1
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Tucci FJ, Rosenzweig AC. Direct Methane Oxidation by Copper- and Iron-Dependent Methane Monooxygenases. Chem Rev 2024; 124:1288-1320. [PMID: 38305159 PMCID: PMC10923174 DOI: 10.1021/acs.chemrev.3c00727] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/03/2024]
Abstract
Methane is a potent greenhouse gas that contributes significantly to climate change and is primarily regulated in Nature by methanotrophic bacteria, which consume methane gas as their source of energy and carbon, first by oxidizing it to methanol. The direct oxidation of methane to methanol is a chemically difficult transformation, accomplished in methanotrophs by complex methane monooxygenase (MMO) enzyme systems. These enzymes use iron or copper metallocofactors and have been the subject of detailed investigation. While the structure, function, and active site architecture of the copper-dependent particulate methane monooxygenase (pMMO) have been investigated extensively, its putative quaternary interactions, regulation, requisite cofactors, and mechanism remain enigmatic. The iron-dependent soluble methane monooxygenase (sMMO) has been characterized biochemically, structurally, spectroscopically, and, for the most part, mechanistically. Here, we review the history of MMO research, focusing on recent developments and providing an outlook for future directions of the field. Engineered biological catalysis systems and bioinspired synthetic catalysts may continue to emerge along with a deeper understanding of the molecular mechanisms of biological methane oxidation. Harnessing the power of these enzymes will necessitate combined efforts in biochemistry, structural biology, inorganic chemistry, microbiology, computational biology, and engineering.
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Affiliation(s)
- Frank J Tucci
- Departments of Molecular Biosciences and of Chemistry, Northwestern University, Evanston, Illinois 60208, United States
| | - Amy C Rosenzweig
- Departments of Molecular Biosciences and of Chemistry, Northwestern University, Evanston, Illinois 60208, United States
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2
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Peng W, Wang Z, Zhang Q, Yan S, Wang B. Unraveling the Valence State and Reactivity of Copper Centers in Membrane-Bound Particulate Methane Monooxygenase. J Am Chem Soc 2023; 145:25304-25317. [PMID: 37955571 DOI: 10.1021/jacs.3c08834] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2023]
Abstract
Particulate methane monooxygenase (pMMO) plays a critical role in catalyzing the conversion of methane to methanol, constituting the initial step in the C1 metabolic pathway within methanotrophic bacteria. However, the membrane-bound pMMO's structure and catalytic mechanism, notably the copper's valence state and genuine active site for methane oxidation, have remained elusive. Based on the recently characterized structure of membrane-bound pMMO, extensive computational studies were conducted to address these long-standing issues. A comprehensive analysis comparing the quantum mechanics/molecular mechanics (QM/MM) molecular dynamics (MD) simulated structures with cryo-EM data indicates that both the CuC and CuD sites tend to stay in the Cu(I) valence state within the membrane environment. Additionally, the concurrent presence of Cu(I) at both CuC and CuD sites leads to the significant reduction of the ligand-binding cavity situated between them, making it less likely to accommodate a reductant molecule such as durohydroquinone (DQH2). Subsequent QM/MM calculations reveal that the CuD(I) site is more reactive than the CuC(I) site in oxygen activation, en route to H2O2 formation and the generation of Cu(II)-O•- species. Finally, our simulations demonstrate that the natural reductant ubiquinol (CoQH2) assumes a productive binding conformation at the CuD(I) site but not at the CuC(I) site. This provides evidence that the true active site of membrane-bound pMMOs may be CuD rather than CuC. These findings clarify pMMO's catalytic mechanism and emphasize the membrane environment's pivotal role in modulating the coordination structure and the activity of copper centers within pMMO.
