSICAL, AND ENGINEERING SCIENCES 2010; 368:3713-3731. [PMID: 20603378 DOI: 10.1098/rsta.2010.0055] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/29/2023]
Abstract
Recent developments in infrared (IR) spectroscopic time resolution, sensitivity and sample manipulation make this technique a powerful addition to the suite of complementary approaches for the study of time-resolved chemistry at metal centres within proteins. Application of IR spectroscopy to proteins has often targeted the amide bands as probes for gross structural change. This article focuses on the possibilities arising from recent IR technical developments for studies that monitor localized vibrational oscillators in proteins--native or exogenous ligands such as NO, CO, SCN(-) or CN(-), or genetically or chemically introduced probes with IR-active vibrations. These report on the electronic and coordination state of metals, the kinetics, intermediates and reaction pathways of ligand release, hydrogen-bonding interactions between the protein and IR probe, and the electrostatic character of sites in a protein. Metalloprotein reactions can be triggered by light/dark transitions, an electrochemical step, a change in solute composition or equilibration with a new gas atmosphere, and spectra can be obtained over a range of time domains as far as the sub-picosecond level. We can expect to see IR spectroscopy exploited, alongside other spectroscopies, and crystallography, to elucidate reactions of a wide range of metalloprotein chemistry with relevance to cell metabolism, health and energy catalysis.
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Affiliation(s)
- Kylie A Vincent
- Inorganic Chemistry Laboratory, Department of Chemistry, University of Oxford, South Parks Road, Oxford OX1 3QR, UK.
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25
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Goodrich LE, Paulat F, Praneeth VKK, Lehnert N. Electronic Structure of Heme-Nitrosyls and Its Significance for Nitric Oxide Reactivity, Sensing, Transport, and Toxicity in Biological Systems. Inorg Chem 2010; 49:6293-316. [DOI: 10.1021/ic902304a] [Citation(s) in RCA: 167] [Impact Index Per Article: 11.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/03/2023]
Affiliation(s)
- Lauren E. Goodrich
- Department of Chemistry, University of Michigan, Ann Arbor, Michigan 48109
| | - Florian Paulat
- Department of Chemistry, University of Michigan, Ann Arbor, Michigan 48109
| | - V. K. K. Praneeth
- Department of Chemistry, University of Michigan, Ann Arbor, Michigan 48109
| | - Nicolai Lehnert
- Department of Chemistry, University of Michigan, Ann Arbor, Michigan 48109
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26
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Wang J, Schopfer MP, Puiu SC, Sarjeant AAN, Karlin KD. Reductive coupling of nitrogen monoxide (*NO) facilitated by heme/copper complexes. Inorg Chem 2010; 49:1404-19. [PMID: 20030370 DOI: 10.1021/ic901431r] [Citation(s) in RCA: 42] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/19/2023]
Abstract
The interactions of nitrogen monoxide (*NO; nitric oxide) with transition metal centers continue to be of great interest, in part due to their importance in biochemical processes. Here, we describe *NO((g)) reductive coupling chemistry of possible relevance to that process (i.e., nitric oxide reductase (NOR) biochemistry), which occurs at the heme/Cu active site of cytochrome c oxidases (CcOs). In this report, heme/Cu/*NO((g)) activity is studied using 1:1 ratios of heme and copper complex components, (F(8))Fe (F(8) = tetrakis(2,6-difluorophenyl)porphyrinate(2-)) and [(tmpa)Cu(I)(MeCN)](+) (TMPA = tris(2-pyridylmethyl)amine). The starting point for heme chemistry is the mononitrosyl complex (F(8))Fe(NO) (lambda(max) = 399 (Soret), 541 nm in acetone). Variable-temperature (1)H and (2)H NMR spectra reveal a broad peak at delta = 6.05 ppm (pyrrole) at room temperature (RT), which gives rise to asymmetrically split pyrrole peaks at 9.12 and 8.54 ppm at -80 degrees C. A new heme dinitrosyl species, (F(8))Fe(NO)(2), obtained by bubbling (F(8))Fe(NO) with *NO((g)) at -80 degrees C, could be reversibly formed, as monitored by UV-vis (lambda(max) = 426 (Soret), 538 nm in acetone), EPR (silent), and NMR spectroscopies; that is, the mono-NO complex was regenerated upon warming to RT. (F(8))Fe(NO)(2) reacts with [(tmpa)Cu(I)(MeCN)](+) and 2 equiv of acid to give [(F(8))Fe(III)](+), [(tmpa)Cu(II)(solvent)](2+), and N(2)O((g)), fitting the stoichiometric *NO((g)) reductive coupling reaction: 2*NO((g)) + Fe(II) + Cu(I) + 2H(+) --> N(2)O((g)) + Fe(III) + Cu(II) + H(2)O, equivalent to one enzyme turnover. Control reaction chemistry shows that both iron and copper centers are required for the NOR-type chemistry observed and that, if acid is not present, half the *NO is trapped as a (F(8))Fe(NO) complex, while the remaining nitrogen monoxide undergoes copper complex promoted disproportionation chemistry. As part of this study, [(F(8))Fe(III)]SbF(6) was synthesized and characterized by X-ray crystallography, along with EPR (77 K: g = 5.84 and 6.12 in CH(2)Cl(2) and THF, respectively) and variable-temperature NMR spectroscopies. These structural and physical properties suggest that at RT this complex consists of an admixture of high and intermediate spin states.
