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  • 1
    Electronic Resource
    Electronic Resource
    Reductive activation of the methyl-tetrahydromethanopterin: coenzyme M methyltransferase from Methanobacterium thermoautotrophicum strain ΔH (1988)
    Springer
    Archives of microbiology 150 (1988), S. 405-412 
    Details
    ISSN: 1432-072X
    Keywords: Methanobacterium thermoautotrophicum ; Activation ; Corrinoid enzyme ; Methyltransferase ; Methanopterin ; Coenzyme M
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The enzymatic conversion of formaldehyde to CH3S-CoM in crude extracts of Methanobacterium thermoautotrophicum was used as a means to investigate the methyl-tetrahydromethanopterin: HS-CoM methyltransferase reaction. All components necessary for formaldehyde conversion were shown to be present in a soluble protein fraction. This soluble cell fraction still contained a major amount of corrinoids. Apart from tetrahydromethanopterin no other soluble cofactors were required for formaldehyde conversion. The dependence of the system on catalytic amounts of ATP was shown to be specific. Several nucleoside triphosphates or ADP were unable to substitute for ATP. Remarkably, various strong reducing systems, especially titanium(III)citrate could replace ATP to a large extent. The ATP-dependent formaldehyde conversion to CH3S-CoM was inhibited in the presence of nitrous oxide, detergents or 2′,3′-dialdehyde-ATP. The results support a role for a corrinoid protein in the methyl-tetrahydromethanopterin: HS-CoM methyltransferase reaction at which ATP is involved in the activation of this protein, probably in the conversion of inactive B12a or B12r to active B12s.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00408315
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  • 2
    Electronic Resource
    Electronic Resource
    The anaerobic fungusPiromyces sp. strain E2: nitrogen requirement and enzymes involved in primary nitrogen metabolism (1996)
    Springer
    Archives of microbiology 166 (1996), S. 399-404 
    Details
    ISSN: 1432-072X
    Keywords: Piromyces ; Nitrogen source ; Glutamate dehydrogenase ; Glutamine synthetase ; Amino transferases
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The anaerobic fungusPiromyces sp. strain E2 appeared restricted in nitrogen utilization. Growth was only supported by ammonium as source of nitrogen. Glutamine also resulted in growth, but this was due to release of ammonia rather than to uptake and utilization of the amino acid. The fungus was not able to grow on other amino acids, albumin, urea, allantoin, or nitrate. Assimilation of ammonium is very likely to be mediated by NADP-linked glutamate dehydrogenase (NADP-GDH) and glutamine synthetase (GS). One transaminating activity, glutamate-oxaloacetate transaminase (GOT), was demonstrated. Glutamate synthase (GOGAT), NAD-dependent glutamate dehydrogenase (NAD-GDH), and the transaminating activity glutamate-pyruvate transaminase (GPT) were not detected in cell-free extracts ofPiromyces sp. strain E2. Specific enzyme activities of both NADP-GDH and GS increased four-to sixfold under nitrogen-limiting conditions.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01682986
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  • 3
    Electronic Resource
    Electronic Resource
    The role of the cellulolytic high molecular mass (HMM) complex of the anaerobic fungus Piromyces sp. strain E2 in the hydrolysis of microcrystalline cellulose (1997)
    Springer
    Archives of microbiology 167 (1997), S. 137-142 
    Details
    ISSN: 1432-072X
    Keywords: Key words Anaerobic fungus ; Piromyces ; Multiprotein complex ; Hydrolysis ; Crystalline cellulose ; Cellulosome
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The anaerobic fungus Piromyces sp. strain E2 produces extracellular cellulolytic enzymes present both in a high molecular mass (HMM) complex or as individual proteins. Although the HMM complex was present in the culture fluid during all growth stages, the highest amounts of complex were obtained when cultures were harvested at the end of fungal growth. The complex obtained after gel-filtration chromatography on Sephacryl S-300 HR was found to be the major factor in hydrolysis of cellulose to glucose (sole product, up to 250 mM). The complex was very stable as demonstrated by identical hydrolysis patterns with fresh preparations or preparations stored at 4° C for 2 months. From inhibition experiments with gluconic acid lactone and glucose, it was concluded that the HMM complex must contain at least one glucohydrolase. SDS-PAGE analysis revealed that a partially purified HMM complex was composed of at least ten polypeptides and contained numerous endoglucanases and one β-glucosidase.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s002030050426
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  • 4
    Electronic Resource
    Electronic Resource