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Affiliation(s)
- Wei Peng
- 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 and Innovation Laboratory for Sciences and Technologies of Energy Materials of Fujian Province (IKKEM), Xiamen University, Xiamen 361005, P. R. China
- Key Laboratory of Aerosol Chemistry and Physics, State Key Laboratory of Loess and Quaternary Geology (SKLLQG), Institute of Earth Environment, Chinese Academy of Sciences, Xi'an 710061, P. R. China
| | - Zikuan Wang
- Max-Planck-Institut für Kohlenforschung, Kaiser-Wilhelm-Platz 1, Mülheim an der Ruhr 45470, Germany
| | - Qiaoyu Zhang
- 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 and Innovation Laboratory for Sciences and Technologies of Energy Materials of Fujian Province (IKKEM), Xiamen University, Xiamen 361005, P. R. China
| | - Shengheng Yan
- 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 and Innovation Laboratory for Sciences and Technologies of Energy Materials of Fujian Province (IKKEM), 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 and Innovation Laboratory for Sciences and Technologies of Energy Materials of Fujian Province (IKKEM), Xiamen University, Xiamen 361005, P. R. China
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3
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Spatola Rossi T, Tolmie AF, Nichol T, Pain C, Harrison P, Smith TJ, Fricker M, Kriechbaumer V. Recombinant expression and subcellular targeting of the particulate methane monooxygenase (pMMO) protein components in plants. Sci Rep 2023; 13:15337. [PMID: 37714899 PMCID: PMC10504283 DOI: 10.1038/s41598-023-42224-9] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/28/2023] [Accepted: 09/07/2023] [Indexed: 09/17/2023] Open
Abstract
Methane is a potent greenhouse gas, which has contributed to approximately a fifth of global warming since pre-industrial times. The agricultural sector produces significant methane emissions, especially from livestock, waste management and rice cultivation. Rice fields alone generate around 9% of total anthropogenic emissions. Methane is produced in waterlogged paddy fields by methanogenic archaea, and transported to the atmosphere through the aerenchyma tissue of rice plants. Thus, bioengineering rice with catalysts to detoxify methane en route could contribute to an efficient emission mitigation strategy. Particulate methane monooxygenase (pMMO) is the predominant methane catalyst found in nature, and is an enzyme complex expressed by methanotrophic bacteria. Recombinant expression of pMMO has been challenging, potentially due to its membrane localization, multimeric structure, and polycistronic operon. Here we show the first steps towards the engineering of plants for methane detoxification with the three pMMO subunits expressed in the model systems tobacco and Arabidopsis. Membrane topology and protein-protein interactions were consistent with correct folding and assembly of the pMMO subunits on the plant ER. Moreover, a synthetic self-cleaving polypeptide resulted in simultaneous expression of all three subunits, although low expression levels precluded more detailed structural investigation. The work presents plant cells as a novel heterologous system for pMMO allowing for protein expression and modification.
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Affiliation(s)
- Tatiana Spatola Rossi
- Endomembrane Structure and Function Research Group, Department of Biological and Medical Sciences, Oxford Brookes University, Oxford, OX3 0BP, UK
| | - A Frances Tolmie
- Endomembrane Structure and Function Research Group, Department of Biological and Medical Sciences, Oxford Brookes University, Oxford, OX3 0BP, UK
| | - Tim Nichol
- Molecular Microbiology Research Group, Biomolecular Sciences Research Centre, Sheffield Hallam University, Sheffield, S1 1WB, UK
| | - Charlotte Pain
- Endomembrane Structure and Function Research Group, Department of Biological and Medical Sciences, Oxford Brookes University, Oxford, OX3 0BP, UK
| | - Patrick Harrison
- Department of Biological and Marine Sciences, University of Hull, Hull, HU6 7RX, UK
| | - Thomas J Smith
- Molecular Microbiology Research Group, Biomolecular Sciences Research Centre, Sheffield Hallam University, Sheffield, S1 1WB, UK
| | - Mark Fricker
- Department of Biology, University of Oxford, Oxford, OX1 3RB, UK
| | - Verena Kriechbaumer
- Endomembrane Structure and Function Research Group, Department of Biological and Medical Sciences, Oxford Brookes University, Oxford, OX3 0BP, UK.
- Centre for Bioimaging, Oxford Brookes University, Oxford, UK.
