1
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Lienhart PH, Rohra V, Clement C, Toppen LC, DeCola AC, Rizzo DM, Scarborough MJ. Landfill intermediate cover soil microbiomes and their potential for mitigating greenhouse gas emissions revealed through metagenomics. THE SCIENCE OF THE TOTAL ENVIRONMENT 2024; 925:171697. [PMID: 38492594 DOI: 10.1016/j.scitotenv.2024.171697] [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: 12/06/2023] [Revised: 03/09/2024] [Accepted: 03/11/2024] [Indexed: 03/18/2024]
Abstract
Landfills are a major source of anthropogenic methane emissions and have been found to produce nitrous oxide, an even more potent greenhouse gas than methane. Intermediate cover soil (ICS) plays a key role in reducing methane emissions but may also result in nitrous oxide production. To assess the potential for microbial methane oxidation and nitrous oxide production, long sequencing reads were generated from ICS microbiome DNA and reads were functionally annotated for 24 samples across ICS at a large landfill in New York. Further, incubation experiments were performed to assess methane consumption and nitrous oxide production with varying amounts of ammonia supplemented. Methane was readily consumed by microbes in the composite ICS and all incubations with methane produced small amounts of nitrous oxide even when ammonia was not supplemented. Incubations without methane produced significantly less nitrous oxide than those incubated with methane. In incubations with methane added, the observed specific rate of methane consumption was 0.776 +/- 0.055 μg CH4 g dry weight (DW) soil-1 h-1 and the specific rate of nitrous oxide production was 3.64 × 10-5 +/- 1.30 × 10-5 μg N2O g DW soil-1 h-1. The methanotrophs Methylobacter and an unclassified genus within the family Methlyococcaceae were present in the original ICS samples and the incubation samples, and their abundance increased during incubations with methane. Genes encoding particulate methane monooxygenase/ ammonia monooxygenase (pMMO) were much more abundant than genes encoding soluble methane monooxygenase (sMMO) across the landfill ICS. Genes encoding proteins that convert hydroxylamine to nitrous oxide were not highly abundant in the ICS or incubation metagenomes. In total, these results suggest that although ammonia oxidation via methanotrophs may result in low levels of nitrous oxide production, ICS microbial communities have the potential to greatly reduce the overall global warming potential of landfill emissions.
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Affiliation(s)
- Peyton H Lienhart
- Department of Civil and Environmental Engineering, University of Vermont, Burlington, VT, United States
| | - Venus Rohra
- Department of Civil and Environmental Engineering, University of Vermont, Burlington, VT, United States
| | - Courtney Clement
- Department of Microbiology, Oregon State University, Corvallis, OR, United States
| | - Lucinda C Toppen
- Department of Civil and Environmental Engineering, University of Vermont, Burlington, VT, United States.
| | - Amy C DeCola
- Department of Civil and Environmental Engineering, University of Vermont, Burlington, VT, United States
| | - Donna M Rizzo
- Department of Civil and Environmental Engineering, University of Vermont, Burlington, VT, United States; Gund Institute for Environment, University of Vermont, Burlington, VT, United States.
| | - Matthew J Scarborough
- Department of Civil and Environmental Engineering, University of Vermont, Burlington, VT, United States; Gund Institute for Environment, University of Vermont, Burlington, VT, United States.
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2
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Decembrino D, Cannella D. The thin line between monooxygenases and peroxygenases. P450s, UPOs, MMOs, and LPMOs: A brick to bridge fields of expertise. Biotechnol Adv 2024; 72:108321. [PMID: 38336187 DOI: 10.1016/j.biotechadv.2024.108321] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/31/2023] [Revised: 02/04/2024] [Accepted: 02/06/2024] [Indexed: 02/12/2024]
Abstract
Many scientific fields, although driven by similar purposes and dealing with similar technologies, often appear so isolated and far from each other that even the vocabularies to describe the very same phenomenon might differ. Concerning the vast field of biocatalysis, a special role is played by those redox enzymes that employ oxygen-based chemistry to unlock transformations otherwise possible only with metal-based catalysts. As such, greener chemical synthesis methods and environmentally-driven biotechnological approaches were enabled over the last decades by the use of several enzymes and ultimately resulted in the first industrial applications. Among what can be called today the environmental biorefinery sector, biomass transformation, greenhouse gas reduction, bio-gas/fuels production, bioremediation, as well as bulk or fine chemicals and even pharmaceuticals manufacturing are all examples of fields in which successful prototypes have been demonstrated employing redox enzymes. In this review we decided to focus on the most prominent enzymes (MMOs, LPMO, P450 and UPO) capable of overcoming the ∼100 kcal mol-1 barrier of inactivated CH bonds for the oxyfunctionalization of organic compounds. Harnessing the enormous potential that lies within these enzymes is of extreme value to develop sustainable industrial schemes and it is still deeply coveted by many within the aforementioned fields of application. Hence, the ambitious scope of this account is to bridge the current cutting-edge knowledge gathered upon each enzyme. By creating a broad comparison, scientists belonging to the different fields may find inspiration and might overcome obstacles already solved by the others. This work is organised in three major parts: a first section will be serving as an introduction to each one of the enzymes regarding their structural and activity diversity, whereas a second one will be encompassing the mechanistic aspects of their catalysis. In this regard, the machineries that lead to analogous catalytic outcomes are depicted, highlighting the major differences and similarities. Finally, a third section will be focusing on the elements that allow the oxyfunctionalization chemistry to occur by delivering redox equivalents to the enzyme by the action of diverse redox partners. Redox partners are often overlooked in comparison to the catalytic counterparts, yet they represent fundamental elements to better understand and further develop practical applications based on mono- and peroxygenases.
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Affiliation(s)
- Davide Decembrino
- Photobiocatalysis Unit - Crop Production and Biostimulation Lab (CPBL), and Biomass Transformation Lab (BTL), École Interfacultaire de Bioingénieurs, Université Libre de Bruxelles, Belgium.
| | - David Cannella
- Photobiocatalysis Unit - Crop Production and Biostimulation Lab (CPBL), and Biomass Transformation Lab (BTL), École Interfacultaire de Bioingénieurs, Université Libre de Bruxelles, Belgium.
