1
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Polêto M, Allen KD, Lemkul JA. Structural Dynamics of the Methyl-Coenzyme M Reductase Active Site Are Influenced by Coenzyme F 430 Modifications. Biochemistry 2024; 63:1783-1794. [PMID: 38914925 PMCID: PMC11256747 DOI: 10.1021/acs.biochem.4c00168] [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] [Received: 04/01/2024] [Revised: 06/13/2024] [Accepted: 06/17/2024] [Indexed: 06/26/2024]
Abstract
Methyl-coenzyme M reductase (MCR) is a central player in methane biogeochemistry, governing methanogenesis and the anaerobic oxidation of methane (AOM) in methanogens and anaerobic methanotrophs (ANME), respectively. The prosthetic group of MCR is coenzyme F430, a nickel-containing tetrahydrocorphin. Several modified versions of F430 have been discovered, including the 172-methylthio-F430 (mtF430) used by ANME-1 MCR. Here, we employ molecular dynamics (MD) simulations to investigate the active site dynamics of MCR from Methanosarcina acetivorans and ANME-1 when bound to the canonical F430 compared to 172-thioether coenzyme F430 variants and substrates (methyl-coenzyme M and coenzyme B) for methane formation. Our simulations highlight the importance of the Gln to Val substitution in accommodating the 172 methylthio modification in ANME-1 MCR. Modifications at the 172 position disrupt the canonical substrate positioning in M. acetivorans MCR. However, in some replicates, active site reorganization to maintain substrate positioning suggests that the modified F430 variants could be accommodated in a methanogenic MCR. We additionally report the first quantitative estimate of MCR intrinsic electric fields that are pivotal in driving methane formation. Our results suggest that the electric field aligned along the CH3-S-CoM thioether bond facilitates homolytic bond cleavage, coinciding with the proposed catalytic mechanism. Structural perturbations, however, weaken and misalign these electric fields, emphasizing the importance of the active site structure in maintaining their integrity. In conclusion, our results deepen the understanding of MCR active site dynamics, the enzyme's organizational role in intrinsic electric fields for catalysis, and the interplay between active site structure and electrostatics.
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Affiliation(s)
- Marcelo
D. Polêto
- Department of Biochemistry, Virginia Tech, 111 Engel Hall, 340 West Campus Drive, Blacksburg, Virginia 24061, United States
| | - Kylie D. Allen
- Department of Biochemistry, Virginia Tech, 111 Engel Hall, 340 West Campus Drive, Blacksburg, Virginia 24061, United States
| | - Justin A. Lemkul
- Department of Biochemistry, Virginia Tech, 111 Engel Hall, 340 West Campus Drive, Blacksburg, Virginia 24061, United States
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2
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Zhao J, Li Y, Zhang Z. Hydraulic retention time and pressure affect anaerobic digestion process treating synthetic glucose wastewater. BIORESOURCE TECHNOLOGY 2023; 370:128531. [PMID: 36574891 DOI: 10.1016/j.biortech.2022.128531] [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: 10/18/2022] [Revised: 12/19/2022] [Accepted: 12/22/2022] [Indexed: 06/17/2023]
Abstract
High-pressure anaerobic digestion (HPAD) can directly upgrade biogas (CH4 content to 90 %) within a reactor. Understanding of how HPAD-related microbiomes are constructed by operational parameters (hydraulic retention time (HRT) and pressure) and their interactions within the biochemical process remain underexplored. In this study, an HPAD reactor was operated at five different HRT (from 40 to 13 d), with pressure around 10-13 bar. In HPAD, pressure was the driving force behind CH4 content. Low HRTs (13-20 d) for HPAD led to volatile fatty acids accumulation, which occurred earlier than that in normal-pressure digestion. HRT mainly affected the archaeal community, whereas pressure mostly affected the bacterial community. Hydrogenotrophic methanogen Methanobacterium prevailed at low HRTs (13-20 d). When operating continuous HPAD, attention should be paid to HRT optimization, as low HRTs (e.g., 13 d) impaired the activity of CH4-synthesizing enzyme Methyl-coenzyme M reductase.
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Affiliation(s)
- Jing Zhao
- Faculty of Science and Engineering, University of Groningen, Nijenborgh 4, 9747 AG Groningen, Netherlands; Center for Water and Ecology, School of Environment, Tsinghua University, Beijing 100084, China
| | - Yu Li
- Faculty of Science and Engineering, University of Groningen, Nijenborgh 4, 9747 AG Groningen, Netherlands; College of Engineering, China Agricultural University, Beijing 100083, China.
| | - Zhenhua Zhang
- Department of Genetics, University Medical Center Groningen, Groningen, Netherlands
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3
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Jespersen M, Pierik AJ, Wagner T. Structures of the sulfite detoxifying F 420-dependent enzyme from Methanococcales. Nat Chem Biol 2023; 19:695-702. [PMID: 36658338 DOI: 10.1038/s41589-022-01232-y] [Citation(s) in RCA: 8] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/08/2022] [Accepted: 11/22/2022] [Indexed: 01/21/2023]
Abstract
Methanogenic archaea are main actors in the carbon cycle but are sensitive to reactive sulfite. Some methanogens use a sulfite detoxification system that combines an F420H2-oxidase with a sulfite reductase, both of which are proposed precursors of modern enzymes. Here, we present snapshots of this coupled system, named coenzyme F420-dependent sulfite reductase (Group I Fsr), obtained from two marine methanogens. Fsr organizes as a homotetramer, harboring an intertwined six-[4Fe-4S] cluster relay characterized by spectroscopy. The wire, spanning 5.4 nm, electronically connects the flavin to the siroheme center. Despite a structural architecture similar to dissimilatory sulfite reductases, Fsr shows a siroheme coordination and a reaction mechanism identical to assimilatory sulfite reductases. Accordingly, the reaction of Fsr is unidirectional, reducing sulfite or nitrite with F420H2. Our results provide structural insights into this unique fusion, in which a primitive sulfite reductase turns a poison into an elementary block of life.
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Affiliation(s)
| | - Antonio J Pierik
- Biochemistry, Faculty of Chemistry, University of Kaiserslautern-Landau, Kaiserslautern, Germany
| | - Tristan Wagner
- Max Planck Institute for Marine Microbiology, Bremen, Germany.
