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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Tucci FJ, Jodts RJ, Hoffman BM, Rosenzweig AC. Product analog binding identifies the copper active site of particulate methane monooxygenase. Nat Catal 2023; 6:1194-1204. [PMID: 38187819 PMCID: PMC10766429 DOI: 10.1038/s41929-023-01051-x] [Citation(s) in RCA: 7] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/14/2023] [Accepted: 09/22/2023] [Indexed: 01/09/2024]
Abstract
Nature's primary methane-oxidizing enzyme, the membrane-bound particulate methane monooxygenase (pMMO), catalyzes the oxidation of methane to methanol. pMMO activity requires copper, and decades of structural and spectroscopic studies have sought to identify the active site among three candidates: the CuB, CuC, and CuD sites. Challenges associated with the isolation of active pMMO have hindered progress toward locating its catalytic center. However, reconstituting pMMO into native lipid nanodiscs stabilizes its structure and recovers its activity. Here, these active samples were incubated with 2,2,2,-trifluoroethanol (TFE), a product analog that serves as a readily visualized active-site probe. Interactions of TFE with the CuD site were observed by both pulsed ENDOR spectroscopy and cryoEM, implicating CuD and the surrounding hydrophobic pocket as the likely site of methane oxidation. Use of these orthogonal techniques on parallel samples is a powerful approach that can circumvent difficulties in interpreting metalloenzyme cryoEM maps.
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Affiliation(s)
- Frank J Tucci
- Departments of Molecular Biosciences and of Chemistry, Northwestern University, Evanston, IL, USA
- These authors contributed equally
| | - Richard J Jodts
- Departments of Molecular Biosciences and of Chemistry, Northwestern University, Evanston, IL, USA
- These authors contributed equally
| | - Brian M Hoffman
- Departments of Molecular Biosciences and of Chemistry, Northwestern University, Evanston, IL, USA
| | - Amy C Rosenzweig
- Departments of Molecular Biosciences and of Chemistry, Northwestern University, Evanston, IL, USA
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3
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Park YR, Krishna S, Lee OK, Lee EY. Biosynthesis of chiral diols from alkenes using metabolically engineered type II methanotroph. BIORESOURCE TECHNOLOGY 2023; 389:129851. [PMID: 37813317 DOI: 10.1016/j.biortech.2023.129851] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/12/2023] [Revised: 10/06/2023] [Accepted: 10/06/2023] [Indexed: 10/11/2023]
Abstract
Methanotrophs are environmentally friendly microorganisms capable of converting gas to liquid using methane monooxygenases (MMOs). In addition to methane-to-methanol conversion, MMOs catalyze the conversion of alkanes to alcohols and alkenes to epoxides. Herein, the efficacy of epoxidation by type I and II methanotrophs was investigated, and type II methanotrophs were observed to be more efficient in converting alkenes to epoxides. Subsequently, three (Epoxide hydrolase) EHs of different origins were overexpressed in the type II methanotroph Methylosinus trichosporium OB3b to produce 1,2-diols from epoxide. Methylosinus trichosporium OB3b expressing Caulobacter crescentus EH produced the highest amount of (R)-1,2-propanediol (251.5 mg/L) from 1-propene. These results demonstrate the possibility of using methanotrophs as a microbial platform for diol production and the development of a continuous bioreactor for industrial applications.
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Affiliation(s)
- Ye Rim Park
- Department of Chemical Engineering (BK21 FOUR Integrated Engineering Program), Kyung Hee University, Yongin-si, Gyeonggi-do 17104, Republic of Korea
| | - Shyam Krishna
- Department of Chemical Engineering (BK21 FOUR Integrated Engineering Program), Kyung Hee University, Yongin-si, Gyeonggi-do 17104, Republic of Korea
| | - Ok Kyung Lee
- Department of Chemical Engineering (BK21 FOUR Integrated Engineering Program), Kyung Hee University, Yongin-si, Gyeonggi-do 17104, Republic of Korea
| | - Eun Yeol Lee
- Department of Chemical Engineering (BK21 FOUR Integrated Engineering Program), Kyung Hee University, Yongin-si, Gyeonggi-do 17104, Republic of Korea.
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4
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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: 4] [Impact Index Per Article: 4.0] [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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5
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Weng C, Peng X, Han Y. From methane to value-added bioproducts: microbial metabolism, enzymes, and metabolic engineering. ADVANCES IN APPLIED MICROBIOLOGY 2023; 124:119-146. [PMID: 37597946 DOI: 10.1016/bs.aambs.2023.07.004] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 08/21/2023]
Abstract
Methane is abundant in nature, and excessive emissions will cause the greenhouse effect. Methane is also an ideal carbon and energy feedstock for biosynthesis. In the review, the microorganisms, metabolism, and enzymes for methane utilization, and the advances of conversion to value-added bioproducts were summarized. First, the physiological characteristics, classification, and methane oxidation process of methanotrophs were introduced. The metabolic pathways for methane utilization and key intermediate metabolites of native and synthetic methanotrophs were summarized. Second, the enzymatic properties, crystal structures, and catalytic mechanisms of methane-oxidizing and metabolizing enzymes in methanotrophs were described. Third, challenges and prospects in metabolic pathways and enzymatic catalysis for methane utilization and conversion to value-added bioproducts were discussed. Finally, metabolic engineering of microorganisms for methane biooxidation and bioproducts synthesis based on different pathways were summarized. Understanding the metabolism and challenges of microbial methane utilization will provide insights into possible strategies for efficient methane-based synthesis.
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Affiliation(s)
- Caihong Weng
- National Key Laboratory of Biochemical Engineering, Institute of Process Engineering, Chinese Academy of Sciences, Beijing, P.R. China; School of Chemical Engineering, University of Chinese Academy of Sciences, Beijing, P.R. China
| | - Xiaowei Peng
- National Key Laboratory of Biochemical Engineering, Institute of Process Engineering, Chinese Academy of Sciences, Beijing, P.R. China; School of Chemical Engineering, University of Chinese Academy of Sciences, Beijing, P.R. China
| | - Yejun Han
- National Key Laboratory of Biochemical Engineering, Institute of Process Engineering, Chinese Academy of Sciences, Beijing, P.R. China; School of Chemical Engineering, University of Chinese Academy of Sciences, Beijing, P.R. China.
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6
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Ali Eltayb W, Abdalla M, Ahmed EL-Arabey A, Boufissiou A, Azam M, Al-Resayes SI, Alam M. Exploring particulate methane monooxygenase (pMMO) proteins using experimentation and computational molecular docking. JOURNAL OF KING SAUD UNIVERSITY - SCIENCE 2023; 35:102634. [DOI: https:/doi.org/10.1016/j.jksus.2023.102634] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 09/01/2023]
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7
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Hodgskiss LH, Melcher M, Kerou M, Chen W, Ponce-Toledo RI, Savvides SN, Wienkoop S, Hartl M, Schleper C. Unexpected complexity of the ammonia monooxygenase in archaea. THE ISME JOURNAL 2023; 17:588-599. [PMID: 36721060 PMCID: PMC10030591 DOI: 10.1038/s41396-023-01367-3] [Citation(s) in RCA: 14] [Impact Index Per Article: 14.0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/08/2022] [Revised: 01/09/2023] [Accepted: 01/12/2023] [Indexed: 02/02/2023]
Abstract
Ammonia oxidation, as the first step of nitrification, constitutes a critical process in the global nitrogen cycle. However, fundamental knowledge of its key enzyme, the copper-dependent ammonia monooxygenase, is lacking, in particular for the environmentally abundant ammonia-oxidizing archaea (AOA). Here the structure of the enzyme is investigated by blue-native gel electrophoresis and proteomics from native membrane complexes of two AOA. Besides the known AmoABC subunits and the earlier predicted AmoX, two new protein subunits, AmoY and AmoZ, were identified. They are unique to AOA, highly conserved and co-regulated, and their genes are linked to other AMO subunit genes in streamlined AOA genomes. Modeling and in-gel cross-link approaches support an overall protomer structure similar to the distantly related bacterial particulate methane monooxygenase but also reveals clear differences in extracellular domains of the enzyme. These data open avenues for further structure-function studies of this ecologically important nitrification complex.
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Affiliation(s)
- Logan H Hodgskiss
- Archaea Biology and Ecogenomics Unit, Department of Functional and Evolutionary Ecology, University of Vienna, Vienna, Austria
| | - Michael Melcher
- Archaea Biology and Ecogenomics Unit, Department of Functional and Evolutionary Ecology, University of Vienna, Vienna, Austria
| | - Melina Kerou
- Archaea Biology and Ecogenomics Unit, Department of Functional and Evolutionary Ecology, University of Vienna, Vienna, Austria
| | - Weiqiang Chen
- Mass Spectrometry Facility, Max Perutz Labs, Vienna BioCenter (VBC), Vienna, Austria
| | - Rafael I Ponce-Toledo
- Archaea Biology and Ecogenomics Unit, Department of Functional and Evolutionary Ecology, University of Vienna, Vienna, Austria
| | - Savvas N Savvides
- Unit for Structural Biology, Department of Biochemistry and Microbiology, Ghent University, Ghent, Belgium
| | - Stefanie Wienkoop
- Molecular Systems Biology Unit, Department of Functional and Evolutionary Ecology, University of Vienna, Vienna, Austria
| | - Markus Hartl
- Mass Spectrometry Facility, Max Perutz Labs, Vienna BioCenter (VBC), Vienna, Austria
- Department of Biochemistry and Cell Biology, Max Perutz Labs, University of Vienna, Vienna, Austria
| | - Christa Schleper
- Archaea Biology and Ecogenomics Unit, Department of Functional and Evolutionary Ecology, University of Vienna, Vienna, Austria.
