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Rose SL, Ferroni FM, Horrell S, Brondino CD, Eady RR, Jaho S, Hough MA, Owen RL, Antonyuk SV, Hasnain SS. Spectroscopically Validated pH-dependent MSOX Movies Provide Detailed Mechanism of Copper Nitrite Reductases. J Mol Biol 2024; 436:168706. [PMID: 39002715 DOI: 10.1016/j.jmb.2024.168706] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/17/2024] [Revised: 07/08/2024] [Accepted: 07/09/2024] [Indexed: 07/15/2024]
Abstract
Copper nitrite reductases (CuNiRs) exhibit a strong pH dependence of their catalytic activity. Structural movies can be obtained by serially recording multiple structures (frames) from the same spot of a crystal using the MSOX serial crystallography approach. This method has been combined with on-line single crystal optical spectroscopy to capture the pH-dependent structural changes that accompany during turnover of CuNiRs from two Rhizobia species. The structural movies, initiated by the redox activation of a type-1 copper site (T1Cu) via X-ray generated photoelectrons, have been obtained for the substrate-free and substrate-bound states at low (high enzymatic activity) and high (low enzymatic activity) pH. At low pH, formation of the product nitric oxide (NO) is complete at the catalytic type-2 copper site (T2Cu) after a dose of 3 MGy (frame 5) with full bleaching of the T1Cu ligand-to-metal charge transfer (LMCT) 455 nm band (S(σ)Cys → T1Cu2+) which in itself indicates the electronic route of proton-coupled electron transfer (PCET) from T1Cu to T2Cu. In contrast at high pH, the changes in optical spectra are relatively small and the formation of NO is only observed in later frames (frame 15 in Br2DNiR, 10 MGy), consistent with the loss of PCET required for catalysis. This is accompanied by decarboxylation of the catalytic AspCAT residue, with CO2 trapped in the catalytic pocket.
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Affiliation(s)
- Samuel L Rose
- Molecular Biophysics Group, Life Sciences Building, Institute of Systems, Molecular and Integrative Biology, Faculty of Health and Life Sciences, University of Liverpool, Liverpool L69 7ZB, United Kingdom
| | - Felix Martín Ferroni
- Molecular Biophysics Group, Life Sciences Building, Institute of Systems, Molecular and Integrative Biology, Faculty of Health and Life Sciences, University of Liverpool, Liverpool L69 7ZB, United Kingdom; Departamento de Física, Facultad de Bioquímica y Ciencias Biológicas, Universidad Nacional del Litoral (UNL), CONICET, Ciudad Universitaria, Paraje El Pozo, Santa Fe, Argentina.
| | - Sam Horrell
- Diamond Light Source, Harwell Science and Innovation Campus, Didcot OX11 0DE, United Kingdom
| | - Carlos Dante Brondino
- Departamento de Física, Facultad de Bioquímica y Ciencias Biológicas, Universidad Nacional del Litoral (UNL), CONICET, Ciudad Universitaria, Paraje El Pozo, Santa Fe, Argentina
| | - Robert R Eady
- Molecular Biophysics Group, Life Sciences Building, Institute of Systems, Molecular and Integrative Biology, Faculty of Health and Life Sciences, University of Liverpool, Liverpool L69 7ZB, United Kingdom
| | - Sofia Jaho
- Diamond Light Source, Harwell Science and Innovation Campus, Didcot OX11 0DE, United Kingdom
| | - Michael A Hough
- Diamond Light Source, Harwell Science and Innovation Campus, Didcot OX11 0DE, United Kingdom
| | - Robin L Owen
- Diamond Light Source, Harwell Science and Innovation Campus, Didcot OX11 0DE, United Kingdom
| | - Svetlana V Antonyuk
- Molecular Biophysics Group, Life Sciences Building, Institute of Systems, Molecular and Integrative Biology, Faculty of Health and Life Sciences, University of Liverpool, Liverpool L69 7ZB, United Kingdom.
| | - S Samar Hasnain
- Molecular Biophysics Group, Life Sciences Building, Institute of Systems, Molecular and Integrative Biology, Faculty of Health and Life Sciences, University of Liverpool, Liverpool L69 7ZB, United Kingdom.
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Feng Y, Yu Y, Shi H, Bai J, Wang L, Yang T, Liu L. Nitrite reductase-mimicking catalysis temporally regulating nitric oxide concentration gradient adaptive for antibacterial therapy. SCIENCE ADVANCES 2024; 10:eadp5935. [PMID: 39213361 PMCID: PMC11364101 DOI: 10.1126/sciadv.adp5935] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 04/03/2024] [Accepted: 07/26/2024] [Indexed: 09/04/2024]
Abstract
The unique bacterial infection microenvironment (IME) usually requires complicated design of nanomaterials to adapt to IME for enhancing antibacterial therapy. Here, an alternative IME adaptative nitrite reductase-mimicking nanozyme is constructed by in situ growth of ultrasmall copper sulfide clusters on the surface of a nanofibrillar lysozyme assembly (NFLA/CuS NHs), which can temporally regulate nitric oxide (NO) gradient concentration to kill bacteria initially and promote tissue regeneration subsequently. Benefiting from a copper nitrite reductase (CuNIR)-inspired structure with CuS cluster as active center and NFLA as skeleton, NFLA/CuS NHs efficiently boost the catalytic reduction of nitrite to NO. The inherent supramolecular fibrillar networks displays excellent bacterial capture capability, facilitating initial high-concentration NO attacks on the bacteria. The subsequent catalytic release of low-concentration NO by NFLA/CuS NHs-mediated nitrite reduction remarkably promotes cell migration and angiogenesis. This work paves the way for dynamically eliminating MDR bacterial infection and promoting tissue regeneration in a simple and smart way through CuNIR-mimicking catalysis.
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Affiliation(s)
- Yonghai Feng
- Institute for Advanced Materials, School of Materials Science and Engineering, Jiangsu University, Zhenjiang 212013, Jiangsu Province, China
| | - Yi Yu
- Institute for Advanced Materials, School of Materials Science and Engineering, Jiangsu University, Zhenjiang 212013, Jiangsu Province, China
| | - Hui Shi
- Institute for Advanced Materials, School of Materials Science and Engineering, Jiangsu University, Zhenjiang 212013, Jiangsu Province, China
| | - Jiaxiang Bai
- Department of Orthopedics, The First Affiliated Hospital of USTC, Division of Life Sciences and Medicine, University of Science and Technology of China, Hefei 230001, Anhui Province, China
| | - Liangliang Wang
- Department of Orthopedics, The Affiliated Changzhou Second People's Hospital of Nanjing Medical University, Changzhou 213003, Jiangsu Province, China
| | - Tianke Yang
- Department of Ophthalmology, The First Affiliated Hospital of USTC, Division of Life Sciences and Medicine, University of Science and Technology of China, Hefei 230001, Anhui Province, China
| | - Lei Liu
- Institute for Advanced Materials, School of Materials Science and Engineering, Jiangsu University, Zhenjiang 212013, Jiangsu Province, China
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3
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Kametani Y, Ikeda K, Yoshizawa K, Shiota Y. Mechanistic Study of Reduction of Nitrite to NO by the Copper(II) Complex: Different Concerted Proton-Electron Transfer Reactivity between Nitrite and Nitro Complexes. Inorg Chem 2023; 62:13765-13774. [PMID: 37590095 DOI: 10.1021/acs.inorgchem.3c01383] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 08/19/2023]
Abstract
The literature contains numerous reports of copper complexes for nitrite (NO2-) reduction. However, details of how protons and electrons arrive and how nitric oxide (NO) is released remain unknown. The influence of the coordination mode of nitrite on reactivity is also under debate. Kundu and co-workers have reported nitrite reduction by a copper(II) complex [J. Am. Chem. Soc. 2020, 142, 1726-1730]. In their report, the copper(II) complex reduced nitrite using a phenol derivative as a reductant, resulting in NO, a hydroxyl copper(II) complex, and the corresponding biphenol. Also, the involvement of proton-coupled electron transfer was proposed by mechanistic studies. Herein, density functional theory calculations were performed to determine a mechanism for reduction of nitrite by a copper(II) complex. As a result of geometry optimization of an initial complex, two possible structures were obtained: Cu-ONO and Cu-NO2. Two possible reaction pathways initiated from Cu-ONO or Cu-NO2 were then considered. The calculation results indicated that the Cu-ONO pathway is energetically favorable. When changes in the electronic structure were considered, both pathways were found to involve concerted proton-electron transfer (CPET). In addition, an intrinsic reaction coordinate analysis revealed that the two pathways were achieved by different types of CPET. Furthermore, an intrinsic bond orbital analysis clearly indicated that, in the Cu-ONO pathway, the chemical events involved proceeded concertedly yet asynchronously.
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Affiliation(s)
- Yohei Kametani
- Institute for Materials Chemistry and Engineering and IRCCS, Kyushu University, 744 Motooka, Nishi-ku, Fukuoka 819-0395, Japan
| | - Kei Ikeda
- Institute for Materials Chemistry and Engineering and IRCCS, Kyushu University, 744 Motooka, Nishi-ku, Fukuoka 819-0395, Japan
| | - Kazunari Yoshizawa
- Institute for Materials Chemistry and Engineering and IRCCS, Kyushu University, 744 Motooka, Nishi-ku, Fukuoka 819-0395, Japan
| | - Yoshihito Shiota
- Institute for Materials Chemistry and Engineering and IRCCS, Kyushu University, 744 Motooka, Nishi-ku, Fukuoka 819-0395, Japan
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4
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van Langevelde P, Engbers S, Buda F, Hetterscheid DGH. Elucidation of the Electrocatalytic Nitrite Reduction Mechanism by Bio-Inspired Copper Complexes. ACS Catal 2023; 13:10094-10103. [PMID: 37560187 PMCID: PMC10407843 DOI: 10.1021/acscatal.3c01989] [Citation(s) in RCA: 4] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/03/2023] [Revised: 06/26/2023] [Indexed: 08/11/2023]
Abstract
Mononuclear copper complexes relevant to the active site of copper nitrite reductases (CuNiRs) are known to be catalytically active for the reduction of nitrite. Yet, their catalytic mechanism has thus far not been resolved. Here, we provide a complete description of the electrocatalytic nitrite reduction mechanism of a bio-inspired CuNiR catalyst Cu(tmpa) (tmpa = tris(2-pyridylmethyl)amine) in aqueous solution. Through a combination of electrochemical studies, reaction kinetics, and density functional theory (DFT) computations, we show that the protonation steps take place in a stepwise manner and are decoupled from electron transfer. The rate-determining step is a general acid-catalyzed protonation of a copper-ligated nitrous acid (HNO2) species. In view of the growing urge to convert nitrogen-containing compounds, this work provides principal reaction parameters for efficient electrochemical nitrite reduction. This contributes to the investigation and development of nitrite reduction catalysts, which is crucial to restore the biogeochemical nitrogen cycle.
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Affiliation(s)
| | - Silène Engbers
- Leiden Institute of Chemistry, Leiden University, 2300 RA Leiden, The Netherlands
| | - Francesco Buda
- Leiden Institute of Chemistry, Leiden University, 2300 RA Leiden, The Netherlands
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5
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Chen L, Li X, Xie Y, Liu N, Qin X, Chen X, Bu Y. Modulation of proton-coupled electron transfer reactions in lysine-containing alpha-helixes: alpha-helixes promoting long-range electron transfer. Phys Chem Chem Phys 2022; 24:14592-14602. [PMID: 35667661 DOI: 10.1039/d2cp00666a] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
The proton-coupled electron transfer (PCET) reaction plays an important role in promoting many biological and chemical reactions. Usually, the rate of the PCET reaction increases with an increase in the electron transfer distance because long-range electron transfer requires more free energy barriers. Our density functional theory calculations here reveal that the mechanism of PCET occurring in lysine-containing alpha(α)-helixes changes with an increasing number of residues in the α-helical structure and the different conformations because of the modulation of the excess electron distribution by the α-helical structures. The rate constants of the corresponding PCET reactions are independent of or substantially shallower dependent on the electron transfer distances along α-helixes. This counter-intuitive behavior can be attributed to the fact that the formation of larger macro-cylindrical dipole moments in longer helixes can promote electron transfer along the α-helix with a low energy barrier. These findings may be useful to gain insights into long-range electron transfer in proteins and design α-helix-based electronics via the regulation of short-range proton transfer.