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4
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Gagsteiger J, Jahn S, Heidinger L, Gericke L, Andexer JN, Friedrich T, Loenarz C, Layer G. A Cobalamin-Dependent Radical SAM Enzyme Catalyzes the Unique C α -Methylation of Glutamine in Methyl-Coenzyme M Reductase. Angew Chem Int Ed Engl 2022; 61:e202204198. [PMID: 35638156 PMCID: PMC9401015 DOI: 10.1002/anie.202204198] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/23/2022] [Indexed: 12/22/2022]
Abstract
Methyl‐coenzyme M reductase, which is responsible for the production of the greenhouse gas methane during biological methane formation, carries several unique posttranslational amino acid modifications, including a 2‐(S)‐methylglutamine. The enzyme responsible for the Cα‐methylation of this glutamine is not known. Herein, we identify and characterize a cobalamin‐dependent radical SAM enzyme as the glutamine C‐methyltransferase. The recombinant protein from Methanoculleus thermophilus binds cobalamin in a base‐off, His‐off conformation and contains a single [4Fe‐4S] cluster. The cobalamin cofactor cycles between the methyl‐cob(III)alamin, cob(II)alamin and cob(I)alamin states during catalysis and produces methylated substrate, 5′‐deoxyadenosine and S‐adenosyl‐l‐homocysteine in a 1 : 1 : 1 ratio. The newly identified glutamine C‐methyltransferase belongs to the class B radical SAM methyltransferases known to catalyze challenging methylation reactions of sp3‐hybridized carbon atoms.
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Affiliation(s)
- Jana Gagsteiger
- Institut für Pharmazeutische Wissenschaften, Pharmazeutische Biologie, Albert-Ludwigs-Universität Freiburg, Stefan-Meier-Str. 19, 79104, Freiburg, Germany
| | - Sören Jahn
- Institut für Pharmazeutische Wissenschaften, Pharmazeutische und Medizinische Chemie, Albert-Ludwigs-Universität Freiburg, Albertstr. 25, 79104, Freiburg, Germany
| | - Lorenz Heidinger
- Institut für Biochemie, Albert-Ludwigs-Universität Freiburg, Albertstr. 21, 79104, Freiburg, Germany
| | - Lukas Gericke
- Institut für Pharmazeutische Wissenschaften, Pharmazeutische und Medizinische Chemie, Albert-Ludwigs-Universität Freiburg, Albertstr. 25, 79104, Freiburg, Germany
| | - Jennifer N Andexer
- Institut für Pharmazeutische Wissenschaften, Pharmazeutische und Medizinische Chemie, Albert-Ludwigs-Universität Freiburg, Albertstr. 25, 79104, Freiburg, Germany
| | - Thorsten Friedrich
- Institut für Biochemie, Albert-Ludwigs-Universität Freiburg, Albertstr. 21, 79104, Freiburg, Germany
| | - Christoph Loenarz
- Institut für Pharmazeutische Wissenschaften, Pharmazeutische und Medizinische Chemie, Albert-Ludwigs-Universität Freiburg, Albertstr. 25, 79104, Freiburg, Germany
| | - Gunhild Layer
- Institut für Pharmazeutische Wissenschaften, Pharmazeutische Biologie, Albert-Ludwigs-Universität Freiburg, Stefan-Meier-Str. 19, 79104, Freiburg, Germany
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5
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Wegener G, Laso-Pérez R, Orphan VJ, Boetius A. Anaerobic Degradation of Alkanes by Marine Archaea. Annu Rev Microbiol 2022; 76:553-577. [PMID: 35917471 DOI: 10.1146/annurev-micro-111021-045911] [Citation(s) in RCA: 13] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
Alkanes are saturated apolar hydrocarbons that range from its simplest form, methane, to high-molecular-weight compounds. Although alkanes were once considered biologically recalcitrant under anaerobic conditions, microbiological investigations have now identified several microbial taxa that can anaerobically degrade alkanes. Here we review recent discoveries in the anaerobic oxidation of alkanes with a specific focus on archaea that use specific methyl coenzyme M reductases to activate their substrates. Our understanding of the diversity of uncultured alkane-oxidizing archaea has expanded through the use of environmental metagenomics and enrichment cultures of syntrophic methane-, ethane-, propane-, and butane-oxidizing marine archaea with sulfate-reducing bacteria. A recently cultured group of archaea directly couples long-chain alkane degradation with methane formation, expanding the range of substrates used for methanogenesis. This article summarizes the rapidly growing knowledge of the diversity, physiology, and habitat distribution of alkane-degrading archaea. Expected final online publication date for the Annual Review of Microbiology, Volume 76 is September 2022. Please see http://www.annualreviews.org/page/journal/pubdates for revised estimates.
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Affiliation(s)
- Gunter Wegener
- MARUM, Center for Marine Environmental Sciences, University Bremen, Bremen, Germany; , .,Max Planck Institute for Marine Microbiology, Bremen, Germany
| | - Rafael Laso-Pérez
- MARUM, Center for Marine Environmental Sciences, University Bremen, Bremen, Germany; , .,Max Planck Institute for Marine Microbiology, Bremen, Germany.,Current affiliation: Systems Biology Department, Centro Nacional de Biotecnología (CNB-CSIC), Madrid, Spain
| | - Victoria J Orphan
- MARUM, Center for Marine Environmental Sciences, University Bremen, Bremen, Germany; , .,Division of Geological and Planetary Sciences and Division of Biology and Biological Engineering, California Institute of Technology, Pasadena, California, USA;
| | - Antje Boetius
- MARUM, Center for Marine Environmental Sciences, University Bremen, Bremen, Germany; , .,Max Planck Institute for Marine Microbiology, Bremen, Germany.,Helmholtz Center for Polar and Marine Research, Bremerhaven, Germany;
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6
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Gagsteiger J, Jahn S, Heidinger L, Gericke L, Andexer JN, Friedrich T, Loenarz C, Layer G. A Cobalamin‐Dependent Radical SAM Enzyme Catalyzes the Unique Cα‐Methylation of Glutamine in Methyl‐Coenzyme M Reductase. Angew Chem Int Ed Engl 2022. [DOI: 10.1002/ange.202204198] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Affiliation(s)
- Jana Gagsteiger
- Albert-Ludwigs-Universität Freiburg, Fakultät für Chemie und Pharmazie Institut für Pharmazeutische Wissenschaften, Pharmazeutische Biologie GERMANY
| | - Sören Jahn
- Albert-Ludwigs-Universität Freiburg, Fakultät für Chemie und Pharmazie Institut für Pharmazeutische Wissenschaften, Pharmazeutische und Medizinische Chemie GERMANY
| | - Lorenz Heidinger
- Albert-Ludwigs-Universität Freiburg Institut für Biochemie GERMANY
| | - Lukas Gericke
- Albert-Ludwigs-Universität Freiburg, Fakultät für Chemie und Pharmazie Institut für Pharmazeutische Wissenschaften, Pharmazeutische und Medizinische Chemie GERMANY
| | - Jennifer N. Andexer
- Albert-Ludwigs-Universität Freiburg, Fakultät für Chemie und Pharmazie Institut für Pharmazeutische Wissenschaften, Pharmazeutische und Medizinische Chemie GERMANY
| | - Thorsten Friedrich