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8
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Andrade LS, Lima HH, Silva CT, Amorim WL, Poço JG, López-Castillo A, Kirillova MV, Carvalho WA, Kirillov AM, Mandelli D. Metal–organic frameworks as catalysts and biocatalysts for methane oxidation: The current state of the art. Coord Chem Rev 2023. [DOI: 10.1016/j.ccr.2023.215042] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/11/2023]
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9
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Liu Z, Wang J, Xie J, Yao D, Yang S, Ge J. Interactions among heavy metals and methane-metabolizing microorganisms and their effects on methane emissions in Dajiuhu peatland. ENVIRONMENTAL SCIENCE AND POLLUTION RESEARCH INTERNATIONAL 2023; 30:37415-37426. [PMID: 36572772 DOI: 10.1007/s11356-022-24868-8] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/28/2022] [Accepted: 12/15/2022] [Indexed: 06/18/2023]
Abstract
Peatlands play a crucial role in mediating the emissions of methane through active biogeochemical cycling of accumulated carbon driven by methane-metabolizing microorganisms; meanwhile, they serve as vital archives of atmospheric heavy metal deposition. Despite many edaphic factors confirmed as determinants to modulate the structure of methanotrophic and methanogenic communities, recognition of interactions among them is limited. In this study, peat soils were collected from Dajiuhu peatland to assess the presence of heavy metals, and methanotrophs and methanogens were investigated via high-throughput sequencing for functional genes mcrA and pmoA. Further analyses of the correlations between methane-related functional groups were conducted. The results demonstrated that both methane-metabolizing microorganisms and heavy metals have prominent vertical heterogeneity upward and downward along the depth of 20 cm. Pb, Cd, and Hg strongly correlated with methanotrophs and methanogens across all seasons and depths, serving as forceful factors in structural variations of methanogenic and methanotrophic communities. Particularly, Pb, Cd, and Hg were identified as excessive elements in Dajiuhu peatland. Furthermore, seasonal variations of networks among methane-related functional groups and environmental factors significantly affected the changes of methane fluxes across different seasons. Concretely, the complicated interactions were detrimental to methane emissions in the Dajiuhu peatland, leading to the minimum methane emissions in winter. Our study identified the key heavy metals affecting the composition of methane-metabolizing microorganisms and linkages between seasonal variations of methane emissions and interaction among heavy metals and methane-metabolizing microorganisms, which provided much new reference and theoretical basis for integrated management of natural peatlands.
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Affiliation(s)
- Ziwei Liu
- School of Environmental Studies, China University of Geosciences (Wuhan), 68 Jincheng Street, Hongshan District, Wuhan, 430078, Hubei Province, China
- Laboratory of Basin Hydrology and Wetland Eco-Restoration, China University of Geosciences (Wuhan), Wuhan, 430078, China
- Hubei Key Laboratory of Wetland Evolution and Ecological Restoration, China University of Geosciences (Wuhan), Wuhan, 430078, China
- Institution of Ecology and Environmental Sciences, China University of Geosciences (Wuhan), Wuhan, 430078, China
| | - Jiumei Wang
- School of Environmental Studies, China University of Geosciences (Wuhan), 68 Jincheng Street, Hongshan District, Wuhan, 430078, Hubei Province, China
- Laboratory of Basin Hydrology and Wetland Eco-Restoration, China University of Geosciences (Wuhan), Wuhan, 430078, China
- Hubei Key Laboratory of Wetland Evolution and Ecological Restoration, China University of Geosciences (Wuhan), Wuhan, 430078, China
- Institution of Ecology and Environmental Sciences, China University of Geosciences (Wuhan), Wuhan, 430078, China
| | - Jinlin Xie
- School of Environmental Studies, China University of Geosciences (Wuhan), 68 Jincheng Street, Hongshan District, Wuhan, 430078, Hubei Province, China
- Laboratory of Basin Hydrology and Wetland Eco-Restoration, China University of Geosciences (Wuhan), Wuhan, 430078, China
- Hubei Key Laboratory of Wetland Evolution and Ecological Restoration, China University of Geosciences (Wuhan), Wuhan, 430078, China
- Institution of Ecology and Environmental Sciences, China University of Geosciences (Wuhan), Wuhan, 430078, China
| | - Dong Yao
- School of Environmental Studies, China University of Geosciences (Wuhan), 68 Jincheng Street, Hongshan District, Wuhan, 430078, Hubei Province, China
- Laboratory of Basin Hydrology and Wetland Eco-Restoration, China University of Geosciences (Wuhan), Wuhan, 430078, China
- Hubei Key Laboratory of Wetland Evolution and Ecological Restoration, China University of Geosciences (Wuhan), Wuhan, 430078, China
- Institution of Ecology and Environmental Sciences, China University of Geosciences (Wuhan), Wuhan, 430078, China
| | - Shiyu Yang
- School of Environmental Studies, China University of Geosciences (Wuhan), 68 Jincheng Street, Hongshan District, Wuhan, 430078, Hubei Province, China
- Laboratory of Basin Hydrology and Wetland Eco-Restoration, China University of Geosciences (Wuhan), Wuhan, 430078, China
- Hubei Key Laboratory of Wetland Evolution and Ecological Restoration, China University of Geosciences (Wuhan), Wuhan, 430078, China
- Institution of Ecology and Environmental Sciences, China University of Geosciences (Wuhan), Wuhan, 430078, China
| | - Jiwen Ge
- School of Environmental Studies, China University of Geosciences (Wuhan), 68 Jincheng Street, Hongshan District, Wuhan, 430078, Hubei Province, China.
- Laboratory of Basin Hydrology and Wetland Eco-Restoration, China University of Geosciences (Wuhan), Wuhan, 430078, China.
- Hubei Key Laboratory of Wetland Evolution and Ecological Restoration, China University of Geosciences (Wuhan), Wuhan, 430078, China.
- Institution of Ecology and Environmental Sciences, China University of Geosciences (Wuhan), Wuhan, 430078, China.
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10
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Koo CW, Hershewe JM, Jewett MC, Rosenzweig AC. Cell-Free Protein Synthesis of Particulate Methane Monooxygenase into Nanodiscs. ACS Synth Biol 2022; 11:4009-4017. [PMID: 36417751 PMCID: PMC9910172 DOI: 10.1021/acssynbio.2c00366] [Citation(s) in RCA: 7] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022]
Abstract
Particulate methane monooxygenase (pMMO) is a multi-subunit membrane metalloenzyme used by methanotrophic bacteria to convert methane to methanol. A major hurdle to studying pMMO is the lack of a recombinant expression system, precluding investigation of individual residues by mutagenesis and hampering a complete understanding of its mechanism. Here, we developed an Escherichia coli lysate-based cell-free protein synthesis (CFPS) system that can be used to express pMMO in vitro in the presence of nanodiscs. We used a SUMO fusion construct to generate the native PmoB subunit and showed that the SUMO protease (Ulp1) cleaves the protein in the reaction mixture. Using an affinity tag to isolate the complete pMMO complex, we demonstrated that the complex forms without the need for exogenous translocon machinery or chaperones, confirmed by negative stain electron microscopy. This work demonstrates the potential for using CFPS to express multi-subunit membrane-bound metalloenzymes directly into lipid bilayers.
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Affiliation(s)
- Christopher W. Koo
- Department of Molecular Biosciences and of Chemistry, Northwestern University, Evanston, Illinois 60208, United States
| | - Jasmine M. Hershewe
- Department of Chemical and Biological Engineering, Northwestern University, Evanston, Illinois 60208, United States
| | - Michael C. Jewett
- Department of Chemical and Biological Engineering and Center for Synthetic Biology, Northwestern University, Evanston, Illinois 60208, United States
| | - Amy C. Rosenzweig
- Department of Molecular Biosciences and of Chemistry and Center for Synthetic Biology, Northwestern University, Evanston, Illinois 60208, United States
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11
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Dummer NF, Willock DJ, He Q, Howard MJ, Lewis RJ, Qi G, Taylor SH, Xu J, Bethell D, Kiely CJ, Hutchings GJ. Methane Oxidation to Methanol. Chem Rev 2022; 123:6359-6411. [PMID: 36459432 PMCID: PMC10176486 DOI: 10.1021/acs.chemrev.2c00439] [Citation(s) in RCA: 26] [Impact Index Per Article: 13.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/04/2022]
Abstract
The direct transformation of methane to methanol remains a significant challenge for operation at a larger scale. Central to this challenge is the low reactivity of methane at conditions that can facilitate product recovery. This review discusses the issue through examination of several promising routes to methanol and an evaluation of performance targets that are required to develop the process at scale. We explore the methods currently used, the emergence of active heterogeneous catalysts and their design and reaction mechanisms and provide a critical perspective on future operation. Initial experiments are discussed where identification of gas phase radical chemistry limited further development by this approach. Subsequently, a new class of catalytic materials based on natural systems such as iron or copper containing zeolites were explored at milder conditions. The key issues of these technologies are low methane conversion and often significant overoxidation of products. Despite this, interest remains high in this reaction and the wider appeal of an effective route to key products from C-H activation, particularly with the need to transition to net carbon zero with new routes from renewable methane sources is exciting.
