The enzyme, which is involved in methanogenesis from methylated thiols, such as methane thiol, dimethyl sulfide, and 3-(methylsulfanyl)propanoate, catalyses two successive steps - the transfer of a methyl group from the substrate to the cobalt cofactor of a methylated-thiol-specific corrinoid protein (MtsB), and the subsequent transfer of the methyl group from the corrinoid protein to CoM. With most other methanogenesis substrates this process is carried out by two different enzymes (for example, EC 2.1.1.90, methanol---corrinoid protein Co-methyltransferase, and EC 2.1.1.246, [methyl-Co(III) methanol-specific corrinoid protein]---coenzyme M methyltransferase). The cobalt is oxidized during methylation from the Co(I) state to the Co(III) state, and is reduced back to the Co(I) form during demethylation.
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The enzyme appears in viruses and cellular organisms
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SYSTEMATIC NAME
IUBMB Comments
methylated-thiol:coenzyme M methyltransferase
The enzyme, which is involved in methanogenesis from methylated thiols, such as methane thiol, dimethyl sulfide, and 3-(methylsulfanyl)propanoate, catalyses two successive steps - the transfer of a methyl group from the substrate to the cobalt cofactor of a methylated-thiol-specific corrinoid protein (MtsB), and the subsequent transfer of the methyl group from the corrinoid protein to CoM. With most other methanogenesis substrates this process is carried out by two different enzymes (for example, EC 2.1.1.90, methanol---corrinoid protein Co-methyltransferase, and EC 2.1.1.246, [methyl-Co(III) methanol-specific corrinoid protein]---coenzyme M methyltransferase). The cobalt is oxidized during methylation from the Co(I) state to the Co(III) state, and is reduced back to the Co(I) form during demethylation.
MtsA acts both to demethylate dimethylsulfide and to methylate CoM using non-protein-bound cobalamin as an intermediate methyl carrier, dependence of the rate of the MtsA-catalyzed methylcobalamin:CoM methyl transfer reaction on methylcobalamin, overview. The subunit carries out both CoM methylation and DMS demethylation and can account for both corrinoid-dependent methyltransferase activities of the methylthiol:CoM methyltransferase. A model for the native methylthiol:coenzyme M methyltransferase in which MtsA mediates the methylation of corrinoid bound to MtsB with dimethylsulfide and subsequently demethylates MtsB-bound corrinoid with coenzyme M, overview
the 480-kDa protein is not methylated by methyltetrahydrosarcinapterin or demethylated by homocysteine. The alpha subunit, not the beta subunit, methylates the thiol of CoM
the methylthiol:CoM methyltransferase reaction is initiated only with the enzyme-bound corrinoid in the methylated state. CoM can demethylate, and dimethylsulfide and methylmercaptoproionate can remethylate, the corrinoid cofactor
the methylthiol:CoM methyltransferase reaction is initiated only with the enzyme-bound corrinoid in the methylated state. CoM can demethylate, and dimethylsulfide and methylmercaptoproionate can remethylate, the corrinoid cofactor
the methylthiol:CoM methyltransferase reaction is initiated only with the enzyme-bound corrinoid in the methylated state. CoM can demethylate, and dimethylsulfide and methylmercaptoproionate can remethylate, the corrinoid cofactor
the enzyme obligately requires the bound methylated corrinoid cofactor for activity. Corrinoid-dependent methyltransferases cycle between methylated corrinoid in the Co(III) redox state and the highly nucleophilic, reducing, and oxygen-sensitive Co(I) state. In the Co(II) form, these methyltransferase is inactive
the enzyme obligately requires the bound methylated corrinoid cofactor for activity. Corrinoid-dependent methyltransferases cycle between methylated corrinoid in the Co(III) redox state and the highly nucleophilic, reducing, and oxygen-sensitive Co(I) state. In the Co(II) form, these methyltransferase is inactive
the enzyme obligately requires the bound methylated corrinoid cofactor for activity. Corrinoid-dependent methyltransferases cycle between methylated corrinoid in the Co(III) redox state and the highly nucleophilic, reducing, and oxygen-sensitive Co(I) state. In the Co(II) form, these methyltransferase is inactive
inhibits methylcobalamin:coenzyme methyl transfer by MtsA. Inhibition by dimethylsulfide is mixed with respect to methylcobalamin, but competitive with coenzyme M
the mtsA transcript is most abundant in cells grown to the late log phase on acetate but barely detectable in cells grown on methanol or trimethylamine, overview
the sequence of MtsA is homologous to the A and M isozymes of methylcobamide:coenzyme M methyltransferases (methyltransferase II), indicating that the alpha polypeptide is a member of the methyltransferase II family of coenzyme M methylases
pathways of dimethylsulfide- and methanethiol-dependent CoM methylation are regulated. Stimulation of methanogenesis in cell extract is due to the inherent ability of the purified 480-kDa CoM methylase to function as a methylthiol:CoM methyltransferase. In the case of CoM methylation by trimethylamine, dimethylamine, monomethylamine, or methanol, separate proteins specific for each substrate exist
pathways of dimethylsulfide- and methanethiol-dependent CoM methylation are regulated. Stimulation of methanogenesis in cell extract is due to the inherent ability of the purified 480-kDa CoM methylase to function as a methylthiol:CoM methyltransferase. In the case of CoM methylation by trimethylamine, dimethylamine, monomethylamine, or methanol, separate proteins specific for each substrate exist