- Albert-Ludwigs-Universität Freiburg, Fakultät für Chemie und Pharmazie Institut für Biochemie GERMANY
| | - Christoph Loenarz
- Albert-Ludwigs-Universität Freiburg, Fakultät für Chemie und Pharmazie Institut für Pharmazeutische Wissenschaften, Pharmazeutische und Medizinische Chemie GERMANY
| | - Gunhild Layer
- Albert-Ludwigs-Universität Freiburg, Fakultät für Chemie und Pharmazie Institut für Pharmazeutische Wissenschaften, Pharmazeutische Biologie Stefan-Meier-Str. 19 79104 Freiburg GERMANY
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7
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Gendron A, Allen KD. Overview of Diverse Methyl/Alkyl-Coenzyme M Reductases and Considerations for Their Potential Heterologous Expression. Front Microbiol 2022; 13:867342. [PMID: 35547147 PMCID: PMC9081873 DOI: 10.3389/fmicb.2022.867342] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/01/2022] [Accepted: 04/01/2022] [Indexed: 12/02/2022] Open
Abstract
Methyl-coenzyme M reductase (MCR) is an archaeal enzyme that catalyzes the final step of methanogenesis and the first step in the anaerobic oxidation of methane, the energy metabolisms of methanogens and anaerobic methanotrophs (ANME), respectively. Variants of MCR, known as alkyl-coenzyme M reductases, are involved in the anaerobic oxidation of short-chain alkanes including ethane, propane, and butane as well as the catabolism of long-chain alkanes from oil reservoirs. MCR is a dimer of heterotrimers (encoded by mcrABG) and requires the nickel-containing tetrapyrrole prosthetic group known as coenzyme F430. MCR houses a series of unusual post-translational modifications within its active site whose identities vary depending on the organism and whose functions remain unclear. Methanogenic MCRs are encoded in a highly conserved mcrBDCGA gene cluster, which encodes two accessory proteins, McrD and McrC, that are believed to be involved in the assembly and activation of MCR, respectively. The requirement of a unique and complex coenzyme, various unusual post-translational modifications, and many remaining questions surrounding assembly and activation of MCR largely limit in vitro experiments to native enzymes with recombinant methods only recently appearing. Production of MCRs in a heterologous host is an important step toward developing optimized biocatalytic systems for methane production as well as for bioconversion of methane and other alkanes into value-added compounds. This review will first summarize MCR catalysis and structure, followed by a discussion of advances and challenges related to the production of diverse MCRs in a heterologous host.
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Affiliation(s)
- Aleksei Gendron
- Department of Biochemistry, Virginia Polytechnic Institute and State University, Blacksburg, VA, United States
| | - Kylie D Allen
- Department of Biochemistry, Virginia Polytechnic Institute and State University, Blacksburg, VA, United States
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8
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Lemaire ON, Wagner T. A Structural View of Alkyl-Coenzyme M Reductases, the First Step of Alkane Anaerobic Oxidation Catalyzed by Archaea. Biochemistry 2022; 61:805-821. [PMID: 35500274 PMCID: PMC9118554 DOI: 10.1021/acs.biochem.2c00135] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
![]()
Microbial anaerobic
oxidation of alkanes intrigues the scientific
community by way of its impact on the global carbon cycle, and its
biotechnological applications. Archaea are proposed to degrade short-
and long-chain alkanes to CO2 by reversing methanogenesis,
a theoretically reversible process. The pathway would start with alkane
activation, an endergonic step catalyzed by methyl-coenzyme M reductase
(MCR) homologues that would generate alkyl-thiols carried by coenzyme
M. While the methane-generating MCR found in methanogens has been
well characterized, the enzymatic activity of the putative alkane-fixing
counterparts has not been validated so far. Such an absence of biochemical
investigations contrasts with the current explosion of metagenomics
data, which draws new potential alkane-oxidizing pathways in various
archaeal phyla. Therefore, validating the physiological function of
these putative alkane-fixing machines and investigating how their
structures, catalytic mechanisms, and cofactors vary depending on
the targeted alkane have become urgent needs. The first structural
insights into the methane- and ethane-capturing MCRs highlighted unsuspected
differences and proposed some explanations for their substrate specificity.
This Perspective reviews the current physiological, biochemical, and
structural knowledge of alkyl-CoM reductases and offers fresh ideas
about the expected mechanistic and chemical differences among members
of this broad family. We conclude with the challenges of the investigation
of these particular enzymes, which might one day generate biofuels
for our modern society.
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Affiliation(s)
- Olivier N Lemaire
- Max Planck Institute for Marine Microbiology, Celsiusstraße 1, 28359 Bremen, Germany
| | - Tristan Wagner
- Max Planck Institute for Marine Microbiology, Celsiusstraße 1, 28359 Bremen, Germany
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9
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Miyazaki Y, Oohora K, Hayashi T. Focusing on a nickel hydrocorphinoid in a protein matrix: methane generation by methyl-coenzyme M reductase with F430 cofactor and its models. Chem Soc Rev 2022; 51:1629-1639. [PMID: 35148362 DOI: 10.1039/d1cs00840d] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Methyl-coenzyme M reductase (MCR) containing a nickel hydrocorphinoid cofactor, F430, is an essential enzyme that catalyzes anaerobic methane generation and oxidation. The active Ni(I) species in MCR converts methyl-coenzyme M (CH3S-CoM) and coenzyme B (HS-CoB) to methane and heterodisulfide (CoM-S-S-CoB). Extensive experimental and theoretical studies focusing on the substrate-binding cavity including the F430 cofactor in MCR have suggested two principally different reaction mechanisms involving an organonickel CH3-Ni(III) species or a transient methyl radical species. In parallel with research on native MCR itself, the functionality of MCR has been investigated in the context of model complexes of F430 and recent protein-based functional models, which include a nickel complex. In the latter case, hemoproteins reconstituted with tetradehydro- and didehydrocorrinoid nickel complexes have been found to represent useful model systems that are responsible for methane generation. These efforts support the proposed mechanism of the enzymatic reaction and provide important insight into replicating the MCR-like methane-generation process. Furthermore, the modeling of MCR described here is expected to lead to understanding of protein-supported nickel porphyrinoid chemistry as well as the creation of MCR-inspired catalysis.