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4
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Tsai YF, Natarajan T, Lin ZH, Tsai IK, Janmanchi D, Chan SI, Yu SSF. Voltage-Gated Electrocatalysis of Efficient and Selective Methane Oxidation by Tricopper Clusters under Ambient Conditions. J Am Chem Soc 2022; 144:9695-9706. [PMID: 35622083 DOI: 10.1021/jacs.2c01169] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/08/2023]
Abstract
Selective methane oxidation is difficult chemistry. Here we describe a strategy for the electrocatalysis of selective methane oxidation by immobilizing tricopper catalysts on the cathodic surface. In the presence of dioxygen and methane, the activation of these catalysts above a threshold cathodic potential can initiate the dioxygen chemistry for O atom transfer to methane. The catalytic turnover is completed by facile electron injections into the tricopper catalysts from the electrode. This technology leads to dramatic enhancements in performance of the catalysts toward methane oxidation. Unprecedented turnover frequencies (>40 min-1) and high product throughputs (turnover numbers >30 000 in 12 h) are achieved for this challenging chemical transformation in water under ambient conditions. The technology is green and suitable for on-site direct conversion of methane into methanol.
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Affiliation(s)
- Yi-Fang Tsai
- Institute of Chemistry, Academia Sinica, Nangang, Taipei 11529, Taiwan
| | | | - Zhi-Han Lin
- Institute of Chemistry, Academia Sinica, Nangang, Taipei 11529, Taiwan.,Chemical Biology and Molecular Biophysics Program, Taiwan International Graduate Program (TIGP), Academia Sinica, Taipei 11529, Taiwan
| | - I-Kuen Tsai
- Institute of Chemistry, Academia Sinica, Nangang, Taipei 11529, Taiwan
| | - Damodar Janmanchi
- Institute of Chemistry, Academia Sinica, Nangang, Taipei 11529, Taiwan
| | - Sunney I Chan
- Institute of Chemistry, Academia Sinica, Nangang, Taipei 11529, Taiwan
| | - Steve S-F Yu
- Institute of Chemistry, Academia Sinica, Nangang, Taipei 11529, Taiwan.,Chemical Biology and Molecular Biophysics Program, Taiwan International Graduate Program (TIGP), Academia Sinica, Taipei 11529, Taiwan
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5
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Chan SI, Wang VC, Chen PP, Yu SS. Methane oxidation by the copper methane monooxygenase: Before and after the cryogenic electron microscopy structure of particulate methane monooxygenase from
Methylococcus capsulatus
(Bath). J CHIN CHEM SOC-TAIP 2022. [DOI: 10.1002/jccs.202200166] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/05/2022]
Affiliation(s)
- Sunney I Chan
- Institute of Chemistry, Academia Sinica Taipei City Taiwan
- Department of Chemistry National Taiwan University Taipei City Taiwan
| | - Vincent C.‐C Wang
- Department of Chemistry National Sun Yat‐Sen University Kaohsiung City Taiwan
| | - Peter P.‐Y. Chen
- Department of Chemistry National Chung Hsing University Taichung City Taiwan
| | - Steve S.‐F. Yu
- Institute of Chemistry, Academia Sinica Taipei City Taiwan
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6
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Mahor D, Cong Z, Weissenborn MJ, Hollmann F, Zhang W. Valorization of Small Alkanes by Biocatalytic Oxyfunctionalization. CHEMSUSCHEM 2022; 15:e202101116. [PMID: 34288540 DOI: 10.1002/cssc.202101116] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/27/2021] [Revised: 07/18/2021] [Indexed: 06/13/2023]
Abstract
The oxidation of alkanes into valuable chemical products is a vital reaction in organic synthesis. This reaction, however, is challenging, owing to the inertness of C-H bonds. Transition metal catalysts for C-H functionalization are frequently explored. Despite chemical alternatives, nature has also evolved powerful oxidative enzymes (e. g., methane monooxygenases, cytochrome P450 oxygenases, peroxygenases) that are capable of transforming C-H bonds under very mild conditions, with only the use of molecular oxygen or hydrogen peroxide as electron acceptors. Although progress in alkane oxidation has been reviewed extensively, little attention has been paid to small alkane oxidation. The latter holds great potential for the manufacture of chemicals. This Minireview provides a concise overview of the most relevant enzyme classes capable of small alkanes (C<6 ) oxyfunctionalization, describes the essentials of the catalytic mechanisms, and critically outlines the current state-of-the-art in preparative applications.
