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Current Biology : CB Jul 2018Methanogenesis is an anaerobic respiration that generates methane as the final product of metabolism. In aerobic respiration, organic matter such as glucose is oxidized...
Methanogenesis is an anaerobic respiration that generates methane as the final product of metabolism. In aerobic respiration, organic matter such as glucose is oxidized to CO, and O is reduced to HO. In contrast, during hydrogenotrophic methanogenesis, H is oxidized to H, and CO is reduced to CH. Although similar in principle to other types of respiration, methanogenesis has some distinctive features: the energy yield is very low, ≤1 ATP per methane generated, and only methanogens - organisms capable of this specialized metabolism - carry out biological methane production. Methanogens, like the process they catalyze, are similarly distinctive. Methanogens are comprised exclusively of archaea. They are obligate methane producers, that is, they do not grow using fermentation or alternative electron acceptors for respiration. Finally, methanogens are strict anaerobes and do not grow in the presence of O. Historically, methanogenesis has been viewed as a highly specialized metabolism restricted to a narrow group of prokaryotes. However, recent developments have revealed enormous diversity within the methanogens and suggest that this metabolism is one of the most ancient on earth.
Topics: Anaerobiosis; Biological Evolution; Euryarchaeota; Life History Traits; Methane
PubMed: 29990451
DOI: 10.1016/j.cub.2018.05.021 -
Science (New York, N.Y.) Mar 2020Many disease pathologies can be understood through the elucidation of localized biomolecular networks, or microenvironments. To this end, enzymatic proximity labeling...
Many disease pathologies can be understood through the elucidation of localized biomolecular networks, or microenvironments. To this end, enzymatic proximity labeling platforms are broadly applied for mapping the wider spatial relationships in subcellular architectures. However, technologies that can map microenvironments with higher precision have long been sought. Here, we describe a microenvironment-mapping platform that exploits photocatalytic carbene generation to selectively identify protein-protein interactions on cell membranes, an approach we term MicroMap (μMap). By using a photocatalyst-antibody conjugate to spatially localize carbene generation, we demonstrate selective labeling of antibody binding targets and their microenvironment protein neighbors. This technique identified the constituent proteins of the programmed-death ligand 1 (PD-L1) microenvironment in live lymphocytes and selectively labeled within an immunosynaptic junction.
Topics: B7-H1 Antigen; Catalysis; Cell Membrane; Cellular Microenvironment; Energy Transfer; Humans; Jurkat Cells; Lymphocytes; Methane; Photochemical Processes; Protein Interaction Mapping; Protein Interaction Maps; Ultraviolet Rays
PubMed: 32139536
DOI: 10.1126/science.aay4106 -
Applied and Environmental Microbiology Mar 2018Aerobic methanotrophs have long been known to play a critical role in the global carbon cycle, being capable of converting methane to biomass and carbon dioxide.... (Review)
Review
Aerobic methanotrophs have long been known to play a critical role in the global carbon cycle, being capable of converting methane to biomass and carbon dioxide. Interestingly, these microbes exhibit great sensitivity to copper and rare-earth elements, with the expression of key genes involved in the central pathway of methane oxidation controlled by the availability of these metals. That is, these microbes have a "copper switch" that controls the expression of alternative methane monooxygenases and a "rare-earth element switch" that controls the expression of alternative methanol dehydrogenases. Further, it has been recently shown that some methanotrophs can detoxify inorganic mercury and demethylate methylmercury; this finding is remarkable, as the canonical organomercurial lyase does not exist in these methanotrophs, indicating that a novel mechanism is involved in methylmercury demethylation. Here, we review recent findings on methanotrophic interactions with metals, with a particular focus on these metal switches and the mechanisms used by methanotrophs to bind and sequester metals.
Topics: Bacteria, Anaerobic; Metals; Methane
PubMed: 29305514
DOI: 10.1128/AEM.02289-17 -
Chemical Society Reviews Mar 2021Methanotrophic bacteria represent a potential route to methane utilization and mitigation of methane emissions. In the first step of their metabolic pathway, aerobic... (Review)
Review
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.
Topics: Bacteria; Bacterial Proteins; Catalytic Domain; Metals; Methane; Oxidation-Reduction; Oxygenases; Protein Engineering
PubMed: 33491685
DOI: 10.1039/d0cs01291b -
Mass Spectrometry Reviews Jul 2022This review is devoted to ion spectroscopy studies of complexes relevant for the understanding of methane activation with metal ions and clusters. Methane activation... (Review)
Review
This review is devoted to ion spectroscopy studies of complexes relevant for the understanding of methane activation with metal ions and clusters. Methane activation starts with the formation of a complex with a metal ion. The degree of the interaction between an intact methane molecule and the ion can be monitored by the perturbations of C-H stretch vibrations in the methane molecule. Binding mediated by the electrostatic interaction results in a η type coordination of methane. In contrast, binding governed by orbital interactions results in a η type coordination of methane. We further review the spectroscopic characterization of activation products of metal-methane reactions, such as the metal-carbene and carbyne products resulting from the interaction of selected 5d metals with methane. The focus of recent research in the field has shifted towards the investigation of interactions between methane and metal clusters. We show examples highlighting that metal clusters can be more reactive in methane activation reactions.