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Affiliation(s)
- Nicholas F. Dummer
- Max Planck−Cardiff Centre on the Fundamentals of Heterogeneous Catalysis FUNCAT, Cardiff Catalysis Institute, School of Chemistry, Cardiff University, Main Building, Park Place, CardiffCF10 3AT, United Kingdom
| | - David J. Willock
- Max Planck−Cardiff Centre on the Fundamentals of Heterogeneous Catalysis FUNCAT, Cardiff Catalysis Institute, School of Chemistry, Cardiff University, Main Building, Park Place, CardiffCF10 3AT, United Kingdom
| | - Qian He
- Department of Materials Science and Engineering, National University of Singapore, Singapore117575, Singapore
| | - Mark J. Howard
- Max Planck−Cardiff Centre on the Fundamentals of Heterogeneous Catalysis FUNCAT, Cardiff Catalysis Institute, School of Chemistry, Cardiff University, Main Building, Park Place, CardiffCF10 3AT, United Kingdom
| | - Richard J. Lewis
- Max Planck−Cardiff Centre on the Fundamentals of Heterogeneous Catalysis FUNCAT, Cardiff Catalysis Institute, School of Chemistry, Cardiff University, Main Building, Park Place, CardiffCF10 3AT, United Kingdom
| | - Guodong Qi
- National Center for Magnetic Resonance in Wuhan, State Key Laboratory of Magnetic Resonance and Atomic and Molecular Physics, Innovation Academy for Precision Measurement Science and Technology, Chinese Academy of Sciences, Wuhan430071, P. R. China
- University of Chinese Academy of Sciences, Beijing100049, P. R. China
| | - Stuart H. Taylor
- Max Planck−Cardiff Centre on the Fundamentals of Heterogeneous Catalysis FUNCAT, Cardiff Catalysis Institute, School of Chemistry, Cardiff University, Main Building, Park Place, CardiffCF10 3AT, United Kingdom
| | - Jun Xu
- National Center for Magnetic Resonance in Wuhan, State Key Laboratory of Magnetic Resonance and Atomic and Molecular Physics, Innovation Academy for Precision Measurement Science and Technology, Chinese Academy of Sciences, Wuhan430071, P. R. China
- University of Chinese Academy of Sciences, Beijing100049, P. R. China
| | - Don Bethell
- Department of Chemistry, University of Liverpool, Crown Street, LiverpoolL69 7ZD, United Kingdom
| | - Christopher J. Kiely
- Department of Materials Science and Engineering, Lehigh University, 5 East Packer Avenue, Bethlehem, Pennsylvania18015, United States
| | - Graham J. Hutchings
- Max Planck−Cardiff Centre on the Fundamentals of Heterogeneous Catalysis FUNCAT, Cardiff Catalysis Institute, School of Chemistry, Cardiff University, Main Building, Park Place, CardiffCF10 3AT, United Kingdom
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12
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Zhu Y, Koo CW, Cassidy CK, Spink MC, Ni T, Zanetti-Domingues LC, Bateman B, Martin-Fernandez ML, Shen J, Sheng Y, Song Y, Yang Z, Rosenzweig AC, Zhang P. Structure and activity of particulate methane monooxygenase arrays in methanotrophs. Nat Commun 2022; 13:5221. [PMID: 36064719 PMCID: PMC9445010 DOI: 10.1038/s41467-022-32752-9] [Citation(s) in RCA: 15] [Impact Index Per Article: 7.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/10/2022] [Accepted: 08/16/2022] [Indexed: 01/29/2023] Open
Abstract
Methane-oxidizing bacteria play a central role in greenhouse gas mitigation and have potential applications in biomanufacturing. Their primary metabolic enzyme, particulate methane monooxygenase (pMMO), is housed in copper-induced intracytoplasmic membranes (ICMs), of which the function and biogenesis are not known. We show by serial cryo-focused ion beam (cryoFIB) milling/scanning electron microscope (SEM) volume imaging and lamellae-based cellular cryo-electron tomography (cryoET) that these ICMs are derived from the inner cell membrane. The pMMO trimer, resolved by cryoET and subtomogram averaging to 4.8 Å in the ICM, forms higher-order hexagonal arrays in intact cells. Array formation correlates with increased enzymatic activity, highlighting the importance of studying the enzyme in its native environment. These findings also demonstrate the power of cryoET to structurally characterize native membrane enzymes in the cellular context.
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Affiliation(s)
- Yanan Zhu
- grid.4991.50000 0004 1936 8948Division of Structural Biology, Wellcome Trust Centre for Human Genetics, University of Oxford, Oxford, UK
| | - Christopher W. Koo
- grid.16753.360000 0001 2299 3507Departments of Molecular Biosciences and of Chemistry, Northwestern University, Evanston, IL USA
| | - C. Keith Cassidy
- grid.4991.50000 0004 1936 8948Department of Biochemistry, University of Oxford, Oxford, UK
| | - Matthew C. Spink
- grid.18785.330000 0004 1764 0696Diamond Light Source, Harwell Science and Innovation Campus, Didcot, UK
| | - Tao Ni
- grid.4991.50000 0004 1936 8948Division of Structural Biology, Wellcome Trust Centre for Human Genetics, University of Oxford, Oxford, UK
| | - Laura C. Zanetti-Domingues
- grid.76978.370000 0001 2296 6998Central Laser Facility, Science and Technology Facility Council, Rutherford Appleton Laboratory, Didcot, Oxfordshire UK
| | - Benji Bateman
- grid.76978.370000 0001 2296 6998Central Laser Facility, Science and Technology Facility Council, Rutherford Appleton Laboratory, Didcot, Oxfordshire UK
| | - Marisa L. Martin-Fernandez
- grid.76978.370000 0001 2296 6998Central Laser Facility, Science and Technology Facility Council, Rutherford Appleton Laboratory, Didcot, Oxfordshire UK
| | - Juan Shen
- grid.4991.50000 0004 1936 8948Division of Structural Biology, Wellcome Trust Centre for Human Genetics, University of Oxford, Oxford, UK
| | - Yuewen Sheng
- grid.18785.330000 0004 1764 0696Diamond Light Source, Harwell Science and Innovation Campus, Didcot, UK
| | - Yun Song
- grid.18785.330000 0004 1764 0696Diamond Light Source, Harwell Science and Innovation Campus, Didcot, UK
| | - Zhengyi Yang
- grid.18785.330000 0004 1764 0696Diamond Light Source, Harwell Science and Innovation Campus, Didcot, UK ,grid.4709.a0000 0004 0495 846XPresent Address: Imaging Centre, European Molecular Biology Laboratory, Heidelberg, Germany
| | - Amy C. Rosenzweig
- grid.16753.360000 0001 2299 3507Departments of Molecular Biosciences and of Chemistry, Northwestern University, Evanston, IL USA
| | - Peijun Zhang
- grid.4991.50000 0004 1936 8948Division of Structural Biology, Wellcome Trust Centre for Human Genetics, University of Oxford, Oxford, UK ,grid.18785.330000 0004 1764 0696Diamond Light Source, Harwell Science and Innovation Campus, Didcot, UK ,grid.4991.50000 0004 1936 8948Chinese Academy of Medical Sciences Oxford Institute, University of Oxford, Oxford, UK
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13
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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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14
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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: 6] [Impact Index Per Article: 3.0] [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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15
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Greening C, Grinter R. Microbial oxidation of atmospheric trace gases. Nat Rev Microbiol 2022; 20:513-528. [PMID: 35414013 DOI: 10.1038/s41579-022-00724-x] [Citation(s) in RCA: 31] [Impact Index Per Article: 15.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 03/11/2022] [Indexed: 02/06/2023]
Abstract
The atmosphere has recently been recognized as a major source of energy sustaining life. Diverse aerobic bacteria oxidize the three most abundant reduced trace gases in the atmosphere, namely hydrogen (H2), carbon monoxide (CO) and methane (CH4). This Review describes the taxonomic distribution, physiological role and biochemical basis of microbial oxidation of these atmospheric trace gases, as well as the ecological, environmental, medical and astrobiological importance of this process. Most soil bacteria and some archaea can survive by using atmospheric H2 and CO as alternative energy sources, as illustrated through genetic studies on Mycobacterium cells and Streptomyces spores. Certain specialist bacteria can also grow on air alone, as confirmed by the landmark characterization of Methylocapsa gorgona, which grows by simultaneously consuming atmospheric CH4, H2 and CO. Bacteria use high-affinity lineages of metalloenzymes, namely hydrogenases, CO dehydrogenases and methane monooxygenases, to utilize atmospheric trace gases for aerobic respiration and carbon fixation. More broadly, trace gas oxidizers enhance the biodiversity and resilience of soil and marine ecosystems, drive primary productivity in extreme environments such as Antarctic desert soils and perform critical regulatory services by mitigating anthropogenic emissions of greenhouse gases and toxic pollutants.
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Affiliation(s)
- Chris Greening
- Department of Microbiology, Biomedicine Discovery Institute, Monash University, Clayton, Victoria, Australia. .,Securing Antarctica's Environmental Future, Monash University, Clayton, Victoria, Australia. .,Centre to Impact AMR, Monash University, Clayton, Victoria, Australia.
| | - Rhys Grinter
- Department of Microbiology, Biomedicine Discovery Institute, Monash University, Clayton, Victoria, Australia.