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Affiliation(s)
- Long Chen
- Chongqing Key Laboratory of Theoretical and Computational Chemistry, School of Chemistry and Chemical Engineering, Chongqing University, Chongqing, 401331, P. R. China.
| | - Xin Li
- Chongqing Key Laboratory of Theoretical and Computational Chemistry, School of Chemistry and Chemical Engineering, Chongqing University, Chongqing, 401331, P. R. China.
| | - Yuxin Xie
- Chongqing Key Laboratory of Theoretical and Computational Chemistry, School of Chemistry and Chemical Engineering, Chongqing University, Chongqing, 401331, P. R. China.
| | - Nian Liu
- Chongqing Key Laboratory of Theoretical and Computational Chemistry, School of Chemistry and Chemical Engineering, Chongqing University, Chongqing, 401331, P. R. China.
| | - Xin Qin
- Chongqing Key Laboratory of Theoretical and Computational Chemistry, School of Chemistry and Chemical Engineering, Chongqing University, Chongqing, 401331, P. R. China.
| | - Xiaohua Chen
- Chongqing Key Laboratory of Theoretical and Computational Chemistry, School of Chemistry and Chemical Engineering, Chongqing University, Chongqing, 401331, P. R. China.
| | - Yuxiang Bu
- School of Chemistry and Chemical Engineering, Shandong University, Jinan, Shandong, 250100, P. R. China.
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6
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Eady RR, Samar Hasnain S. New horizons in structure-function studies of copper nitrite reductase. Coord Chem Rev 2022. [DOI: 10.1016/j.ccr.2022.214463] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/16/2023]
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7
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Chang YL, Chen HY, Chen SH, Kao CL, Chiang MY, Hsu SCN. An investigation on catalytic nitrite reduction reaction by bioinspired Cu II complexes. Dalton Trans 2022; 51:7715-7722. [PMID: 35522169 DOI: 10.1039/d1dt04102a] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Catalytic nitrite reductions by CuII complexes containing anionic Me2Tp, neutral Me2Tpm, or neutral iPrTIC ligands in the presence of L-ascorbic acid, which served as an electron donor and proton source, were investigated. The results showed that auxiliary ligands are important for copper-mediated catalytic nitrite reduction. Furthermore, the electronic effects of the ligand govern the nitrite reduction efficiency, which should be considered at two control points: one is the susceptibility of the LCuI-nitrite species to protonation and the other is the susceptibility of LCuII to reduction giving LCuI. In addition, an external strong acid leads to the production of nitrous acid, which may suggest that the reactivity of nitrous acid toward the LCuI species is a third control point.
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Affiliation(s)
- Yu-Lun Chang
- Department of Medicinal and Applied Chemistry, Kaohsiung Medical University, 100 Shi-Chuan 1st Rd., San-Ming District, Kaohsiung 807, Taiwan.
| | - Hsing-Yin Chen
- Department of Medicinal and Applied Chemistry, Kaohsiung Medical University, 100 Shi-Chuan 1st Rd., San-Ming District, Kaohsiung 807, Taiwan.
| | - Si-Hong Chen
- Department of Medicinal and Applied Chemistry, Kaohsiung Medical University, 100 Shi-Chuan 1st Rd., San-Ming District, Kaohsiung 807, Taiwan.
| | - Chai-Lin Kao
- Department of Medicinal and Applied Chemistry, Kaohsiung Medical University, 100 Shi-Chuan 1st Rd., San-Ming District, Kaohsiung 807, Taiwan.
| | - Michael Y Chiang
- Department of Chemistry, National Sun Yat-Sen University No. 70, Lienhai Rd., Kaohsiung 804, Taiwan
| | - Sodio C N Hsu
- Department of Medicinal and Applied Chemistry, Kaohsiung Medical University, 100 Shi-Chuan 1st Rd., San-Ming District, Kaohsiung 807, Taiwan. .,Department of Chemistry, National Sun Yat-Sen University No. 70, Lienhai Rd., Kaohsiung 804, Taiwan.,Department of Medical Research, Kaohsiung Medical University Hospital, Kaohsiung 807, Taiwan
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8
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Gupta S, Arora S, Mondal A, Stieber SCE, Gupta P, Kundu S. A Copper(II)‐Nitrite Complex Hydrogen‐Bonded to a Protonated Amine in the Second‐Coordination‐Sphere. Eur J Inorg Chem 2022. [DOI: 10.1002/ejic.202200105] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
Affiliation(s)
- Shourya Gupta
- IISER-TVM: Indian Institute of Science Education Research Thiruvananthapuram Chemistry INDIA
| | - Sumangla Arora
- IIT Roorkee: Indian Institute of Technology Roorkee Chemistry INDIA
| | - Aditesh Mondal
- IISER-TVM: Indian Institute of Science Education Research Thiruvananthapuram Chemistry INDIA
| | | | - Puneet Gupta
- IIT Roorkee: Indian Institute of Technology Roorkee Chemistry INDIA
| | - Subrata Kundu
- Indian Institute of Science Education and Research Thiruvananthapuram Chemistry Maruthamala POVithura 695551 Thiruvananthapuram INDIA
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9
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Bouchey CJ, Tolman WB. Involvement of a Formally Copper(III) Nitrite Complex in Proton-Coupled Electron Transfer and Nitration of Phenols. Inorg Chem 2022; 61:2662-2668. [PMID: 35078314 PMCID: PMC9835712 DOI: 10.1021/acs.inorgchem.1c03790] [Citation(s) in RCA: 8] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/16/2023]
Abstract
A unique high-valent copper nitrite species, LCuNO2, was accessed via the reversible one-electron oxidation of [M][LCuNO2] (M = NBu4+ or PPN+). The complex LCuNO2 reacts with 2,4,6-tri-tert-butylphenol via a typical proton-coupled electron transfer (PCET) to yield LCuTHF and the 2,4,6-tri-tert-butylphenoxyl radical. The reaction between LCuNO2 and 2,4-di-tert-butylphenol was more complicated. It yielded two products: the coupled bisphenol product expected from a H-atom abstraction and 2,4-di-tert-butyl-6-nitrophenol, the product of an unusual anaerobic nitration. Various mechanisms for the latter transformation were considered.
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Affiliation(s)
- Caitlin J Bouchey
- Department of Chemistry, Washington University in St. Louis, One Brookings Drive, Campus Box 1134, St. Louis, Missouri 63130, United States
- Department of Chemistry, University of Minnesota, 207 Pleasant Street SE, Minneapolis, Minnesota 55455, United States
| | - William B Tolman
- Department of Chemistry, Washington University in St. Louis, One Brookings Drive, Campus Box 1134, St. Louis, Missouri 63130, United States
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10
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Nath AK, Dey SG. Simultaneous Binding of Heme and Cu to Amyloid β Peptides: Active Site and Reactivities. Dalton Trans 2022; 51:4986-4999. [DOI: 10.1039/d2dt00162d] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Amyloid imbalance and Aβ plaque formation are key histopathological features of Alzheimer’s disease (AD). These amyloid plaques observed in post-mortem AD brains have been found to contain increased levels of...
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11
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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: 96] [Impact Index Per Article: 32.0] [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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12
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González PJ, Rivas MG, Ferroni FM, Rizzi AC, Brondino CD. Electron transfer pathways and spin–spin interactions in Mo- and Cu-containing oxidoreductases. Coord Chem Rev 2021. [DOI: 10.1016/j.ccr.2021.214202] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/20/2022]
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13
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Schröder GC, Meilleur F. Metalloprotein catalysis: structural and mechanistic insights into oxidoreductases from neutron protein crystallography. Acta Crystallogr D Struct Biol 2021; 77:1251-1269. [PMID: 34605429 PMCID: PMC8489226 DOI: 10.1107/s2059798321009025] [Citation(s) in RCA: 9] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/22/2021] [Accepted: 08/31/2021] [Indexed: 11/11/2022] Open
Abstract
Metalloproteins catalyze a range of reactions, with enhanced chemical functionality due to their metal cofactor. The reaction mechanisms of metalloproteins have been experimentally characterized by spectroscopy, macromolecular crystallography and cryo-electron microscopy. An important caveat in structural studies of metalloproteins remains the artefacts that can be introduced by radiation damage. Photoreduction, radiolysis and ionization deriving from the electromagnetic beam used to probe the structure complicate structural and mechanistic interpretation. Neutron protein diffraction remains the only structural probe that leaves protein samples devoid of radiation damage, even when data are collected at room temperature. Additionally, neutron protein crystallography provides information on the positions of light atoms such as hydrogen and deuterium, allowing the characterization of protonation states and hydrogen-bonding networks. Neutron protein crystallography has further been used in conjunction with experimental and computational techniques to gain insight into the structures and reaction mechanisms of several transition-state metal oxidoreductases with iron, copper and manganese cofactors. Here, the contribution of neutron protein crystallography towards elucidating the reaction mechanism of metalloproteins is reviewed.
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Affiliation(s)
- Gabriela C. Schröder
- Department of Molecular and Structural Biochemistry, North Carolina State University, Raleigh, NC 27695, USA
- Neutron Scattering Division, Oak Ridge National Laboratory, Oak Ridge, TN 37831, USA
| | - Flora Meilleur
- Department of Molecular and Structural Biochemistry, North Carolina State University, Raleigh, NC 27695, USA
- Neutron Scattering Division, Oak Ridge National Laboratory, Oak Ridge, TN 37831, USA
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14
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Sen K, Hough MA, Strange RW, Yong C, Keal TW. QM/MM Simulations of Protein Crystal Reactivity Guided by MSOX Crystallography: A Copper Nitrite Reductase Case Study. J Phys Chem B 2021; 125:9102-9114. [PMID: 34357776 DOI: 10.1021/acs.jpcb.1c03661] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
The recently developed multiple structures from one crystal (MSOX) serial crystallography method can be used to provide multiple snapshots of the progress of enzymatic reactions taking place within a protein crystal. Such MSOX snapshots can be used as a reference for combined quantum mechanical/molecular mechanical (QM/MM) simulations of enzyme reactivity within the crystal. QM/MM calculations are used to identify details of reference states that cannot be directly observed by X-ray diffraction experiments, such as protonation and oxidation states. These reference states are then used as known fixed endpoints for the modeling of reaction paths. We investigate the mechanism of nitrite reduction in an Achromobacter cycloclastes copper nitrite reductase crystal using MSOX-guided QM/MM calculations, identifying the change in nitrite binding orientation with a change in copper oxidation state, and determining the reaction path to the final NO-bound MSOX structure. The results are compared with QM/MM simulations performed in a solvated environment.
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Affiliation(s)
- Kakali Sen
- School of Life Sciences, University of Essex, Wivenhoe Park, Colchester, Essex CO4 3SQ, United Kingdom.,Scientific Computing Department, STFC Daresbury Laboratory, Keckwick Lane, Daresbury, Warrington, Cheshire WA4 4AD, United Kingdom
| | - Michael A Hough
- School of Life Sciences, University of Essex, Wivenhoe Park, Colchester, Essex CO4 3SQ, United Kingdom
| | - Richard W Strange
- School of Life Sciences, University of Essex, Wivenhoe Park, Colchester, Essex CO4 3SQ, United Kingdom
| | - Chin Yong
- Scientific Computing Department, STFC Daresbury Laboratory, Keckwick Lane, Daresbury, Warrington, Cheshire WA4 4AD, United Kingdom
| | - Thomas W Keal
- Scientific Computing Department, STFC Daresbury Laboratory, Keckwick Lane, Daresbury, Warrington, Cheshire WA4 4AD, United Kingdom
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15
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Li X, Sun W, Qin X, Xie Y, Liu N, Luo X, Wang Y, Chen X. An interesting possibility of forming special hole stepping stones with high-stacking aromatic rings in proteins: three-π five-electron and four-π seven-electron resonance bindings. RSC Adv 2021; 11:26672-26682. [PMID: 35479969 PMCID: PMC9037495 DOI: 10.1039/d1ra05341h] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/12/2021] [Accepted: 07/30/2021] [Indexed: 11/30/2022] Open
Abstract
Long-range hole transfer of proteins plays an important role in many biological processes of living organisms. Therefore, it is highly useful to examine the possible hole stepping stones, which can facilitate hole transfer in proteins. However, the structures of stepping stones are diverse because of the complexity of the protein structures. In the present work, we proposed a series of special stepping stones, which are instantaneously formed by three and four packing aromatic side chains of amino acids to capture a hole, corresponding to three-π five-electron (π:π∴π↔π∴π:π) and four-π seven-electron (π:π∴π:π↔π:π:π∴π) resonance bindings with appropriate binding energies. The aromatic amino acids include histidine (His), phenylalanine (Phe), tyrosine (Tyr) and tryptophan (Trp). The formations of these special stepping stones can effectively reduce the local ionization potential of the high π-stacking region to efficiently capture the migration hole. The quick formations and separations of them promote the efficient hole transfer in proteins. More interestingly, we revealed that a hole cannot delocalize over infinite aromatic rings along the high π-π packing structure at the same time and the micro-surroundings of proteins can modulate the formations of π:π∴π↔π∴π:π and π:π∴π:π↔π:π:π∴π bindings. These results may contribute a new avenue to better understand the potential hole transfer pathway in proteins.