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Affiliation(s)
- Yuta Miyazaki
- Department of Applied Chemistry, Graduate School of Engineering, Osaka University, Suita 565-0871, Japan.
| | - Koji Oohora
- Department of Applied Chemistry, Graduate School of Engineering, Osaka University, Suita 565-0871, Japan.
| | - Takashi Hayashi
- Department of Applied Chemistry, Graduate School of Engineering, Osaka University, Suita 565-0871, Japan.
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10
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Crystallographic snapshots of a B 12-dependent radical SAM methyltransferase. Nature 2022; 602:336-342. [PMID: 35110733 PMCID: PMC8828468 DOI: 10.1038/s41586-021-04355-9] [Citation(s) in RCA: 25] [Impact Index Per Article: 12.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/25/2021] [Accepted: 12/15/2021] [Indexed: 01/01/2023]
Abstract
By catalysing the microbial formation of methane, methyl-coenzyme M reductase has a central role in the global levels of this greenhouse gas1,2. The activity of methyl-coenzyme M reductase is profoundly affected by several unique post-translational modifications3–6, such as a unique C-methylation reaction catalysed by methanogenesis marker protein 10 (Mmp10), a radical S-adenosyl-l-methionine (SAM) enzyme7,8. Here we report the spectroscopic investigation and atomic resolution structure of Mmp10 from Methanosarcina acetivorans, a unique B12 (cobalamin)-dependent radical SAM enzyme9. The structure of Mmp10 reveals a unique enzyme architecture with four metallic centres and critical structural features involved in the control of catalysis. In addition, the structure of the enzyme–substrate complex offers a glimpse into a B12-dependent radical SAM enzyme in a precatalytic state. By combining electron paramagnetic resonance spectroscopy, structural biology and biochemistry, our study illuminates the mechanism by which the emerging superfamily of B12-dependent radical SAM enzymes catalyse chemically challenging alkylation reactions and identifies distinctive active site rearrangements to provide a structural rationale for the dual use of the SAM cofactor for radical and nucleophilic chemistry. Structural and spectroscopic studies show how a B12-dependent radical SAM enzyme catalyses unique and challenging alkylation chemistry, including protein post-translational modification required for methane biosynthesis.
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11
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Mizrahi I, Wallace RJ, Moraïs S. The rumen microbiome: balancing food security and environmental impacts. Nat Rev Microbiol 2021; 19:553-566. [PMID: 33981031 DOI: 10.1038/s41579-021-00543-6] [Citation(s) in RCA: 133] [Impact Index Per Article: 44.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 03/09/2021] [Indexed: 02/03/2023]
Abstract
Ruminants produce edible products and contribute to food security. They house a complex rumen microbial community that enables the host to digest their plant feed through microbial-mediated fermentation. However, the rumen microbiome is also responsible for the production of one of the most potent greenhouse gases, methane, and contributes about 18% of its total anthropogenic emissions. Conventional methods to lower methane production by ruminants have proved successful, but to a limited and often temporary extent. An increased understanding of the host-microbiome interactions has led to the development of new mitigation strategies. In this Review we describe the composition, ecology and metabolism of the rumen microbiome, and the impact on host physiology and the environment. We also discuss the most pertinent methane mitigation strategies that emerged to balance food security and environmental impacts.
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Affiliation(s)
- Itzhak Mizrahi
- Department of Life Sciences, Ben-Gurion University of the Negev and the National Institute for Biotechnology in the Negev, Marcus Family Campus, Be'er-Sheva, Israel.
| | - R John Wallace
- The Rowett Institute, University of Aberdeen, Aberdeen, UK
| | - Sarah Moraïs
- Department of Life Sciences, Ben-Gurion University of the Negev and the National Institute for Biotechnology in the Negev, Marcus Family Campus, Be'er-Sheva, Israel
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12
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Hahn CJ, Lemaire ON, Kahnt J, Engilberge S, Wegener G, Wagner T. Crystal structure of a key enzyme for anaerobic ethane activation. Science 2021; 373:118-121. [PMID: 34210888 DOI: 10.1126/science.abg1765] [Citation(s) in RCA: 17] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/15/2020] [Accepted: 05/28/2021] [Indexed: 02/01/2023]
Abstract
Ethane, the second most abundant hydrocarbon gas in the seafloor, is efficiently oxidized by anaerobic archaea in syntrophy with sulfate-reducing bacteria. Here, we report the 0.99-angstrom-resolution structure of the proposed ethane-activating enzyme and describe the specific traits that distinguish it from methane-generating and -consuming methyl-coenzyme M reductases. The widened catalytic chamber, harboring a dimethylated nickel-containing F430 cofactor, would adapt the chemistry of methyl-coenzyme M reductases for a two-carbon substrate. A sulfur from methionine replaces the oxygen from a canonical glutamine as the nickel lower-axial ligand, a feature conserved in thermophilic ethanotrophs. Specific loop extensions, a four-helix bundle dilatation, and posttranslational methylations result in the formation of a 33-angstrom-long hydrophobic tunnel, which guides the ethane to the buried active site as confirmed with xenon pressurization experiments.
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Affiliation(s)
- Cedric J Hahn
- Max Planck Institute for Marine Microbiology, Bremen 28359, Germany
| | | | - Jörg Kahnt
- Max Planck Institute for Terrestrial Microbiology, Marburg, Germany
| | | | - Gunter Wegener
- Max Planck Institute for Marine Microbiology, Bremen 28359, Germany. .,Center for Marine Environmental Sciences (MARUM), University of Bremen, Bremen, Germany.,Alfred Wegener Institute Helmholtz Center for Polar and Marine Research, Bremerhaven, Germany
| | - Tristan Wagner
- Max Planck Institute for Marine Microbiology, Bremen 28359, Germany.
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13
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Structural Insights into the Methane-Generating Enzyme from a Methoxydotrophic Methanogen Reveal a Restrained Gallery of Post-Translational Modifications. Microorganisms 2021; 9:microorganisms9040837. [PMID: 33919946 PMCID: PMC8070964 DOI: 10.3390/microorganisms9040837] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/25/2021] [Revised: 03/24/2021] [Accepted: 04/10/2021] [Indexed: 11/24/2022] Open
Abstract
Methanogenic archaea operate an ancient, if not primordial, metabolic pathway that releases methane as an end-product. This last step is orchestrated by the methyl-coenzyme M reductase (MCR), which uses a nickel-containing F430-cofactor as the catalyst. MCR astounds the scientific world by its unique reaction chemistry, its numerous post-translational modifications, and its importance in biotechnology not only for production but also for capturing the greenhouse gas methane. In this report, we investigated MCR natively isolated from Methermicoccus shengliensis. This methanogen was isolated from a high-temperature oil reservoir and has recently been shown to convert lignin and coal derivatives into methane through a process called methoxydotrophic methanogenesis. A methoxydotrophic culture was obtained by growing M. shengliensis with 3,4,5-trimethoxybenzoate as the main carbon and energy source. Under these conditions, MCR represents more than 12% of the total protein content. The native MCR structure refined at a resolution of 1.6-Å precisely depicts the organization of a dimer of heterotrimers. Despite subtle surface remodeling and complete conservation of its active site with other homologues, MCR from the thermophile M. shengliensis contains the most limited number of post-translational modifications reported so far, questioning their physiological relevance in other relatives.