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16
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Theoretical perspective on mononuclear copper-oxygen mediated C–H and O–H activations: A comparison between biological and synthetic systems. CHINESE JOURNAL OF CATALYSIS 2022. [DOI: 10.1016/s1872-2067(21)63974-8] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
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17
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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: 38] [Impact Index Per Article: 19.0] [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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18
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Wang Z, Fang W, Peng W, Wu P, Wang B. Recent Computational Insights into the Oxygen Activation by Copper-Dependent Metalloenzymes. Top Catal 2022. [DOI: 10.1007/s11244-021-01444-x] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
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19
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Le HTQ, Nguyen AD, Park YR, Lee EY. Sustainable biosynthesis of chemicals from methane and glycerol via reconstruction of multi-carbon utilizing pathway in obligate methanotrophic bacteria. Microb Biotechnol 2021; 14:2552-2565. [PMID: 33830652 PMCID: PMC8601198 DOI: 10.1111/1751-7915.13809] [Citation(s) in RCA: 10] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/27/2020] [Revised: 03/19/2021] [Accepted: 03/19/2021] [Indexed: 01/26/2023] Open
Abstract
Obligate methanotrophic bacteria can utilize methane, an inexpensive carbon feedstock, as a sole energy and carbon substrate, thus are considered as the only nature-provided biocatalyst for sustainable biomanufacturing of fuels and chemicals from methane. To address the limitation of native C1 metabolism of obligate type I methanotrophs, we proposed a novel platform strain that can utilize methane and multi-carbon substrates, such as glycerol, simultaneously to boost growth rates and chemical production in Methylotuvimicrobium alcaliphilum 20Z. To demonstrate the uses of this concept, we reconstructed a 2,3-butanediol biosynthetic pathway and achieved a fourfold higher titer of 2,3-butanediol production by co-utilizing methane and glycerol compared with that of methanotrophic growth. In addition, we reported the creation of a methanotrophic biocatalyst for one-step bioconversion of methane to methanol in which glycerol was used for cell growth, and methane was mainly used for methanol production. After the deletion of genes encoding methanol dehydrogenase (MDH), 11.6 mM methanol was obtained after 72 h using living cells in the absence of any chemical inhibitors of MDH and exogenous NADH source. A further improvement of this bioconversion was attained by using resting cells with a significantly increased titre of 76 mM methanol after 3.5 h with the supply of 40 mM formate. The work presented here provides a novel framework for a variety of approaches in methane-based biomanufacturing.
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Affiliation(s)
- Hoa Thi Quynh Le
- Department of Chemical Engineering (Integrated Engineering)Kyung Hee University17104Yongin‐siGyeonggi‐doSouth Korea
| | - Anh Duc Nguyen
- Department of Chemical Engineering (Integrated Engineering)Kyung Hee University17104Yongin‐siGyeonggi‐doSouth Korea
| | - Ye Rim Park
- Department of Chemical Engineering (Integrated Engineering)Kyung Hee University17104Yongin‐siGyeonggi‐doSouth Korea
| | - Eun Yeol Lee
- Department of Chemical Engineering (Integrated Engineering)Kyung Hee University17104Yongin‐siGyeonggi‐doSouth Korea
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20
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Peifer R, Müller L, Hoof S, Beckmann F, Cula B, Limberg C. Mimicking of the histidine brace structural motif in molecular copper(I) compounds. Z Anorg Allg Chem 2021. [DOI: 10.1002/zaac.202100145] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
Affiliation(s)
- R. Peifer
- Institut für Chemie Humboldt-Universität zu Berlin Brook-Taylor-Straße 2 12489 Berlin Germany
| | - L. Müller
- Institut für Chemie Humboldt-Universität zu Berlin Brook-Taylor-Straße 2 12489 Berlin Germany
| | - S. Hoof
- Institut für Chemie Humboldt-Universität zu Berlin Brook-Taylor-Straße 2 12489 Berlin Germany
| | - F. Beckmann
- Institut für Chemie Humboldt-Universität zu Berlin Brook-Taylor-Straße 2 12489 Berlin Germany
| | - B. Cula
- Institut für Chemie Humboldt-Universität zu Berlin Brook-Taylor-Straße 2 12489 Berlin Germany
| | - C. Limberg
- Institut für Chemie Humboldt-Universität zu Berlin Brook-Taylor-Straße 2 12489 Berlin Germany
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21
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Jodts RJ, Ross MO, Koo CW, Doan PE, Rosenzweig AC, Hoffman BM. Coordination of the Copper Centers in Particulate Methane Monooxygenase: Comparison between Methanotrophs and Characterization of the Cu C Site by EPR and ENDOR Spectroscopies. J Am Chem Soc 2021; 143:15358-15368. [PMID: 34498465 DOI: 10.1021/jacs.1c07018] [Citation(s) in RCA: 22] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022]
Abstract
In nature, methane is oxidized to methanol by two enzymes, the iron-dependent soluble methane monooxygenase (sMMO) and the copper-dependent particulate MMO (pMMO). While sMMO's diiron metal active site is spectroscopically and structurally well-characterized, pMMO's copper sites are not. Recent EPR and ENDOR studies have established the presence of two monocopper sites, but the coordination environment of only one has been determined, that within the PmoB subunit and denoted CuB. Moreover, this recent work only focused on a type I methanotrophic pMMO, while previous observations of the type II enzyme were interpreted in terms of the presence of a dicopper site. First, this report shows that the type II Methylocystis species strain Rockwell pMMO, like the type I pMMOs, contains two monocopper sites and that its CuB site has a coordination environment identical to that of type I enzymes. As such, for the full range of pMMOs this report completes the refutation of prior and ongoing suggestions of multicopper sites. Second, and of primary importance, EPR/ENDOR measurements (a) for the first time establish the coordination environment of the spectroscopically observed site, provisionally denoted CuC, in both types of pMMO, thereby (b) establishing the assignment of this site observed by EPR to the crystallographically observed metal-binding site in the PmoC subunit. Finally, these results further indicate that CuC is the likely site of biological methane oxidation by pMMO, a conclusion that will serve as a foundation for proposals regarding the mechanism of this reaction.
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Affiliation(s)
- Richard J Jodts
- Departments of Chemistry and Molecular Biosciences, Northwestern University, Evanston, Illinois 60208, United States
| | - Matthew O Ross
- Departments of Chemistry and Molecular Biosciences, Northwestern University, Evanston, Illinois 60208, United States
| | - Christopher W Koo
- Departments of Chemistry and Molecular Biosciences, Northwestern University, Evanston, Illinois 60208, United States
| | - Peter E Doan
- Departments of Chemistry and Molecular Biosciences, Northwestern University, Evanston, Illinois 60208, United States
| | - Amy C Rosenzweig
- Departments of Chemistry and Molecular Biosciences, Northwestern University, Evanston, Illinois 60208, United States
| | - Brian M Hoffman
- Departments of Chemistry and Molecular Biosciences, Northwestern University, Evanston, Illinois 60208, United States
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22
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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: 7] [Impact Index Per Article: 2.3] [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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23
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Lee JL, Ross DL, Barman SK, Ziller JW, Borovik AS. C-H Bond Cleavage by Bioinspired Nonheme Metal Complexes. Inorg Chem 2021; 60:13759-13783. [PMID: 34491738 DOI: 10.1021/acs.inorgchem.1c01754] [Citation(s) in RCA: 24] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
Abstract
The functionalization of C-H bonds is one of the most challenging transformations in synthetic chemistry. In biology, these processes are well-known and are achieved with a variety of metalloenzymes, many of which contain a single metal center within their active sites. The most well studied are those with Fe centers, and the emerging experimental data show that high-valent iron oxido species are the intermediates responsible for cleaving the C-H bond. This Forum Article describes the state of this field with an emphasis on nonheme Fe enzymes and current experimental results that provide insights into the properties that make these species capable of C-H bond cleavage. These parameters are also briefly considered in regard to manganese oxido complexes and Cu-containing metalloenzymes. Synthetic iron oxido complexes are discussed to highlight their utility as spectroscopic and mechanistic probes and reagents for C-H bond functionalization. Avenues for future research are also examined.
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Affiliation(s)
- Justin L Lee
- Department of Chemistry, University of California-Irvine, 1102 Natural Sciences II, Irvine, California 92697, United States
| | - Dolores L Ross
- Department of Chemistry, University of California-Irvine, 1102 Natural Sciences II, Irvine, California 92697, United States
| | - Suman K Barman
- Department of Chemistry, University of California-Irvine, 1102 Natural Sciences II, Irvine, California 92697, United States
| | - Joseph W Ziller
- Department of Chemistry, University of California-Irvine, 1102 Natural Sciences II, Irvine, California 92697, United States
| | - A S Borovik
- Department of Chemistry, University of California-Irvine, 1102 Natural Sciences II, Irvine, California 92697, United States
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24
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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: 31] [Impact Index Per Article: 10.3] [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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25
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Copper binding by a unique family of metalloproteins is dependent on kynurenine formation. Proc Natl Acad Sci U S A 2021; 118:2100680118. [PMID: 34074779 DOI: 10.1073/pnas.2100680118] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Some methane-oxidizing bacteria use the ribosomally synthesized, posttranslationally modified natural product methanobactin (Mbn) to acquire copper for their primary metabolic enzyme, particulate methane monooxygenase. The operons encoding the machinery to biosynthesize and transport Mbns typically include genes for two proteins, MbnH and MbnP, which are also found as a pair in other genomic contexts related to copper homeostasis. While the MbnH protein, a member of the bacterial diheme cytochrome c peroxidase (bCcP)/MauG superfamily, has been characterized, the structure and function of MbnP, the relationship between the two proteins, and their role in copper homeostasis remain unclear. Biochemical characterization of MbnP from the methanotroph Methylosinus trichosporium OB3b now reveals that MbnP binds a single copper ion, present in the +1 oxidation state, with high affinity. Copper binding to MbnP in vivo is dependent on oxidation of the first tryptophan in a conserved WxW motif to a kynurenine, a transformation that occurs through an interaction of MbnH with MbnP. The 2.04-Å-resolution crystal structure of MbnP reveals a unique fold and an unusual copper-binding site involving a histidine, a methionine, a solvent ligand, and the kynurenine. Although the kynurenine residue may not serve as a CuI primary-sphere ligand, being positioned ∼2.9 Å away from the CuI ion, its presence is required for copper binding. Genomic neighborhood analysis indicates that MbnP proteins, and by extension kynurenine-containing copper sites, are widespread and may play diverse roles in microbial copper homeostasis.