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Affiliation(s)
- Xin Li
- Chongqing Key Laboratory of Theoretical and Computational Chemistry, School of Chemistry and Chemical Engineering, Chongqing University Chongqing 401331 P.R. China
- National-Municipal Joint Engineering Laboratory for Chemical Process Intensification and Reaction, Chongqing University Chongqing 401331 P.R. China
| | - Weichao Sun
- Chongqing Key Laboratory of Theoretical and Computational Chemistry, School of Chemistry and Chemical Engineering, Chongqing University Chongqing 401331 P.R. China
- National-Municipal Joint Engineering Laboratory for Chemical Process Intensification and Reaction, Chongqing University Chongqing 401331 P.R. China
| | - Xin Qin
- Chongqing Key Laboratory of Theoretical and Computational Chemistry, School of Chemistry and Chemical Engineering, Chongqing University Chongqing 401331 P.R. China
- National-Municipal Joint Engineering Laboratory for Chemical Process Intensification and Reaction, Chongqing University Chongqing 401331 P.R. China
| | - Yuxin Xie
- Chongqing Key Laboratory of Theoretical and Computational Chemistry, School of Chemistry and Chemical Engineering, Chongqing University Chongqing 401331 P.R. China
- National-Municipal Joint Engineering Laboratory for Chemical Process Intensification and Reaction, Chongqing University Chongqing 401331 P.R. China
| | - Nian Liu
- Chongqing Key Laboratory of Theoretical and Computational Chemistry, School of Chemistry and Chemical Engineering, Chongqing University Chongqing 401331 P.R. China
- National-Municipal Joint Engineering Laboratory for Chemical Process Intensification and Reaction, Chongqing University Chongqing 401331 P.R. China
| | - Xin Luo
- Chongqing Key Laboratory of Theoretical and Computational Chemistry, School of Chemistry and Chemical Engineering, Chongqing University Chongqing 401331 P.R. China
- National-Municipal Joint Engineering Laboratory for Chemical Process Intensification and Reaction, Chongqing University Chongqing 401331 P.R. China
| | - Yuanying Wang
- Chongqing Key Laboratory of Theoretical and Computational Chemistry, School of Chemistry and Chemical Engineering, Chongqing University Chongqing 401331 P.R. China
- National-Municipal Joint Engineering Laboratory for Chemical Process Intensification and Reaction, Chongqing University Chongqing 401331 P.R. China
| | - Xiaohua Chen
- Chongqing Key Laboratory of Theoretical and Computational Chemistry, School of Chemistry and Chemical Engineering, Chongqing University Chongqing 401331 P.R. China
- National-Municipal Joint Engineering Laboratory for Chemical Process Intensification and Reaction, Chongqing University Chongqing 401331 P.R. China
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16
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Kono F, Tamada T. Neutron crystallography for the elucidation of enzyme catalysis. Curr Opin Struct Biol 2021; 71:36-42. [PMID: 34214927 DOI: 10.1016/j.sbi.2021.05.007] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/31/2021] [Revised: 05/08/2021] [Accepted: 05/22/2021] [Indexed: 11/26/2022]
Abstract
Hydrogen atoms and hydration water molecules in proteins are indispensable for many biochemical processes, especially enzymatic catalysis. The locations of hydrogen atoms in proteins are usually predicted based on X-ray structures, but it is still very difficult to know the ionization states of the catalytic residues, the hydration structure of the protein, and the characteristics of hydrogen-bonding interactions. Neutron crystallography allows the direct observation of hydrogen atoms that play crucial roles in molecular recognition and the catalytic reactions of enzymes. In this review, we present the current status of neutron crystallography in structural biology and recent neutron structural analyses of three enzymes: ascorbate peroxidase, the main protease of severe acute respiratory syndrome coronavirus 2, and copper-containing nitrite reductase.
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Affiliation(s)
- Fumiaki Kono
- Institute for Quantum Life Science, National Institutes for Quantum and Radiological Science and Technology, 2-4 Shirakata, Tokai, Ibaraki 319-1106, Japan
| | - Taro Tamada
- Institute for Quantum Life Science, National Institutes for Quantum and Radiological Science and Technology, 2-4 Shirakata, Tokai, Ibaraki 319-1106, Japan.
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17
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Qin X, Chen X. Remote Water-Mediated Proton Transfer Triggers Inter-Cu Electron Transfer: Nitrite Reduction Activation in Copper-Containing Nitrite Reductase. Chembiochem 2021; 22:1405-1414. [PMID: 33295048 DOI: 10.1002/cbic.202000644] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/10/2020] [Revised: 12/07/2020] [Indexed: 11/05/2022]
Abstract
The copper-containing nitrite reductase (CuNiR) catalyzes the biological conversion of nitrite to nitric oxide; key long-range electron/proton transfers are involved in the catalysis. However, the details of the electron-/proton-transfer mechanism are still unknown. In particular, the driving force of the electron transfer from the type-1 copper (T1Cu) site to the type-2 copper (T2Cu) site is ambiguous. Here, we explored the two possible proton-transfer channels, the high-pH proton channel and the primary proton channel, by using two-layered ONIOM calculations. Our calculation results reveal that the driving force for electron transfer from T1Cu to T2Cu comes from a remote water-mediated triple-proton-coupled electron-transfer mechanism. In the high-pH proton channel, the water-mediated triple-proton transfer occurs from Glu113 to an intermediate water molecule, whereas in the primary channel, the transfer is from Lys128 to His260. Subsequently, the two channels employ another two or three distinct proton-transfer steps to deliver the proton to the nitrite substrate at the T2Cu site. These findings explain the detailed proton-/electron-transfer mechanisms of copper-containing nitrite reductase and could extend our understanding of the diverse proton-coupled electron-transfer mechanisms in complicated proteins.
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Affiliation(s)
- Xin Qin
- Chongqing Key Laboratory of Theoretical and Computational Chemistry, School of Chemistry and Chemical Engineering, Chongqing University, 55 University City South Road, Shapingba District, Chongqing, 401331, P. R. China.,National-Municipal Joint Engineering Laboratory for Chemical Process Intensification and Reaction, Chongqing University, Chongqing, 401331, P. R. China
| | - Xiaohua Chen
- Chongqing Key Laboratory of Theoretical and Computational Chemistry, School of Chemistry and Chemical Engineering, Chongqing University, 55 University City South Road, Shapingba District, Chongqing, 401331, P. R. China.,National-Municipal Joint Engineering Laboratory for Chemical Process Intensification and Reaction, Chongqing University, Chongqing, 401331, P. R. China
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18
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Rose SL, Antonyuk SV, Sasaki D, Yamashita K, Hirata K, Ueno G, Ago H, Eady RR, Tosha T, Yamamoto M, Hasnain SS. An unprecedented insight into the catalytic mechanism of copper nitrite reductase from atomic-resolution and damage-free structures. SCIENCE ADVANCES 2021; 7:eabd8523. [PMID: 33523860 PMCID: PMC7775769 DOI: 10.1126/sciadv.abd8523] [Citation(s) in RCA: 16] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/16/2020] [Accepted: 10/27/2020] [Indexed: 05/31/2023]
Abstract
Copper-containing nitrite reductases (CuNiRs), encoded by nirK gene, are found in all kingdoms of life with only 5% of CuNiR denitrifiers having two or more copies of nirK Recently, we have identified two copies of nirK genes in several α-proteobacteria of the order Rhizobiales including Bradyrhizobium sp. ORS 375, encoding a four-domain heme-CuNiR and the usual two-domain CuNiR (Br 2DNiR). Compared with two of the best-studied two-domain CuNiRs represented by the blue (AxNiR) and green (AcNiR) subclasses, Br 2DNiR, a blue CuNiR, shows a substantially lower catalytic efficiency despite a sequence identity of ~70%. Advanced synchrotron radiation and x-ray free-electron laser are used to obtain the most accurate (atomic resolution with unrestrained SHELX refinement) and damage-free (free from radiation-induced chemistry) structures, in as-isolated, substrate-bound, and product-bound states. This combination has shed light on the protonation states of essential catalytic residues, additional reaction intermediates, and how catalytic efficiency is modulated.
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Affiliation(s)
- Samuel L Rose
- Molecular Biophysics Group, Life Sciences Building and Institute of Systems, Molecular and Integrative Biology, Faculty of Health and Life Sciences, University of Liverpool, Liverpool L69 7ZB, UK
| | - Svetlana V Antonyuk
- Molecular Biophysics Group, Life Sciences Building and Institute of Systems, Molecular and Integrative Biology, Faculty of Health and Life Sciences, University of Liverpool, Liverpool L69 7ZB, UK
| | - Daisuke Sasaki
- Molecular Biophysics Group, Life Sciences Building and Institute of Systems, Molecular and Integrative Biology, Faculty of Health and Life Sciences, University of Liverpool, Liverpool L69 7ZB, UK
| | - Keitaro Yamashita
- Department of Biological Sciences, Graduate School of Science, The University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo 113-0033, Japan
| | - Kunio Hirata
- RIKEN SPring-8 Center, 1-1-1 Kouto, Sayo, Hyogo 679-5148, Japan
| | - Go Ueno
- RIKEN SPring-8 Center, 1-1-1 Kouto, Sayo, Hyogo 679-5148, Japan
| | - Hideo Ago
- RIKEN SPring-8 Center, 1-1-1 Kouto, Sayo, Hyogo 679-5148, Japan
| | - Robert R Eady
- Molecular Biophysics Group, Life Sciences Building and Institute of Systems, Molecular and Integrative Biology, Faculty of Health and Life Sciences, University of Liverpool, Liverpool L69 7ZB, UK
| | - Takehiko Tosha
- RIKEN SPring-8 Center, 1-1-1 Kouto, Sayo, Hyogo 679-5148, Japan
| | - Masaki Yamamoto
- RIKEN SPring-8 Center, 1-1-1 Kouto, Sayo, Hyogo 679-5148, Japan.
| | - S Samar Hasnain
- Molecular Biophysics Group, Life Sciences Building and Institute of Systems, Molecular and Integrative Biology, Faculty of Health and Life Sciences, University of Liverpool, Liverpool L69 7ZB, UK.
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19
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Cristaldi JC, Ferroni FM, Duré AB, Ramírez CS, Dalosto SD, Rizzi AC, González PJ, Rivas MG, Brondino CD. Heterologous production and functional characterization of Bradyrhizobium japonicum copper-containing nitrite reductase and its physiological redox partner cytochrome c550. Metallomics 2020; 12:2084-2097. [PMID: 33226040 DOI: 10.1039/d0mt00177e] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Two domain copper-nitrite reductases (NirK) contain two types of copper centers, one electron transfer (ET) center of type 1 (T1) and a catalytic site of type 2 (T2). NirK activity is pH-dependent, which has been suggested to be produced by structural modifications at high pH of some catalytically relevant residues. To characterize the pH-dependent kinetics of NirK and the relevance of T1 covalency in intraprotein ET, we studied the biochemical, electrochemical, and spectroscopic properties complemented with QM/MM calculations of Bradyrhizobium japonicum NirK (BjNirK) and of its electron donor cytochrome c550 (BjCycA). BjNirK presents absorption spectra determined mainly by a S(Cys)3pπ → Cu2+ ligand-to-metal charge-transfer (LMCT) transition. The enzyme shows low activity likely due to the higher flexibility of a protein loop associated with BjNirK/BjCycA interaction. Nitrite is reduced at high pH in a T1-decoupled way without T1 → T2 ET in which proton delivery for nitrite reduction at T2 is maintained. Our results are analyzed in comparison with previous results found by us in Sinorhizobium meliloti NirK, whose main UV-vis absorption features are determined by S(Cys)3pσ/π → Cu2+ LMCT transitions.
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Affiliation(s)
- Julio C Cristaldi
- Departamento de Física, Facultad de Bioquímica y Ciencias Biológicas, Universidad Nacional del Litoral and CONICET, S3000ZAA Santa Fe, Argentina.