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3
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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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4
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Kang NK, Chau THT, Lee EY. Engineered methane biocatalysis: strategies to assimilate methane for chemical production. Curr Opin Biotechnol 2024; 85:103031. [PMID: 38101295 DOI: 10.1016/j.copbio.2023.103031] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/30/2023] [Revised: 11/17/2023] [Accepted: 11/21/2023] [Indexed: 12/17/2023]
Abstract
Methane (CH4), one of the greenhouse gases, is considered a promising feedstock for the biological production of fuels and chemicals. Although recent studies have demonstrated the capability of methanotrophs to convert CH4 into various bioproducts by metabolic engineering, the productivity has not reached commercial levels. As such, there is a growing interest in synthetic methanotrophic systems as an alternative. This review summarizes the strategies for enhancing native CH4 assimilation and discusses the challenges for the construction of synthetic methanotrophy into nonmethanotrophic industrial strains. Additionally, we suggest a mixed heterotrophic approach that integrates CH4 assimilation with glucose and xylose metabolism to improve productivity. The synthetic methanotrophic system presented in this review could pave the way for sustainable and efficient biomanufacturing using CH4.
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Affiliation(s)
- Nam Kyu Kang
- Department of Chemical Engineering (BK21 FOUR Integrated Engineering Program), Kyung Hee University, 17104 Yongin-si, Gyeonggi-do, South Korea
| | - Tin Hoang Trung Chau
- Department of Chemical Engineering (BK21 FOUR Integrated Engineering Program), Kyung Hee University, 17104 Yongin-si, Gyeonggi-do, South Korea
| | - Eun Yeol Lee
- Department of Chemical Engineering (BK21 FOUR Integrated Engineering Program), Kyung Hee University, 17104 Yongin-si, Gyeonggi-do, South Korea.
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5
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Peng P, Yang J, DiSpirito AA, Semrau JD. MmoD regulates soluble methane monooxygenase and methanobactin production in Methylosinus trichosporium OB3b. Appl Environ Microbiol 2023; 89:e0160123. [PMID: 38014956 PMCID: PMC10734442 DOI: 10.1128/aem.01601-23] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/12/2023] [Accepted: 10/10/2023] [Indexed: 11/29/2023] Open
Abstract
IMPORTANCE Aerobic methanotrophs play a critical role in the global carbon cycle, particularly in controlling net emissions of methane to the atmosphere. As methane is a much more potent greenhouse gas than carbon dioxide, there is increasing interest in utilizing these microbes to mitigate future climate change by increasing their ability to consume methane. Any such efforts, however, require a detailed understanding of how to manipulate methanotrophic activity. Herein, we show that methanotrophic activity is strongly controlled by MmoD, i.e., MmoD regulates methanotrophy through the post-transcriptional regulation of the soluble methane monooxygenase and controls the ability of methanotrophs to collect copper. Such data are likely to prove quite useful in future strategies to enhance the use of methanotrophs to not only reduce methane emissions but also remove methane from the atmosphere.
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Affiliation(s)
- Peng Peng
- Department of Civil and Environmental Engineering, University of Michigan, Ann Arbor, Michigan, USA
| | - Junwon Yang
- Department of Civil and Environmental Engineering, University of Michigan, Ann Arbor, Michigan, USA
| | - Alan A. DiSpirito
- Roy J. Carver Department of Biochemistry, Biophysics and Molecular Biology, Iowa State University, Ames, Iowa, USA
| | - Jeremy D. Semrau
- Department of Civil and Environmental Engineering, University of Michigan, Ann Arbor, Michigan, USA
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6
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Hwang Y, Na JG, Lee SJ. Transcriptional regulation of soluble methane monooxygenase via enhancer-binding protein derived from Methylosinus sporium 5. Appl Environ Microbiol 2023; 89:e0210422. [PMID: 37668365 PMCID: PMC10537576 DOI: 10.1128/aem.02104-22] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/15/2022] [Accepted: 07/07/2023] [Indexed: 09/06/2023] Open
Abstract
Methane is a major greenhouse gas, and methanotrophs regulate the methane level in the carbon cycle. Soluble methane monooxygenase (sMMO) is expressed in various methanotroph genera, including Alphaproteobacteria and Gammaproteobacteria, and catalyzes the hydroxylation of methane to methanol. It has been proposed that MmoR regulates the expression of sMMO as an enhancer-binding protein under copper-limited conditions; however, details on this transcriptional regulation remain limited. Herein, we elucidate the transcriptional pathway of sMMO depending on copper ion concentration, which affects the interaction of MmoR and sigma factor. MmoR and sigma-54 (σ54) from Methylosinus sporium 5 were successfully overexpressed in Escherichia coli and purified to investigate sMMO transcription in methanotrophs. The results indicated that σ54 binds to a promoter positioned -24 (GG) and -12 (TGC) upstream between mmoG and mmoX1. The binding affinity and selectivity are lower (Kd = 184.6 ± 6.2 nM) than those of MmoR. MmoR interacts with the upstream activator sequence (UAS) with a strong binding affinity (Kd = 12.5 ± 0.5 nM). Mutational studies demonstrated that MmoR has high selectivity to its binding partner (ACA-xx-TGT). Titration assays have demonstrated that MmoR does not coordinate with copper ions directly; however, its binding affinity to UAS decreases in a low-copper-containing medium. MmoR strongly interacts with adenosine triphosphate (Kd = 62.8 ± 0.5 nM) to generate RNA polymerase complex. This study demonstrated that the binding events of both MmoR and σ54 that regulate transcription in M. sporium 5 depend on the copper ion concentration. IMPORTANCE This study provides biochemical evidence of transcriptional regulation of soluble methane monooxygenase (sMMO) in methanotrophs that control methane levels in ecological systems. Previous studies have proposed transcriptional regulation of MMOs, including sMMO and pMMO, while we provide further evidence to elucidate its mechanism using a purified enhancer-binding protein (MmoR) and transcription factor (σ54). The characterization studies of σ54 and MmoR identified the promoter binding sites and enhancer-binding sequences essential for sMMO expression. Our findings also demonstrate that MmoR functions as a trigger for sMMO expression due to the high specificity and selectivity for enhancer-binding sequences. The UV-visible spectrum of purified MmoR suggested an iron coordination like other GAF domain, and that ATP is essential for the initiation of enhancer elements. Binding assays indicated that these interactions are blocked by the copper ion. These results provide novel insights into gene regulation of methanotrophs.
