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  • 1
    Electronic Resource
    Electronic Resource
    Di-cluster, seven-iron ferredoxins from hyperthermophilic Sulfolobales (1998)
    Springer
    JBIC 3 (1998), S. 499-507 
    Details
    ISSN: 1432-1327
    Keywords: Key words Ferredoxins ; Thermophiles ; Archaea ; EPR ; Iron-sulfur
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Chemistry and Pharmacology
    Notes: Abstract  Seven-iron ferredoxins from the thermoacidophilic archaea Acidianus ambivalens, A. infernus, Metalosphaera prunae and Sulfolobus metallicus were extensively characterised, allowing study of their expression under aerobic and anaerobic growth conditions as well as the putative role in thermal stability of a recently described zinc centre. The archaeon S. metallicus was found to express, under the same growth conditions, two ferredoxins in almost identical amounts, a novelty among Archaea. Most interestingly, these two ferredoxins differ at the N-terminal amino acid sequence in that one has a zinc binding motif (FdA) and the other does not (FdB); in agreement with these findings, FdA contains a zinc ion and FdB does not. These two ferredoxins have identical thermal stabilities, indicating that the zinc atom is not determinant in the protein thermostability. Further, the presence of the additional zinc centre does not interfere with the redox properties of the iron-sulfur clusters since their reduction potentials are almost identical. From the other three archaea, independently of the growth mode in respect to oxygen, only a single zinc-containing ferredoxin was found. EPR studies on the purified proteins, both in the oxidised and dithionite reduced states, allowed the identification of one [3Fe-4S]1+/0 centre and one [4Fe-4S]2+/1+ centre in all proteins studied. The complete sequence of A. ambivalens ferredoxin is reported. Together with the data gathered in this study, the properties of the seven-iron ferredoxins from Sulfolobales so far known are re-discussed.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s007750050260
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  • 2
    Electronic Resource
    Electronic Resource
    Thermococcus chitonophagus sp. nov., a novel, chitin-degrading, hyperthermophilic archaeum from a deep-sea hydrothermal vent environment (1995)
    Springer
    Archives of microbiology 164 (1995), S. 255-264 
    Details
    ISSN: 1432-072X
    Keywords: Key wordsThermococcus ; Archaea ; Hyperthermophile ; Deep-sea hydrothermal vent ; Chitin ; Riftia pachyptila
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract From a hydrothermal vent site off the Mexican west coast (20°50′N, 109°06′W) at a depth of 2,600 m, a novel, hyperthermophilic, anaerobic archaeum was isolated. Cells were round to slightly irregular cocci, 1.2–2.5 μm in diameter and were motile by means of a tuft of flagella. The new isolate grew between 60 and 93°C (optimum: 85°C), from pH 3.5 to 9 (optimum: pH 6.7), and from 0.8 to 8% NaCl (optimum: 2%). The isolate was an obligate organotroph, using chitin, yeast extract, meat extract, and peptone for growth. Chitin was fermented to H2, CO2, NH3, acetate, and formate. H2S was formed in the presence of sulfur. The chitinoclastic enzyme system was oxygen-stable, cell-associated, and inducible by chitin. The cell wall was composed of a surface layer of hex- americ protein complexes arranged on a p6 lattice. The core lipids consisted of glycerol diphytanyl diethers and acyclic and cyclic glycerol diphytanyl tetraethers. The G+C content was 46.5 mol%. DNA/DNA hybridization and 16S rRNA sequencing indicated that the new isolate belongs to the genus Thermococcus, representing a new species, Thermococcus chitonophagus. The type strain is isolate GC74, DSM 10152.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s002030050262
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  • 3
    Electronic Resource
    Electronic Resource
    Methanoplanus limicola, a plate-shaped methanogen representing a novel family, the methanoplanaceae (1982)
    Springer
    Archives of microbiology 132 (1982), S. 31-36 
    Details
    ISSN: 1432-072X
    Keywords: Methanogens ; Archaebacteria ; Cell division ; Glycoprotein ; Acetate ; Taxonomy
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract An angular plate-shaped weakly motile mesophilic methanogen was isolated from a swamp of drilling waste in Italy. Growth occurs on H2/CO2 or on formate. Acetate is required in addition. The optimal doubling time is 7 h at 40° C. The cell envelope is composed most likely of glycoprotein subunits in hexagonal arrangement. The GC-content of its DNA is 47.5 mol%. On the basis of DNA-RNA hybridization it was found to represent a new family, the Methanoplanaceae within the order Methanomicrobiales.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00690813