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14
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Chen H, Gan Q, Fan C. Methyl-Coenzyme M Reductase and Its Post-translational Modifications. Front Microbiol 2020; 11:578356. [PMID: 33162960 PMCID: PMC7581889 DOI: 10.3389/fmicb.2020.578356] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/30/2020] [Accepted: 09/11/2020] [Indexed: 11/13/2022] Open
Abstract
The methyl-coenzyme M reductase (MCR) is a central enzyme in anaerobic microbial methane metabolism, which consists of methanogenesis and anaerobic oxidation of methane (AOM). MCR catalyzes the final step of methanogenesis and the first step of AOM to achieve the production and oxidation of methane, respectively. Besides a unique nickel tetrahydrocorphinoid (coenzyme F430), MCR also features several unusual post-translational modifications (PTMs), which are assumed to play important roles in regulating MCR functions. However, only few studies have been implemented on MCR PTMs. Therefore, to recapitulate current knowledge and prospect future studies, this review summarizes and discusses studies on MCR and its PTMs.
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Affiliation(s)
- Hao Chen
- Cell and Molecular Biology Program, University of Arkansas, Fayetteville, AR, United States
| | - Qinglei Gan
- Department of Chemistry and Biochemistry, University of Arkansas, Fayetteville, AR, United States
| | - Chenguang Fan
- Cell and Molecular Biology Program, University of Arkansas, Fayetteville, AR, United States.,Department of Chemistry and Biochemistry, University of Arkansas, Fayetteville, AR, United States
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15
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Shima S, Huang G, Wagner T, Ermler U. Structural Basis of Hydrogenotrophic Methanogenesis. Annu Rev Microbiol 2020; 74:713-733. [DOI: 10.1146/annurev-micro-011720-122807] [Citation(s) in RCA: 13] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
Most methanogenic archaea use the rudimentary hydrogenotrophic pathway—from CO2and H2to methane—as the terminal step of microbial biomass degradation in anoxic habitats. The barely exergonic process that just conserves sufficient energy for a modest lifestyle involves chemically challenging reactions catalyzed by complex enzyme machineries with unique metal-containing cofactors. The basic strategy of the methanogenic energy metabolism is to covalently bind C1species to the C1carriers methanofuran, tetrahydromethanopterin, and coenzyme M at different oxidation states. The four reduction reactions from CO2to methane involve one molybdopterin-based two-electron reduction, two coenzyme F420–based hydride transfers, and one coenzyme F430–based radical process. For energy conservation, one ion-gradient-forming methyl transfer reaction is sufficient, albeit supported by a sophisticated energy-coupling process termed flavin-based electron bifurcation for driving the endergonic CO2reduction and fixation. Here, we review the knowledge about the structure-based catalytic mechanism of each enzyme of hydrogenotrophic methanogenesis.
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Affiliation(s)
- Seigo Shima
- Max Planck Institute for Terrestrial Microbiology, 35043 Marburg, Germany
| | - Gangfeng Huang
- Max Planck Institute for Terrestrial Microbiology, 35043 Marburg, Germany
| | - Tristan Wagner
- Max Planck Institute for Marine Microbiology, 28359 Bremen, Germany
| | - Ulrich Ermler
- Max Planck Institute of Biophysics, 60438 Frankfurt am Main, Germany
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16
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Lynch ML, Dudek MF, Bowman SE. A Searchable Database of Crystallization Cocktails in the PDB: Analyzing the Chemical Condition Space. PATTERNS (NEW YORK, N.Y.) 2020; 1:100024. [PMID: 32776019 PMCID: PMC7409820 DOI: 10.1016/j.patter.2020.100024] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 12/31/2019] [Revised: 03/22/2020] [Accepted: 03/30/2020] [Indexed: 10/26/2022]
Abstract
Nearly 90% of structural models in the Protein Data Bank (PDB), the central resource worldwide for three-dimensional structural information, are currently derived from macromolecular crystallography (MX). A major bottleneck in determining MX structures is finding conditions in which a biomolecule will crystallize. Here, we present a searchable database of the chemicals associated with successful crystallization experiments from the PDB. We use these data to examine the relationship between protein secondary structure and average molecular weight of polyethylene glycol and to investigate patterns in crystallization conditions. Our analyses reveal striking patterns of both redundancy of chemical compositions in crystallization experiments and extreme sparsity of specific chemical combinations, underscoring the challenges faced in generating predictive models for de novo optimal crystallization experiments.
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Affiliation(s)
- Miranda L. Lynch
- High-Throughput Crystallization Screening Center, Hauptman-Woodward Medical Research Institute, Buffalo, NY 14203, USA
| | - Max F. Dudek
- University of Pittsburgh, Pittsburgh, PA 15261, USA
| | - Sarah E.J. Bowman
- High-Throughput Crystallization Screening Center, Hauptman-Woodward Medical Research Institute, Buffalo, NY 14203, USA
- Department of Biochemistry, Jacobs School of Medicine & Biomedical Sciences at the University at Buffalo, Buffalo, NY 14203, USA
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17
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Catalytic activity regulation through post-translational modification: the expanding universe of protein diversity. ADVANCES IN PROTEIN CHEMISTRY AND STRUCTURAL BIOLOGY 2020; 122:97-125. [PMID: 32951817 PMCID: PMC7320668 DOI: 10.1016/bs.apcsb.2020.05.001] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Indexed: 12/15/2022]
Abstract
Protein composition is restricted by the genetic code to a relatively small number of natural amino acids. Similarly, the known three-dimensional structures adopt a limited number of protein folds. However, proteins exert a large variety of functions and show a remarkable ability for regulation and immediate response to intracellular and extracellular stimuli. To some degree, the wide variability of protein function can be attributed to the post-translational modifications. Post-translational modifications have been observed in all kingdoms of life and give to proteins a significant degree of chemical and consequently functional and structural diversity. Their importance is partly reflected in the large number of genes dedicated to their regulation. So far, hundreds of post-translational modifications have been observed while it is believed that many more are to be discovered along with the technological advances in sequencing, proteomics, mass spectrometry and structural biology. Indeed, the number of studies which report novel post translational modifications is getting larger supporting the notion that their space is still largely unexplored. In this review we explore the impact of post-translational modifications on protein structure and function with emphasis on catalytic activity regulation. We present examples of proteins and protein families whose catalytic activity is substantially affected by the presence of post translational modifications and we describe the molecular basis which underlies the regulation of the protein function through these modifications. When available, we also summarize the current state of knowledge on the mechanisms which introduce these modifications to protein sites.