    The enzymes of the ammonia assimilation in Pseudomonas aeruginosa (1980)
    Springer
    Archives of microbiology 124 (1980), S. 197-203 
    Details
    ISSN: 1432-072X
    Keywords: Glutamine synthetase ; Glutamate synthase ; Glutamate dehydrogenase ; Ammonia assimilation ; Pseudomonas aeruginosa
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Glutamine synthetase from Pseudomonas aeruginosa is regulated by repression/derepression of enzyme synthesis and by adenylylation/deadenylylation control. High levels of deadenylylated biosynthetically active glutamine synthetase were observed in cultures growing with limiting amounts of nitrogen while synthesis of the enzyme was repressed and that present was adenylylated in cultures with excess nitrogen. NADP-and NAD-dependent glutamate dehydrogenase could be separated by column chromatography and showed molecular weights of 110,000 and 220,000, respectively. Synthesis of the NADP-dependent glutamate dehydrogenase is repressed under nitrogen limitation and by growth on glutamate. In contrast, NAD-dependent glutamate dehydrogenase is derepressed by glutamate. Glutamate synthase is repressed by glutamate but not by excess nitrogen.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00427727
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  • 5
    Electronic Resource
    Electronic Resource
    Methanol conversion in Eubacterium limosum (1984)
    Springer
    Archives of microbiology 138 (1984), S. 360-364 
    Details
    ISSN: 1432-072X
    Keywords: Eubacterium limosum ; Methanol conversion ; Methanol: cobalamin methyltransferase ; Methanosarcina barkeri ; Methanobacterium formicicum ; Acetate production
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The conversion of methanol by cell-free extracts of the acetogenic bacterium Eubacterium limosum was studied. Incubation of mixed cell-free extracts of both E. limosum and Methanobacterium formicicum resulted in methane formation from methanol in the presence of ATP and 2-mercaptoethanesulfonic acid. The separate extracts were not able to perform this reaction. Addition of ferredoxin obtained from Methanosarcina barkeri to the mixed extracts resulted in increased methane formation. The enzyme, responsible for methanol binding in cell-free extract of E. limosum, was inactivated by FAD under N2 and exhibited maximal activity under an atmosphere of H2. This enzyme contains a firmly bound cobalamin which was methylated by methanol in the presence of ATP. It was demethylated in the presence of methylcobalamin: coenzyme M methyltransferase obtained from M. barkeri under concomitant formation of methylated coenzyme M. These properties are similar to those of methanol: 5-hydroxybenzimidazolylcobamide methyltransferase from M. barkeri. It was proposed that methylotrophic acetogens and methylotrophic methanogens use similar enzymes in the first step of methanol conversion.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00410904
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  • 6
    Electronic Resource
    Electronic Resource
    The anaerobic fungus Piromyces sp. strain E2: nitrogen requirement and enzymes involved in primary nitrogen metabolism (1997)
    Springer
    Archives of microbiology 166 (1997), S. 399-404 
    Details
    ISSN: 1432-072X
    Keywords: Key wordsPiromyces ; Nitrogen source ; Glutamate ; dehydrogenase ; Glutamine synthetase ; Amino ; transferases
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The anaerobic fungus Piromyces sp. strain E2 appeared restricted in nitrogen utilization. Growth was only supported by ammonium as source of nitrogen. Glutamine also resulted in growth, but this was due to release of ammonia rather than to uptake and utilization of the amino acid. The fungus was not able to grow on other amino acids, albumin, urea, allantoin, or nitrate. Assimilation of ammonium is very likely to be mediated by NADP-linked glutamate dehydrogenase (NADP-GDH) and glutamine synthetase (GS). One transaminating activity, glutamate-oxaloacetate transaminase (GOT), was demonstrated. Glutamate synthase (GOGAT), NAD-dependent glutamate dehydrogenase (NAD-GDH), and the transaminating activity glutamate-pyruvate transaminase (GPT) were not detected in cell-free extracts of Piromyces sp. strain E2. Specific enzyme activities of both NADP-GDH and GS increased four- to sixfold under nitrogen-limiting conditions.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01682986
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  • 7
    Electronic Resource
    Electronic Resource
    Nitrogen control in Pseudomonas aeruginosa: A role for glutamine in the regulation of the synthesis of NADP-dependent glutamate dehydrogenase, urease and histidase (1981)
    Springer
    Archives of microbiology 128 (1981), S. 398-402 
    Details
    ISSN: 1432-072X
    Keywords: Nitrogen control ; Glutamate dehydrogenase ; Urease ; Histidase ; Glutamine auxotrophs ; Glutamine synthetase ; Pseudomonas aeruginosa