Topics: Ions; Mass Spectrometry; Metals; Methane; Spectrum Analysis
PubMed: 34008884
DOI: 10.1002/mas.21698 -
Journal of Zhejiang University....Methane is the simplest hydrocarbon, consisting of one carbon atom and four hydrogen atoms. It is abundant in marsh gas, livestock rumination, and combustible ice.... (Review)
Review
Methane is the simplest hydrocarbon, consisting of one carbon atom and four hydrogen atoms. It is abundant in marsh gas, livestock rumination, and combustible ice. Little is known about the use of methane in human disease treatment. Current research indicates that methane is useful for treating several diseases including ischemia and reperfusion injury, and inflammatory diseases. The mechanisms underlying the protective effects of methane appear primarily to involve anti-oxidation, anti-inflammation, and anti-apoptosis. In this review, we describe the beneficial effects of methane on different diseases, summarize possible mechanisms by which methane may act in these conditions, and discuss the purpose of methane production in hypoxic conditions. Then we propose several promising directions for the future research.
Topics: Antioxidants; Apoptosis; Humans; Inflammation; Ischemia; Methane; Reperfusion Injury
PubMed: 32748575
DOI: 10.1631/jzus.B1900629 -
Medical Gas Research 2023Methane has shown protective effects on a variety of diseases. Among these, neurological diseases have attracted much attention. However, there are many different... (Review)
Review
Methane has shown protective effects on a variety of diseases. Among these, neurological diseases have attracted much attention. However, there are many different indicators and application methods of methane in the treatment of neurological diseases. In this review, we summarize the indicators related to the protective effects of methane and evaluate the preparation and administration of methane. Thus, we hope to offer available indicators and effective ways to produce and administer methane in future research.
Topics: Methane; Nervous System Diseases; Humans
PubMed: 37077112
DOI: 10.4103/2045-9912.372663 -
Annual Review of Microbiology Sep 2022Methane is one of the most important greenhouse gases on Earth and holds an important place in the global carbon cycle. Archaea are the only organisms that use... (Review)
Review
Methane is one of the most important greenhouse gases on Earth and holds an important place in the global carbon cycle. Archaea are the only organisms that use methanogenesis to produce energy and rely on the methyl-coenzyme M reductase complex (Mcr). Over the last decade, new results have significantly reshaped our view of the diversity of methane-related pathways in the Archaea. Many new lineages that synthesize or use methane have been identified across the whole archaeal tree, leading to a greatly expanded diversity of substrates and mechanisms. In this review, we present the state of the art of these advances and how they challenge established scenarios of the origin and evolution of methanogenesis, and we discuss the potential trajectories that may have led to this strikingly wide range of metabolisms.
Topics: Archaea; Methane; Oxidation-Reduction; Phylogeny
PubMed: 35759872
DOI: 10.1146/annurev-micro-041020-024935 -
Biotechnology and Applied Biochemistry Sep 2020
Topics: Bacteria; Biofuels; Butanols; Ethanol; Industrial Microbiology; Lignin; Methane; Renewable Energy
PubMed: 33002228
DOI: 10.1002/bab.2046 -
Environmental Science & Technology Feb 2022Natural gas stoves in >40 million U.S. residences release methane (CH)─a potent greenhouse gas─through post-meter leaks and incomplete combustion. We quantified...
Natural gas stoves in >40 million U.S. residences release methane (CH)─a potent greenhouse gas─through post-meter leaks and incomplete combustion. We quantified methane released in 53 homes during all phases of stove use: steady-state-off (appliance not in use), steady-state-on (during combustion), and transitory periods of ignition and extinguishment. We estimated that natural gas stoves emit 0.8-1.3% of the gas they use as unburned methane and that total U.S. stove emissions are 28.1 [95% confidence interval: 18.5, 41.2] Gg CH year. More than three-quarters of methane emissions we measured originated during steady-state-off. Using a 20-year timeframe for methane, annual methane emissions from all gas stoves in U.S. homes have a climate impact comparable to the annual carbon dioxide emissions of 500 000 cars. In addition to methane emissions, co-emitted health-damaging air pollutants such as nitrogen oxides (NO) are released into home air and can trigger respiratory diseases. In 32 homes, we measured NO (NO and NO) emissions and found them to be linearly related to the amount of natural gas burned ( = 0.76; ≪ 0.01). Emissions averaged 21.7 [20.5, 22.9] ng NO J, comprised of 7.8 [7.1, 8.4] ng NO J and 14.0 [12.8, 15.1] ng NO J. Our data suggest that families who don't use their range hoods or who have poor ventilation can surpass the 1-h national standard of NO (100 ppb) within a few minutes of stove usage, particularly in smaller kitchens.
Topics: Air Pollutants; Household Articles; Humans; Methane; Natural Gas; Nitrogen Dioxide
PubMed: 35081712
DOI: 10.1021/acs.est.1c04707