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26
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Peng W, Qu X, Shaik S, Wang B. Deciphering the oxygen activation mechanism at the CuC site of particulate methane monooxygenase. Nat Catal 2021. [DOI: 10.1038/s41929-021-00591-4] [Citation(s) in RCA: 23] [Impact Index Per Article: 7.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023]
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27
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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: 20] [Impact Index Per Article: 6.7] [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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28
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Abstract
Methanotrophic bacteria represent a potential route to methane utilization and mitigation of methane emissions. In the first step of their metabolic pathway, aerobic methanotrophs use methane monooxygenases (MMOs) to activate methane, oxidizing it to methanol. There are two types of MMOs: a particulate, membrane-bound enzyme (pMMO) and a soluble, cytoplasmic enzyme (sMMO). The two MMOs are completely unrelated, with different architectures, metal cofactors, and mechanisms. The more prevalent of the two, pMMO, is copper-dependent, but the identity of its copper active site remains unclear. By contrast, sMMO uses a diiron active site, the catalytic cycle of which is well understood. Here we review the current state of knowledge for both MMOs, with an emphasis on recent developments and emerging hypotheses. In addition, we discuss obstacles to developing expression systems, which are needed to address outstanding questions and to facilitate future protein engineering efforts.
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Affiliation(s)
- Christopher W Koo
- Departments of Molecular Biosciences and of Chemistry, Northwestern University, Evanston, IL 60208, USA.
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29
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Calisto F, Sousa FM, Sena FV, Refojo PN, Pereira MM. Mechanisms of Energy Transduction by Charge Translocating Membrane Proteins. Chem Rev 2021; 121:1804-1844. [PMID: 33398986 DOI: 10.1021/acs.chemrev.0c00830] [Citation(s) in RCA: 21] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
Life relies on the constant exchange of different forms of energy, i.e., on energy transduction. Therefore, organisms have evolved in a way to be able to harvest the energy made available by external sources (such as light or chemical compounds) and convert these into biological useable energy forms, such as the transmembrane difference of electrochemical potential (Δμ̃). Membrane proteins contribute to the establishment of Δμ̃ by coupling exergonic catalytic reactions to the translocation of charges (electrons/ions) across the membrane. Irrespectively of the energy source and consequent type of reaction, all charge-translocating proteins follow two molecular coupling mechanisms: direct- or indirect-coupling, depending on whether the translocated charge is involved in the driving reaction. In this review, we explore these two coupling mechanisms by thoroughly examining the different types of charge-translocating membrane proteins. For each protein, we analyze the respective reaction thermodynamics, electron transfer/catalytic processes, charge-translocating pathways, and ion/substrate stoichiometries.
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Affiliation(s)
- Filipa Calisto
- Instituto de Tecnologia Química e Biológica-António Xavier, Universidade Nova de Lisboa, Av. da República EAN, 2780-157, Oeiras, Portugal.,BioISI-Biosystems & Integrative Sciences Institute, University of Lisboa, Faculty of Sciences, Campo Grande, 1749-016 Lisboa, Portugal
| | - Filipe M Sousa
- Instituto de Tecnologia Química e Biológica-António Xavier, Universidade Nova de Lisboa, Av. da República EAN, 2780-157, Oeiras, Portugal.,BioISI-Biosystems & Integrative Sciences Institute, University of Lisboa, Faculty of Sciences, Campo Grande, 1749-016 Lisboa, Portugal
| | - Filipa V Sena
- Instituto de Tecnologia Química e Biológica-António Xavier, Universidade Nova de Lisboa, Av. da República EAN, 2780-157, Oeiras, Portugal.,BioISI-Biosystems & Integrative Sciences Institute, University of Lisboa, Faculty of Sciences, Campo Grande, 1749-016 Lisboa, Portugal
| | - Patricia N Refojo
- Instituto de Tecnologia Química e Biológica-António Xavier, Universidade Nova de Lisboa, Av. da República EAN, 2780-157, Oeiras, Portugal
| | - Manuela M Pereira
- Instituto de Tecnologia Química e Biológica-António Xavier, Universidade Nova de Lisboa, Av. da República EAN, 2780-157, Oeiras, Portugal.,BioISI-Biosystems & Integrative Sciences Institute, University of Lisboa, Faculty of Sciences, Campo Grande, 1749-016 Lisboa, Portugal
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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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31
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Guggenheim C, Freimann R, Mayr MJ, Beck K, Wehrli B, Bürgmann H. Environmental and Microbial Interactions Shape Methane-Oxidizing Bacterial Communities in a Stratified Lake. Front Microbiol 2020; 11:579427. [PMID: 33178162 PMCID: PMC7593551 DOI: 10.3389/fmicb.2020.579427] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/02/2020] [Accepted: 09/04/2020] [Indexed: 11/13/2022] Open
Abstract
In stratified lakes, methane-oxidizing bacteria (MOB) are strongly mitigating methane fluxes to the atmosphere by consuming methane entering the water column from the sediments. MOB communities in lakes are diverse and vertically structured, but their spatio-temporal dynamics along the water column as well as physico-chemical parameters and interactions with other bacterial species that drive the community assembly have so far not been explored in depth. Here, we present a detailed investigation of the MOB and bacterial community composition and a large set of physico-chemical parameters in a shallow, seasonally stratified, and sub-alpine lake. Four highly resolved vertical profiles were sampled in three different years and during various stages of development of the stratified water column. Non-randomly assembled MOB communities were detected in all compartments. We could identify methane and oxygen gradients and physico-chemical parameters like pH, light, available copper and iron, and total dissolved nitrogen as important drivers of the MOB community structure. In addition, MOB were well-integrated into a bacterial-environmental network. Partial redundancy analysis of the relevance network of physico-chemical variables and bacteria explained up to 84% of the MOB abundances. Spatio-temporal MOB community changes were 51% congruent with shifts in the total bacterial community and 22% of variance in MOB abundances could be explained exclusively by the bacterial community composition. Our results show that microbial interactions may play an important role in structuring the MOB community along the depth gradient of stratified lakes.
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Affiliation(s)
- Carole Guggenheim
- Department of Environmental Systems Science, Institute of Biogeochemistry and Pollutant Dynamics, ETH Zurich - Swiss Federal Institute of Technology, Zurich, Switzerland.,Department of Surface Waters - Research and Management, Eawag - Swiss Federal Institute of Aquatic Science and Technology, Kastanienbaum, Switzerland
| | - Remo Freimann
- Department of Biology, Institute of Molecular Health Sciences, ETH Zurich - Swiss Federal Institute of Technology, Zurich, Switzerland
| | - Magdalena J Mayr
- Department of Environmental Systems Science, Institute of Biogeochemistry and Pollutant Dynamics, ETH Zurich - Swiss Federal Institute of Technology, Zurich, Switzerland.,Department of Surface Waters - Research and Management, Eawag - Swiss Federal Institute of Aquatic Science and Technology, Kastanienbaum, Switzerland
| | - Karin Beck
- Department of Surface Waters - Research and Management, Eawag - Swiss Federal Institute of Aquatic Science and Technology, Kastanienbaum, Switzerland
| | - Bernhard Wehrli
- Department of Environmental Systems Science, Institute of Biogeochemistry and Pollutant Dynamics, ETH Zurich - Swiss Federal Institute of Technology, Zurich, Switzerland.,Department of Surface Waters - Research and Management, Eawag - Swiss Federal Institute of Aquatic Science and Technology, Kastanienbaum, Switzerland
| | - Helmut Bürgmann
- Department of Surface Waters - Research and Management, Eawag - Swiss Federal Institute of Aquatic Science and Technology, Kastanienbaum, Switzerland
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32
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Musiani F, Broll V, Evangelisti E, Ciurli S. The model structure of the copper-dependent ammonia monooxygenase. J Biol Inorg Chem 2020; 25:995-1007. [PMID: 32926231 PMCID: PMC7584546 DOI: 10.1007/s00775-020-01820-0] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/24/2020] [Accepted: 09/02/2020] [Indexed: 12/24/2022]
Abstract
Abstract Ammonia monooxygenase is a copper-dependent membrane-bound enzyme that catalyzes the first step of nitrification in ammonia-oxidizing bacteria to convert ammonia to hydroxylamine, through the reductive insertion of a dioxygen-derived O atom in an N–H bond. This reaction is analogous to that carried out by particulate methane monooxygenase, which catalyzes the conversion of methane to methanol. The enzymatic activity of ammonia monooxygenase must be modulated to reduce the release of nitrogen-based soil nutrients for crop production into the atmosphere or underground waters, a phenomenon known to significantly decrease the efficiency of primary production as well as increase air and water pollution. The structure of ammonia monooxygenase is not available, rendering the rational design of enzyme inhibitors impossible. This study describes a successful attempt to build a structural model of ammonia monooxygenase, and its accessory proteins AmoD and AmoE, from Nitrosomonas europaea, taking advantage of the high sequence similarity with particulate methane monooxygenase and the homologous PmoD protein, for which crystal structures are instead available. The results obtained not only provide the structural details of the proteins ternary and quaternary structures, but also suggest a location for the copper-containing active site for both ammonia and methane monooxygenases, as well as support a proposed structure of a CuA-analogue dinuclear copper site in AmoD and PmoD. Graphic abstract ![]()
Electronic supplementary material The online version of this article (10.1007/s00775-020-01820-0) contains supplementary material, which is available to authorized users.
