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  • 1
    ISSN: 1365-2958
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology , Medicine
    Notes: The genome of Methanopyrus kandleri was found to harbour a gene, fwuB, predicted to encode the catalytic subunit of a tungsten formylmethanofuran dehydrogenase with an active site selenocysteine, and a second gene, fwcB, encoding a tungsten formylmethanofuran dehydrogenase with an active site cysteine. Northern blot and primer-extension analysis revealed that both genes were differentially transcribed. During growth of the methanogen on medium supplemented with selenium only fwuB was transcribed, whereas transcription of both fwuB and fwcB was observed on selenium-deprived medium. Growth of M. kandleri was stimulated by tungstate and selenite but not by molybdate. The findings indicate that the hyperthermophilic archaeon contains two tungsten isoenzymes of formylmethanofuran dehydrogenase, one of which is a novel selenium enzyme. They also indicate that the hyperthermophilic methanogen probably does not contain a molybdenum formylmethanofuran dehydrogenase which appears to be present only in thermophilic and mesophilic methanogens.
    Type of Medium: Electronic Resource
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  • 2
    ISSN: 1432-072X
    Keywords: Key words Formyltransferase ; Formyltetrahydrofolate ; synthase ; Hyperthermophilic enzymes ; Methanogenic ; Archaea ; Methanosarcina barkeri
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The ftr gene encoding formylmethanofuran: tetrahydromethanopterin formyltransferase (Ftr) from Methanosarcina barkeri was cloned, sequenced, and functionally expressed in Escherichia coli. The overproduced enzyme was purified eightfold to apparent homogeneity, and its catalytic properties were determined. The primary structure and the hydropathic character of the formyltransferase from Methanosarcina barkeri were compared with those of the enzymes from Methanobacterium thermoautotrophicum, Methanothermus fervidus, and Methanopyrus kandleri. The amino acid sequence of the enzyme from Methanosarcina barkeri was 64%, 61%, and 59% identical to that of the enzyme from Methanobacterium thermoautotrophicum, Methanothermus fervidus, and Methanopyrus kandleri, respectively. A negative correlation between the hydrophobicity of the enzymes and both the growth temperature optimum and the intracellular salt concentration of the four organisms was observed. The hydrophobicity of amino acid composition was +21.6 for the enzyme from Methanosarcina barkeri (growth temperature optimum 37° C, intracellular salt concentration ≈ 0.3 M), +9.9 for the enzyme from Methanobacterium thermoautotrophicum (65°C, ≈ 0.7 M), –20.8 for the enzyme from Methanothermus fervidus (83° C, ≈ 1.0 M) and –31.4 for the enzyme from Methanopyrus kandleri (98° C, 〉 1.1 M). Generally, a positive correlation between hydrophobicity and thermophilicity of enzymes and a negative correlation between hydrophobicity and halophilicity of enzymes are observed. The findings therefore indicate that the hydropathic character of the formyltransferases compared is mainly determined by the intracellular salt concentration rather than by temperature. Sequence similarities between the formyltransferases from methanogens and an open reading frame from Methylobacterium extorquens AM1 are discussed.
    Type of Medium: Electronic Resource
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  • 3
    ISSN: 1433-4909
    Keywords: Key words Hyperthermophilic enzymes ; N5 ; N10-Methenyltetrahydromethanopterin cyclohydrolase ; Tetrahydromethanopterin-dependent enzymes ; Methanogenic Archaea ; Methanopyrus kandleri
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: N 5,N 10-Methenyltetrahydromethanopterin cyclohydrolase (Mch) is an enzyme involved in methanogenesis from CO2 and H2 which represents the energy metabolism of Methanopyrus kandleri, a methanogenic Archaeon growing at a temperature optimum of 98°C. The gene mch from M. kandleri was cloned, sequenced, and expressed in Escherichia coli. The overproduced enzyme could be purified in yields above 90% in one step by chromatography on phenyl Sepharose in 80% ammonium sulfate. From 3.5 g cells (250 mg protein), approximately 18 mg cyclohydrolase was obtained. The purified enzyme showed essentially the same catalytic properties as the enzyme purified from M. kandleri cells. The primary structure and properties of the cyclohydrolase are compared with those of the enzyme from Methanococcus jannaschii (growth temperature optimum 85°C), from Methanobacterium thermoautotrophicum (65°C), and from Methanosarcina barkeri (37°C). Of the four enzymes, that from M. kandleri has the lowest isoelectric point (3.8) and the lowest hydrophobicity of amino acid composition. Besides, it has the highest relative content of glutamate, leucine, and valine and the lowest relative content of isoleucine, serine, and lysine. Some of these properties are unusual for enzymes from hyperthermophilic organisms. They may reflect the observation that the cyclohydrolase from M. kandleri is not only adapted to hyperthermophilic conditions but also to the high intracellular concentrations of lyotrophic salts prevailing in this organism.
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  • 4
    Publication Date: 2022-05-25
    Description: Author Posting. © The Author(s), 2011. This is the author's version of the work. It is posted here by permission of John Wiley & Sons for personal use, not for redistribution. The definitive version was published in Environmental Microbiology 14 (2012): 140-146, doi:10.1111/j.1462-2920.2011.02554.x.
    Description: The above-ground surfaces of terrestrial plants, the phyllosphere, comprise the main interface between the terrestrial biosphere and solar radiation. It is estimated to host up to 1026 microbial cells that may intercept part of the photon flux impinging on the leaves. Based on 454- pyrosequencing generated metagenome data, we report on the existence of diverse microbial rhodopsins in five distinct phyllospheres from tamarisk (Tamarix nilotica), soybean (Glycine max), Arabidopsis (Arabidopsis thaliana), clover (Trifolium repens) and rice (Oryza sativa). Our findings, for the first time describing microbial rhodopsins from non-aquatic habitats, point toward the potential coexistence of microbial rhodopsin-based phototrophy and plant chlorophyll-based photosynthesis, with the different pigments absorbing non-overlapping fractions of the light spectrum.
    Description: This work was supported in part by a grant from Bridging the Rift Foundation (O.B. & S.B.), Israel Science Foundation grant 1203/06 (O.B.), the Gruss-Lipper Family Foundation at MBL (O.M.F., S.B. & A.F.P.), a US-Israel Binational Science Foundation grant 2006324 (S.B.), and DOE National Institutes of Health Grant R37GM27750, Department of Energy Grant DE-FG02-07ER15867, and endowed chair AU-0009 from the Robert A. Welch Foundation (J.L.S.).
    Repository Name: Woods Hole Open Access Server
    Type: Preprint
    Format: application/pdf
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  • 5
    Publication Date: 2019-02-01
    Description: The potential of the diverse chemistries present in natural products (NP) for biotechnology and medicine remains untapped because NP databases are not searchable with raw data and the NP community has no way to share data other than in published papers. Although mass spectrometry (MS) techniques are well-suited to high-throughput characterization of NP, there is a pressing need for an infrastructure to enable sharing and curation of data. We present Global Natural Products Social Molecular Networking (GNPS; http://gnps.ucsd.edu), an open-access knowledge base for community-wide organization and sharing of raw, processed or identified tandem mass (MS/MS) spectrometry data. In GNPS, crowdsourced curation of freely available community-wide reference MS libraries will underpin improved annotations. Data-driven social-networking should facilitate identification of spectra and foster collaborations. We also introduce the concept of 'living data' through continuous reanalysis of deposited data.
    Type: Article , PeerReviewed
    Format: text
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