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Affiliation(s)
- Yunha Hwang
- Department of Chemistry, Jeonbuk National University , Jeonju, South Korea
| | - Jeong-Geol Na
- Department of Chemical Engineering, Sogang University , Seoul, South Korea
| | - Seung Jae Lee
- Department of Chemistry, Jeonbuk National University , Jeonju, South Korea
- Institute of Molecular Biology and Genetics, Jeonbuk National University , Jeonju, South Korea
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7
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Sui J, Gao ML, Qian B, Liu C, Pan Y, Meng Z, Yuan D, Jiang HL. Bioinspired microenvironment modulation of metal-organic framework-based catalysts for selective methane oxidation. Sci Bull (Beijing) 2023; 68:1886-1893. [PMID: 37544879 DOI: 10.1016/j.scib.2023.07.031] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/08/2023] [Revised: 06/21/2023] [Accepted: 07/07/2023] [Indexed: 08/08/2023]
Abstract
Inspiration from natural enzymes enabling creationary catalyst design is appealing yet remains extremely challenging for selective methane (CH4) oxidation. This study presents the construction of a biomimetic catalyst platform for CH4 oxidation, which is constructed by incorporating Fe-porphyrin into a robust metal-organic framework, UiO-66, furnished with saturated monocarboxylic fatty acid bearing different long alkyl chains. The catalysts demonstrate the high efficiency in the CH4 to methanol (CH3OH) conversion at 50 °C. Moreover, the selectivity to CH3OH can be effectively regulated and promoted through a fine-tuned microenvironment by hydrophobic modification around the Fe-porphyrin. The long-chain fatty acids anchored on the Zr-oxo cluster of UiO-66 can not only tune the electronic state of the Fe sites to improve CH4 adsorption, but also restrict the amount of H2O2 around the Fe sites to reduce the overoxidation. This behavior resembles the microenvironment regulation in methane monooxygenase, resulting in high CH3OH selectivity.
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Affiliation(s)
- Jianfei Sui
- Department of Chemistry, University of Science and Technology of China, Hefei 230026, China
| | - Ming-Liang Gao
- Department of Chemistry, University of Science and Technology of China, Hefei 230026, China
| | - Bing Qian
- National Synchrotron Radiation Laboratory (NSRL), University of Science and Technology of China, Hefei 230029, China
| | - Chengyuan Liu
- National Synchrotron Radiation Laboratory (NSRL), University of Science and Technology of China, Hefei 230029, China
| | - Yang Pan
- National Synchrotron Radiation Laboratory (NSRL), University of Science and Technology of China, Hefei 230029, China
| | - Zheng Meng
- Department of Chemistry, University of Science and Technology of China, Hefei 230026, China.
| | - Daqiang Yuan
- State Key Laboratory of Structural Chemistry, Fujian Institute of Research on the Structure of Matter, Chinese Academy of Sciences, Fuzhou 350002, China
| | - Hai-Long Jiang
- Department of Chemistry, University of Science and Technology of China, Hefei 230026, China.
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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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Ahn E, Kim B, Park S, Erwin AL, Sung SH, Hovden R, Mosalaganti S, Cho US. Batch Production of High-Quality Graphene Grids for Cryo-EM: Cryo-EM Structure of Methylococcus capsulatus Soluble Methane Monooxygenase Hydroxylase. ACS NANO 2023; 17:6011-6022. [PMID: 36926824 PMCID: PMC10062032 DOI: 10.1021/acsnano.3c00463] [Citation(s) in RCA: 4] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 01/16/2023] [Accepted: 03/13/2023] [Indexed: 06/18/2023]
Abstract
Cryogenic electron microscopy (cryo-EM) has become a widely used tool for determining the protein structure. Despite recent technical advances, sample preparation remains a major bottleneck for several reasons, including protein denaturation at the air-water interface, the presence of preferred orientations, nonuniform ice layers, etc. Graphene, a two-dimensional allotrope of carbon consisting of a single atomic layer, has recently gained attention as a near-ideal support film for cryo-EM that can overcome these challenges because of its superior properties, including mechanical strength and electrical conductivity. Here, we introduce a reliable, easily implemented, and reproducible method to produce 36 graphene-coated grids within 1.5 days. To demonstrate their practical application, we determined the cryo-EM structure of Methylococcus capsulatus soluble methane monooxygenase hydroxylase (sMMOH) at resolutions of 2.9 and 2.5 Å using Quantifoil and graphene-coated grids, respectively. We found that the graphene-coated grid has several advantages, including a smaller amount of protein required and avoiding protein denaturation at the air-water interface. By comparing the cryo-EM structure of sMMOH with its crystal structure, we identified subtle yet significant geometrical changes at the nonheme diiron center, which may better indicate the active site configuration of sMMOH in the resting/oxidized state.