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20
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Hough MA, Conradie J, Strange RW, Antonyuk SV, Eady RR, Ghosh A, Hasnain SS. Nature of the copper-nitrosyl intermediates of copper nitrite reductases during catalysis. Chem Sci 2020; 11:12485-12492. [PMID: 34094452 PMCID: PMC8163067 DOI: 10.1039/d0sc04797j] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
Abstract
The design and synthesis of copper complexes that can reduce nitrite to NO has attracted considerable interest. They have been guided by the structural information on the catalytic Cu centre of the widespread enzymes Cu nitrite reductases but the chemically novel side-on binding of NO observed in all crystallographic studies of these enzymes has been questioned in terms of its functional relevance. We show conversion of NO2− to NO in the crystal maintained at 170 K and present ‘molecular movies’ defining events during enzyme turnover including the formation of side-on Cu-NO intermediate. DFT modelling suggests that both true {CuNO}11 and formal {CuNO}10 states may occur as side-on forms in an enzymatic active site with the stability of the {CuNO}10 side-on form governed by the protonation state of the histidine ligands. Formation of a copper-nitrosyl intermediate thus needs to be accommodated in future design templates for functional synthetic Cu-NiR complexes. Observation of side-on copper-nitrosyl intermediate and its confirmation by DFT during catalysis of copper nitrite reductases.![]()
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Affiliation(s)
- Michael A Hough
- School of Life Sciences, University of Essex Wivenhoe Park Colchester CO4 3SQW UK
| | - Jeanet Conradie
- Department of Chemistry, Faculty of Natural and Agricultural Sciences, University of the Free State PO Box 339 Bloemfontein South Africa.,Department of Chemistry, UiT, The Arctic University of Tromsø 9037 Tromsø Norway
| | - Richard W Strange
- School of Life Sciences, University of Essex Wivenhoe Park Colchester CO4 3SQW UK
| | - Svetlana V Antonyuk
- Molecular Biophysics Group, Institute of Systems, Molecular and Integrative Biology, Faculty of Health and Life Sciences, University of Liverpool Liverpool L69 7ZB UK
| | - Robert R Eady
- Molecular Biophysics Group, Institute of Systems, Molecular and Integrative Biology, Faculty of Health and Life Sciences, University of Liverpool Liverpool L69 7ZB UK
| | - Abhik Ghosh
- Department of Chemistry, UiT, The Arctic University of Tromsø 9037 Tromsø Norway
| | - S Samar Hasnain
- Molecular Biophysics Group, Institute of Systems, Molecular and Integrative Biology, Faculty of Health and Life Sciences, University of Liverpool Liverpool L69 7ZB UK
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21
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Hedison TM, Shanmugam M, Heyes DJ, Edge R, Scrutton NS. Active Intermediates in Copper Nitrite Reductase Reactions Probed by a Cryotrapping-Electron Paramagnetic Resonance Approach. Angew Chem Int Ed Engl 2020; 59:13936-13940. [PMID: 32352195 PMCID: PMC7497095 DOI: 10.1002/anie.202005052] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/07/2020] [Indexed: 11/25/2022]
Abstract
Redox active metalloenzymes catalyse a range of biochemical processes essential for life. However, due to their complex reaction mechanisms, and often, their poor optical signals, detailed mechanistic understandings of them are limited. Here, we develop a cryoreduction approach coupled to electron paramagnetic resonance measurements to study electron transfer between the copper centers in the copper nitrite reductase (CuNiR) family of enzymes. Unlike alternative methods used to study electron transfer reactions, the cryoreduction approach presented here allows observation of the redox state of both metal centers, a direct read-out of electron transfer, determines the presence of the substrate/product in the active site and shows the importance of protein motion in inter-copper electron transfer catalyzed by CuNiRs. Cryoreduction-EPR is broadly applicable for the study of electron transfer in other redox enzymes and paves the way to explore transient states in multiple redox-center containing proteins (homo and hetero metal ions).
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Affiliation(s)
- Tobias M. Hedison
- Manchester Institute of Biotechnology and School of ChemistryUniversity of ManchesterPrincess StreetManchesterM1 7DNUK
- BBSRC and EPSRC funded Future Biomanfacturing Research HubManchester Institute of Biotechnology and School of ChemistryUniversity of ManchesterPrincess StreetManchesterM1 7DNUK
| | - Muralidharan Shanmugam
- Manchester Institute of Biotechnology and School of ChemistryUniversity of ManchesterPrincess StreetManchesterM1 7DNUK
| | - Derren J. Heyes
- Manchester Institute of Biotechnology and School of ChemistryUniversity of ManchesterPrincess StreetManchesterM1 7DNUK
| | - Ruth Edge
- Dalton Cumbrian FacilityThe University of ManchesterCumbriaUK
| | - Nigel S. Scrutton
- Manchester Institute of Biotechnology and School of ChemistryUniversity of ManchesterPrincess StreetManchesterM1 7DNUK
- BBSRC and EPSRC funded Future Biomanfacturing Research HubManchester Institute of Biotechnology and School of ChemistryUniversity of ManchesterPrincess StreetManchesterM1 7DNUK
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22
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Hedison TM, Shanmugam M, Heyes DJ, Edge R, Scrutton NS. Active Intermediates in Copper Nitrite Reductase Reactions Probed by a Cryotrapping‐Electron Paramagnetic Resonance Approach. Angew Chem Int Ed Engl 2020. [DOI: 10.1002/ange.202005052] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
Affiliation(s)
- Tobias M. Hedison
- Manchester Institute of Biotechnology and School of Chemistry University of Manchester Princess Street Manchester M1 7DN UK
- BBSRC and EPSRC funded Future Biomanfacturing Research Hub Manchester Institute of Biotechnology and School of Chemistry University of Manchester Princess Street Manchester M1 7DN UK
| | - Muralidharan Shanmugam
- Manchester Institute of Biotechnology and School of Chemistry University of Manchester Princess Street Manchester M1 7DN UK
| | - Derren J. Heyes
- Manchester Institute of Biotechnology and School of Chemistry University of Manchester Princess Street Manchester M1 7DN UK
| | - Ruth Edge
- Dalton Cumbrian Facility The University of Manchester Cumbria UK
| | - Nigel S. Scrutton
- Manchester Institute of Biotechnology and School of Chemistry University of Manchester Princess Street Manchester M1 7DN UK
- BBSRC and EPSRC funded Future Biomanfacturing Research Hub Manchester Institute of Biotechnology and School of Chemistry University of Manchester Princess Street Manchester M1 7DN UK
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23
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Sasaki D, Watanabe TF, Eady RR, Garratt RC, Antonyuk SV, Hasnain SS. Reverse protein engineering of a novel 4-domain copper nitrite reductase reveals functional regulation by protein-protein interaction. FEBS J 2020; 288:262-280. [PMID: 32255260 DOI: 10.1111/febs.15324] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/16/2019] [Revised: 03/16/2020] [Accepted: 04/01/2020] [Indexed: 01/03/2023]
Abstract
Cu-containing nitrite reductases that convert NO2 - to NO are critical enzymes in nitrogen-based energy metabolism. Among organisms in the order Rhizobiales, we have identified two copies of nirK, one encoding a new class of 4-domain CuNiR that has both cytochrome and cupredoxin domains fused at the N terminus and the other, a classical 2-domain CuNiR (Br2D NiR). We report the first enzymatic studies of a novel 4-domain CuNiR from Bradyrhizobium sp. ORS 375 (BrNiR), its genetically engineered 3- and 2-domain variants, and Br2D NiR revealing up to ~ 500-fold difference in catalytic efficiency in comparison with classical 2-domain CuNiRs. Contrary to the expectation that tethering would enhance electron delivery by restricting the conformational search by having a self-contained donor-acceptor system, we demonstrate that 4-domain BrNiR utilizes N-terminal tethering for downregulating enzymatic activity instead. Both Br2D NiR and an engineered 2-domain variant of BrNiR (Δ(Cytc-Cup) BrNiR) have 3 to 5% NiR activity compared to the well-characterized 2-domain CuNiRs from Alcaligenes xylosoxidans (AxNiR) and Achromobacter cycloclastes (AcNiR). Structural comparison of Δ(Cytc-Cup) BrNiR and Br2D NiR with classical 2-domain AxNiR and AcNiR reveals structural differences of the proton transfer pathway that could be responsible for the lowering of activity. Our study provides insights into unique structural and functional characteristics of naturally occurring 4-domain CuNiR and its engineered 3- and 2-domain variants. The reverse protein engineering approach utilized here has shed light onto the broader question of the evolution of transient encounter complexes and tethered electron transfer complexes. ENZYME: Copper-containing nitrite reductase (CuNiR) (EC 1.7.2.1). DATABASE: The atomic coordinate and structure factor of Δ(Cytc-Cup) BrNiR and Br2D NiR have been deposited in the Protein Data Bank (http://www.rcsb.org/) under the accession code 6THE and 6THF, respectively.
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Affiliation(s)
- Daisuke Sasaki
- Molecular Biophysics Group, Institute of Systems, Molecular and Integrative Biology, Faculty of Health and Life Sciences, University of Liverpool, UK
| | - Tatiana F Watanabe
- Molecular Biophysics Group, Institute of Systems, Molecular and Integrative Biology, Faculty of Health and Life Sciences, University of Liverpool, UK.,The São Carlos Institute of Physics, University of São Paulo, São Carlos, Brazil
| | - Robert R Eady
- Molecular Biophysics Group, Institute of Systems, Molecular and Integrative Biology, Faculty of Health and Life Sciences, University of Liverpool, UK
| | - Richard C Garratt
- The São Carlos Institute of Physics, University of São Paulo, São Carlos, Brazil
| | - Svetlana V Antonyuk
- Molecular Biophysics Group, Institute of Systems, Molecular and Integrative Biology, Faculty of Health and Life Sciences, University of Liverpool, UK
| | - S Samar Hasnain
- Molecular Biophysics Group, Institute of Systems, Molecular and Integrative Biology, Faculty of Health and Life Sciences, University of Liverpool, UK
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24
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High-resolution neutron crystallography visualizes an OH-bound resting state of a copper-containing nitrite reductase. Proc Natl Acad Sci U S A 2020; 117:4071-4077. [PMID: 32041886 PMCID: PMC7049163 DOI: 10.1073/pnas.1918125117] [Citation(s) in RCA: 18] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022] Open
Abstract
X-ray crystallography often fails to determine the positions of hydrogen atoms, which play crucial roles in enzymatic reactions. Despite many X-ray crystallographic studies, the reaction mechanism of copper-containing nitrite reductases (CuNIRs), which reduce nitrite using two protons, has been controversial. The high-resolution neutron structure of a CuNIR reveals the protonation states of catalytic residues and key water molecules, thus providing insights into the catalytic mechanism. The catalytic Cu is shown to be coordinated by a hydroxide ion and not water. Furthermore, the hydrogen-deuterium exchange ratio suggests that intramolecular electron transfer is involved in a hydrogen-bond jump. These observations are consistent with previous computational chemistry; therefore, our study forms a bridge between the structural biology and quantum chemistry of CuNIRs. Copper-containing nitrite reductases (CuNIRs) transform nitrite to gaseous nitric oxide, which is a key process in the global nitrogen cycle. The catalytic mechanism has been extensively studied to ultimately achieve rational control of this important geobiochemical reaction. However, accumulated structural biology data show discrepancies with spectroscopic and computational studies; hence, the reaction mechanism is still controversial. In particular, the details of the proton transfer involved in it are largely unknown. This situation arises from the failure of determining positions of hydrogen atoms and protons, which play essential roles at the catalytic site of CuNIRs, even with atomic resolution X-ray crystallography. Here, we determined the 1.50 Å resolution neutron structure of a CuNIR from Geobacillus thermodenitrificans (trimer molecular mass of ∼106 kDa) in its resting state at low pH. Our neutron structure reveals the protonation states of catalytic residues (deprotonated aspartate and protonated histidine), thus providing insights into the catalytic mechanism. We found that a hydroxide ion can exist as a ligand to the catalytic Cu atom in the resting state even at a low pH. This OH-bound Cu site is unexpected from previously given X-ray structures but consistent with a reaction intermediate suggested by computational chemistry. Furthermore, the hydrogen-deuterium exchange ratio in our neutron structure suggests that the intramolecular electron transfer pathway has a hydrogen-bond jump, which is proposed by quantum chemistry. Our study can seamlessly link the structural biology to the computational chemistry of CuNIRs, boosting our understanding of the enzymes at the atomic and electronic levels.
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25
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Mondal A, Reddy KP, Bertke JA, Kundu S. Phenol Reduces Nitrite to NO at Copper(II): Role of a Proton-Responsive Outer Coordination Sphere in Phenol Oxidation. J Am Chem Soc 2020; 142:1726-1730. [PMID: 31910624 DOI: 10.1021/jacs.9b11597] [Citation(s) in RCA: 18] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
Abstract
In the view of physiological significance, the transition-metal-mediated routes for nitrite (NO2-) to nitric oxide (NO) conversion and phenol oxidation are of prime importance. Probing the reactivity of substituted phenols toward the nitritocopper(II) cryptate complex [mC]Cu(κ2-O2N)(ClO4) (1a), this report illustrates NO release from nitrite at copper(II) following a proton-coupled electron transfer (PCET) pathway. Moreover, a different protonated state of 1a with a proton hosted in the outer coordination sphere, [mCH]Cu(κ2-O2N)(ClO4)2 (3), also reacts with substituted phenols via primary electron transfer from the phenol. Intriguingly, the alternative mechanism operative because of the presence of a proton at the remote site in 3 facilitates an unusual anaerobic pathway for phenol nitration.