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Affiliation(s)
- Francesco Musiani
- Laboratory of Bioinorganic Chemistry, Department of Pharmacy and Biotechnology, University of Bologna, Viale G. Fanin 40, 40127, Bologna, Italy.
| | - Valquiria Broll
- Laboratory of Bioinorganic Chemistry, Department of Pharmacy and Biotechnology, University of Bologna, Viale G. Fanin 40, 40127, Bologna, Italy
| | - Elisa Evangelisti
- Laboratory of Bioinorganic Chemistry, Department of Pharmacy and Biotechnology, University of Bologna, Viale G. Fanin 40, 40127, Bologna, Italy
| | - Stefano Ciurli
- Laboratory of Bioinorganic Chemistry, Department of Pharmacy and Biotechnology, University of Bologna, Viale G. Fanin 40, 40127, Bologna, Italy.
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33
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Morris RH. Methane activation by a single copper center in particulate methane monooxygenase: A computational study. Inorganica Chim Acta 2020. [DOI: 10.1016/j.ica.2020.119441] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/26/2022]
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34
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Abstract
Methane activation chemistry, despite being widely reported in literature, remains to date a subject of debate. The challenges in this reaction are not limited to methane activation but extend to stabilization of the intermediate species. The low C-H dissociation energy of intermediates vs. reactants leads to CO2 formation. For selective oxidation, nature presents methane monooxygenase as a benchmark. This enzyme selectively consumes methane by breaking it down into methanol. To assemble an active site similar to monooxygenase, the literature reports Cu-ZSM-5, Fe-ZSM-5, and Cu-MOR, using zeolites and systems like CeO2/Cu2O/Cu. However, the trade-off between methane activation and methanol selectivity remains a challenge. Density functional theory (DFT) calculations and spectroscopic studies indicate catalyst reducibility, oxygen mobility, and water as co-feed as primary factors that can assist in enabling higher selectivity. The use of chemical looping can further improve selectivity. However, in all systems, improvements in productivity per cycle are required in order to meet the economical/industrial standards.
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35
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Kasprzycka A, Lalak-Kańczugowska J, Walkiewicz A, Bulak P, Proc K, Stępień Ł. Biocatalytic conversion of methane – selected aspects. Curr Opin Chem Eng 2019. [DOI: 10.1016/j.coche.2019.07.006] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/12/2023]
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36
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Avdeeva LV, Gvozdev RI. Effect of Heavy Metal Salts on Propylene Oxidation by Methanotrophic Bacteria. RUSSIAN JOURNAL OF PHYSICAL CHEMISTRY B 2019. [DOI: 10.1134/s1990793119060022] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
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37
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Fisher OS, Sendzik MR, Ross MO, Lawton TJ, Hoffman BM, Rosenzweig AC. PCu AC domains from methane-oxidizing bacteria use a histidine brace to bind copper. J Biol Chem 2019; 294:16351-16363. [PMID: 31527086 PMCID: PMC6827282 DOI: 10.1074/jbc.ra119.010093] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/08/2019] [Revised: 09/09/2019] [Indexed: 01/07/2023] Open
Abstract
Copper is critically important for methanotrophic bacteria because their primary metabolic enzyme, particulate methane monooxygenase (pMMO), is copper-dependent. In addition to pMMO, many other copper proteins are encoded in the genomes of methanotrophs, including proteins that contain periplasmic copper-Achaperone (PCuAC) domains. Using bioinformatics analyses, we identified three distinct classes of PCuAC domain-containing proteins in methanotrophs, termed PmoF1, PmoF2, and PmoF3. PCuAC domains from other types of bacteria bind a single Cu(I) ion via an HXnMX21/22HXM motif, which is also present in PmoF3, but PmoF1 and PmoF2 lack this motif entirely. Instead, the PCuAC domains of PmoF1 and PmoF2 bind only Cu(II), and PmoF1 binds additional Cu(II) ions in a His-rich extension to its PCuAC domain. Crystal structures of the PmoF1 and PmoF2 PCuAC domains reveal that Cu(II) is coordinated by an N-terminal histidine brace HX10H motif. This binding site is distinct from those of previously characterized PCuAC domains but resembles copper centers in CopC proteins and lytic polysaccharide monooxygenase (LPMO) enzymes. Bioinformatics analysis of the entire PCuAC family reveals previously unappreciated diversity, including sequences that contain both the HXnMX21/22HXM and HX10H motifs, and sequences that lack either set of copper-binding ligands. These findings provide the first characterization of an additional class of copper proteins from methanotrophs, further expand the PCuAC family, and afford new insight into the biological significance of histidine brace-mediated copper coordination.
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Affiliation(s)
- Oriana S. Fisher
- Departments of Molecular Biosciences and of Chemistry, Northwestern University, Evanston, Illinois 60208
| | - Madison R. Sendzik
- Departments of Molecular Biosciences and of Chemistry, Northwestern University, Evanston, Illinois 60208
| | - Matthew O. Ross
- Departments of Molecular Biosciences and of Chemistry, Northwestern University, Evanston, Illinois 60208
| | - Thomas J. Lawton
- Departments of Molecular Biosciences and of Chemistry, Northwestern University, Evanston, Illinois 60208
| | - Brian M. Hoffman
- Departments of Molecular Biosciences and of Chemistry, Northwestern University, Evanston, Illinois 60208
| | - Amy C. Rosenzweig
- Departments of Molecular Biosciences and of Chemistry, Northwestern University, Evanston, Illinois 60208, To whom correspondence should be addressed:
Depts. of Molecular Biosciences and Chemistry, Northwestern University, Evanston, IL 60208. Tel.:
847-467-5301; Fax:
847-467-6489; E-mail:
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38
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Native top-down mass spectrometry provides insights into the copper centers of membrane-bound methane monooxygenase. Nat Commun 2019; 10:2675. [PMID: 31209220 PMCID: PMC6572826 DOI: 10.1038/s41467-019-10590-6] [Citation(s) in RCA: 63] [Impact Index Per Article: 12.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/06/2019] [Accepted: 05/15/2019] [Indexed: 01/12/2023] Open
Abstract
Aerobic methane oxidation is catalyzed by particulate methane monooxygenase (pMMO), a copper-dependent, membrane metalloenzyme composed of subunits PmoA, PmoB, and PmoC. Characterization of the copper active site has been limited by challenges in spectroscopic analysis stemming from the presence of multiple copper binding sites, effects of detergent solubilization on activity and crystal structures, and the lack of a heterologous expression system. Here we utilize nanodiscs coupled with native top-down mass spectrometry (nTDMS) to determine the copper stoichiometry in each pMMO subunit and to detect post-translational modifications (PTMs). These results indicate the presence of a mononuclear copper center in both PmoB and PmoC. pMMO-nanodisc complexes with a higher stoichiometry of copper-bound PmoC exhibit increased activity, suggesting that the PmoC copper site plays a role in methane oxidation activity. These results provide key insights into the pMMO copper centers and demonstrate the ability of nTDMS to characterize complex membrane-bound metalloenzymes.
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Ross MO, MacMillan F, Wang J, Nisthal A, Lawton TJ, Olafson BD, Mayo SL, Rosenzweig AC, Hoffman BM. Particulate methane monooxygenase contains only mononuclear copper centers. Science 2019; 364:566-570. [PMID: 31073062 PMCID: PMC6664434 DOI: 10.1126/science.aav2572] [Citation(s) in RCA: 171] [Impact Index Per Article: 34.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/29/2018] [Accepted: 04/15/2019] [Indexed: 12/23/2022]
Abstract
Bacteria that oxidize methane to methanol are central to mitigating emissions of methane, a potent greenhouse gas. The nature of the copper active site in the primary metabolic enzyme of these bacteria, particulate methane monooxygenase (pMMO), has been controversial owing to seemingly contradictory biochemical, spectroscopic, and crystallographic results. We present biochemical and electron paramagnetic resonance spectroscopic characterization most consistent with two monocopper sites within pMMO: one in the soluble PmoB subunit at the previously assigned active site (CuB) and one ~2 nanometers away in the membrane-bound PmoC subunit (CuC). On the basis of these results, we propose that a monocopper site is able to catalyze methane oxidation in pMMO.
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Affiliation(s)
- Matthew O Ross
- Department of Molecular Biosciences, Northwestern University, 2205 Tech Drive, Evanston, IL 60208, USA
- Department of Chemistry, Northwestern University, 2145 Sheridan Road, Evanston, IL 60208, USA
| | - Fraser MacMillan
- Henry Wellcome Unit for Biological Electron Paramagnetic Resonance Spectroscopy, School of Chemistry, University of East Anglia, Norwich NR4 7TJ, UK
| | - Jingzhou Wang
- Division of Biology, California Institute of Technology, MC 114-96, 1200 East California Boulevard, Pasadena, CA 91125, USA
- Division of Chemistry and Chemical Engineering, California Institute of Technology, MC 114-96, 1200 East California Boulevard, Pasadena, CA 91125, USA
| | - Alex Nisthal
- Division of Biology, California Institute of Technology, MC 114-96, 1200 East California Boulevard, Pasadena, CA 91125, USA
- Division of Chemistry and Chemical Engineering, California Institute of Technology, MC 114-96, 1200 East California Boulevard, Pasadena, CA 91125, USA
| | - Thomas J Lawton
- Department of Molecular Biosciences, Northwestern University, 2205 Tech Drive, Evanston, IL 60208, USA
- Department of Chemistry, Northwestern University, 2145 Sheridan Road, Evanston, IL 60208, USA
| | - Barry D Olafson
- Protabit, 1010 E. Union Street, Suite 110, Pasadena, CA 91106, USA
| | - Stephen L Mayo
- Division of Biology, California Institute of Technology, MC 114-96, 1200 East California Boulevard, Pasadena, CA 91125, USA
- Division of Chemistry and Chemical Engineering, California Institute of Technology, MC 114-96, 1200 East California Boulevard, Pasadena, CA 91125, USA
| | - Amy C Rosenzweig
- Department of Molecular Biosciences, Northwestern University, 2205 Tech Drive, Evanston, IL 60208, USA.