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Affiliation(s)
- Durga Mahor
- National Innovation Center for Synthetic Biotechnology, Tianjin Institute of Industrial Biotechnology, Chinese Academy of Sciences, 32 West 7th Avenue, Tianjin Airport Economic Area, Tianjin, 300308, P. R. China
- Indian Institute of Science Education and Research Berhampur, Odisha, 760010, India
| | - Zhiqi Cong
- CAS Key Laboratory of Biofuels and Shandong Provincial Key Laboratory of Synthetic Biology, Qingdao Institute of Bioenergy and Bioprocess Technology Chinese Academy of Sciences, Qingdao, Shandong, 266101, P. R. China
| | - Martin J Weissenborn
- Leibniz Institute of Plant Biochemistry, Weinberg 3, 06120 Halle, Saale), Germany
| | - Frank Hollmann
- Department of Biotechnology, Delft University of Technology, Van der Maasweg 9, 2629HZ, Delft, The Netherlands
| | - Wuyuan Zhang
- National Innovation Center for Synthetic Biotechnology, Tianjin Institute of Industrial Biotechnology, Chinese Academy of Sciences, 32 West 7th Avenue, Tianjin Airport Economic Area, Tianjin, 300308, P. R. China
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7
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Koo CW, Tucci FJ, He Y, Rosenzweig AC. Recovery of particulate methane monooxygenase structure and activity in a lipid bilayer. Science 2022; 375:1287-1291. [PMID: 35298269 PMCID: PMC9357287 DOI: 10.1126/science.abm3282] [Citation(s) in RCA: 33] [Impact Index Per Article: 16.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/25/2022]
Abstract
Bacterial methane oxidation using the enzyme particulate methane monooxygenase (pMMO) contributes to the removal of environmental methane, a potent greenhouse gas. Crystal structures determined using inactive, detergent-solubilized pMMO lack several conserved regions neighboring the proposed active site. We show that reconstituting pMMO in nanodiscs with lipids extracted from the native organism restores methane oxidation activity. Multiple nanodisc-embedded pMMO structures determined by cryo-electron microscopy to 2.14- to 2.46-angstrom resolution reveal the structure of pMMO in a lipid environment. The resulting model includes stabilizing lipids, regions of the PmoA and PmoC subunits not observed in prior structures, and a previously undetected copper-binding site in the PmoC subunit with an adjacent hydrophobic cavity. These structures provide a revised framework for understanding and engineering pMMO function.
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Affiliation(s)
- Christopher W. Koo
- Department of Molecular Biosciences, Northwestern University, Evanston, IL 60208, USA
| | - Frank J. Tucci
- Department of Molecular Biosciences, Northwestern University, Evanston, IL 60208, USA
| | - Yuan He
- Department of Molecular Biosciences, Northwestern University, Evanston, IL 60208, USA
| | - Amy C. Rosenzweig
- Department of Molecular Biosciences, Northwestern University, Evanston, IL 60208, USA
- Department of Chemistry, Northwestern University, Evanston, IL 60208, USA
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8
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Chan SI, Chang WH, Huang SH, Lin HH, Yu SSF. Catalytic machinery of methane oxidation in particulate methane monooxygenase (pMMO). J Inorg Biochem 2021; 225:111602. [PMID: 34547604 DOI: 10.1016/j.jinorgbio.2021.111602] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/19/2021] [Revised: 08/21/2021] [Accepted: 09/09/2021] [Indexed: 10/20/2022]
Abstract
In this focused review, we portray the recently reported 2.5 Å cyro-EM structure of the particulate methane monooxygenase (pMMO) from M. capsulatus (Bath). The structure of the functional holo-pMMO near atomic resolution has uncovered the sites of the copper cofactors including the location of the active site in the enzyme. The three coppers seen in the original X-ray crystal structures of the enzyme are now augmented by additional coppers in the transmembrane domain as well as in the water-exposed C-terminal subdomain of the PmoB subunit. The cryo-EM structure offers the first glimpse of the catalytic machinery capable of methane oxidation with high selectivity and efficiency. The findings are entirely consistent with the biochemical and biophysical findings previously reported in the literature, including the chemistry of hydrocarbon hydroxylation, regeneration of the catalyst for multiple turnovers, and the mechanism of aborting non-productive cycles to ensure kinetic competence.