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Affiliation(s)
- Eungjin Ahn
- Department
of Biological Chemistry, University of Michigan, Ann Arbor, Michigan 48109, United States
| | - Byungchul Kim
- Department
of Biological Chemistry, University of Michigan, Ann Arbor, Michigan 48109, United States
| | - Soyoung Park
- Department
of Biological Chemistry, University of Michigan, Ann Arbor, Michigan 48109, United States
- Department
of Fine Chemistry, Seoul National University
of Science and Technology, Seoul 139-743, Korea
| | - Amanda L. Erwin
- Department
of Cell and Developmental Biology, University
of Michigan, Ann Arbor, Michigan 48109, United
States
- Life
Sciences Institute, University of Michigan, Ann Arbor, Michigan 48109, United States
| | - Suk Hyun Sung
- Department
of Materials Science and Engineering, University
of Michigan, Ann Arbor, Michigan 48105, United
States
| | - Robert Hovden
- Department
of Materials Science and Engineering, University
of Michigan, Ann Arbor, Michigan 48105, United
States
- Applied
Physics Program, University of Michigan, Ann Arbor, Michigan 48105, United States
| | - Shyamal Mosalaganti
- Department
of Cell and Developmental Biology, University
of Michigan, Ann Arbor, Michigan 48109, United
States
- Life
Sciences Institute, University of Michigan, Ann Arbor, Michigan 48109, United States
| | - Uhn-Soo Cho
- Department
of Biological Chemistry, University of Michigan, Ann Arbor, Michigan 48109, United States
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10
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Cupples AM, Li Z, Wilson FP, Ramalingam V, Kelly A. In silico analysis of soil, sediment and groundwater microbial communities to predict biodegradation potential. J Microbiol Methods 2022; 202:106595. [DOI: 10.1016/j.mimet.2022.106595] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/06/2022] [Revised: 09/30/2022] [Accepted: 09/30/2022] [Indexed: 12/27/2022]
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11
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Mukherjee IA, Gabel C, Noinaj N, Bondy-Denomy J, Chang L. Structural basis of AcrIF24 as an anti-CRISPR protein and transcriptional suppressor. Nat Chem Biol 2022; 18:1417-1424. [PMID: 36163386 PMCID: PMC9691602 DOI: 10.1038/s41589-022-01137-w] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/04/2022] [Accepted: 08/08/2022] [Indexed: 11/09/2022]
Abstract
Anti-CRISPR (Acr) proteins are encoded by phages to inactivate CRISPR-Cas systems of bacteria and archaea and are used to enhance the CRISPR toolbox for genome editing. Here we report the structure and mechanism of AcrIF24, an Acr protein that inhibits the type I-F CRISPR-Cas system from Pseudomonas aeruginosa. AcrIF24 is a homodimer that associates with two copies of the surveillance complex (Csy) and prevents the hybridization between CRISPR RNA and target DNA. Furthermore, AcrIF24 functions as an anti-CRISPR-associated (Aca) protein to repress the transcription of the acrIF23-acrIF24 operon. Alone or in complex with Csy, AcrIF24 is capable of binding to the acrIF23-acrIF24 promoter DNA with nanomolar affinity. The structure of a Csy-AcrIF24-promoter DNA complex at 2.7 Å reveals the mechanism for transcriptional suppression. Our results reveal that AcrIF24 functions as an Acr-Aca fusion protein, and they extend understanding of the diverse mechanisms used by Acr proteins.
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Affiliation(s)
| | - Clinton Gabel
- Department of Biological Sciences, Purdue University, West Lafayette, IN, USA
| | - Nicholas Noinaj
- Department of Biological Sciences, Purdue University, West Lafayette, IN, USA
| | - Joseph Bondy-Denomy
- Department of Microbiology and Immunology, University of California, San Francisco, San Francisco, CA, USA.,Quantitative Biosciences Institute, University of California, San Francisco, San Francisco, CA, USA.,Innovative Genomics Institute, Berkeley, CA, USA
| | - Leifu Chang
- Department of Biological Sciences, Purdue University, West Lafayette, IN, USA. .,Purdue University Center for Cancer Research, Purdue University, West Lafayette, IN, USA.
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12
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Yang L, Zhang L, Yin P, Ding H, Xiao Y, Zeng J, Wang W, Zhou H, Wang Q, Zhang Y, Chen Z, Yang M, Feng Y. Insights into the inhibition of type I-F CRISPR-Cas system by a multifunctional anti-CRISPR protein AcrIF24. Nat Commun 2022; 13:1931. [PMID: 35411005 PMCID: PMC9001735 DOI: 10.1038/s41467-022-29581-1] [Citation(s) in RCA: 14] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/01/2021] [Accepted: 03/16/2022] [Indexed: 11/18/2022] Open
Abstract
CRISPR-Cas systems are prokaryotic adaptive immune systems and phages use anti-CRISPR proteins (Acrs) to counteract these systems. Here, we report the structures of AcrIF24 and its complex with the crRNA-guided surveillance (Csy) complex. The HTH motif of AcrIF24 can bind the Acr promoter region and repress its transcription, suggesting its role as an Aca gene in self-regulation. AcrIF24 forms a homodimer and further induces dimerization of the Csy complex. Apart from blocking the hybridization of target DNA to the crRNA, AcrIF24 also induces the binding of non-sequence-specific dsDNA to the Csy complex, similar to AcrIF9, although this binding seems to play a minor role in AcrIF24 inhibitory capacity. Further structural and biochemical studies of the Csy-AcrIF24-dsDNA complexes and of AcrIF24 mutants reveal that the HTH motif of AcrIF24 and the PAM recognition loop of the Csy complex are structural elements essential for this non-specific dsDNA binding. Moreover, AcrIF24 and AcrIF9 display distinct characteristics in inducing non-specific DNA binding. Together, our findings highlight a multifunctional Acr and suggest potential wide distribution of Acr-induced non-specific DNA binding. Phages use anti-CRISPR proteins (Acrs) to counteract the bacterial CRISPR-Cas systems. Here, the authors characterize AcrIF24, which functions as an Aca (Acr-associated) to repress and regulate its own transcription, dimerizes the Csy complex, blocks the hybridization of target DNA, and tethers non-sequence-specific DNA to the Csy complex.