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Affiliation(s)
- Aditesh Mondal
- School of Chemistry , Indian Institute of Science Education and Research Thiruvananthapuram (IISER-TVM) , Thiruvananthapuram 695551 , India
| | - Kiran P Reddy
- School of Chemistry , Indian Institute of Science Education and Research Thiruvananthapuram (IISER-TVM) , Thiruvananthapuram 695551 , India
| | - Jeffery A Bertke
- Department of Chemistry , Georgetown University , Box 571227-1227, Washington , D.C. 20057 , United States
| | - Subrata Kundu
- School of Chemistry , Indian Institute of Science Education and Research Thiruvananthapuram (IISER-TVM) , Thiruvananthapuram 695551 , India
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26
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Cheng R, Wu C, Cao Z, Wang B. QM/MM MD simulations reveal an asynchronous PCET mechanism for nitrite reduction by copper nitrite reductase. Phys Chem Chem Phys 2020; 22:20922-20928. [DOI: 10.1039/d0cp03053h] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
The nitrite reduction in copper nitrite reductase is found to proceed through an asynchronous proton-coupled electron transfer (PCET) mechanism, with electron transfer from T1-Cu to T2-Cu preceding the proton transfer from Asp98 to nitrite.
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Affiliation(s)
- Ronny Cheng
- State Key Laboratory of Physical Chemistry of Solid Surfaces and Fujian Provincial Key Laboratory of Theoretical and Computational Chemistry
- College of Chemistry and Chemical Engineering
- Xiamen University
- Xiamen 361005
- P. R. China
| | - Chun Wu
- College of Science and Mathematics
- Rowan University
- Glassboro
- 08028 USA
| | - Zexing Cao
- State Key Laboratory of Physical Chemistry of Solid Surfaces and Fujian Provincial Key Laboratory of Theoretical and Computational Chemistry
- College of Chemistry and Chemical Engineering
- Xiamen University
- Xiamen 361005
- P. R. China
| | - Binju Wang
- State Key Laboratory of Physical Chemistry of Solid Surfaces and Fujian Provincial Key Laboratory of Theoretical and Computational Chemistry
- College of Chemistry and Chemical Engineering
- Xiamen University
- Xiamen 361005
- P. R. China
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27
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Hedison T, Shenoy RT, Iorgu AI, Heyes DJ, Fisher K, Wright GSA, Hay S, Eady RR, Antonyuk SV, Hasnain SS, Scrutton NS. Unexpected Roles of a Tether Harboring a Tyrosine Gatekeeper Residue in Modular Nitrite Reductase Catalysis. ACS Catal 2019; 9:6087-6099. [PMID: 32051772 PMCID: PMC7007197 DOI: 10.1021/acscatal.9b01266] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/27/2019] [Revised: 05/19/2019] [Indexed: 01/26/2023]
Abstract
It is generally assumed that tethering enhances rates of electron harvesting and delivery to active sites in multidomain enzymes by proximity and sampling mechanisms. Here, we explore this idea in a tethered 3-domain, trimeric copper-containing nitrite reductase. By reverse engineering, we find that tethering does not enhance the rate of electron delivery from its pendant cytochrome c to the catalytic copper-containing core. Using a linker that harbors a gatekeeper tyrosine in a nitrite access channel, the tethered haem domain enables catalysis by other mechanisms. Tethering communicates the redox state of the haem to the distant T2Cu center that helps initiate substrate binding for catalysis. It also tunes copper reduction potentials, suppresses reductive enzyme inactivation, enhances enzyme affinity for substrate, and promotes intercopper electron transfer. Tethering has multiple unanticipated beneficial roles, the combination of which fine-tunes function beyond simplistic mechanisms expected from proximity and restrictive sampling models.
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Affiliation(s)
- Tobias
M. Hedison
- Manchester
Institute of Biotechnology and School of Chemistry, Faculty of Science
and Engineering, The University of Manchester, 131 Princess Street, Manchester M1 7DN, United Kingdom
| | - Rajesh T. Shenoy
- Molecular
Biophysics Group, Institute of Integrative Biology, Faculty of Health
and Life Sciences, University of Liverpool, Liverpool L69 7ZB, United Kingdom
| | - Andreea I. Iorgu
- Manchester
Institute of Biotechnology and School of Chemistry, Faculty of Science
and Engineering, The University of Manchester, 131 Princess Street, Manchester M1 7DN, United Kingdom
| | - Derren J. Heyes
- Manchester
Institute of Biotechnology and School of Chemistry, Faculty of Science
and Engineering, The University of Manchester, 131 Princess Street, Manchester M1 7DN, United Kingdom
| | - Karl Fisher
- Manchester
Institute of Biotechnology and School of Chemistry, Faculty of Science
and Engineering, The University of Manchester, 131 Princess Street, Manchester M1 7DN, United Kingdom
| | - Gareth S. A. Wright
- Molecular
Biophysics Group, Institute of Integrative Biology, Faculty of Health
and Life Sciences, University of Liverpool, Liverpool L69 7ZB, United Kingdom
| | - Sam Hay
- Manchester
Institute of Biotechnology and School of Chemistry, Faculty of Science
and Engineering, The University of Manchester, 131 Princess Street, Manchester M1 7DN, United Kingdom
| | - Robert R. Eady
- Molecular
Biophysics Group, Institute of Integrative Biology, Faculty of Health
and Life Sciences, University of Liverpool, Liverpool L69 7ZB, United Kingdom
| | - Svetlana V. Antonyuk
- Molecular
Biophysics Group, Institute of Integrative Biology, Faculty of Health
and Life Sciences, University of Liverpool, Liverpool L69 7ZB, United Kingdom
| | - S. Samar Hasnain
- Molecular
Biophysics Group, Institute of Integrative Biology, Faculty of Health
and Life Sciences, University of Liverpool, Liverpool L69 7ZB, United Kingdom
| | - Nigel S. Scrutton
- Manchester
Institute of Biotechnology and School of Chemistry, Faculty of Science
and Engineering, The University of Manchester, 131 Princess Street, Manchester M1 7DN, United Kingdom
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28
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Halsted TP, Yamashita K, Gopalasingam CC, Shenoy RT, Hirata K, Ago H, Ueno G, Blakeley MP, Eady RR, Antonyuk SV, Yamamoto M, Hasnain SS. Catalytically important damage-free structures of a copper nitrite reductase obtained by femtosecond X-ray laser and room-temperature neutron crystallography. IUCRJ 2019; 6:761-772. [PMID: 31316819 PMCID: PMC6608623 DOI: 10.1107/s2052252519008285] [Citation(s) in RCA: 18] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/27/2019] [Accepted: 06/12/2019] [Indexed: 05/31/2023]
Abstract
Copper-containing nitrite reductases (CuNiRs) that convert NO2 - to NO via a CuCAT-His-Cys-CuET proton-coupled redox system are of central importance in nitrogen-based energy metabolism. These metalloenzymes, like all redox enzymes, are very susceptible to radiation damage from the intense synchrotron-radiation X-rays that are used to obtain structures at high resolution. Understanding the chemistry that underpins the enzyme mechanisms in these systems requires resolutions of better than 2 Å. Here, for the first time, the damage-free structure of the resting state of one of the most studied CuNiRs was obtained by combining X-ray free-electron laser (XFEL) and neutron crystallography. This represents the first direct comparison of neutron and XFEL structural data for any protein. In addition, damage-free structures of the reduced and nitrite-bound forms have been obtained to high resolution from cryogenically maintained crystals by XFEL crystallography. It is demonstrated that AspCAT and HisCAT are deprotonated in the resting state of CuNiRs at pH values close to the optimum for activity. A bridging neutral water (D2O) is positioned with one deuteron directed towards AspCAT Oδ1 and one towards HisCAT N∊2. The catalytic T2Cu-ligated water (W1) can clearly be modelled as a neutral D2O molecule as opposed to D3O+ or OD-, which have previously been suggested as possible alternatives. The bridging water restricts the movement of the unprotonated AspCAT and is too distant to form a hydrogen bond to the O atom of the bound nitrite that interacts with AspCAT. Upon the binding of NO2 - a proton is transferred from the bridging water to the Oδ2 atom of AspCAT, prompting electron transfer from T1Cu to T2Cu and reducing the catalytic redox centre. This triggers the transfer of a proton from AspCAT to the bound nitrite, enabling the reaction to proceed.
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Affiliation(s)
- Thomas P. Halsted
- Molecular Biophysics Group, Institute of Integrative Biology, Faculty of Health and Life Sciences, University of Liverpool, Liverpool L69 7ZB, England
| | - Keitaro Yamashita
- SR Life Science Instrumentation Unit, RIKEN SPring-8 Centre, Sayo 679-5148, Japan
| | - Chai C. Gopalasingam
- Molecular Biophysics Group, Institute of Integrative Biology, Faculty of Health and Life Sciences, University of Liverpool, Liverpool L69 7ZB, England
| | - Rajesh T. Shenoy
- Molecular Biophysics Group, Institute of Integrative Biology, Faculty of Health and Life Sciences, University of Liverpool, Liverpool L69 7ZB, England
| | - Kunio Hirata
- SR Life Science Instrumentation Unit, RIKEN SPring-8 Centre, Sayo 679-5148, Japan
| | - Hideo Ago
- SR Life Science Instrumentation Unit, RIKEN SPring-8 Centre, Sayo 679-5148, Japan
| | - Go Ueno
- SR Life Science Instrumentation Unit, RIKEN SPring-8 Centre, Sayo 679-5148, Japan
| | - Matthew P. Blakeley
- Large-Scale Structures Group, Institut Laue–Langevin, 71 Avenue des Martyrs, 38000 Grenoble, France
| | - Robert R. Eady
- Molecular Biophysics Group, Institute of Integrative Biology, Faculty of Health and Life Sciences, University of Liverpool, Liverpool L69 7ZB, England
| | - Svetlana V. Antonyuk
- Molecular Biophysics Group, Institute of Integrative Biology, Faculty of Health and Life Sciences, University of Liverpool, Liverpool L69 7ZB, England
| | - Masaki Yamamoto
- SR Life Science Instrumentation Unit, RIKEN SPring-8 Centre, Sayo 679-5148, Japan
| | - S. Samar Hasnain
- Molecular Biophysics Group, Institute of Integrative Biology, Faculty of Health and Life Sciences, University of Liverpool, Liverpool L69 7ZB, England
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29
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Nath AK, Ghosh C, Roy M, Seal M, Ghosh Dey S. Nitrite reductase activity of heme and copper bound Aβ peptides. Dalton Trans 2019; 48:7451-7461. [PMID: 31086893 DOI: 10.1039/c9dt00914k] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022]
Abstract
A significant abundance of copper (Cu) and iron in amyloid β (Aβ) plaques, and several heme related metabolic disorders are directly correlated with Alzheimer's disease (AD), and these together with co-localization of Aβ plaques with heme rich deposits in the brains of AD sufferers indicates a possible association of the said metals with the disease. Recently, the Aβ peptides have been found to bind heme and Cu individually as well as simultaneously. Another significant finding relevant to this is the lower levels of nitrite and nitrate found in the brains of patients suffering from AD. In this study, a combination of absorption and electron paramagnetic resonance spectroscopy and kinetic assays have been used to study the interaction of nitrite with the metal bound Aβ complexes. The data indicate that heme(III)-Cu(i)-Aβ, heme(II)-Cu(i)-Aβ, heme(II)-Aβ and Cu(i)-Aβ can reduce nitrite to nitric oxide (NO), an important biological messenger also related to AD, and thus behave as nitrite reductases. However these complexes reduce nitrite at different rates with heme(III)-Cu(i)-Aβ being the fastest following an inner sphere electron transfer mechanism. The rest of the metal-Aβ adducts follow an outer sphere electron transfer mechanism during nitrite reduction. Protonation from the Arg5 residue triggering the N-O bond heterolysis in heme(III) bound nitrite with a simultaneous electron transfer from the Cu(i) center to produce NO is the rate determining step, indicating a proton transfer followed by electron transfer (PTET) mechanism.
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Affiliation(s)
- Arnab Kumar Nath
- School of Chemical Sciences, Indian Association for the Cultivation of Science, Jadavpur, Kolkata 700032, India.
| | - Chandradeep Ghosh
- School of Chemical Sciences, Indian Association for the Cultivation of Science, Jadavpur, Kolkata 700032, India.
| | - Madhuparna Roy
- School of Chemical Sciences, Indian Association for the Cultivation of Science, Jadavpur, Kolkata 700032, India.
| | - Manas Seal
- School of Chemical Sciences, Indian Association for the Cultivation of Science, Jadavpur, Kolkata 700032, India.
| | - Somdatta Ghosh Dey
- School of Chemical Sciences, Indian Association for the Cultivation of Science, Jadavpur, Kolkata 700032, India.