- Department of Chemistry, Northwestern University, 2145 Sheridan Road, Evanston, IL 60208, USA
| | - Brian M Hoffman
- Department of Molecular Biosciences, Northwestern University, 2205 Tech Drive, Evanston, IL 60208, USA.
- Department of Chemistry, Northwestern University, 2145 Sheridan Road, Evanston, IL 60208, USA
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40
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Kim HJ, Huh J, Kwon YW, Park D, Yu Y, Jang YE, Lee BR, Jo E, Lee EJ, Heo Y, Lee W, Lee J. Biological conversion of methane to methanol through genetic reassembly of native catalytic domains. Nat Catal 2019. [DOI: 10.1038/s41929-019-0255-1] [Citation(s) in RCA: 43] [Impact Index Per Article: 8.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
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41
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42
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Miyaji A, Nitta M, Baba T. Influence of copper ions removal from membrane-bound form of particulate methane monooxygenase from Methylosinus trichosporium OB3b on its activity for methane hydroxylation. J Biotechnol 2019; 306S:100001. [PMID: 34112370 DOI: 10.1016/j.btecx.2018.100001] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/05/2018] [Revised: 12/11/2018] [Accepted: 12/14/2018] [Indexed: 11/26/2022]
Abstract
The influence of metal removal with a chelating reagent, ethylenediaminetetraacetic acid (EDTA), and metal reconstitution on the activity of particulate methane monooxygenase (pMMO) from Methylosinus trichosporium OB3b toward methane oxidation to methanol was investigated. For this study, a membrane fraction containing pMMO and bacterial cell membrane components was prepared. pMMO activity was assessed with two different reductants, nicotinamide adenine dinucleotide (NADH) and 2,3,5,6-tetramethyl hydroquinone (duroquinol). The partial removal of metal ions with EDTA resulted in the selective inhibition of NADH-driven activity. The NADH-driven activity was restored by exogenous copper ions, but not by other divalent metal cations. Furthermore, both NADH- and duroquinol-driven activities were lost completely by increasing the amount of metal removed. Duroquinol-driven activity of the metal-deficient membrane fraction increased with increasing the amount of copper ions added, while NADH-driven activity increased when more than 5 mol of copper ions per mol of pMMO monomer was added. These results suggest that NADH-driven pMMO activity requires not only the catalytic copper center of pMMO but also copper ions outside the catalytic site.
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Affiliation(s)
- Akimitsu Miyaji
- Department of Environmental Chemistry and Engineering, Tokyo Institute of Technology, G1-14, Nagatsuta-cho, Midori-ku, Yokohama 226-8502, Japan.
| | - Muneyuki Nitta
- Department of Environmental Chemistry and Engineering, Tokyo Institute of Technology, G1-14, Nagatsuta-cho, Midori-ku, Yokohama 226-8502, Japan
| | - Toshihide Baba
- Department of Environmental Chemistry and Engineering, Tokyo Institute of Technology, G1-14, Nagatsuta-cho, Midori-ku, Yokohama 226-8502, Japan
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43
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Adam SM, Wijeratne GB, Rogler PJ, Diaz DE, Quist DA, Liu JJ, Karlin KD. Synthetic Fe/Cu Complexes: Toward Understanding Heme-Copper Oxidase Structure and Function. Chem Rev 2018; 118:10840-11022. [PMID: 30372042 PMCID: PMC6360144 DOI: 10.1021/acs.chemrev.8b00074] [Citation(s) in RCA: 132] [Impact Index Per Article: 22.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022]
Abstract
Heme-copper oxidases (HCOs) are terminal enzymes on the mitochondrial or bacterial respiratory electron transport chain, which utilize a unique heterobinuclear active site to catalyze the 4H+/4e- reduction of dioxygen to water. This process involves a proton-coupled electron transfer (PCET) from a tyrosine (phenolic) residue and additional redox events coupled to transmembrane proton pumping and ATP synthesis. Given that HCOs are large, complex, membrane-bound enzymes, bioinspired synthetic model chemistry is a promising approach to better understand heme-Cu-mediated dioxygen reduction, including the details of proton and electron movements. This review encompasses important aspects of heme-O2 and copper-O2 (bio)chemistries as they relate to the design and interpretation of small molecule model systems and provides perspectives from fundamental coordination chemistry, which can be applied to the understanding of HCO activity. We focus on recent advancements from studies of heme-Cu models, evaluating experimental and computational results, which highlight important fundamental structure-function relationships. Finally, we provide an outlook for future potential contributions from synthetic inorganic chemistry and discuss their implications with relevance to biological O2-reduction.
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Affiliation(s)
- Suzanne M. Adam
- Department of Chemistry, Johns Hopkins University, Baltimore, Maryland 21218, United States
| | - Gayan B. Wijeratne
- Department of Chemistry, Johns Hopkins University, Baltimore, Maryland 21218, United States
| | - Patrick J. Rogler
- Department of Chemistry, Johns Hopkins University, Baltimore, Maryland 21218, United States
| | - Daniel E. Diaz
- Department of Chemistry, Johns Hopkins University, Baltimore, Maryland 21218, United States
| | - David A. Quist
- Department of Chemistry, Johns Hopkins University, Baltimore, Maryland 21218, United States
| | - Jeffrey J. Liu
- Department of Chemistry, Johns Hopkins University, Baltimore, Maryland 21218, United States
| | - Kenneth D. Karlin
- Department of Chemistry, Johns Hopkins University, Baltimore, Maryland 21218, United States
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44
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Biocatalytic Oxidations of Substrates through Soluble Methane Monooxygenase from Methylosinus sporium 5. Catalysts 2018. [DOI: 10.3390/catal8120582] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022] Open
Abstract
Methane, an important greenhouse gas, has a 20-fold higher heat capacity than carbon dioxide. Earlier, through advanced spectroscopy and structural studies, the mechanisms underlying the extremely stable C–H activation of soluble methane monooxygenase (sMMO) have been elucidated in Methylosinus trichosporium OB3b and Methylococcus capsulatus Bath. Here, sMMO components—including hydroxylase (MMOH), regulatory (MMOB), and reductase (MMOR)—were expressed and purified from a type II methanotroph, Methylosinus sporium strain 5 (M. sporium 5), to characterize its hydroxylation mechanism. Two molar equivalents of MMOB are necessary to achieve catalytic activities and oxidized a broad range of substrates including alkanes, alkenes, halogens, and aromatics. Optimal activities were observed at pH 7.5 for most substrates possibly because of the electron transfer environment in MMOR. Substitution of MMOB or MMOR from another type II methanotroph, Methylocystis species M, retained specific enzyme activities, demonstrating the successful cross-reactivity of M. sporium 5. These results will provide fundamental information for further enzymatic studies to elucidate sMMO mechanisms.
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45
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Fisher OS, Kenney GE, Ross MO, Ro SY, Lemma BE, Batelu S, Thomas PM, Sosnowski VC, DeHart CJ, Kelleher NL, Stemmler TL, Hoffman BM, Rosenzweig AC. Characterization of a long overlooked copper protein from methane- and ammonia-oxidizing bacteria. Nat Commun 2018; 9:4276. [PMID: 30323281 PMCID: PMC6189053 DOI: 10.1038/s41467-018-06681-5] [Citation(s) in RCA: 38] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/02/2018] [Accepted: 09/20/2018] [Indexed: 12/24/2022] Open
Abstract
Methane-oxidizing microbes catalyze the oxidation of the greenhouse gas methane using the copper-dependent enzyme particulate methane monooxygenase (pMMO). Isolated pMMO exhibits lower activity than whole cells, however, suggesting that additional components may be required. A pMMO homolog, ammonia monooxygenase (AMO), converts ammonia to hydroxylamine in ammonia-oxidizing bacteria (AOB) which produce another potent greenhouse gas, nitrous oxide. Here we show that PmoD, a protein encoded within many pmo operons that is homologous to the AmoD proteins encoded within AOB amo operons, forms a copper center that exhibits the features of a well-defined CuA site using a previously unobserved ligand set derived from a cupredoxin homodimer. PmoD is critical for copper-dependent growth on methane, and genetic analyses strongly support a role directly related to pMMO and AMO. These findings identify a copper-binding protein that may represent a missing link in the function of enzymes critical to the global carbon and nitrogen cycles. Methane- and ammonia-oxidizing bacteria use the integral membrane, copper-dependent enzymes particulate methane monooxygenase (pMMO) and ammonia monooxygenase (AMO) to oxidize methane and ammonia. Here the authors structurally characterize the copper-binding protein PmoD, which contains an unusual CuA site and their genetic analyses strongly support a pMMO and AMO related function of PmoD.