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13
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Zill D, Lettau E, Lorent C, Seifert F, Singh P, Lauterbach L. Crucial role of the chaperonin GroES/EL for heterologous production of the soluble methane monooxygenase from Methylomonas methanica MC09. Chembiochem 2022; 23:e202200195. [PMID: 35385600 PMCID: PMC9324122 DOI: 10.1002/cbic.202200195] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/05/2022] [Indexed: 11/15/2022]
Abstract
Methane is a widespread energy source and can serve as an attractive C1 building block for a future bioeconomy. The soluble methane monooxygenase (sMMO) is able to break the strong C−H bond of methane and convert it to methanol. The high structural complexity, multiplex cofactors, and unfamiliar folding or maturation procedures of sMMO have hampered the heterologous production and thus biotechnological applications. Here, we demonstrate the heterologous production of active sMMO from the marine Methylomonas methanica MC09 in Escherichia coli by co‐synthesizing the GroES/EL chaperonin. Iron determination, electron paramagnetic resonance spectroscopy, and native gel immunoblots revealed the incorporation of the non‐heme diiron centre and homodimer formation of active sMMO. The production of recombinant sMMO will enable the expansion of the possibilities of detailed studies, allowing for a variety of novel biotechnological applications.
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Affiliation(s)
- Domenic Zill
- RWTH Aachen Fakultät für Mathematik Informatik und Naturwissenschaften: Rheinisch Westfalische Technische Hochschule Aachen Fakultat fur Mathematik Informatik und Naturwissenschaften, Institute of Applied Microbiology, GERMANY
| | - Elisabeth Lettau
- RWTH Aachen Faculty of Mathematics Computer Science and Natural Sciences: Rheinisch Westfalische Technische Hochschule Aachen Fakultat fur Mathematik Informatik und Naturwissenschaften, Institute of Applied Microbiology, GERMANY
| | - Christian Lorent
- TU Berlin: Technische Universitat Berlin, Institute for Chemistry, GERMANY
| | - Franziska Seifert
- Martin-Luther-Universität Halle-Wittenberg: Martin-Luther-Universitat Halle-Wittenberg, Institut für Pharmazeutische Technologie und Biopharmazie, GERMANY
| | - Praveen Singh
- RWTH Aachen Faculty of Mathematics Computer Science and Natural Sciences: Rheinisch Westfalische Technische Hochschule Aachen Fakultat fur Mathematik Informatik und Naturwissenschaften, Institute of Applied Microbiology, GERMANY
| | - Lars Lauterbach
- RWTH Aachen University: Rheinisch-Westfalische Technische Hochschule Aachen, Institute of Applied Microbiology, Worringer Weg 1, 52074, Aachen, GERMANY
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Lee C, Hwang Y, Kang HG, Lee SJ. Electron Transfer to Hydroxylase through Component Interactions in Soluble Methane Monooxygenase. J Microbiol Biotechnol 2022; 32:287-293. [PMID: 35131957 PMCID: PMC9628860 DOI: 10.4014/jmb.2201.01029] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/24/2022] [Revised: 02/02/2022] [Accepted: 02/03/2022] [Indexed: 12/15/2022]
Abstract
The hydroxylation of methane (CH4) is crucial to the field of environmental microbiology, owing to the heat capacity of methane, which is much higher than that of carbon dioxide (CO2). Soluble methane monooxygenase (sMMO), a member of the bacterial multicomponent monooxygenase (BMM) superfamily, is essential for the hydroxylation of specific substrates, including hydroxylase (MMOH), regulatory component (MMOB), and reductase (MMOR). The diiron active site positioned in the MMOH α-subunit is reduced through the interaction of MMOR in the catalytic cycle. The electron transfer pathway, however, is not yet fully understood due to the absence of complex structures with reductases. A type II methanotroph, Methylosinus sporium 5, successfully expressed sMMO and hydroxylase, which were purified for the study of the mechanisms. Studies on the MMOH-MMOB interaction have demonstrated that Tyr76 and Trp78 induce hydrophobic interactions through π-π stacking. Structural analysis and sequencing of the ferredoxin domain in MMOR (MMOR-Fd) suggested that Tyr93 and Tyr95 could be key residues for electron transfer. Mutational studies of these residues have shown that the concentrations of flavin adenine dinucleotide (FAD) and iron ions are changed. The measurements of dissociation constants (Kds) between hydroxylase and mutated reductases confirmed that the binding affinities were not significantly changed, although the specific enzyme activities were significantly reduced by MMOR-Y93A. This result shows that Tyr93 could be a crucial residue for the electron transfer route at the interface between hydroxylase and reductase.
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Affiliation(s)
- Chaemin Lee
- Department of Chemistry, Jeonbuk National University, Jeonju 54896, Republic of Korea
| | - Yunha Hwang
- Department of Chemistry, Jeonbuk National University, Jeonju 54896, Republic of Korea
| | - Hyun Goo Kang
- Department of Neurology, Research Institute of Clinical Medicine of Jeonbuk National University and Biomedical Research Institute of Jeonbuk National University Hospital, Jeonju 54907, Republic of Korea,Corresponding authors H.G. Kang Phone: +82-63-250-1590 Fax: +82-63-251-9363 E-mail:
| | - Seung Jae Lee
- Department of Chemistry, Jeonbuk National University, Jeonju 54896, Republic of Korea,Institute for Molecular Biology and Genetics, Jeonbuk National University, Jeonju 54896, Republic of Korea,
S.J. Lee Phone: +82-63-270-3412 Fax: +82-63-270-3407 E-mail:
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15
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Banerjee R, Srinivas V, Lebrette H. Ferritin-Like Proteins: A Conserved Core for a Myriad of Enzyme Complexes. Subcell Biochem 2022; 99:109-153. [PMID: 36151375 DOI: 10.1007/978-3-031-00793-4_4] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/16/2023]
Abstract
Ferritin-like proteins share a common fold, a four α-helix bundle core, often coordinating a pair of metal ions. Although conserved, the ferritin fold permits a diverse set of reactions, and is central in a multitude of macromolecular enzyme complexes. Here, we emphasize this diversity through three members of the ferritin-like superfamily: the soluble methane monooxygenase, the class I ribonucleotide reductase and the aldehyde deformylating oxygenase. They all rely on dinuclear metal cofactors to catalyze different challenging oxygen-dependent reactions through the formation of multi-protein complexes. Recent studies using cryo-electron microscopy, serial femtosecond crystallography at an X-ray free electron laser source, or single-crystal X-ray diffraction, have reported the structures of the active protein complexes, and revealed unprecedented insights into the molecular mechanisms of these three enzymes.
