Attention:The NSF Public Access Repository (PAR) system and access will be unavailable from 11:00 PM ET on Thursday, October 15th until 12:00 AM ET on Friday, October 16th due to maintenance. We apologize for the inconvenience.

Explore Research Products in the PAR
It may take a few hours for recently added research products to appear in PAR search results.


Title: MmoD regulates soluble methane monooxygenase and methanobactin production in Methylosinus trichosporium OB3b
ABSTRACT Methane oxidation by aerobic methanotrophs is well known to be strongly regulated by the availability of copper, i.e., the “copper switch.” That is, there are two forms of methane monooxygenase: a cytoplasmic or soluble methane monooxygenase (sMMO) and a membrane-bound or particulate methane monooxygenase (pMMO). sMMO is only expressed and active in the absence of copper, while pMMO requires copper. Previous work has also shown that one gene in the operon of the soluble methane monooxygenase—mmoD—also plays a critical role in the “copper switch,” but its function is still vague. Herein, we show that MmoD is not needed for the expression of genes in the sMMO gene cluster but is critical for the formation of sMMO polypeptides and sMMO activity inMethylosinus trichosporiumOB3b, indicating that MmoD plays a key post-transcriptional role in the maturation of sMMO. Furthermore, data also show that MmoD controls the expression of methanobactin, a copper-binding compound used by some methanotrophs, includingM. trichosporiumOB3b, for copper sequestration. Collectively, these results provide greater insights into the components of the “copper switch” and provide new strategies to manipulate methanotrophic activity. IMPORTANCEAerobic 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.  more » « less
Award ID(s):
1912482
PAR ID:
10546442
Author(s) / Creator(s):
; ; ;
Editor(s):
Zhou, Ning-Yi
Publisher / Repository:
American Society for Microbiology
Date Published:
Journal Name:
Applied and Environmental Microbiology
Volume:
89
Issue:
12
ISSN:
0099-2240
Subject(s) / Keyword(s):
methanotrophy, copper, methane monooxygenase, methanobactin, MmoD
Format(s):
Medium: X
Sponsoring Org:
National Science Foundation
More Like this
  1. ; (, Metabolic Engineering Communications)
    Antoniewicz, Maciek (Ed.)
    Methanotrophs, which utilize methane as their sole carbon and energy source, are promising platforms for valorizing methane to industrially valuable products, such as bioplastics or biofuels. However, methanotrophic activity is highly affected by the availability of metals, and therefore, a greater understanding of these effects is important for efficient conversion of methane by methanotrophs. To address this, the impact of copper on methanotrophy was investigated at a systems level via the reconstruction of a genome-scale metabolic model (GEM) for Methylosinus trichosporium OB3b. The GEM was further integrated with transcriptomic data for improved functionality, which was then employed to identify metabolic engineering strategies for increased putrescine production. Despite these efforts, the GEM framework was not successful in significantly enhancing putrescine production. Therefore, the steady-state 13C-metabolic flux analysis was conducted to estimate intracellular flux distributions and to validate the GEM functionality, revealing the indispensability of the ethylmalonyl-CoA cycle and inflexibility of flux utilization in central methane metabolism. These findings highlight key pathway constraints for methane valorization and expand the system-level understanding of copper-regulated methanotrophic metabolism. 
    more » « less
  2. ; ; ; ; (, Applied and Environmental Microbiology)
    ABSTRACT 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. 
    more » « less
  3. ; (, Microbial Biotechnology)
    Abstract Methane capture via oxidation is considered one of the ‘Holy Grails’ of catalysis (Tucci and Rosenzweig, 2024). Methane is also a primary greenhouse gas that has to be reduced by 1.2 billion metric tonnes in 10 years to decrease global warming by only 0.23°C (He and Lidstrom, 2024); hence, new technologies are needed to reduce atmospheric methane levels. In Nature, methane is captured aerobically by methanotrophs and anaerobically by anaerobic methanotrophic archaea; however, the anaerobic process dominates. Here, we describe the history and potential of using the two remarkable enzymes that have been cloned with activity for capturing methane: aerobic capture via soluble methane monooxygenase and anaerobic capture via methyl‐coenzyme M reductase. We suggest these two enzymes may play a prominent, sustainable role in addressing our current global warming crisis. 
    more » « less
  4. ; (, Environmental Microbiology)
    Boyd, Eric (Ed.)
    ABSTRACT Methylosinus trichosporiumOB3b is a model methanotroph that converts methane to CO2with methanol, formaldehyde, and formate as intermediates. Here we show that copper has a significant impact on the ability ofMsn. trichosporiumOB3b to grow on methanol, that is, growth consistently occurred on methanol in the absence of copper but not in its presence. Growth on methanol in the presence of copper, however, occurred in the presence of MOPS buffer that stabilized pH. Examination of transcriptome profiles, NADH/NAD ratios, and formate production indicates that growth disruption in the presence of copper was likely caused by a confluence of (1) overgeneration of reducing power from methanol oxidation; (2) formate accumulation leading to acidification of the growth medium and inactivation of formate dehydrogenase; and (3) lack of expression of oxidative stress defence genes. Finally, transcriptomic analysis showed that expression of two putative siderophore gene clusters (one on a plasmid and the other on the chromosome) was significantly controlled by both the availability of copper as well as growth substrate (i.e., methane vs. methanol). Specifically, the presence of methanol and copper significantly repressed the expression of these siderophore gene clusters, suggesting that these metallophores play a key role in facilitating methanotrophic growth. 
    more » « less
  5. ; ; ; ; ; ; (, Biomolecules)
    Particulate methane monooxygenase (pMMO), a membrane-bound enzyme having three subunits (α, β, and γ) and copper-containing centers, is found in most of the methanotrophs that selectively catalyze the oxidation of methane into methanol. Active sites in the pMMO of Methylosinus trichosporium OB3b were determined by docking the modeled structure with ethylbenzene, toluene, 1,3-dibutadiene, and trichloroethylene. The docking energy between the modeled pMMO structure and ethylbenzene, toluene, 1,3-dibutadiene, and trichloroethylene was −5.2, −5.7, −4.2, and −3.8 kcal/mol, respectively, suggesting the existence of more than one active site within the monomeric subunits due to the presence of multiple binding sites within the pMMO monomer. The evaluation of tunnels and cavities of the active sites and the docking results showed that each active site is specific to the radius of the substrate. To increase the catalysis rates of methane in the pMMO of M. trichosporium OB3b, selected amino acid residues interacting at the binding site of ethylbenzene, toluene, 1,3-dibutadiene, and trichloroethylene were mutated. Based on screening the strain energy, docking energy, and physiochemical properties, five mutants were downselected, B:Leu31Ser, B:Phe96Gly, B:Phe92Thr, B:Trp106Ala, and B:Tyr110Phe, which showed the docking energy of −6.3, −6.7, −6.3, −6.5, and −6.5 kcal/mol, respectively, as compared to the wild type (−5.2 kcal/mol) with ethylbenzene. These results suggest that these five mutants would likely increase methane oxidation rates compared to wild-type pMMO. 
    more » « less
  • Citation Formats
  • MLA
  • APA
  • Chicago
  • BibTeX
  • Text Encoded Conversion
  • XML
  • Save / Share this Record
  • Send to Email