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Affiliation(s)
- Sunney I Chan
- Institute of Chemistry, Academia Sinica, Nankang, Taipei 11529, Taiwan.
| | - Wei-Hau Chang
- Institute of Chemistry, Academia Sinica, Nankang, Taipei 11529, Taiwan.
| | - Shih-Hsin Huang
- Institute of Chemistry, Academia Sinica, Nankang, Taipei 11529, Taiwan
| | - Hsin-Hung Lin
- Institute of Chemistry, Academia Sinica, Nankang, Taipei 11529, Taiwan
| | - Steve S-F Yu
- Institute of Chemistry, Academia Sinica, Nankang, Taipei 11529, Taiwan.
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9
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Chang WH, Lin HH, Tsai IK, Huang SH, Chung SC, Tu IP, Yu SSF, Chan SI. Copper Centers in the Cryo-EM Structure of Particulate Methane Monooxygenase Reveal the Catalytic Machinery of Methane Oxidation. J Am Chem Soc 2021; 143:9922-9932. [PMID: 34170126 DOI: 10.1021/jacs.1c04082] [Citation(s) in RCA: 18] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/27/2022]
Abstract
The particulate methane monooxygenase (pMMO) is the first enzyme in the C1 metabolic pathway in methanotrophic bacteria. As this enzyme converts methane into methanol efficiently near room temperature, it has become the paradigm for developing an understanding of this difficult C1 chemistry. pMMO is a membrane-bound protein with three subunits (PmoB, PmoA, and PmoC) and 12-14 coppers distributed among different sites. X-ray crystal structures that have revealed only three mononuclear coppers at three sites have neither disclosed the location of the active site nor the catalytic mechanism of the enzyme. Here we report a cyro-EM structure of holo-pMMO from Methylococcus capsulatus (Bath) at 2.5 Å, and develop quantitative electrostatic-potential profiling to scrutinize the nonprotein densities for signatures of the copper cofactors. Our results confirm a mononuclear CuI at the A site, resolve two CuIs at the B site, and uncover additional CuI clusters at the PmoA/PmoC interface within the membrane (D site) and in the water-exposed C-terminal subdomain of the PmoB (E clusters). These findings complete the minimal set of copper factors required for catalytic turnover of pMMO, offering a glimpse of the catalytic machinery for methane oxidation according to the chemical principles underlying the mechanism proposed earlier.
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Affiliation(s)
- W-H Chang
- Institute of Chemistry, Academia Sinica, Nangang, Taipei 11529, Taiwan
| | - H-H Lin
- Institute of Chemistry, Academia Sinica, Nangang, Taipei 11529, Taiwan
| | - I-K Tsai
- Institute of Chemistry, Academia Sinica, Nangang, Taipei 11529, Taiwan
| | - S-H Huang
- Institute of Chemistry, Academia Sinica, Nangang, Taipei 11529, Taiwan
| | - S-C Chung
- Institute of Statistical Science, Academia Sinica, Nangang, Taipei 11529, Taiwan
| | - I-P Tu
- Institute of Statistical Science, Academia Sinica, Nangang, Taipei 11529, Taiwan
| | - S S-F Yu
- Institute of Chemistry, Academia Sinica, Nangang, Taipei 11529, Taiwan
| | - S I Chan
- Institute of Chemistry, Academia Sinica, Nangang, Taipei 11529, Taiwan
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10
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Cutsail GE, Ross MO, Rosenzweig AC, DeBeer S. Towards a unified understanding of the copper sites in particulate methane monooxygenase: an X-ray absorption spectroscopic investigation. Chem Sci 2021; 12:6194-6209. [PMID: 33996018 PMCID: PMC8098663 DOI: 10.1039/d1sc00676b] [Citation(s) in RCA: 16] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022] Open
Abstract
