Methanol conversion in Eubacterium limosum |
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Authors: | Peter van der Meijden Chris van der Drift Godfried D. Vogels |
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Affiliation: | (1) Department of Microbiology, Faculty of Science, University of Nijmegen, Toernooiveld, NL-6525 ED Nijmegen, The Netherlands |
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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.Abbreviations HS-CoM 2-mercaptoethanesulfonic acid - CH3S-CoM 2-(methylthio)ethanesulfonic acid - BrES 2-bromoethanesulfonic acid - TES N-tris(hydroxymethyl)-methyl-2-aminoethanesulfonic acid - MT1 methanol: 5-hydroxybenzimidazolylcobamide methyltransferase - MT2 methylcobalamin - HS-CoM methyltransferase - DMBI 5,6-dimethylbenzimidazole and HBI, 5-hydroxybenzimidazole, are -ligands of corrinoids - (S-CoM)2 2,2-dithiodiethanesulfonic acid |
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Keywords: | Eubacterium limosum Methanol conversion Methanol: cobalamin methyltransferase Methanosarcina barkeri Methanobacterium formicicum Acetate production |
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