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18
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Nayak DD, Liu A, Agrawal N, Rodriguez-Carerro R, Dong SH, Mitchell DA, Nair SK, Metcalf WW. Functional interactions between posttranslationally modified amino acids of methyl-coenzyme M reductase in Methanosarcina acetivorans. PLoS Biol 2020; 18:e3000507. [PMID: 32092071 PMCID: PMC7058361 DOI: 10.1371/journal.pbio.3000507] [Citation(s) in RCA: 24] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/04/2019] [Revised: 03/05/2020] [Accepted: 02/04/2020] [Indexed: 01/27/2023] Open
Abstract
The enzyme methyl-coenzyme M reductase (MCR) plays an important role in mediating global levels of methane by catalyzing a reversible reaction that leads to the production or consumption of this potent greenhouse gas in methanogenic and methanotrophic archaea. In methanogenic archaea, the alpha subunit of MCR (McrA) typically contains four to six posttranslationally modified amino acids near the active site. Recent studies have identified enzymes performing two of these modifications (thioglycine and 5-[S]-methylarginine), yet little is known about the formation and function of the remaining posttranslationally modified residues. Here, we provide in vivo evidence that a dedicated S-adenosylmethionine-dependent methyltransferase encoded by a gene we designated methylcysteine modification (mcmA) is responsible for formation of S-methylcysteine in Methanosarcina acetivorans McrA. Phenotypic analysis of mutants incapable of cysteine methylation suggests that the S-methylcysteine residue might play a role in adaption to mesophilic conditions. To examine the interactions between the S-methylcysteine residue and the previously characterized thioglycine, 5-(S)-methylarginine modifications, we generated M. acetivorans mutants lacking the three known modification genes in all possible combinations. Phenotypic analyses revealed complex, physiologically relevant interactions between the modified residues, which alter the thermal stability of MCR in a combinatorial fashion that is not readily predictable from the phenotypes of single mutants. High-resolution crystal structures of inactive MCR lacking the modified amino acids were indistinguishable from the fully modified enzyme, suggesting that interactions between the posttranslationally modified residues do not exert a major influence on the static structure of the enzyme but rather serve to fine-tune the activity and efficiency of MCR.
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Affiliation(s)
- Dipti D. Nayak
- Carl R. Woese Institute of Genomic Biology, University of Illinois, Urbana, Illinois, United States of America
- Department of Microbiology, University of Illinois, Urbana, Illinois, United States of America
| | - Andi Liu
- Department of Microbiology, University of Illinois, Urbana, Illinois, United States of America
| | - Neha Agrawal
- Department of Biochemistry, University of Illinois, Urbana, Illinois, United States of America
| | - Roy Rodriguez-Carerro
- Department of Microbiology, University of Illinois, Urbana, Illinois, United States of America
| | - Shi-Hui Dong
- Department of Biochemistry, University of Illinois, Urbana, Illinois, United States of America
| | - Douglas A. Mitchell
- Carl R. Woese Institute of Genomic Biology, University of Illinois, Urbana, Illinois, United States of America
- Department of Microbiology, University of Illinois, Urbana, Illinois, United States of America
- Department of Chemistry, University of Illinois, Urbana, Illinois, United States of America
| | - Satish K. Nair
- Department of Biochemistry, University of Illinois, Urbana, Illinois, United States of America
- Center for Biophysics & Quantitative Biology, University of Illinois, Urbana, Illinois, United States of America
| | - William W. Metcalf
- Carl R. Woese Institute of Genomic Biology, University of Illinois, Urbana, Illinois, United States of America
- Department of Microbiology, University of Illinois, Urbana, Illinois, United States of America
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19
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Posttranslational Methylation of Arginine in Methyl Coenzyme M Reductase Has a Profound Impact on both Methanogenesis and Growth of Methanococcus maripaludis. J Bacteriol 2020; 202:JB.00654-19. [PMID: 31740491 DOI: 10.1128/jb.00654-19] [Citation(s) in RCA: 19] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/16/2019] [Accepted: 11/09/2019] [Indexed: 02/05/2023] Open
Abstract
Catalyzing the key step for anaerobic production and/or oxidation of methane and likely other short-chain alkanes, methyl coenzyme M reductase (Mcr) and its homologs play a key role in the global carbon cycle. The McrA subunit possesses up to five conserved posttranslational modifications (PTMs) at its active site. It was previously suggested that methanogenesis marker protein 10 (Mmp10) could play an important role in methanogenesis. To systematically examine its physiological role, mmpX (locus tag MMP1554), the gene encoding Mmp10 in Methanococcus maripaludis, was deleted with a new genetic tool, resulting in the complete loss of the 5-C-(S)-methylarginine PTM of residue 275 in the McrA subunit. When the ΔmmpX mutant was complemented with the wild-type gene expressed by either a strong or a weak promoter, methylation was fully restored. Compared to the parental strain, maximal rates of methane formation by whole cells were reduced by 40 to 60% in the ΔmmpX mutant. The reduction in activity was fully reversed by the complement with the strong promoter. Site-directed mutagenesis of mmpX resulted in a differential loss of arginine methylation among the mutants in vivo, suggesting that activities of Mmp10 directly modulated methylation. R275 was present in a highly conserved PXRR275(A/S)R(G/A) signature sequence in McrAs. The only other protein in M. maripaludis containing a similar sequence was not methylated, suggesting that Mmp10 is specific for McrA. In conclusion, Mmp10 modulates the methyl-Arg PTM on McrA in a highly specific manner, which has a profound impact on Mcr activity.IMPORTANCE Mcr is the key enzyme in methanogenesis and a promising candidate for bioengineering the conversion of methane to liquid fuel. Our knowledge of Mcr is still limited. In terms of complexity, uniqueness, and environmental importance, Mcr is more comparable to photosynthetic reaction centers than conventional enzymes. PTMs have long been hypothesized to play key roles in modulating Mcr activity. Here, we directly link the mmpX gene to the arginine PTM of Mcr, demonstrate its association with methanogenesis activity, and offer insights into its substrate specificity and putative cofactor binding sites. This is also the first time that a PTM of McrA has been shown to have a substantial impact on both methanogenesis and growth in the absence of additional stressors.