pathways of dimethylsulfide- and methanethiol-dependent CoM methylation are regulated. Stimulation of methanogenesis in cell extract is due to the inherent ability of the purified 480-kDa CoM methylase to function as a methylthiol:CoM methyltransferase. In the case of CoM methylation by trimethylamine, dimethylamine, monomethylamine, or methanol, separate proteins specific for each substrate exist
methanogenesis from dimethylsulfide requires the intermediate methylation of coenzyme M. This reaction is catalyzed by a methylthiol:coenzymeMmethyltransferase composed of two polypeptides, MtsA, which is a methylcobalamin:coenzyme M methyltransferase, and MtsB, which is homologous to a class of corrinoid proteins involved in methanogenesis. MtsA is an active methylcobalamin:coenzyme M methyltransferase, but also methylates cob(I)alamin with dimethylsulfide, yielding equimolar methylcobalamin and methanethiol
the 480-kDa corrinoid protein functions as a CoM methylase during methanogenesis from dimethylsulfide and methylmercaptopropionate, since the monomethylamine corrinoid protein and the A isozyme of methylcobamide:CoM methyltransferase, EC 2.1.1.247, do not catalyze CoM methylation with methylated thiols
the 480-kDa corrinoid protein functions as a CoM methylase during methanogenesis from dimethylsulfide and methylmercaptopropionate, since the monomethylamine corrinoid protein and the A isozyme of methylcobamide:CoM methyltransferase, EC 2.1.1.247, do not catalyze CoM methylation with methylated thiols
the 480-kDa corrinoid protein functions as a CoM methylase during methanogenesis from dimethylsulfide and methylmercaptopropionate, since the monomethylamine corrinoid protein and the A isozyme of methylcobamide:CoM methyltransferase, EC 2.1.1.247, do not catalyze CoM methylation with methylated thiols
methylated thiol-dependent methanogenesis in cell extract is a function of the growth substrate, methanogenesis from either diethylsulfide or methylmercaptopropionate in cell extracts is coupled with the formation of methanethiol or mercaptopropionate, respectively. Consumption of methanethiol itself for methane formation also occurs. Dimethylsulfide is converted to methane by an initial demethylation which results in the formation of methanethiol. number of other compounds, including dimethylsulfoniopropionate, alanine, methionine, glycine, sarcoscine, N,N-dimethyl glycine, betaine, trimethylamine, choline, creatinine, and acetone, are not converted to methane at significant rates
methylated thiol-dependent methanogenesis in cell extract is a function of the growth substrate, methanogenesis from either diethylsulfide or methylmercaptopropionate in cell extracts is coupled with the formation of methanethiol or mercaptopropionate, respectively. Consumption of methanethiol itself for methane formation also occurs. Dimethylsulfide is converted to methane by an initial demethylation which results in the formation of methanethiol. number of other compounds, including dimethylsulfoniopropionate, alanine, methionine, glycine, sarcoscine, N,N-dimethyl glycine, betaine, trimethylamine, choline, creatinine, and acetone, are not converted to methane at significant rates
methylated thiol-dependent methanogenesis in cell extract is a function of the growth substrate, methanogenesis from either diethylsulfide or methylmercaptopropionate in cell extracts is coupled with the formation of methanethiol or mercaptopropionate, respectively. Consumption of methanethiol itself for methane formation also occurs. Dimethylsulfide is converted to methane by an initial demethylation which results in the formation of methanethiol. number of other compounds, including dimethylsulfoniopropionate, alanine, methionine, glycine, sarcoscine, N,N-dimethyl glycine, betaine, trimethylamine, choline, creatinine, and acetone, are not converted to methane at significant rates
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CLONED (Commentary)
ORGANISM
UNIPROT
LITERATURE
gene mtsA, DNA and amino acid sequence determination and analysis, expression in Escherichia coli strain DH5alpha. The gene encoding the alpha subunit of the CoM methylase, mtsA, is 5' to the gene encoding the beta subunit, mtsB, regulated cotranscription of mtsA and mtsB
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RENATURED/Commentary
ORGANISM
UNIPROT
LITERATURE
recombinant enzyme from inclusion bodies harvested from cells solubilized using 6 M guanidine hydrochloride, 50 mM DTT, and 20 mM 2-mercaptoethanol. The solubilized protein is diluted 60fold with protein refolding at room temperature for 24 h in refolding buffer consisting of 500 mM Tris, pH 8.0, 1 M KCl, 10 mM DTT, 10 mM 2-mercaptoethanol, and 100 mM ZnCl2. Refolding buffers containing 500 mM guanidine hydrochloride, 33 mM CHAPS, 0.5% Triton X-100, 5 mM SDS, or 20% glycerol do not produce active methyltransferase, nor do refolding at 4°C in the optimal refolding buffer
Krer, M.; Haumann, M.; Meyer-Klaucke, W.; Thauer, R.; Dau, H.
The role of zinc in the methylation of the coenzyme M thiol group in methanol:coenzyme M methyltransferase from Methanosarcina barkeri: new insights from X-ray absorption spectroscopy
Sequence and transcript analysis of a novel Methanosarcina barkeri methyltransferase II homolog and its associated corrinoid protein homologous to methionine synthase
The MtsA subunit of the methylthiol:coenzyme M methyltransferase of Methanosarcina barkeri catalyses both half-reactions of corrinoid-dependent dimethylsulfide: coenzyme M methyl transfer