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Affiliation(s)
- Jun Wang
- Department of Chemistry, The Johns Hopkins University, Baltimore, Maryland 21218, USA
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27
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Roles of glutamates and metal ions in a rationally designed nitric oxide reductase based on myoglobin. Proc Natl Acad Sci U S A 2010; 107:8581-6. [PMID: 20421510 DOI: 10.1073/pnas.1000526107] [Citation(s) in RCA: 97] [Impact Index Per Article: 6.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
A structural and functional model of bacterial nitric oxide reductase (NOR) has been designed by introducing two glutamates (Glu) and three histidines (His) in sperm whale myoglobin. X-ray structural data indicate that the three His and one Glu (V68E) residues bind iron, mimicking the putative Fe(B) site in NOR, while the second Glu (I107E) interacts with a water molecule and forms a hydrogen bonding network in the designed protein. Unlike the first Glu (V68E), which lowered the heme reduction potential by approximately 110 mV, the second Glu has little effect on the heme potential, suggesting that the negatively charged Glu has a different role in redox tuning. More importantly, introducing the second Glu resulted in a approximately 100% increase in NOR activity, suggesting the importance of a hydrogen bonding network in facilitating proton delivery during NOR reactivity. In addition, EPR and X-ray structural studies indicate that the designed protein binds iron, copper, or zinc in the Fe(B) site, each with different effects on the structures and NOR activities, suggesting that both redox activity and an intermediate five-coordinate heme-NO species are important for high NOR activity. The designed protein offers an excellent model for NOR and demonstrates the power of using designed proteins as a simpler and more well-defined system to address important chemical and biological issues.
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28
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Lu C, Zhao X, Lu Y, Rousseau DL, Yeh SR. Role of copper ion in regulating ligand binding in a myoglobin-based cytochrome C oxidase model. J Am Chem Soc 2010; 132:1598-605. [PMID: 20070118 DOI: 10.1021/ja907777f] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Cytochrome c oxidase (CcO), the terminal enzyme in the mitochondrial respiratory chain, catalyzes the four-electron reduction of dioxygen to water in a binuclear center comprised of a high-spin heme (heme a(3)) and a copper atom (Cu(B)) coordinated by three histidine residues. As a minimum model for CcO, a mutant of sperm whale myoglobin, named Cu(B)Mb, has been engineered, in which a copper atom is held in the distal heme pocket by the native E7 histidine and two nonnative histidine residues. In this work, the role of the copper in regulating ligand binding in Cu(B)Mb was investigated. Resonance Raman studies show that the presence of copper in CO-bound Cu(B)Mb leads to a CcO-like distal heme pocket. Stopped-flow data show that, upon the initiation of the CO binding reaction, the ligand first binds to the Cu(+); it subsequently transfers from Cu(+) to Fe(2+) in an intramolecular process, similar to that reported for CcO. The high CO affinity toward Cu(+) and the slow intramolecular CO transfer rate between Cu(+) and Fe(2+) in the Cu(B)Mb/Cu(+) complex are analogous to those in Thermus thermophilus CcO (TtCcO) but distinct from those in bovine CcO (bCcO). Additional kinetic studies show that, upon photolysis of the NO-bound Cu(B)Mb/Cu(+) complex, the photolyzed ligand transiently binds to Cu(+) and subsequently rebinds to Fe(2+), accounting for the 100% geminate recombination yield, similar to that found in TtCcO. The data demonstrate that the Cu(B)Mb/Cu(+) complex reproduces essential structural and kinetic features of CcO and that the complex is more akin to TtCcO than to bCcO.
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Affiliation(s)
- Changyuan Lu
- Department of Physiology and Biophysics, Albert Einstein College of Medicine, Bronx, New York 10461, USA
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29
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Lucas HR, Meyer GJ, Karlin KD. Carbon monoxide and nitrogen monoxide ligand dynamics in synthetic heme and heme-copper complex systems. J Am Chem Soc 2009; 131:13924-5. [PMID: 19736941 DOI: 10.1021/ja906172c] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Intermolecular nitrogen monoxide (*NO) and carbon monoxide (CO) transfer from iron to copper and back, a phenomenon not previously observed, has been accomplished by employing transient-absorbance laser flash photolysis methods. A 1:1 heme/copper component system consisting of a six-coordinate ferrous species, F(8)Fe(II)(CO)(DCIM) or F(8)Fe(II)(NO)(thf) [F(8) = tetrakis(2,6-difluorophenyl)porphyrinate(2-); DCIM = 1,5-dicyclohexylimidazole; thf = tetrahydrofuran], and two ligand-copper(I) complexes, one with tridentate [(Bz)L = (benzyl)bis(2-pyridylmethyl)amine] and one with tetradentate coordination [(Py)L = tris(2-pyridylmethyl)amine], was utilized. The results suggest a lower affinity for NO versus CO binding to copper(I) and a higher rate for NO versus CO binding to heme. In fact, the latter event has been observed in cytochrome c oxidase aa(3).
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Affiliation(s)
- Heather R Lucas
- Department of Chemistry, The Johns Hopkins University, Baltimore, Maryland 21218, USA
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