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Affiliation(s)
- Oriana S Fisher
- Departments of Molecular Biosciences and Chemistry, Northwestern University, Evanston, 60208, IL, USA
| | - Grace E Kenney
- Departments of Molecular Biosciences and Chemistry, Northwestern University, Evanston, 60208, IL, USA
| | - Matthew O Ross
- Departments of Molecular Biosciences and Chemistry, Northwestern University, Evanston, 60208, IL, USA
| | - Soo Y Ro
- Departments of Molecular Biosciences and Chemistry, Northwestern University, Evanston, 60208, IL, USA
| | - Betelehem E Lemma
- Departments of Molecular Biosciences and Chemistry, Northwestern University, Evanston, 60208, IL, USA
| | - Sharon Batelu
- Department of Pharmaceutical Sciences, Wayne State University, Detroit, 48201, MI, USA
| | - Paul M Thomas
- Departments of Molecular Biosciences and Chemistry, Northwestern University, Evanston, 60208, IL, USA
| | - Victoria C Sosnowski
- Departments of Molecular Biosciences and Chemistry, Northwestern University, Evanston, 60208, IL, USA
| | - Caroline J DeHart
- Departments of Molecular Biosciences and Chemistry, Northwestern University, Evanston, 60208, IL, USA
| | - Neil L Kelleher
- Departments of Molecular Biosciences and Chemistry, Northwestern University, Evanston, 60208, IL, USA
| | - Timothy L Stemmler
- Department of Pharmaceutical Sciences, Wayne State University, Detroit, 48201, MI, USA
| | - Brian M Hoffman
- 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.
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46
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Abstract
Copper-binding metallophores, or chalkophores, play a role in microbial copper homeostasis that is analogous to that of siderophores in iron homeostasis. The best-studied chalkophores are members of the methanobactin (Mbn) family-ribosomally produced, posttranslationally modified natural products first identified as copper chelators responsible for copper uptake in methane-oxidizing bacteria. To date, Mbns have been characterized exclusively in those species, but there is genomic evidence for their production in a much wider range of bacteria. This review addresses the current state of knowledge regarding the function, biosynthesis, transport, and regulation of Mbns. While the roles of several proteins in these processes are supported by substantial genetic and biochemical evidence, key aspects of Mbn manufacture, handling, and regulation remain unclear. In addition, other natural products that have been proposed to mediate copper uptake as well as metallophores that have biologically relevant roles involving copper binding, but not copper uptake, are discussed.
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Affiliation(s)
- Grace E Kenney
- Department of Molecular Biosciences, Northwestern University, Evanston, Illinois 60208, USA; ,
| | - Amy C Rosenzweig
- Department of Molecular Biosciences, Northwestern University, Evanston, Illinois 60208, USA; ,
- Department of Chemistry, Northwestern University, Evanston, Illinois 60208, USA
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47
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Ro SY, Ross MO, Deng YW, Batelu S, Lawton TJ, Hurley JD, Stemmler TL, Hoffman BM, Rosenzweig AC. From micelles to bicelles: Effect of the membrane on particulate methane monooxygenase activity. J Biol Chem 2018; 293:10457-10465. [PMID: 29739854 DOI: 10.1074/jbc.ra118.003348] [Citation(s) in RCA: 40] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/07/2018] [Revised: 05/06/2018] [Indexed: 11/06/2022] Open
Abstract
Particulate methane monooxygenase (pMMO) is a copper-dependent integral membrane metalloenzyme that converts methane to methanol in methanotrophic bacteria. Studies of isolated pMMO have been hindered by loss of enzymatic activity upon its removal from the native membrane. To characterize pMMO in a membrane-like environment, we reconstituted pMMOs from Methylococcus (Mcc.) capsulatus (Bath) and Methylomicrobium (Mm.) alcaliphilum 20Z into bicelles. Reconstitution into bicelles recovers methane oxidation activity lost upon detergent solubilization and purification without substantial alterations to copper content or copper electronic structure, as observed by electron paramagnetic resonance (EPR) spectroscopy. These findings suggest that loss of pMMO activity upon isolation is due to removal from the membranes rather than caused by loss of the catalytic copper ions. A 2.7 Å resolution crystal structure of pMMO from Mm. alcaliphilum 20Z reveals a mononuclear copper center in the PmoB subunit and indicates that the transmembrane PmoC subunit may be conformationally flexible. Finally, results from extended X-ray absorption fine structure (EXAFS) analysis of pMMO from Mm. alcaliphilum 20Z were consistent with the observed monocopper center in the PmoB subunit. These results underscore the importance of studying membrane proteins in a membrane-like environment and provide valuable insight into pMMO function.
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Affiliation(s)
- Soo Y Ro
- From the Departments of Molecular Biosciences and Chemistry, Northwestern University, Evanston, Illinois 60208 and
| | - Matthew O Ross
- From the Departments of Molecular Biosciences and Chemistry, Northwestern University, Evanston, Illinois 60208 and
| | - Yue Wen Deng
- From the Departments of Molecular Biosciences and Chemistry, Northwestern University, Evanston, Illinois 60208 and
| | - Sharon Batelu
- the Department of Pharmaceutical Sciences, Wayne State University, Detroit, Michigan 48201
| | - Thomas J Lawton
- From the Departments of Molecular Biosciences and Chemistry, Northwestern University, Evanston, Illinois 60208 and
| | - Joseph D Hurley
- From the Departments of Molecular Biosciences and Chemistry, Northwestern University, Evanston, Illinois 60208 and
| | - Timothy L Stemmler
- the Department of Pharmaceutical Sciences, Wayne State University, Detroit, Michigan 48201
| | - Brian M Hoffman
- From the Departments of Molecular Biosciences and Chemistry, Northwestern University, Evanston, Illinois 60208 and
| | - Amy C Rosenzweig
- From the Departments of Molecular Biosciences and Chemistry, Northwestern University, Evanston, Illinois 60208 and
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48
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Cao L, Caldararu O, Rosenzweig AC, Ryde U. Quantum Refinement Does Not Support Dinuclear Copper Sites in Crystal Structures of Particulate Methane Monooxygenase. Angew Chem Int Ed Engl 2018; 57:162-166. [PMID: 29164769 PMCID: PMC5808928 DOI: 10.1002/anie.201708977] [Citation(s) in RCA: 99] [Impact Index Per Article: 16.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/31/2017] [Revised: 11/06/2017] [Indexed: 01/23/2023]
Abstract
Particulate methane monooxygenase (pMMO) is one of the few enzymes that can activate methane. The metal content of this enzyme has been highly controversial, with suggestions of a dinuclear Fe site or mono-, di-, or trinuclear Cu sites. Crystal structures have shown a mono- or dinuclear Cu site, but the resolution was low and the geometry of the dinuclear site unusual. We have employed quantum refinement (crystallographic refinement enhanced with quantum-mechanical calculations) to improve the structure of the active site. We compared a number of different mono- and dinuclear geometries, in some cases enhanced with more protein ligands or one or two water molecules, to determine which structure fits two sets of crystallographic raw data best. In all cases, the best results were obtained with mononuclear Cu sites, occasionally with an extra water molecule. Thus, we conclude that there is no crystallographic support for a dinuclear Cu site in pMMO.
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Affiliation(s)
- Lili Cao
- Department of Theoretical Chemistry, Lund University, Chemical Centre, P.O. Box 124, 22100, Lund, Sweden
| | - Octav Caldararu
- Department of Theoretical Chemistry, Lund University, Chemical Centre, P.O. Box 124, 22100, Lund, Sweden
| | - Amy C Rosenzweig
- Departments of Molecular Biosciences and of Chemistry, Northwestern University, Evanston, IL, 60208, USA
| | - Ulf Ryde
- Department of Theoretical Chemistry, Lund University, Chemical Centre, P.O. Box 124, 22100, Lund, Sweden
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49
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Cao L, Caldararu O, Rosenzweig AC, Ryde U. Quantum Refinement Does Not Support Dinuclear Copper Sites in Crystal Structures of Particulate Methane Monooxygenase. Angew Chem Int Ed Engl 2017. [DOI: 10.1002/ange.201708977] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
Affiliation(s)
- Lili Cao
- Department of Theoretical Chemistry; Lund University, Chemical Centre; P.O. Box 124 22100 Lund Sweden
| | - Octav Caldararu
- Department of Theoretical Chemistry; Lund University, Chemical Centre; P.O. Box 124 22100 Lund Sweden
| | - Amy C. Rosenzweig
- Departments of Molecular Biosciences and of Chemistry; Northwestern University; Evanston IL 60208 USA
| | - Ulf Ryde
- Department of Theoretical Chemistry; Lund University, Chemical Centre; P.O. Box 124 22100 Lund Sweden
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50
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Ross MO, Rosenzweig AC. A tale of two methane monooxygenases. J Biol Inorg Chem 2017; 22:307-319. [PMID: 27878395 PMCID: PMC5352483 DOI: 10.1007/s00775-016-1419-y] [Citation(s) in RCA: 148] [Impact Index Per Article: 21.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/10/2016] [Accepted: 11/15/2016] [Indexed: 11/24/2022]
Abstract
Methane monooxygenase (MMO) enzymes activate O2 for oxidation of methane. Two distinct MMOs exist in nature, a soluble form that uses a diiron active site (sMMO) and a membrane-bound form with a catalytic copper center (pMMO). Understanding the reaction mechanisms of these enzymes is of fundamental importance to biologists and chemists, and is also relevant to the development of new biocatalysts. The sMMO catalytic cycle has been elucidated in detail, including O2 activation intermediates and the nature of the methane-oxidizing species. By contrast, many aspects of pMMO catalysis remain unclear, most notably the nuclearity and molecular details of the copper active site. Here, we review the current state of knowledge for both enzymes, and consider pMMO O2 activation intermediates suggested by computational and synthetic studies in the context of existing biochemical data. Further work is needed on all fronts, with the ultimate goal of understanding how these two remarkable enzymes catalyze a reaction not readily achieved by any other metalloenzyme or biomimetic compound.
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Affiliation(s)
- Matthew O Ross
- Departments of Molecular Biosciences and of Chemistry, Northwestern University, Evanston, IL, 60208, USA
| | - Amy C Rosenzweig
- Departments of Molecular Biosciences and of Chemistry, Northwestern University, Evanston, IL, 60208, USA.
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