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract In Pseudomonas aeruginosa the formation of urease, histidase and some other enzymes involved in nitrogen assimilation is repressed by ammonia in the growth medium. The key metabolite in this process appears to be glutamine or a product derived from it, since ammonia and glutamate did not repress urease and histidase synthesis in a mutant lacking glutamine synthetase activity when growth was limited for glutamine. The synthesis of these enzymes was repressed in cells growing in the presence of excess glutamine. High levels of glutamine were also required for the derepression of NADP-dependent glutamate dehydrogenase formation in the glutamine synthetase-negative mutant.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00405920
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  • 8
    Electronic Resource
    Electronic Resource
    Regulation of amidase formation in mutants from Pseudomonas aeruginosa PAO lacking glutamine synthetase activity (1982)
    Springer
    Archives of microbiology 131 (1982), S. 344-346 
    Details
    ISSN: 1432-072X
    Keywords: Amidase ; Nitrogen control ; Glutamine synthetase ; Pseudomonas aeruginosa
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The formation of amidase was studied in mutants from Pseudomonas aeruginosa PAO lacking glutamine synthetase activity. It appeared that catabolite repression of amidase synthesis by succinate was partially relieved when cellular growth was limited by glutamine. Under these conditions, a correlation between amidase and urease formation was observed. The results suggest that amidase formation in strain PAO is subject to nitrogen control and that glutamine or some compound derived from it mediates the nitrogen repression of amidase.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00411183
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  • 9
    Electronic Resource
    Electronic Resource
    Methyltransferases involved in methanol conversion by Methanosarcina barkeri (1983)
    Springer
    Archives of microbiology 134 (1983), S. 238-242 
    Details
    ISSN: 1432-072X
    Keywords: Methanosarcina barkeri ; Methanol conversion to methane ; Methanol: cobalamin methyltransferase ; Methylcobalamin: coenzyme M methyltransferase
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract 2-(Methylthio)ethanesulfonate (CH3S-CoM) is formed as an intermediate in methanogenesis from methanol by cell-free extracts of Methanosarcina barkeri. The enzyme system involved in the methyltransfer from methanol to 2-mercaptoethanesulfonate (HS-CoM) was resolved into two enzyme fractions. One enzyme (methanol: 5-hydroxybenzimidazolylcobamide methyltransferase) appears to be a cobalamin-containing protein, which is oxygen sensitive. The other enzyme (Co-methyl-5-hydroxybenzimidazolylcobamide: HS-CoM methyltransferase) was purified. It is insensitive to oxygen and it transfers also the methylgroup from Co-methyl-5,6-dimethylbenzimidazolylcobamide to HS-CoM.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00407765
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  • 10
    Electronic Resource
    Electronic Resource
    Stimulation of the methyltetrahydromethanopterin: coenzyme M methyltransferase reaction in cell-free extracts of Methanobacterium thermoautotrophicum by the heterodisulfide of coenzyme M and 7-mercaptoheptanoylthreonine phosphate (1990)
    Springer
    Archives of microbiology 154 (1990), S. 156-161 
    Details
    ISSN: 1432-072X
    Keywords: Methanobacterium thermoautotrophicum ; Coenzyme M ; 7-Mercaptoheptanoylthreonine phosphate ; 5-Methyltetrahydromethanopterin: coenzyme M methyltransferase ; Corrinoid enzyme ; Reductive activation
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The conversion of formaldehyde to methylcoenzyme M in cell-free extracts of Methanobacterium thermoautotrophicum was stimulated up to 10-fold by catalytic amounts of the heterodisulfide (CoM-S-S-HTP) of coenzyme M and 7-mercaptoheptanoylthreonine phosphate. The stimulation required the additional presence of ATP, also in catalytic concentrations. ATP and CoM-S-S-HTP were mutually stimulatory on the methylcoenzyme M formation and it was concluded that the compounds were both involved in the reductive activation of the methyltetrahydromethanopterin: coenzyme M methyltransferase. Micromolar concentrations of benzyl viologen or cyanocobalamin inhibited the formaldehyde conversion; these compounds, however, strongly stimulated the reduction of CoM-S-S-HTP. The results described here closely resemble observations made on the activation and reduction of CO2 to formylmethanofuran indicating that this step and the reductive activation of the methyltransferase are controlled by some common mechanism.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00423326
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