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Affiliation(s)
- Rahul Banerjee
- Department of Biochemistry, Molecular Biology and Biophysics, University of Minnesota, Minneapolis, MN, USA
| | - Vivek Srinivas
- Department of Biochemistry and Biophysics, Stockholm University, Stockholm, Sweden
| | - Hugo Lebrette
- Department of Biochemistry and Biophysics, Stockholm University, Stockholm, Sweden.
- Laboratoire de Microbiologie et Génétique Moléculaires (LMGM), Centre de Biologie Intégrative (CBI), CNRS, UPS, Université de Toulouse, Toulouse, France.
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16
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Cupples AM, Thelusmond JR. Predicting the occurrence of monooxygenases and their associated phylotypes in soil microcosms. METHODS IN MICROBIOLOGY 2021; 193:106401. [PMID: 34973287 DOI: 10.1016/j.mimet.2021.106401] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/30/2021] [Revised: 12/23/2021] [Accepted: 12/23/2021] [Indexed: 10/19/2022]
Abstract
Cometabolic oxidation involves the oxidation of chemicals often by monooxygenases or dioxygenases and can be a removal process for environmental contaminants such as trichloroethene (TCE) or 1,4-dioxane. Information on the occurrence of these genes and their associated microorganisms in environmental samples has the potential to enhance our understanding of contaminant removal. The overall aims were to 1) ascertain which genes encoding for monooxygenases (from methanotrophs, ammonia oxidizing bacteria and toluene/phenol oxidizers) and other key enzymes are present in soil microcosms and 2) determine which phylotypes are associated with those genes. The approach involved a predictive tool called PICRUSt2 and 16S rRNA gene amplicon datasets from two previous soil microcosm studies. The following targets from the KEGG database were examined: pmo/amo, mmo, dmp/pox/tomA, tmo/tbu/tou, bssABC (and downstream genes), tod, xylM, xylA, gst, dhaA, catE, dbfA1, dbfA2 and phenol 2-monooxygenase. A large number of phylotypes were associated with pmo/amo, while mmo was linked to only five. Several phylotypes were associated with both pmo/amo and mmo. The most dominant microorganism predicted for mmoX was Mycobacterium (also predicted for pmo/amo). A large number of phylotypes were associated with all six genes from the dmp/pox/tomA KEGG group. The taxonomic associations predicted for the tmo/tbu/tou KEGG group were more limited. In both datasets, Geobacter was a key phylotype for benzylsuccinate synthase. The dioxygenase-mediated toluene degradation pathway encoded by todC1C2BA was largely absent, as were the genes (xylM, xylA) encoding for xylene monooxygenase. All other genes investigated were predicted to be present and were associated with a number of microorganisms. Overall, the analysis predicted the genes encoding for sMMO (mmo), T3MO/T3MO/ToMO (tmo/tbu/tou) and benzylsuccinate synthase (bssABC) are present for a limited number of phylotypes compared to those encoding for pMMO/AMO (pmo/amo) and phenol monooxygenase/T2MO (dmp/poxA/tomA). These findings suggest in soils contaminant removal via pMMO/AMO or phenol monooxygenase/T2MO may be common because of the occurrence of these enzymes with a large number of phylotypes.
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Affiliation(s)
- Alison M Cupples
- Department of Civil and Environmental Engineering, Michigan State University, East Lansing, MI, USA.
| | - Jean-Rene Thelusmond
- Department of Civil and Environmental Engineering, Michigan State University, East Lansing, MI, USA
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17
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Lee C, Ha SC, Rao Z, Hwang Y, Kim DS, Kim SY, Yoo H, Yoon C, Na JG, Park JH, Lee SJ. Elucidation of the electron transfer environment in the MMOR FAD-binding domain from Methylosinus sporium 5. Dalton Trans 2021; 50:16493-16498. [PMID: 34734616 DOI: 10.1039/d1dt03273a] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/24/2022]
Abstract
By facilitating electron transfer to the hydroxylase diiron center, MMOR-a reductase-serves as an essential component of the catalytic cycle of soluble methane monooxygenase. Here, the X-ray structure analysis of the FAD-binding domain of MMOR identified crucial residues and its influence on the catalytic cycle.
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Affiliation(s)
- Chaemin Lee
- Department of Chemistry and Institute of Molecular Biology and Genetics, Jeonbuk National University, Jeonju 54796, Republic of Korea.
| | - Sung Chul Ha
- Pohang Accelerator Laboratory, Pohang University of Science and Technology, Pohang 37673, Republic of Korea
| | - Zhili Rao
- Division of Biotechnology, College of Environmental & Bioresources Sciences, Jeonbuk National University, Iksan 54596, Republic of Korea.
| | - Yunha Hwang
- Department of Chemistry and Institute of Molecular Biology and Genetics, Jeonbuk National University, Jeonju 54796, Republic of Korea.
| | - Da Som Kim
- Division of Biotechnology, College of Environmental & Bioresources Sciences, Jeonbuk National University, Iksan 54596, Republic of Korea.
| | - So Young Kim
- Division of Biotechnology, College of Environmental & Bioresources Sciences, Jeonbuk National University, Iksan 54596, Republic of Korea.
| | - Heeseon Yoo
- Department of Chemistry and Institute of Molecular Biology and Genetics, Jeonbuk National University, Jeonju 54796, Republic of Korea.
| | - Chungwoon Yoon
- Department of Chemistry and Institute of Molecular Biology and Genetics, Jeonbuk National University, Jeonju 54796, Republic of Korea.
| | - Jeong-Geol Na
- Department of Chemical and Biomolecular Engineering, Sogang University, Seoul 04107, Republic of Korea.
| | - Jung Hee Park
- Division of Biotechnology, College of Environmental & Bioresources Sciences, Jeonbuk National University, Iksan 54596, Republic of Korea. .,Advanced Institute of Environment and Bioscience, College of Environmental & Bioresources Sciences, Jeonbuk National University, Iksan 54596, Republic of Korea
| | - Seung Jae Lee
- Department of Chemistry and Institute of Molecular Biology and Genetics, Jeonbuk National University, Jeonju 54796, Republic of Korea.