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  • 4
    Electronic Resource
    Electronic Resource
    Methanococcus thermolithotrophicus, a novel thermophilic lithotrophic methanogen (1982)
    Springer
    Archives of microbiology 132 (1982), S. 47-50 
    Details
    ISSN: 1432-072X
    Keywords: Methanogens ; Archaebacteria ; Autotrophic ; Thermophilic
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract An autotrophic thermophilic motile coccoid methanogen was isolated from geothermally heated sea sediments close to Naples, Italy. Growth occurs on H2/CO2 and on formate between 30 and 70°C with an optimum at 65°C. The optimal doubling time is only 55 min. The NaCl-concentration ranges from 1.3% to 8.3% with an optimum around 4%. By its G+C-content of 31.3 mol%, its subunit envelope, and by DNA-RNA hybridization the new isolate is clearly defined to be a member of the genusMethanococcus. We name itMethanococcus thermolithotrophicus.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00690816
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  • 5
    Electronic Resource
    Electronic Resource
    Methanopyrus kandleri, gen. and sp. nov. represents a novel group of hyperthermophilic methanogens, growing at 110°C (1991)
    Springer
    Archives of microbiology 156 (1991), S. 239-247 
    Details
    ISSN: 1432-072X
    Keywords: Methanopyrus ; Methanogens ; Archaea ; Hyperthermophilic ; Marine ; Vents
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract A novel group of hyperthermophilic rod-shaped motile methanogens was isolated from a hydrothermally heated deep sea sediment (Guaymas Basin, Gulf of California) and from a shallow marine hydrothermal system (Kolbeinsey ridge, Iceland). The grew between 84 and 110°C (opt: 98°C) and from 0.2% to 4% NaCl (opt. 2%) and pH 5.5 to 7 (opt: 6.5). The isolates were obligate chemolithoautotrophes using H2/CO2 as energy and carbon sources. In the presence of sulfur, H2S was formed and cells tended to lyse. The cell wall consisted of a new type of pseudomurein containing ornithin in addition to lysine and no N-acetylglucosamine. The pseudomurein layer was covered by a detergent-sensitive protein surface layer. The core lipid consisted exclusively of phytanyl diether. The GC content of the DNA was 60 mol%. By 16S rRNA comparisons the new organisms were not related to any of the three methanogenic lineages. Based on the physiological and molecular properties of the new isolates, we describe here a new genus, which we name Methanopyrus (the “methane fire”). The type species is Methanopyrus kandleri (type strain: AV19; DSM 6324).
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00262992
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  • 6
    Electronic Resource
    Electronic Resource
    A F420-dependent NADP reductase in the extremely thermophilic sulfate-reducing Archaeoglobus fulgidus (1993)
    Springer
    Archives of microbiology 160 (1993), S. 199-205 
    Details
    ISSN: 1432-072X
    Keywords: Archaea ; Sulfate reducers ; Hyperthermophiles ; Coenzyme F420 ; Deazaflavin ; F420-dependent NADP reducatase ; Stereoselectivity ; Stereospecificity ; Archaeoglobus fulgidus
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Archaeoglobus fulgidus, a sulfate-reducing Archaeon with a growth temperature optimum of 83°C, uses the 5-deazaflavin coenzyme F420 rather than pyridine nucleotides in catabolic redox processes. The organism does, however, require reduced pyridine nuclcotides for biosynthetic purposes. We describe here that the Archaeon contains a coenzyme F420-dependent NADP reductase which links anabolism to catabolism. The highly thermostable enzyme was purfied 3600-fold by affinity chromatography to apparent homogeneity in a 60% yield. The native enzyme with an apparent molecular mass of 55 kDa was composed of only one type of subunit of apparent molecular mass of 28 kDa. Spectroscopic analysis of the enzyme did not reveal the presence of any chromophoric prosthetic group. The purified enzyme catalyzed the reversible reduction of NADP (apparent K M 40 μM) with reduced F420 (apparent K M 20μM) with a specific activity of 660 U/mg (apparent V max) at pH 8.0 (pH optimum) and 80°C (temperature optimum). It was specific for both coenzyme F420 and NADP. Sterochemical investigations showed that the F420-dependent NADP reductase was Si face specific with respect to C5 of F420 and Si face specific with respect to C4 of NADP.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00249125
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