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  • 1
    Publication Date: 2017-06-20
    Description: The anaerobic oxidation of methane (AOM) with sulphate, an area currently generating great interest in microbiology, is accomplished by consortia of methanotrophic archaea (ANME) and sulphate-reducing bacteria1, 2. The enzyme activating methane in methanotrophic archaea has tentatively been identified as a homologue of methyl-coenzyme M reductase (MCR) that catalyses the methane-forming step in methanogenic archaea3, 4. Here we report an X-ray structure of the 280 kDa heterohexameric ANME-1 MCR complex. It was crystallized uniquely from a protein ensemble purified from consortia of microorganisms collected with a submersible from a Black Sea mat catalysing AOM with sulphate4. Crystals grown from the heterogeneous sample diffract to 2.1 Å resolution and consist of a single ANME-1 MCR population, demonstrating the strong selective power of crystallization. The structure revealed ANME-1 MCR in complex with coenzyme M and coenzyme B, indicating the same substrates for MCR from methanotrophic and methanogenic archaea. Differences between the highly similar structures of ANME-1 MCR and methanogenic MCR include a F430 modification, a cysteine-rich patch and an altered post-translational amino acid modification pattern, which may tune the enzymes for their functions in different biological contexts.
    Type: Article , PeerReviewed
    Format: text
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  • 2
    Publication Date: 2020-07-16
    Description: Microbial mats collected at cold methane seeps in the Black Sea carry out anaerobic oxidation of methane (AOM) to carbon dioxide using sulfate as the electron acceptor. These mats, which predominantly consist of sulfate-reducing bacteria and archaea of the ANME-1 and ANME-2 type, contain large amounts of proteins very similar to methyl-coenzyme M reductase from methanogenic archaea. Mass spectrometry of mat samples revealed the presence of two nickel-containing cofactors in comparable amounts, one with the same mass as coenzyme F430 from methanogens (m/z = 905) and one with a mass that is 46 Da higher (m/z = 951). The two cofactors were isolated and purified, and their constitution and absolute configuration were determined. The cofactor with m/z = 905 was proven to be identical to coenzyme F430 from methanogens. For the m/z = 951 species, high resolution ICP-MS pointed to F430 + CH2S as the molecular formula, and LA-ICP-SF MS finally confirmed the presence of one sulfur atom per nickel. Esterification gave two stereoisomeric pentamethyl esters with m/z = 1021, which could be purified by reverse phase HPLC and were subjected to comprehensive NMR analysis, allowing determination of their constitution and configuration as (172S)−172-methylthio-F430 pentamethyl ester and (172R)−172-methylthio-F430 pentamethyl ester. The corresponding diastereoisomeric pentaacids could also be separated by HPLC and were correlated to the esters via mild hydrolysis of the latter. Equilibration of the pentaacids under acid catalysis showed that the (172S) isomer is the naturally occurring albeit thermodynamically less stable one. The more stable (172R) isomer (80% at equilibrium) is an isolation artifact generated under the acidic conditions necessary for the isolation of the cofactors from the calcium carbonate-encrusted mats.
    Type: Article , PeerReviewed
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  • 3
    Publication Date: 2016-10-07
    Description: Large amounts (estimates range from 70 Tg per year to 300 Tg per year) of the potent greenhouse gas methane are oxidized to carbon dioxide in marine sediments by communities of methanotrophic archaea and sulphate-reducing bacteria1, 2, 3, and thus are prevented from escaping into the atmosphere. Indirect evidence indicates that the anaerobic oxidation of methane might proceed as the reverse of archaeal methanogenesis from carbon dioxide with the nickel-containing methyl-coenzyme M reductase (MCR) as the methane-activating enzyme4, 5. However, experiments showing that MCR can catalyse the endergonic back reaction have been lacking. Here we report that purified MCR from Methanothermobacter marburgensis converts methane into methyl-coenzyme M under equilibrium conditions with apparent Vmax (maximum rate) and Km (Michaelis constant) values consistent with the observed in vivo kinetics of the anaerobic oxidation of methane with sulphate6, 7, 8. This result supports the hypothesis of ‘reverse methanogenesis’4, 9 and is paramount to understanding the still-unknown mechanism of the last step of methanogenesis. The ability of MCR to cleave the particularly strong C–H bond of methane without the involvement of highly reactive oxygen-derived intermediates is directly relevant to catalytic C–H activation, currently an area of great interest in chemistry10, 11, 12, 13.
    Type: Article , PeerReviewed
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  • 4
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    Springer International
    In:  Springer International, Cham, X, 150 pp. ISBN 978-331991229-5; 978-331991228-8
    Publication Date: 2021-02-08
    Description: This is the first book that analyses the future raw materials supply from the demand side of a society that chiefly relies on renewable energies, which is of great significance for us all. It addresses primary and secondary resources and substitution, not only from technical but also socioeconomic and ethical points of view. The "Energiewende" (Energy Transition) will change our consumption of natural resources significantly. When in future our energy requirements will be covered mostly by wind, solar power and biomass, we will need less coal, oil and natural gas. However, the consumption of minerals, especially metallic resources, will increase to build wind generators, solar panels or energy storage facilities. Besides e.g. copper, nickel or cobalt, rare earth elements and other high-tech elements will be increasingly used. With regard to primary metals, Germany is 100 % import dependent; only secondary material is produced within Germany. Though sufficient geological primary resources exist worldwide, their availability on the market is crucial. The future supply of the market is dependent on the development of prices, the transparency of the market and the question of social and ethical standards in the raw materials industry, as well as the social license to operate, which especially applies to mining. The book offers a valuable resource for everyone interested in the future raw material supply of our way of life, which will involve more and more renewable energies.
    Type: Book , NonPeerReviewed
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