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30
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Hedison TM, Heyes DJ, Shanmugam M, Iorgu AI, Scrutton NS. Solvent-slaved protein motions accompany proton coupled electron transfer reactions catalysed by copper nitrite reductase. Chem Commun (Camb) 2019; 55:5863-5866. [DOI: 10.1039/c9cc01026b] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
A novel approach to study PCET reactions illustrates the importance of solvent-slaved protein motions in copper nitrite reductase catalysis.
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Affiliation(s)
- Tobias M. Hedison
- The Manchester Institute of Biotechnology
- University of Manchester
- Manchester
- UK
| | - Derren J. Heyes
- The Manchester Institute of Biotechnology
- University of Manchester
- Manchester
- UK
| | | | - Andreea I. Iorgu
- The Manchester Institute of Biotechnology
- University of Manchester
- Manchester
- UK
| | - Nigel S. Scrutton
- The Manchester Institute of Biotechnology
- University of Manchester
- Manchester
- UK
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31
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Sen K, Hough MA, Strange RW, Yong CW, Keal TW. A QM/MM Study of Nitrite Binding Modes in a Three-Domain Heme-Cu Nitrite Reductase. Molecules 2018; 23:molecules23112997. [PMID: 30453538 PMCID: PMC6278305 DOI: 10.3390/molecules23112997] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/29/2018] [Revised: 11/13/2018] [Accepted: 11/14/2018] [Indexed: 11/16/2022] Open
Abstract
Copper-containing nitrite reductases (CuNiRs) play a key role in the global nitrogen cycle by reducing nitrite (NO2−) to nitric oxide, a reaction that involves one electron and two protons. In typical two-domain CuNiRs, the electron is acquired from an external electron-donating partner. The recently characterised Rastonia picketti (RpNiR) system is a three-domain CuNiR, where the cupredoxin domain is tethered to a heme c domain that can function as the electron donor. The nitrite reduction starts with the binding of NO2− to the T2Cu centre, but very little is known about how NO2− binds to native RpNiR. A recent crystallographic study of an RpNiR mutant suggests that NO2− may bind via nitrogen rather than through the bidentate oxygen mode typically observed in two-domain CuNiRs. In this work we have used combined quantum mechanical/molecular mechanical (QM/MM) methods to model the binding mode of NO2− with native RpNiR in order to determine whether the N-bound or O-bound orientation is preferred. Our results indicate that binding via nitrogen or oxygen is possible for the oxidised Cu(II) state of the T2Cu centre, but in the reduced Cu(I) state the N-binding mode is energetically preferred.
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Affiliation(s)
- Kakali Sen
- School of Biological Sciences, University of Essex, Wivenhoe Park, Colchester, Essex CO4 3SQ, UK.
- Scientific Computing Department, STFC Daresbury Laboratory, Warrington, Cheshire WA4 4AD, UK.
| | - Michael A Hough
- School of Biological Sciences, University of Essex, Wivenhoe Park, Colchester, Essex CO4 3SQ, UK.
| | - Richard W Strange
- School of Biological Sciences, University of Essex, Wivenhoe Park, Colchester, Essex CO4 3SQ, UK.
| | - Chin W Yong
- Scientific Computing Department, STFC Daresbury Laboratory, Warrington, Cheshire WA4 4AD, UK.
| | - Thomas W Keal
- Scientific Computing Department, STFC Daresbury Laboratory, Warrington, Cheshire WA4 4AD, UK.
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32
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Chuang WJ, Narwane M, Chen HY, Kao CL, Huang B, Hsu KM, Wang YM, Hsu SCN. Nitric oxide-release study of a bio-inspired copper(i)-nitrito complex under chemical and biological conditions. Dalton Trans 2018; 47:13151-13157. [PMID: 30175363 DOI: 10.1039/c8dt02281j] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022]
Abstract
The selective and efficient nitrite reduction process is ubiquitous in biological systems. To understand copper-mediated nitrite reduction, we developed a bio-inspired model system to investigate the mechanism of copper-containing nitrite reductase. A well-characterized copper(i)-nitrate complex with amino functionalized 2-(diphenylphosphino)aniline ligands, [(Ph2PC6H4(o-NH2))2Cu(ONO)], demonstrated the aniline protonation will cause NO release in an acidic environment. To further understand NO releasing ability, we also performed pH-dependency experiments and confocal imaging to release NO under physiological buffer conditions. According to titration and spectroscopic studies on the protonation reaction of complex [(Ph2PC6H4(o-NH2))2Cu(ONO)], we proposed a mechanistic pathway for proton transfer and NO release. Furthermore, DFT calculations predicted that the release of NO takes place via aniline in both organic and aqueous media. These results highlight the importance of the proton-rich microenvironment around the copper(i)-nitrite core to induce nitrate reduction in a chemical and biological environment.
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Affiliation(s)
- Wan-Jung Chuang
- Department of Medicinal and Applied Chemistry, Kaohsiung Medical University, Kaohsiung 807, Taiwan.
| | - Manmath Narwane
- Department of Medicinal and Applied Chemistry, Kaohsiung Medical University, Kaohsiung 807, Taiwan.
| | - Hsing-Yin Chen
- Department of Medicinal and Applied Chemistry, Kaohsiung Medical University, Kaohsiung 807, Taiwan.
| | - Chai-Lin Kao
- Department of Medicinal and Applied Chemistry, Kaohsiung Medical University, Kaohsiung 807, Taiwan. and Department of Medical Research, Kaohsiung Medical University Hospital, Kaohsiung 807, Taiwan
| | - Bin Huang
- Department of Biomedical Science and Environmental Biology, Kaohsiung Medical University, Kaohsiung 807, Taiwan
| | - Kuang-Mei Hsu
- Department of Biological Science and Technology, Institute of Molecular Medicine and Bioengineering, National Chiao Tung University, Hsinchu 300, Taiwan.
| | - Yun-Ming Wang
- Department of Biomedical Science and Environmental Biology, Kaohsiung Medical University, Kaohsiung 807, Taiwan and Department of Biological Science and Technology, Institute of Molecular Medicine and Bioengineering, National Chiao Tung University, Hsinchu 300, Taiwan.
| | - Sodio C N Hsu
- Department of Medicinal and Applied Chemistry, Kaohsiung Medical University, Kaohsiung 807, Taiwan. and Department of Medical Research, Kaohsiung Medical University Hospital, Kaohsiung 807, Taiwan
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33
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Koebke KJ, Pecoraro VL. Development of de Novo Copper Nitrite Reductases: Where We Are and Where We Need To Go. ACS Catal 2018; 8:8046-8057. [PMID: 30294504 DOI: 10.1021/acscatal.8b02153] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023]
Abstract
The development of redox-active metalloprotein catalysts is a challenging objective of de novo protein design. Within this Perspective we detail our efforts to create a redox-active Cu nitrite reductase (NiR) by incorporating Cu into the hydrophobic interior of well-defined three-stranded coiled coils (3SCCs). The scaffold contains three histidine residues that provide a layer of three nitrogen donors that mimic the type 2 catalytic site of NiR. We have found that this strategy successfully produces an active and stable CuNiR model that functions for over 1000 turnovers. Spectroscopic evidence indicates that the Cu(I) site has a lower coordination number in comparison to the enzyme, whereas the Cu(II) geometry may more faithfully reproduce the NiR type 2 center. Mutations at the helical interface successfully produce a hydrogen bond between an interfacial Glu residue and the Culigating His residue, which allows for the tuning of the redox potential over a 100 mV range. We successfully created constructs with as much as a 120-fold improvement from the original design by modifying the steric bulk above or below the Cu binding site. These systems are now the most active water-soluble and stable artificial NiR catalysts yet produced. Several avenues for improving the catalytic efficiency of later designs are detailed within this Perspective, including adjustment of their resting oxidation state, the use of asymmetric scaffolds to allow for single amino acid mutation within the second coordination sphere, and the design of hydrogen-bonding networks to tune residue orientation and electronics. Through these studies the TRI-H system has given insight into the difficulties that arise in creating a de novo redox active enzyme. Work to improve upon this model will provide strategies by which redox-active de novo enzymes may be tuned and detail how native enzymes accomplish catalytic efficiencies through proton gated redox catalysis.
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Affiliation(s)
- Karl J. Koebke
- Department of Chemistry, University of Michigan Ann Arbor, Michigan 48109, United States
| | - Vincent L. Pecoraro
- Department of Chemistry, University of Michigan Ann Arbor, Michigan 48109, United States
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34
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Feldt M, Mata RA. Hybrid Local Molecular Orbital: Molecular Orbital Calculations for Open Shell Systems. J Chem Theory Comput 2018; 14:5192-5202. [DOI: 10.1021/acs.jctc.8b00727] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Affiliation(s)
- Milica Feldt
- Institut für Physikalische Chemie, Universität Göttingen, Tammannstrasse 6, D-37077 Göttingen, Germany
| | - Ricardo A. Mata
- Institut für Physikalische Chemie, Universität Göttingen, Tammannstrasse 6, D-37077 Göttingen, Germany
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35
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Dong J, Sasaki D, Eady RR, Antonyuk SV, Hasnain SS. Identification of a tyrosine switch in copper-haem nitrite reductases. IUCRJ 2018; 5:510-518. [PMID: 30002851 PMCID: PMC6038957 DOI: 10.1107/s2052252518008242] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 02/16/2018] [Accepted: 06/04/2018] [Indexed: 06/08/2023]
Abstract
There are few cases where tyrosine has been shown to be involved in catalysis or the control of catalysis despite its ability to carry out chemistry at much higher potentials (1 V versus NHE). Here, it is shown that a tyrosine that blocks the hydrophobic substrate-entry channel in copper-haem nitrite reductases can be activated like a switch by the treatment of crystals of Ralstonia pickettii nitrite reductase (RpNiR) with nitric oxide (NO) (-0.8 ± 0.2 V). Treatment with NO results in an opening of the channel originating from the rotation of Tyr323 away from AspCAT97. Remarkably, the structure of a catalytic copper-deficient enzyme also shows Tyr323 in the closed position despite the absence of type 2 copper (T2Cu), clearly demonstrating that the status of Tyr323 is not controlled by T2Cu or its redox chemistry. It is also shown that the activation by NO is not through binding to haem. It is proposed that activation of the Tyr323 switch is controlled by NO through proton abstraction from tyrosine and the formation of HNO. The insight gained here for the use of tyrosine as a switch in catalysis has wider implications for catalysis in biology.
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Affiliation(s)
- Jianshu Dong
- Molecular Biophysics Group, Institute of Integrative Biology, Faculty of Health and Life Sciences, University of Liverpool, Liverpool L69 7ZX, England
| | - Daisuke Sasaki
- Molecular Biophysics Group, Institute of Integrative Biology, Faculty of Health and Life Sciences, University of Liverpool, Liverpool L69 7ZX, England
| | - Robert R. Eady
- Molecular Biophysics Group, Institute of Integrative Biology, Faculty of Health and Life Sciences, University of Liverpool, Liverpool L69 7ZX, England
| | - Svetlana V. Antonyuk
- Molecular Biophysics Group, Institute of Integrative Biology, Faculty of Health and Life Sciences, University of Liverpool, Liverpool L69 7ZX, England
| | - S. Samar Hasnain
- Molecular Biophysics Group, Institute of Integrative Biology, Faculty of Health and Life Sciences, University of Liverpool, Liverpool L69 7ZX, England
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36
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Horrell S, Kekilli D, Sen K, Owen RL, Dworkowski FSN, Antonyuk SV, Keal TW, Yong CW, Eady RR, Hasnain SS, Strange RW, Hough MA. Enzyme catalysis captured using multiple structures from one crystal at varying temperatures. IUCRJ 2018; 5:283-292. [PMID: 29755744 PMCID: PMC5929374 DOI: 10.1107/s205225251800386x] [Citation(s) in RCA: 19] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/11/2017] [Accepted: 03/05/2018] [Indexed: 05/24/2023]
Abstract
High-resolution crystal structures of enzymes in relevant redox states have transformed our understanding of enzyme catalysis. Recent developments have demonstrated that X-rays can be used, via the generation of solvated electrons, to drive reactions in crystals at cryogenic temperatures (100 K) to generate 'structural movies' of enzyme reactions. However, a serious limitation at these temperatures is that protein conformational motion can be significantly supressed. Here, the recently developed MSOX (multiple serial structures from one crystal) approach has been applied to nitrite-bound copper nitrite reductase at room temperature and at 190 K, close to the glass transition. During both series of multiple structures, nitrite was initially observed in a 'top-hat' geometry, which was rapidly transformed to a 'side-on' configuration before conversion to side-on NO, followed by dissociation of NO and substitution by water to reform the resting state. Density functional theory calculations indicate that the top-hat orientation corresponds to the oxidized type 2 copper site, while the side-on orientation is consistent with the reduced state. It is demonstrated that substrate-to-product conversion within the crystal occurs at a lower radiation dose at 190 K, allowing more of the enzyme catalytic cycle to be captured at high resolution than in the previous 100 K experiment. At room temperature the reaction was very rapid, but it remained possible to generate and characterize several structural states. These experiments open up the possibility of obtaining MSOX structural movies at multiple temperatures (MSOX-VT), providing an unparallelled level of structural information during catalysis for redox enzymes.