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18
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Design of a Microbial Remediation Inoculation Program for Petroleum Hydrocarbon Contaminated Sites Based on Degradation Pathways. INTERNATIONAL JOURNAL OF ENVIRONMENTAL RESEARCH AND PUBLIC HEALTH 2021; 18:ijerph18168794. [PMID: 34444543 PMCID: PMC8395025 DOI: 10.3390/ijerph18168794] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 06/29/2021] [Revised: 08/12/2021] [Accepted: 08/18/2021] [Indexed: 11/24/2022]
Abstract
This paper analyzed the degradation pathways of petroleum hydrocarbon degradation bacteria, screened the main degradation pathways, and found the petroleum hydrocarbon degradation enzymes corresponding to each step of the degradation pathway. Through the Copeland method, the best inoculation program of petroleum hydrocarbon degradation bacteria in a polluted site was selected as follows: single oxygenation path was dominated by Streptomyces avermitilis, hydroxylation path was dominated by Methylosinus trichosporium OB3b, secondary oxygenation path was dominated by Pseudomonas aeruginosa, secondary hydroxylation path was dominated by Methylococcus capsulatus, double oxygenation path was dominated by Acinetobacter baylyi ADP1, hydrolysis path was dominated by Rhodococcus erythropolis, and CoA path was dominated by Geobacter metallireducens GS-15 to repair petroleum hydrocarbon contaminated sites. The Copeland method score for this solution is 22, which is the highest among the 375 solutions designed in this paper, indicating that it has the best degradation effect. Meanwhile, we verified its effect by the Cdocker method, and the Cdocker energy of this solution is −285.811 kcal/mol, which has the highest absolute value. Among the inoculation programs of the top 13 petroleum hydrocarbon degradation bacteria, the effect of the best inoculation program of petroleum hydrocarbon degradation bacteria was 18% higher than that of the 13th group, verifying that this solution has the best overall degradation effect. The inoculation program of petroleum hydrocarbon degradation bacteria designed in this paper considered the main pathways of petroleum hydrocarbon pollutant degradation, especially highlighting the degradability of petroleum hydrocarbon intermediate degradation products, and enriching the theoretical program of microbial remediation of petroleum hydrocarbon contaminated sites.
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19
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Caldas Nogueira ML, Pastore AJ, Davidson VL. Diversity of structures and functions of oxo-bridged non-heme diiron proteins. Arch Biochem Biophys 2021; 705:108917. [PMID: 33991497 DOI: 10.1016/j.abb.2021.108917] [Citation(s) in RCA: 11] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/05/2021] [Revised: 05/04/2021] [Accepted: 05/06/2021] [Indexed: 02/07/2023]
Abstract
Oxo-bridged diiron proteins are a distinct class of non-heme iron proteins. Their active sites are composed of two irons that are coordinated by amino acid side chains, and a bridging oxygen that interacts with each iron. These proteins are members of the ferritin superfamily and share the structural feature of a four α-helix bundle that provides the residues that coordinate the irons. The different proteins also display a wide range of structures and functions. A prototype of this family is hemerythrin, which functions as an oxygen transporter. Several other hemerythrin-like proteins have been described with a diversity of functions including oxygen and iron sensing, and catalytic activities. Rubrerythrins react with hydrogen peroxide and rubrerythrin-like proteins possess a rubredoxin domain, in addition to the oxo-bridged diiron center. Other redox enzymes with oxo-bridged irons include flavodiiron proteins that act as O2 or NO reductases, ribonucleotide reductase and methane monooxygenase. Ferritins have an oxo-bridged diiron in the ferroxidase center of the protein, which plays a role in the iron storage function of these proteins. There are also bacterial ferritins that exhibit catalytic activities. The structures and functions of this broad class of oxo-bridged diiron proteins are described and compared in this review.
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Affiliation(s)
- Maria Luiza Caldas Nogueira
- Burnett School of Biomedical Sciences, College of Medicine, University of Central Florida, Orlando, FL, 32827, United States
| | - Anthony J Pastore
- Burnett School of Biomedical Sciences, College of Medicine, University of Central Florida, Orlando, FL, 32827, United States
| | - Victor L Davidson
- Burnett School of Biomedical Sciences, College of Medicine, University of Central Florida, Orlando, FL, 32827, United States.