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20
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Szilagyi RK, Hanscam R, Shepard EM, McGlynn SE. Natural selection based on coordination chemistry: computational assessment of [4Fe-4S]-maquettes with non-coded amino acids. Interface Focus 2019; 9:20190071. [PMID: 31641437 DOI: 10.1098/rsfs.2019.0071] [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: 07/02/2019] [Accepted: 08/27/2019] [Indexed: 12/21/2022] Open
Abstract
Cysteine is the only coded amino acid in biology that contains a thiol functional group. Deprotonated thiolate is essential for anchoring iron-sulfur ([Fe-S]) clusters, as prosthetic groups to the protein matrix. [Fe-S] metalloproteins and metalloenzymes are involved in biological electron transfer, radical chemistry, small molecule activation and signalling. These are key metabolic and regulatory processes that would likely have been present in the earliest organisms. In the context of emergence of life theories, the selection and evolution of the cysteine-specific R-CH2-SH side chain is a fascinating question to confront. We undertook a computational [4Fe-4S]-maquette modelling approach to evaluate how side chain length can influence [Fe-S] cluster binding and stability in short 7-mer and long 16-mer peptides, which contained either thioglycine, cysteine or homocysteine. Force field-based molecular dynamics simulations for [4Fe-4S] cluster nest formation were supplemented with density functional theory calculations of a ligand-exchange reaction between a preassembled cluster and the peptide. Secondary structure analysis revealed that peptides with cysteine are found with greater frequency nested to bind preformed [4Fe-4S] clusters. Additionally, the presence of the single methylene group in cysteine ligands mitigates the steric bulk, maintains the H-bonding and dipole network, and provides covalent Fe-S(thiolate) bonds that together create the optimal electronic and geometric structural conditions for [4Fe-4S] cluster binding compared to thioglycine or homocysteine ligands. Our theoretical work forms an experimentally testable hypothesis of the natural selection of cysteine through coordination chemistry.
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Affiliation(s)
- Robert K Szilagyi
- Department of Chemistry and Biochemistry, Montana State University, Bozeman, MT 59717, USA
| | - Rebecca Hanscam
- Department of Chemistry and Biochemistry, Montana State University, Bozeman, MT 59717, USA
| | - Eric M Shepard
- Department of Chemistry and Biochemistry, Montana State University, Bozeman, MT 59717, USA
| | - Shawn E McGlynn
- Earth-Life Science Institute, Tokyo Institute of Technology, Ookayama, Meguro-ku, Tokyo 152-8550, Japan.,Blue Marble Space Institute of Science, Seattle, WA 98154, USA.,Biofunctional Catalyst Research Team, RIKEN Center for Sustainable Resource Science (CSRS), 2-1 Hirosawa, Wako, Saitama 351-0198, Japan
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21
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Radle MI, Miller DV, Laremore TN, Booker SJ. Methanogenesis marker protein 10 (Mmp10) from Methanosarcina acetivorans is a radical S-adenosylmethionine methylase that unexpectedly requires cobalamin. J Biol Chem 2019; 294:11712-11725. [PMID: 31113866 DOI: 10.1074/jbc.ra119.007609] [Citation(s) in RCA: 30] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/23/2019] [Revised: 05/10/2019] [Indexed: 11/06/2022] Open
Abstract
Methyl coenzyme M reductase (MCR) catalyzes the last step in the biological production of methane by methanogenic archaea, as well as the first step in the anaerobic oxidation of methane to methanol by methanotrophic archaea. MCR contains a number of unique post-translational modifications in its α subunit, including thioglycine, 1-N-methylhistidine, S-methylcysteine, 5-C-(S)-methylarginine, and 2-C-(S)-methylglutamine. Recently, genes responsible for the thioglycine and methylarginine modifications have been identified in bioinformatics studies and in vivo complementation of select mutants; however, none of these reactions has been verified in vitro Herein, we purified and biochemically characterized the radical S-adenosylmethionine (SAM) protein MaMmp10, the product of the methanogenesis marker protein 10 gene in the methane-producing archaea Methanosarcina acetivorans Using an array of approaches, including kinetic assays, LC-MS-based quantification, and MALDI TOF-TOF MS analyses, we found that MaMmp10 catalyzes the methylation of the equivalent of Arg285 in a peptide substrate surrogate, but only in the presence of cobalamin. We noted that the methyl group derives from SAM, with cobalamin acting as an intermediate carrier, and that MaMmp10 contains a C-terminal cobalamin-binding domain. Given that Mmp10 has not been annotated as a cobalamin-binding protein, these findings suggest that cobalamin-dependent radical SAM proteins are more prevalent than previously thought.
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Affiliation(s)
- Matthew I Radle
- Department of Chemistry, Pennsylvania State University, University Park, Pennsylvania 16802
| | - Danielle V Miller
- Department of Chemistry, Pennsylvania State University, University Park, Pennsylvania 16802
| | - Tatiana N Laremore
- Huck Institutes of the Life Sciences, Pennsylvania State University, University Park, Pennsylvania 16802
| | - Squire J Booker
- Department of Chemistry, Pennsylvania State University, University Park, Pennsylvania 16802 .,Department of Biochemistry and Molecular Biology, Pennsylvania State University, University Park, Pennsylvania 16802.,Howard Hughes Medical Institute, Pennsylvania State University, University Park, Pennsylvania 16802
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22
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Thauer RK. Methyl (Alkyl)-Coenzyme M Reductases: Nickel F-430-Containing Enzymes Involved in Anaerobic Methane Formation and in Anaerobic Oxidation of Methane or of Short Chain Alkanes. Biochemistry 2019; 58:5198-5220. [PMID: 30951290 PMCID: PMC6941323 DOI: 10.1021/acs.biochem.9b00164] [Citation(s) in RCA: 59] [Impact Index Per Article: 11.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
![]()
Methyl-coenzyme
M reductase (MCR) catalyzes the methane-forming
step in methanogenic archaea. The active enzyme harbors the nickel(I)
hydrocorphin coenzyme F-430 as a prosthetic group and catalyzes the
reversible reduction of methyl-coenzyme M (CH3–S-CoM)
with coenzyme B (HS-CoM) to methane and CoM-S–S-CoB. MCR is
also involved in anaerobic methane oxidation in reverse of methanogenesis
and most probably in the anaerobic oxidation of ethane, propane, and
butane. The challenging question is how the unreactive CH3–S thioether bond in methyl-coenzyme M and the even more unreactive
C–H bond in methane and the other hydrocarbons are anaerobically
cleaved. A key to the answer is the negative redox potential (Eo′) of the Ni(II)F-430/Ni(I)F-430 couple
below −600 mV and the radical nature of Ni(I)F-430. However,
the negative one-electron redox potential is also the Achilles heel
of MCR; it makes the nickel enzyme one of the most O2-sensitive
enzymes known to date. Even under physiological conditions, the Ni(I)
in MCR is oxidized to the Ni(II) or Ni(III) states, e.g., when in
the cells the redox potential (E′) of the
CoM-S–S-CoB/HS-CoM and HS-CoB couple (Eo′ = −140 mV) gets too high. Methanogens therefore
harbor an enzyme system for the reactivation of inactivated MCR in
an ATP-dependent reduction reaction. Purification of active MCR in
the Ni(I) oxidation state is very challenging and has been achieved
in only a few laboratories. This perspective reviews the function,
structure, and properties of MCR, what is known and not known about
the catalytic mechanism, how the inactive enzyme is reactivated, and
what remains to be discovered.