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Affiliation(s)
- Sam Horrell
- School of Biological Sciences, University of Essex, Wivenhoe Park, Colchester CO4 3SQ, England
| | - Demet Kekilli
- School of Biological Sciences, University of Essex, Wivenhoe Park, Colchester CO4 3SQ, England
| | - Kakali Sen
- School of Biological Sciences, University of Essex, Wivenhoe Park, Colchester CO4 3SQ, England
- Scientific Computing Department, STFC Daresbury Laboratory, Warrington WA4 4AD, England
| | - Robin L. Owen
- Diamond Light Source, Harwell Science and Innovation Campus, Didcot OX11 0DE, England
| | | | - Svetlana V. Antonyuk
- Molecular Biophysics Group, Institute of Integrative Biology, University of Liverpool, Crown Street, Liverpool L69 7ZB, England
| | - Thomas W. Keal
- Scientific Computing Department, STFC Daresbury Laboratory, Warrington WA4 4AD, England
| | - Chin W. Yong
- Scientific Computing Department, STFC Daresbury Laboratory, Warrington WA4 4AD, England
| | - Robert R. Eady
- Molecular Biophysics Group, Institute of Integrative Biology, University of Liverpool, Crown Street, Liverpool L69 7ZB, England
| | - S. Samar Hasnain
- Molecular Biophysics Group, Institute of Integrative Biology, University of Liverpool, Crown Street, Liverpool L69 7ZB, England
| | - Richard W. Strange
- School of Biological Sciences, University of Essex, Wivenhoe Park, Colchester CO4 3SQ, England
| | - Michael A. Hough
- School of Biological Sciences, University of Essex, Wivenhoe Park, Colchester CO4 3SQ, England
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37
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Cioncoloni G, Roger I, Wheatley PS, Wilson C, Morris RE, Sproules S, Symes MD. Proton-Coupled Electron Transfer Enhances the Electrocatalytic Reduction of Nitrite to NO in a Bioinspired Copper Complex. ACS Catal 2018. [DOI: 10.1021/acscatal.8b00361] [Citation(s) in RCA: 34] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Affiliation(s)
- Giacomo Cioncoloni
- WestCHEM, School of Chemistry, University of Glasgow, University Avenue, Glasgow G12 8QQ, United Kingdom
| | - Isolda Roger
- WestCHEM, School of Chemistry, University of Glasgow, University Avenue, Glasgow G12 8QQ, United Kingdom
| | - Paul S. Wheatley
- EaStCHEM School of Chemistry, University of St Andrews, Purdie Building, St Andrews KY16 9ST, United Kingdom
| | - Claire Wilson
- WestCHEM, School of Chemistry, University of Glasgow, University Avenue, Glasgow G12 8QQ, United Kingdom
| | - Russell E. Morris
- EaStCHEM School of Chemistry, University of St Andrews, Purdie Building, St Andrews KY16 9ST, United Kingdom
| | - Stephen Sproules
- WestCHEM, School of Chemistry, University of Glasgow, University Avenue, Glasgow G12 8QQ, United Kingdom
| | - Mark D. Symes
- WestCHEM, School of Chemistry, University of Glasgow, University Avenue, Glasgow G12 8QQ, United Kingdom
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38
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Chang YL, Lin YF, Chuang WJ, Kao CL, Narwane M, Chen HY, Chiang MY, Hsu SCN. Structure and nitrite reduction reactivity study of bio-inspired copper(i)-nitro complexes in steric and electronic considerations of tridentate nitrogen ligands. Dalton Trans 2018; 47:5335-5341. [PMID: 29589010 DOI: 10.1039/c7dt03843g] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/17/2023]
Abstract
Two copper(i)-nitro complexes [Tpm3-tBuCu(NO2)] (1) and [(Ph3P)2N][Tp3-tBuCu(NO2)] (2), containing steric bulky neutral tris(3-tert-butylpyrazolyl)methane and anionic hydrotris(3-tert-butylpyrazolyl)borate ligands, have been synthesized and characterized. Complex 2 adopts a unique κ2-binding mode of Tp3-tBu around the copper(i)-nitro environment in the solid state and shows a four-coordinated tetrahedral geometry surrounded by a nitro and three pz3-tBu groups in solution. Both complexes 1 and 2 allow for the stoichiometric reduction of NO2- to NO with H+ addition. The results of this effort show that increasing steric bulk and electron donation properties on the nitrogen ancillary ligand will improve the nitrite reduction ability of the copper(i)-nitro model complexes.
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Affiliation(s)
- Yu-Lun Chang
- Department of Medicinal and Applied Chemistry, Kaohsiung Medical University, Kaohsiung 807, Taiwan.
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Chandra Maji R, Mishra S, Bhandari A, Singh R, Olmstead MM, Patra AK. A Copper(II) Nitrite That Exhibits Change of Nitrite Binding Mode and Formation of Copper(II) Nitrosyl Prior to Nitric Oxide Evolution. Inorg Chem 2018; 57:1550-1561. [DOI: 10.1021/acs.inorgchem.7b02897] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Affiliation(s)
- Ram Chandra Maji
- Department of Chemistry, National Institute of Technology Durgapur, Mahatma Gandhi Avenue, Durgapur 713 209, India
| | - Saikat Mishra
- Department of Chemistry, National Institute of Technology Durgapur, Mahatma Gandhi Avenue, Durgapur 713 209, India
| | - Anirban Bhandari
- Department of Chemistry, National Institute of Technology Durgapur, Mahatma Gandhi Avenue, Durgapur 713 209, India
| | - Ravindra Singh
- Department of Chemistry, Indian Institute of Technology (IIT) Kanpur, Kanpur 208 016, India
| | - Marilyn M. Olmstead
- Department of Chemistry, University of California, Davis, California 95616, United States
| | - Apurba K. Patra
- Department of Chemistry, National Institute of Technology Durgapur, Mahatma Gandhi Avenue, Durgapur 713 209, India
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40
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Lintuluoto M, Lintuluoto JM. Intra-electron transfer induced by protonation in copper-containing nitrite reductase. Metallomics 2018. [DOI: 10.1039/c7mt00323d] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/27/2022]
Abstract
Electron transfer between two Cu sites in the enzyme induced by protonation of remote catalytic residues.
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Affiliation(s)
- Masami Lintuluoto
- Graduate School of Life and Environmental Sciences, Kyoto Prefectural University
- Kyoto 606-8522
- Japan
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41
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Halsted TP, Yamashita K, Hirata K, Ago H, Ueno G, Tosha T, Eady RR, Antonyuk SV, Yamamoto M, Hasnain SS. An unprecedented dioxygen species revealed by serial femtosecond rotation crystallography in copper nitrite reductase. IUCRJ 2018; 5:22-31. [PMID: 29354268 PMCID: PMC5755574 DOI: 10.1107/s2052252517016128] [Citation(s) in RCA: 19] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/05/2017] [Accepted: 11/07/2017] [Indexed: 05/24/2023]
Abstract
Synchrotron-based X-ray structural studies of ligand-bound enzymes are powerful tools to further our understanding of reaction mechanisms. For redox enzymes, it is necessary to study both the oxidized and reduced active sites to fully elucidate the reaction, an objective that is complicated by potential X-ray photoreduction. In the presence of the substrate, this can be exploited to construct a structural movie of the events associated with catalysis. Using the newly developed approach of serial femtosecond rotation crystallography (SF-ROX), an X-ray damage-free structure of the as-isolated copper nitrite reductase (CuNiR) was visualized. The sub-10 fs X-ray pulse length from the SACLA X-ray free-electron laser allowed diffraction data to be collected to 1.6 Å resolution in a 'time-frozen' state. The extremely short duration of the X-ray pulses ensures the capture of data prior to the onset of radiation-induced changes, including radiolysis. Unexpectedly, an O2 ligand was identified bound to the T2Cu in a brand-new binding mode for a diatomic ligand in CuNiRs. The observation of O2 in a time-frozen structure of the as-isolated oxidized enzyme provides long-awaited clear-cut evidence for the mode of O2 binding in CuNiRs. This provides an insight into how CuNiR from Alcaligenes xylosoxidans can function as an oxidase, reducing O2 to H2O2, or as a superoxide dismutase (SOD) since it was shown to have ∼56% of the dismutase activity of the bovine SOD enzyme some two decades ago.
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Affiliation(s)
- Thomas P. Halsted
- Molecular Biophysics Group, Institute of Integrative Biology, Faculty of Health and Life Sciences, University of Liverpool, Liverpool L69 7ZB, England
| | - Keitaro Yamashita
- SR Life Science Instrumentation Unit, RIKEN SPring-8 Centre, Sayo 679-5148, Japan
| | - Kunio Hirata
- SR Life Science Instrumentation Unit, RIKEN SPring-8 Centre, Sayo 679-5148, Japan
| | - Hideo Ago
- SR Life Science Instrumentation Unit, RIKEN SPring-8 Centre, Sayo 679-5148, Japan
| | - Go Ueno
- SR Life Science Instrumentation Unit, RIKEN SPring-8 Centre, Sayo 679-5148, Japan
| | - Takehiko Tosha
- Biometal Science Laboratory, RIKEN SPring-8 Centre, Sayo 679-5148, Japan
| | - Robert R. Eady
- Molecular Biophysics Group, Institute of Integrative Biology, Faculty of Health and Life Sciences, University of Liverpool, Liverpool L69 7ZB, England
| | - Svetlana V. Antonyuk
- Molecular Biophysics Group, Institute of Integrative Biology, Faculty of Health and Life Sciences, University of Liverpool, Liverpool L69 7ZB, England
| | - Masaki Yamamoto
- SR Life Science Instrumentation Unit, RIKEN SPring-8 Centre, Sayo 679-5148, Japan
| | - S. Samar Hasnain
- Molecular Biophysics Group, Institute of Integrative Biology, Faculty of Health and Life Sciences, University of Liverpool, Liverpool L69 7ZB, England
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42
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Study of the Cys-His bridge electron transfer pathway in a copper-containing nitrite reductase by site-directed mutagenesis, spectroscopic, and computational methods. Biochim Biophys Acta Gen Subj 2017; 1862:752-760. [PMID: 29051066 DOI: 10.1016/j.bbagen.2017.10.011] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/10/2017] [Revised: 09/06/2017] [Accepted: 10/12/2017] [Indexed: 11/22/2022]
Abstract
The Cys-His bridge as electron transfer conduit in the enzymatic catalysis of nitrite to nitric oxide by nitrite reductase from Sinorhizobium meliloti 2011 (SmNir) was evaluated by site-directed mutagenesis, steady state kinetic studies, UV-vis and EPR spectroscopic measurements as well as computational calculations. The kinetic, structural and spectroscopic properties of the His171Asp (H171D) and Cys172Asp (C172D) SmNir variants were compared with the wild type enzyme. Molecular properties of H171D and C172D indicate that these point mutations have not visible effects on the quaternary structure of SmNir. Both variants are catalytically incompetent using the physiological electron donor pseudoazurin, though C172D presents catalytic activity with the artificial electron donor methyl viologen (kcat=3.9(4) s-1) lower than that of wt SmNir (kcat=240(50) s-1). QM/MM calculations indicate that the lack of activity of H171D may be ascribed to the Nδ1H…OC hydrogen bond that partially shortcuts the T1-T2 bridging Cys-His covalent pathway. The role of the Nδ1H…OC hydrogen bond in the pH-dependent catalytic activity of wt SmNir is also analyzed by monitoring the T1 and T2 oxidation states at the end of the catalytic reaction of wt SmNir at pH6 and 10 by UV-vis and EPR spectroscopies. These data provide insight into how changes in Cys-His bridge interrupts the electron transfer between T1 and T2 and how the pH-dependent catalytic activity of the enzyme are related to pH-dependent structural modifications of the T1-T2 bridging chemical pathway.