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20
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Liu J, Wu P, Yan S, Li Y, Cao Z, Wang B. Spin-Regulated Inner-Sphere Electron Transfer Enables Efficient O—O Bond Activation in Nonheme Diiron Monooxygenase MIOX. ACS Catal 2021. [DOI: 10.1021/acscatal.1c00898] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/23/2022]
Affiliation(s)
- Jia Liu
- State Key Laboratory of Structural Chemistry of Solid Surface and Fujian Provincial Key Laboratory of Theoretical and Computational Chemistry, College of Chemistry and Chemical Engineering, Xiamen University, Xiamen 361005, People’s Republic of China
| | - Peng Wu
- State Key Laboratory of Structural Chemistry of Solid Surface and Fujian Provincial Key Laboratory of Theoretical and Computational Chemistry, College of Chemistry and Chemical Engineering, Xiamen University, Xiamen 361005, People’s Republic of China
| | - Shengheng Yan
- State Key Laboratory of Structural Chemistry of Solid Surface and Fujian Provincial Key Laboratory of Theoretical and Computational Chemistry, College of Chemistry and Chemical Engineering, Xiamen University, Xiamen 361005, People’s Republic of China
| | - Yuanyuan Li
- College of Chemistry and Chemical Engineering, Henan University, Kaifeng, Henan 475004, China
| | - Zexing Cao
- State Key Laboratory of Structural Chemistry of Solid Surface and Fujian Provincial Key Laboratory of Theoretical and Computational Chemistry, College of Chemistry and Chemical Engineering, Xiamen University, Xiamen 361005, People’s Republic of China
| | - Binju Wang
- State Key Laboratory of Structural Chemistry of Solid Surface and Fujian Provincial Key Laboratory of Theoretical and Computational Chemistry, College of Chemistry and Chemical Engineering, Xiamen University, Xiamen 361005, People’s Republic of China
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21
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Schulz CE, Castillo RG, Pantazis DA, DeBeer S, Neese F. Structure-Spectroscopy Correlations for Intermediate Q of Soluble Methane Monooxygenase: Insights from QM/MM Calculations. J Am Chem Soc 2021; 143:6560-6577. [PMID: 33884874 PMCID: PMC8154522 DOI: 10.1021/jacs.1c01180] [Citation(s) in RCA: 27] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022]
Abstract
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The determination
of the diiron core intermediate structures involved
in the catalytic cycle of soluble methane monooxygenase (sMMO), the
enzyme that selectively catalyzes the conversion of methane to methanol,
has been a subject of intense interest within the bioinorganic scientific
community. Particularly, the specific geometry and electronic structure
of the intermediate that precedes methane binding, known as intermediate
Q (or MMOHQ), has been debated for over 30 years. Some
reported studies support a bis-μ-oxo-bridged Fe(IV)2O2 closed-core conformation Fe(IV)2O2 core, whereas others favor an open-core geometry, with a longer
Fe–Fe distance. The lack of consensus calls for a thorough
re-examination and reinterpretation of the spectroscopic data available
on the MMOHQ intermediate. Herein, we report extensive
simulations based on a hybrid quantum mechanics/molecular mechanics
approach (QM/MM) approach that takes into account the complete enzyme
to explore possible conformations for intermediates MMOHox and MMOHQ of the sMMOH catalytic cycle. High-level quantum
chemical approaches are used to correlate specific structural motifs
with geometric parameters for comparison with crystallographic and
EXAFS data, as well as with spectroscopic data from Mössbauer
spectroscopy, Fe K-edge high-energy resolution X-ray absorption spectroscopy
(HERFD XAS), and resonance Raman 16O–18O difference spectroscopy. The results provide strong support for
an open-core-type configuration in MMOHQ, with the most
likely topology involving mono-oxo-bridged Fe ions and alternate terminal
Fe-oxo and Fe-hydroxo groups that interact via intramolecular hydrogen
bonding. The implications of an open-core intermediate Q on the reaction
mechanism of sMMO are discussed.
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Affiliation(s)
- Christine E Schulz
- Max-Planck-Institut für Kohlenforschung, Kaiser-Wilhelm-Platz 1, 45470 Mülheim an der Ruhr, Germany
| | - Rebeca G Castillo
- Max Planck Institute for Chemical Energy Conversion, Stiftstr. 34-36, 45470 Mülheim an der Ruhr, Germany
| | - Dimitrios A Pantazis
- Max-Planck-Institut für Kohlenforschung, Kaiser-Wilhelm-Platz 1, 45470 Mülheim an der Ruhr, Germany
| | - Serena DeBeer
- Max Planck Institute for Chemical Energy Conversion, Stiftstr. 34-36, 45470 Mülheim an der Ruhr, Germany
| | - Frank Neese
- Max-Planck-Institut für Kohlenforschung, Kaiser-Wilhelm-Platz 1, 45470 Mülheim an der Ruhr, Germany
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22
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Khider MLK, Brautaset T, Irla M. Methane monooxygenases: central enzymes in methanotrophy with promising biotechnological applications. World J Microbiol Biotechnol 2021; 37:72. [PMID: 33765207 PMCID: PMC7994243 DOI: 10.1007/s11274-021-03038-x] [Citation(s) in RCA: 14] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/04/2020] [Accepted: 03/09/2021] [Indexed: 12/02/2022]
Abstract
Worldwide, the use of methane is limited to generating power, electricity, heating, and for production of chemicals. We believe this valuable gas can be employed more widely. Here we review the possibility of using methane as a feedstock for biotechnological processes based on the application of synthetic methanotrophs. Methane monooxygenase (MMO) enables aerobic methanotrophs to utilize methane as a sole carbon and energy source, in contrast to industrial microorganisms that grow on carbon sources, such as sugar cane, which directly compete with the food market. However, naturally occurring methanotrophs have proven to be difficult to manipulate genetically and their current industrial use is limited to generating animal feed biomass. Shifting the focus from genetic engineering of methanotrophs, towards introducing metabolic pathways for methane utilization in familiar industrial microorganisms, may lead to construction of efficient and economically feasible microbial cell factories. The applications of a technology for MMO production are not limited to methane-based industrial synthesis of fuels and value-added products, but are also of interest in bioremediation where mitigating anthropogenic pollution is an increasingly relevant issue. Published research on successful functional expression of MMO does not exist, but several attempts provide promising future perspectives and a few recent patents indicate that there is an ongoing research in this field. Combining the knowledge on genetics and metabolism of methanotrophy with tools for functional heterologous expression of MMO-encoding genes in non-methanotrophic bacterial species, is a key step for construction of synthetic methanotrophs that holds a great biotechnological potential.
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Affiliation(s)
- May L K Khider
- Department of Biotechnology and Food Science, Norwegian University of Science and Technology, Trondheim, Norway
| | - Trygve Brautaset
- Department of Biotechnology and Food Science, Norwegian University of Science and Technology, Trondheim, Norway
| | - Marta Irla
- Department of Biotechnology and Food Science, Norwegian University of Science and Technology, Trondheim, Norway.
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23
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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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