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Affiliation(s)
- Rudolf K Thauer
- Max Planck Institute for Terrestrial Microbiology , Karl-von-Frisch-Strasse 10 , Marburg 35043 , Germany
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23
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An evolving view of methane metabolism in the Archaea. Nat Rev Microbiol 2019; 17:219-232. [DOI: 10.1038/s41579-018-0136-7] [Citation(s) in RCA: 231] [Impact Index Per Article: 46.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/07/2017] [Accepted: 11/26/2018] [Indexed: 11/08/2022]
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24
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Identification of a unique Radical SAM methyltransferase required for the sp 3-C-methylation of an arginine residue of methyl-coenzyme M reductase. Sci Rep 2018; 8:7404. [PMID: 29743535 PMCID: PMC5943407 DOI: 10.1038/s41598-018-25716-x] [Citation(s) in RCA: 29] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/10/2018] [Accepted: 04/27/2018] [Indexed: 12/27/2022] Open
Abstract
The biological formation of methane (methanogenesis) is a globally important process, which is exploited in biogas technology, but also contributes to global warming through the release of a potent greenhouse gas into the atmosphere. The last and methane-releasing step of methanogenesis is catalysed by the enzyme methyl-coenzyme M reductase (MCR), which carries several exceptional posttranslational amino acid modifications. Among these, a 5-C-(S)-methylarginine is located close to the active site of the enzyme. Here, we show that a unique Radical S-adenosyl-L-methionine (SAM) methyltransferase is required for the methylation of the arginine residue. The gene encoding the methyltransferase is currently annotated as “methanogenesis marker 10” whose function was unknown until now. The deletion of the methyltransferase gene ma4551 in Methanosarcina acetivorans WWM1 leads to the production of an active MCR lacking the C-5-methylation of the respective arginine residue. The growth behaviour of the corresponding M. acetivorans mutant strain and the biophysical characterization of the isolated MCR indicate that the methylated arginine is important for MCR stability under stress conditions.
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25
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Assembly of Methyl Coenzyme M Reductase in the Methanogenic Archaeon Methanococcus maripaludis. J Bacteriol 2018; 200:JB.00746-17. [PMID: 29339414 DOI: 10.1128/jb.00746-17] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/09/2017] [Accepted: 01/04/2018] [Indexed: 01/22/2023] Open
Abstract
Methyl coenzyme M reductase (MCR) is a complex enzyme that catalyzes the final step in biological methanogenesis. To better understand its assembly, the recombinant MCR from the thermophile Methanothermococcus okinawensis (rMCRok) was expressed in the mesophile Methanococcus maripaludis The rMCRok was posttranslationally modified correctly and contained McrD and the unique nickel tetrapyrrole coenzyme F430 Subunits of the native M. maripaludis (MCRmar) were largely absent, suggesting that the recombinant enzyme was formed by an assembly of cotranscribed subunits. Strong support for this hypothesis was obtained by expressing a chimeric operon comprising the His-tagged mcrA from M. maripaludis and the mcrBDCG from M. okinawensis in M. maripaludis The His-tagged purified rMCR then contained the M. maripaludis McrA and the M. okinawensis McrBDG. The present study prompted us to form a working model for MCR assembly, which can be further tested by the heterologous expression system established here.IMPORTANCE Approximately 1.6% of the net primary production of plants, algae, and cyanobacteria are processed by biological methane production in anoxic environments. This accounts for about 74% of the total global methane production, up to 25% of which is consumed by anaerobic oxidation of methane (AOM). Methyl coenzyme M reductase (MCR) is the key enzyme in both methanogenesis and AOM. MCR is assembled as a dimer of two heterotrimers, where posttranslational modifications and F430 cofactors are embedded in the active sites. However, this complex assembly process remains unknown. Here, we established a heterologous expression system for MCR to learn how MCR is assembled.
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26
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Archaeal acetoacetyl-CoA thiolase/HMG-CoA synthase complex channels the intermediate via a fused CoA-binding site. Proc Natl Acad Sci U S A 2018. [PMID: 29531083 DOI: 10.1073/pnas.1718649115] [Citation(s) in RCA: 35] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Many reactions within a cell are thermodynamically unfavorable. To efficiently run some of those endergonic reactions, nature evolved intermediate-channeling enzyme complexes, in which the products of the first endergonic reactions are immediately consumed by the second exergonic reactions. Based on this concept, we studied how archaea overcome the unfavorable first reaction of isoprenoid biosynthesis-the condensation of two molecules of acetyl-CoA to acetoacetyl-CoA catalyzed by acetoacetyl-CoA thiolases (thiolases). We natively isolated an enzyme complex comprising the thiolase and 3-hydroxy-3-methylglutaryl (HMG)-CoA synthase (HMGCS) from a fast-growing methanogenic archaeon, Methanothermococcus thermolithotrophicus HMGCS catalyzes the second reaction in the mevalonate pathway-the exergonic condensation of acetoacetyl-CoA and acetyl-CoA to HMG-CoA. The 380-kDa crystal structure revealed that both enzymes are held together by a third protein (DUF35) with so-far-unknown function. The active-site clefts of thiolase and HMGCS form a fused CoA-binding site, which allows for efficient coupling of the endergonic thiolase reaction with the exergonic HMGCS reaction. The tripartite complex is found in almost all archaeal genomes and in some bacterial ones. In addition, the DUF35 proteins are also important for polyhydroxyalkanoate (PHA) biosynthesis, most probably by functioning as a scaffold protein that connects thiolase with 3-ketoacyl-CoA reductase. This natural and highly conserved enzyme complex offers great potential to improve isoprenoid and PHA biosynthesis in biotechnologically relevant organisms.
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