The enzymatic conversion of the greenhouse gas, methane, to a liquid fuel, methanol, is performed by methane monooxygenases (MMOs) under mild conditions. The copper stoichiometry of particulate MMO (pMMO) has been long debated, with a dicopper site previously proposed on the basis of a 2.51 Å Cu–Cu feature in extended X-ray absorption fine structure (EXAFS) data. However, recent crystallographic data and advanced electron paramagnetic resonance (EPR) characterization support the presence of only mononuclear copper sites. To reconcile these data, we have collected high-energy resolution fluorescence detected (HERFD) and partial fluorescence yield (PFY) EXAFS spectra of Methylococcus (M.) capsulatus (Bath) pMMO. Both methods reveal only monocopper sites. These data were compared to previously published pMMO PFY-EXAFS data from M. capsulatus (Bath) and Methylomicrobium alcaliphilum 20Z, supporting dicopper and monocopper sites, respectively. The FT-EXAFS feature previously attributed to a dicopper site can be reproduced by the inclusion of a metallic copper background signal. The exact position of this feature is dependent on the nature of the sample and the percentage of background contamination, indicating that visual inspection is not sufficient for identifying background metallic contributions. Additionally, an undamaged X-ray absorption spectrum was obtained, consistent with the copper oxidation-state speciation determined by EPR quantification. X-ray photodamage studies suggest that the previously observed Cu(i) XAS features are in part attributable to photodamage. This study illustrates the complex array of factors involved in EXAFS measurement and modeling of pMMO and more generally, dilute metalloproteins with multiple metal centers. Extended X-ray absorption fine structure spectroscopic analysis of particulate methane monooxygenase reveals only monocopper sites and investigates the possible origins of the previous observed dicopper signals.![]()
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Affiliation(s)
- George E Cutsail
- Max Planck Institute for Chemical Energy Conversion Stiftstrasse 34-36 D-45470 Mülheim an der Ruhr Germany .,University of Duisburg-Essen Universitätsstrasse 7 D-45151 Essen Germany
| | - Matthew O Ross
- Departments of Molecular Biosciences and Chemistry, Northwestern University Evanston 60208 IL USA
| | - Amy C Rosenzweig
- Departments of Molecular Biosciences and Chemistry, Northwestern University Evanston 60208 IL USA
| | - Serena DeBeer
- Max Planck Institute for Chemical Energy Conversion Stiftstrasse 34-36 D-45470 Mülheim an der Ruhr Germany
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11
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Miyaji A, Satou K, Baba T. Influence of tryptic hydrolysis on the enzymatic function of the membrane-bound form of particulate methane monooxygenase from Methylosinus trichosporium OB3b. J Biotechnol 2020; 323:98-106. [PMID: 32828830 DOI: 10.1016/j.jbiotec.2020.08.006] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/03/2020] [Revised: 07/30/2020] [Accepted: 08/17/2020] [Indexed: 11/29/2022]
Abstract
Particulate methane monooxygenase (pMMO) is a membrane protein embedded in the intracytoplasmic membrane of methane-oxidizing bacteria. Structural analysis of pMMO showed the existence of a hydrophilic region exposed outside of the bacterial membrane. To obtain information regarding the role of this hydrophilic region in the enzymatic function of pMMO, trypsin proteolysis of the membrane-bound form of pMMO from Methylosinus trichosporium OB3b was performed at 4 °C. The polypeptides produced by this hydrolysis were analyzed by polyacrylamide gel electrophoresis and MALDI-TOF/TOF. Furthermore, the influence of this tryptic digestion on the methane hydroxylation and propene epoxidation enzymatic activities of pMMO was investigated. Among the three subunits of pMMO, PmoB and PmoC were hydrolyzed by trypsin, but PmoA was not. With 10 mg L-1 trypsin, both terminal regions or the C-terminal region of PmoC polypeptide was selectively hydrolyzed. Furthermore, the stability of pMMO was decreased by this digestion. These results indicate that PmoC plays a role in maintaining the stability of pMMO in vitro. On the other hand, the digestion of PmoB with 100 mg L-1 trypsin produced several polypeptides, indicating that trypsin digestion occurs at several sites of the hydrophilic region of PmoB. Hydrolysis led to a decrease in pMMO activity towards methane hydroxylation and propene epoxidation. These results indicate that the hydrophilic region of PmoB is critically important for the enzymatic function of pMMO, which is consistent with the models of the functional mechanism of pMMO proposed so far.