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43
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Qin X, Deng L, Hu C, Li L, Chen X. Copper-Containing Nitrite Reductase Employing Proton-Coupled Spin-Exchanged Electron-Transfer and Multiproton Synchronized Transfer to Reduce Nitrite. Chemistry 2017; 23:14900-14910. [DOI: 10.1002/chem.201703221] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/12/2017] [Indexed: 11/08/2022]
Affiliation(s)
- Xin Qin
- National-Municipal Joint Engineering Laboratory for Chemical; Process Intensification and Reaction; School of Chemistry and Chemical Engineering; Chongqing University; Chongqing 401331 P.R. China
| | - Li Deng
- National-Municipal Joint Engineering Laboratory for Chemical; Process Intensification and Reaction; School of Chemistry and Chemical Engineering; Chongqing University; Chongqing 401331 P.R. China
| | - Caihong Hu
- National-Municipal Joint Engineering Laboratory for Chemical; Process Intensification and Reaction; School of Chemistry and Chemical Engineering; Chongqing University; Chongqing 401331 P.R. China
| | - Li Li
- National-Municipal Joint Engineering Laboratory for Chemical; Process Intensification and Reaction; School of Chemistry and Chemical Engineering; Chongqing University; Chongqing 401331 P.R. China
| | - Xiaohua Chen
- National-Municipal Joint Engineering Laboratory for Chemical; Process Intensification and Reaction; School of Chemistry and Chemical Engineering; Chongqing University; Chongqing 401331 P.R. China
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44
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Roger I, Wilson C, Senn HM, Sproules S, Symes MD. An investigation into the unusual linkage isomerization and nitrite reduction activity of a novel tris(2-pyridyl) copper complex. ROYAL SOCIETY OPEN SCIENCE 2017; 4:170593. [PMID: 28879000 PMCID: PMC5579116 DOI: 10.1098/rsos.170593] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/01/2017] [Accepted: 07/18/2017] [Indexed: 05/05/2023]
Abstract
The copper-containing nitrite reductases (CuNIRs) are a class of enzymes that mediate the reduction of nitrite to nitric oxide in biological systems. Metal-ligand complexes that reproduce the salient features of the active site of CuNIRs are therefore of fundamental interest, both for elucidating the possible mode of action of the enzymes and for developing biomimetic catalysts for nitrite reduction. Herein, we describe the synthesis and characterization of a new tris(2-pyridyl) copper complex ([Cu1(NO2)2]) that binds two molecules of nitrite, and displays all three of the common binding modes for [Formula: see text], with one nitrite bound in an asymmetric quasi-bidentate κ2-ONO manner and the other bound in a monodentate fashion with a linkage isomerism between the κ1-ONO and κ1-NO2 binding modes. We use density functional theory to help rationalize the presence of all three of these linkage isomers in one compound, before assessing the redox activity of [Cu1(NO2)2]. These latter studies show that the complex is not a competent nitrite reduction electrocatalyst in non-aqueous solvent, even in the presence of additional proton donors, a finding which may have implications for the design of biomimetic catalysts for nitrite reduction.
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Affiliation(s)
| | | | | | | | - Mark D. Symes
- WestCHEM, School of Chemistry, University of Glasgow, University Avenue, Glasgow G12 8QQ, UK
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45
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Sen K, Horrell S, Kekilli D, Yong CW, Keal TW, Atakisi H, Moreau DW, Thorne RE, Hough MA, Strange RW. Active-site protein dynamics and solvent accessibility in native Achromobacter cycloclastes copper nitrite reductase. IUCRJ 2017; 4:495-505. [PMID: 28875036 PMCID: PMC5571812 DOI: 10.1107/s2052252517007527] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 02/27/2017] [Accepted: 05/21/2017] [Indexed: 06/07/2023]
Abstract
Microbial nitrite reductases are denitrifying enzymes that are a major component of the global nitrogen cycle. Multiple structures measured from one crystal (MSOX data) of copper nitrite reductase at 240 K, together with molecular-dynamics simulations, have revealed protein dynamics at the type 2 copper site that are significant for its catalytic properties and for the entry and exit of solvent or ligands to and from the active site. Molecular-dynamics simulations were performed using different protonation states of the key catalytic residues (AspCAT and HisCAT) involved in the nitrite-reduction mechanism of this enzyme. Taken together, the crystal structures and simulations show that the AspCAT protonation state strongly influences the active-site solvent accessibility, while the dynamics of the active-site 'capping residue' (IleCAT), a determinant of ligand binding, are influenced both by temperature and by the protonation state of AspCAT. A previously unobserved conformation of IleCAT is seen in the elevated temperature series compared with 100 K structures. DFT calculations also show that the loss of a bound water ligand at the active site during the MSOX series is consistent with reduction of the type 2 Cu atom.
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Affiliation(s)
- Kakali Sen
- School of Biological Sciences, University of Essex, Wivenhoe Park, Colchester CO4 3SQ, England
- Scientific Computing Department, STFC Daresbury Laboratory, Warrington WA4 4AD, England
| | - Sam Horrell
- School of Biological Sciences, University of Essex, Wivenhoe Park, Colchester CO4 3SQ, England
| | - Demet Kekilli
- School of Biological Sciences, University of Essex, Wivenhoe Park, Colchester CO4 3SQ, England
| | - Chin W. Yong
- Scientific Computing Department, STFC Daresbury Laboratory, Warrington WA4 4AD, England
| | - Thomas W. Keal
- Scientific Computing Department, STFC Daresbury Laboratory, Warrington WA4 4AD, England
| | - Hakan Atakisi
- Physics Department, Cornell University, Ithaca, NY 14853, USA
| | - David W. Moreau
- Physics Department, Cornell University, Ithaca, NY 14853, USA
| | | | - Michael A. Hough
- School of Biological Sciences, University of Essex, Wivenhoe Park, Colchester CO4 3SQ, England
| | - Richard W. Strange
- School of Biological Sciences, University of Essex, Wivenhoe Park, Colchester CO4 3SQ, England
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46
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Metz S. N 2O Formation via Reductive Disproportionation of NO by Mononuclear Copper Complexes: A Mechanistic DFT Study. Inorg Chem 2017; 56:3820-3833. [PMID: 28291346 DOI: 10.1021/acs.inorgchem.6b02551] [Citation(s) in RCA: 22] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
The mechanism of the copper(I)-mediated reductive disproportionation reaction of NO to form N2O was investigated for five different 3,5-substituted tris(pyrazolyl)borate copper complexes (CuTpR1,R2) by means of DFT calculations. A thorough search of the potential surface was performed, using the B3LYP functional with the def2-SVP basis set for optimization purposes and def2-TZVP single-point calculations for constructing the potential energy surface for two of these complexes. The results can be condensed into six competing reaction mechanisms, two of which were more closely investigated using full def2-TZVP optimized potential and free energies. The results consistently predict the same mechanism to have the lowest overall barrier. For all five different complexes, this is found to be in good agreement with the experimental reaction barriers. The key intermediate for the transition from the N-bound reactant to the O-bound product contains a stable (NO)3 unit with one N-Cu and one O-Cu bond, which was not included in the mechanistic considerations reported in the literature. Further analysis of the charge distribution and the spin density demonstrates the formation of a Cu(II)-(N2O2-) intermediate and the electronic influence of the different ligands.
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Affiliation(s)
- Sebastian Metz
- Scientific Computing Department, STFC Daresbury Laboratory , Daresbury, Warrington, U.K
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47
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Horrell S, Kekilli D, Strange RW, Hough MA. Recent structural insights into the function of copper nitrite reductases. Metallomics 2017; 9:1470-1482. [DOI: 10.1039/c7mt00146k] [Citation(s) in RCA: 38] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Copper nitrite reductases (CuNiRs) catalyse the reduction of nitrite to nitric oxide as part of the denitrification pathway. In this review, we describe insights into CuNiR function from structural studies.
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Affiliation(s)
- Sam Horrell
- School of Biological Sciences
- University of Essex
- Colchester
- UK
| | - Demet Kekilli
- School of Biological Sciences
- University of Essex
- Colchester
- UK
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48
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Lintuluoto M, Lintuluoto JM. DFT Study on Enzyme Turnover Including Proton and Electron Transfers of Copper-Containing Nitrite Reductase. Biochemistry 2016; 55:4697-707. [DOI: 10.1021/acs.biochem.6b00423] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/24/2023]
Affiliation(s)
- Masami Lintuluoto
- Graduate
School of Life and Environmental Sciences, Kyoto Prefectural University, Shimogamohanki-cho,
Sakyo, Kyoto 606-8522, Japan
| | - Juha M. Lintuluoto
- Graduate
School of Engineering, Kyoto University, Katsura Campus, Nishikyo-ku, Kyoto 615-8530, Japan
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49
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Timmons AJ, Symes MD. Converting between the oxides of nitrogen using metal-ligand coordination complexes. Chem Soc Rev 2016; 44:6708-22. [PMID: 26158348 DOI: 10.1039/c5cs00269a] [Citation(s) in RCA: 66] [Impact Index Per Article: 8.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
Abstract
The oxides of nitrogen (chiefly NO, NO3(-), NO2(-) and N2O) are key components of the natural nitrogen cycle and are intermediates in a range of processes of enormous biological, environmental and industrial importance. Nature has evolved numerous enzymes which handle the conversion of these oxides to/from other small nitrogen-containing species and there also exist a number of heterogeneous catalysts that can mediate similar reactions. In the chemical space between these two extremes exist metal-ligand coordination complexes that are easier to interrogate than heterogeneous systems and simpler in structure than enzymes. In this Tutorial Review, we will examine catalysts for the inter-conversions of the various nitrogen oxides that are based on such complexes, looking in particular at more recent examples that take inspiration from the natural systems.
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Affiliation(s)
- Andrew J Timmons
- WestCHEM, School of Chemistry, University of Glasgow, University Avenue, Glasgow, G12 8QQ, UK.
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50
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Berry SM, Strange JN, Bladholm EL, Khatiwada B, Hedstrom CG, Sauer AM. Nitrite Reductase Activity in Engineered Azurin Variants. Inorg Chem 2016; 55:4233-47. [PMID: 27055058 DOI: 10.1021/acs.inorgchem.5b03006] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Nitrite reductase (NiR) activity was examined in a series of dicopper P.a. azurin variants in which a surface binding copper site was added through site-directed mutagenesis. Four variants were synthesized with copper binding motifs inspired by the catalytic type 2 copper binding sites found in the native noncoupled dinuclear copper enzymes nitrite reductase and peptidylglycine α-hydroxylating monooxygenase. The four azurin variants, denoted Az-NiR, Az-NiR3His, Az-PHM, and Az-PHM3His, maintained the azurin electron transfer copper center, with the second designed copper site located over 13 Å away and consisting of mutations Asn10His,Gln14Asp,Asn16His-azurin, Asn10His,Gln14His,Asn16His-azurin, Gln8Met,Gln14His,Asn16His-azurin, and Gln8His,Gln14His,Asn16His-azurin, respectively. UV-visible absorption spectroscopy, EPR spectroscopy, and electrochemistry of the sites demonstrate copper binding as well as interaction with small exogenous ligands. The nitrite reduction activity of the variants was determined, including the catalytic Michaelis-Menten parameters. The variants showed activity (0.34-0.59 min(-1)) that was slower than that of native NiRs but comparable to that of other model systems. There were small variations in activity of the four variants that correlated with the number of histidines in the added copper site. Catalysis was found to be reversible, with nitrite produced from NO. Reactions starting with reduced azurin variants demonstrated that electrons from both copper centers were used to reduce nitrite, although steady-state catalysis required the T2 copper center and did not require the T1 center. Finally, experiments separating rates of enzyme reduction from rates of reoxidation by nitrite demonstrated that the reaction with nitrite was rate limiting during catalysis.
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Affiliation(s)
- Steven M Berry
- Department of Chemistry and Biochemistry, University of Minnesota Duluth , 1039 University Drive, Duluth, Minnesota 55812, United States
| | - Jacob N Strange
- Department of Chemistry and Biochemistry, University of Minnesota Duluth , 1039 University Drive, Duluth, Minnesota 55812, United States
| | - Erika L Bladholm
- Department of Chemistry and Biochemistry, University of Minnesota Duluth , 1039 University Drive, Duluth, Minnesota 55812, United States
| | - Balabhadra Khatiwada
- Department of Chemistry and Biochemistry, University of Minnesota Duluth , 1039 University Drive, Duluth, Minnesota 55812, United States
| | - Christine G Hedstrom
- Department of Chemistry and Biochemistry, University of Minnesota Duluth , 1039 University Drive, Duluth, Minnesota 55812, United States
| | - Alexandra M Sauer
- Department of Chemistry and Biochemistry, University of Minnesota Duluth , 1039 University Drive, Duluth, Minnesota 55812, United States
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