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Affiliation(s)
- Akimitsu Miyaji
- Department of Environmental Chemistry and Engineering, Tokyo Institute of Technology, 4259-G1-14, Nagatsuta-cho, Midori-ku, Yokohama 226-8502, Japan.
| | - Keita Satou
- Department of Environmental Chemistry and Engineering, Tokyo Institute of Technology, 4259-G1-14, Nagatsuta-cho, Midori-ku, Yokohama 226-8502, Japan
| | - Toshihide Baba
- Department of Environmental Chemistry and Engineering, Tokyo Institute of Technology, 4259-G1-14, Nagatsuta-cho, Midori-ku, Yokohama 226-8502, Japan
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12
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Wright CL, Schatteman A, Crombie AT, Murrell JC, Lehtovirta-Morley LE. Inhibition of Ammonia Monooxygenase from Ammonia-Oxidizing Archaea by Linear and Aromatic Alkynes. Appl Environ Microbiol 2020; 86:e02388-19. [PMID: 32086308 PMCID: PMC7170481 DOI: 10.1128/aem.02388-19] [Citation(s) in RCA: 32] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/18/2019] [Accepted: 02/15/2020] [Indexed: 01/20/2023] Open
Abstract
Ammonia monooxygenase (AMO) is a key nitrogen-transforming enzyme belonging to the same copper-dependent membrane monooxygenase family (CuMMO) as the particulate methane monooxygenase (pMMO). The AMO from ammonia-oxidizing archaea (AOA) is very divergent from both the AMO of ammonia-oxidizing bacteria (AOB) and the pMMO from methanotrophs, and little is known about the structure or substrate range of the archaeal AMO. This study compares inhibition by C2 to C8 linear 1-alkynes of AMO from two phylogenetically distinct strains of AOA, "Candidatus Nitrosocosmicus franklandus" C13 and "Candidatus Nitrosotalea sinensis" Nd2, with AMO from Nitrosomonas europaea and pMMO from Methylococcus capsulatus (Bath). An increased sensitivity of the archaeal AMO to short-chain-length alkynes (≤C5) appeared to be conserved across AOA lineages. Similarities in C2 to C8 alkyne inhibition profiles between AMO from AOA and pMMO from M. capsulatus suggested that the archaeal AMO has a narrower substrate range than N. europaea AMO. Inhibition of AMO from "Ca Nitrosocosmicus franklandus" and N. europaea by the aromatic alkyne phenylacetylene was also investigated. Kinetic data revealed that the mechanisms by which phenylacetylene inhibits "Ca Nitrosocosmicus franklandus" and N. europaea are different, indicating differences in the AMO active site between AOA and AOB. Phenylacetylene was found to be a specific and irreversible inhibitor of AMO from "Ca Nitrosocosmicus franklandus," and it does not compete with NH3 for binding at the active site.IMPORTANCE Archaeal and bacterial ammonia oxidizers (AOA and AOB, respectively) initiate nitrification by oxidizing ammonia to hydroxylamine, a reaction catalyzed by ammonia monooxygenase (AMO). AMO enzyme is difficult to purify in its active form, and its structure and biochemistry remain largely unexplored. The bacterial AMO and the closely related particulate methane monooxygenase (pMMO) have a broad range of hydrocarbon cooxidation substrates. This study provides insights into the AMO of previously unstudied archaeal genera, by comparing the response of the archaeal AMO, a bacterial AMO, and pMMO to inhibition by linear 1-alkynes and the aromatic alkyne, phenylacetylene. Reduced sensitivity to inhibition by larger alkynes suggests that the archaeal AMO has a narrower hydrocarbon substrate range than the bacterial AMO, as previously reported for other genera of AOA. Phenylacetylene inhibited the archaeal and bacterial AMOs at different thresholds and by different mechanisms of inhibition, highlighting structural differences between the two forms of monooxygenase.
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Affiliation(s)
- Chloë L Wright
- School of Biological Sciences, University of East Anglia, Norwich, United Kingdom
| | - Arne Schatteman
- School of Biological Sciences, University of East Anglia, Norwich, United Kingdom
| | - Andrew T Crombie
- School of Biological Sciences, University of East Anglia, Norwich, United Kingdom
| | - J Colin Murrell
- School of Environmental Sciences, University of East Anglia, Norwich, United Kingdom
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Chen Y, Wu C, Sung P, Chan SI, Chen PP. Turnover of a Methane Oxidation Tricopper Cluster Catalyst: Implications for the Mechanism of the Particulate Methane Monooxygenase (pMMO). ChemCatChem 2020. [DOI: 10.1002/cctc.202000322] [Citation(s) in RCA: 13] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Affiliation(s)
- Yu‐Hsuan Chen
- Department of ChemistryNational Chung Hsing University 145 Xingda Road South District Taichung 402 Taiwan
| | - Chang‐Quan Wu
- Department of ChemistryNational Chung Hsing University 145 Xingda Road South District Taichung 402 Taiwan
| | - Pei‐Hua Sung
- Department of ChemistryNational Chung Hsing University 145 Xingda Road South District Taichung 402 Taiwan
| | - Sunney I. Chan
- Institute of ChemistryAcademia Sinica 128 Academia Road Sec. 2, Nankang Taipei 11529 Taiwan
- Department of ChemistryNational Taiwan University No. 1, Sec. 4, Roosevelt Road Taipei 10617 Taiwan
| | - Peter Ping‐Yu Chen
- Department of ChemistryNational Chung Hsing University 145 Xingda Road South District Taichung 402 Taiwan
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Xin JY, Sun LR, Lin HY, Zhang S, Xia CG. Hybridization of Particulate Methane Monooxygenase by Methanobactin-Modified AuNPs. Molecules 2019; 24:E4027. [PMID: 31703299 PMCID: PMC6891627 DOI: 10.3390/molecules24224027] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/10/2019] [Revised: 10/28/2019] [Accepted: 11/05/2019] [Indexed: 11/16/2022] Open
Abstract
Particulate methane monooxygenase (pMMO) is a characteristic membrane-bound metalloenzyme of methane-oxidizing bacteria that can catalyze the bioconversion of methane to methanol. However, in order to achieve pMMO-based continuous methane-to-methanol bioconversion, the problems of reducing power in vitro regeneration and pMMO stability need to be overcome. Methanobactin (Mb) is a small copper-chelating molecule that functions not only as electron carrier for pMMO catalysis and pMMO protector against oxygen radicals, but also as an agent for copper acquisition and uptake. In order to improve the activity and stability of pMMO, methanobactin-Cu (Mb-Cu)-modified gold nanoparticle (AuNP)-pMMO nanobiohybrids were straightforwardly synthesized via in situ reduction of HAuCl4 to AuNPs in a membrane fraction before further association with Mb-Cu. Mb-Cu modification can greatly improve the activity and stability of pMMO in the AuNP-pMMO nanobiohybrids. It is shown that the Mb-Cu-modified AuNP-pMMO nanobiohybrids can persistently catalyze the conversion of methane to methanol with hydroquinone as electron donor. The artificial heterogeneous nanobiohybrids exhibited excellent reusability and reproducibility in three cycles of catalysis, and they provide a model for achieving hydroquinone-driven conversion of methane to methanol.
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Affiliation(s)
- Jia-Ying Xin
- Key Laboratory of Food Science and Engineering, Harbin University of Commerce, Harbin 150076, China
- State Key Laboratory of Oxo Synthesis and Selective Oxidation, Lanzhou Institute of Chemical Physics, Chinese Academy of Sciences, Lanzhou 730000, China
| | - Li-Rui Sun
- Key Laboratory of Food Science and Engineering, Harbin University of Commerce, Harbin 150076, China
| | - Hui-Ying Lin
- Key Laboratory of Food Science and Engineering, Harbin University of Commerce, Harbin 150076, China
| | - Shuai Zhang
- Key Laboratory of Food Science and Engineering, Harbin University of Commerce, Harbin 150076, China
| | - Chun-Gu Xia
- State Key Laboratory of Oxo Synthesis and Selective Oxidation, Lanzhou Institute of Chemical Physics, Chinese Academy of Sciences, Lanzhou 730000, China
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