The enzyme, which is involved in methanogenesis from methanol, catalyses the transfer of a methyl group from a corrinoid protein (see EC 2.1.1.90, methanol---corrinoid protein Co-methyltransferase), where it is bound to the cobalt cofactor, to CoM, forming the substrate for EC 2.8.4.1, coenzyme-B sulfoethylthiotransferase, the enzyme that catalyses the final step in methanogenesis. Free methylcob(I)alamin can substitute for the corrinoid protein in vitro .
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SYSTEMATIC NAME
IUBMB Comments
methylated methanol-specific corrinoid protein:coenzyme M methyltransferase
The enzyme, which is involved in methanogenesis from methanol, catalyses the transfer of a methyl group from a corrinoid protein (see EC 2.1.1.90, methanol---corrinoid protein Co-methyltransferase), where it is bound to the cobalt cofactor, to CoM, forming the substrate for EC 2.8.4.1, coenzyme-B sulfoethylthiotransferase, the enzyme that catalyses the final step in methanogenesis. Free methylcob(I)alamin can substitute for the corrinoid protein in vitro [5].
the enzyme methylcobamide:CoM methyltransferase, MT2, catalyzes the transfer of the methyl group from the MT1-bound methylcobamide prosthetic group to coenzyme M
methyltransferase 2, MT2, transfers the methyl group from the methylated corrinoid protein to coenzyme M, i.e. 2-mercaptoethanesulfonic acid. Methyl-coenzyme M is then disproportionated, with one molecule being oxidized to CO2 to provide the six electrons required for reduction of three additional methyl-coenzyme M molecules to methane
transferase MtaA catalyzes the transfer of the methyl group from methylated transferase MtaBC to coenzyme M. Instead of methylated transferase MtaBC, MtaA can also use free methylcobalamin as the methyl donor. MtaA activates coenzyme M for nucleophilic attack of the methyl group of the methylcobamide
conversions of monomethylamine and dimethylamine to CH3-SCoM are dependent upon MT2-A, and are not supported by MT2-M. In contrast, MT2-M acts specifically in metabolism of methanol, but does not substitute for MT2-A in conversion of monomethylamine or dimethylamine. Nevertheless, both isozymes are capable of supporting the conversion of trimethylamine
conversions of monomethylamine and dimethylamine to CH3-SCoM are dependent upon MT2-A, and are not supported by MT2-M. In contrast, MT2-M acts specifically in metabolism of methanol, but does not substitute for MT2-A in conversion of monomethylamine or dimethylamine. Nevertheless, both isozymes are capable of supporting the conversion of trimethylamine
in the assay for methanol:coenzyme M methyltransferase activity cob(I)alamin can be substituted by cob(I)inamide which is devoid of the nucleotide loopmethylation of cob(I)inamide with methanol is dependent on imidazole but not on the demethylation of methylcob(III)inamide with coenzyme M
recombinant MtaA catalyzes the formation of methyl-coenzyme M from free CH3-cob(III)alamin and coenzyme M at specific rates comparable to those predicted for MtaA-catalyzed MtaC demethylation
the reaction for possible production of methanol from the anaerobic oxidation of methane can be reversed in vitro. Develoment of an in vitro functional assay that demonstrates MtaABC can catalyze the energetically unfavorable reverse reaction starting from methyl coenzyme M and generating methanol as a product, overview. MtaABC enzyme protein complex to catalyze the methyl transfer from methanol to CoM to form methyl-CoM, which is energetically favorable in the forward reaction. MtaB catalyzes a methyl transfer from methanol to the corrinoid cofactor of the MtaC subunit. MtaA then catalyzes the transfer of the methyl group to CoM to form methyl-CoM. DTNB assays for the forward and reverse MtaABC reactions. Methylcobalamin assay of purified recombinant MtaA.Demethylation of methylcobalamin in a CoM-dependent manner by MtaA
methyltransferase 2, MT2, transfers the methyl group from the methylated corrinoid protein to coenzyme M, i.e. 2-mercaptoethanesulfonic acid. Methyl-coenzyme M is then disproportionated, with one molecule being oxidized to CO2 to provide the six electrons required for reduction of three additional methyl-coenzyme M molecules to methane
transferase MtaA catalyzes the transfer of the methyl group from methylated transferase MtaBC to coenzyme M. Instead of methylated transferase MtaBC, MtaA can also use free methylcobalamin as the methyl donor. MtaA activates coenzyme M for nucleophilic attack of the methyl group of the methylcobamide
conversions of monomethylamine and dimethylamine to CH3-SCoM are dependent upon MT2-A, and are not supported by MT2-M. In contrast, MT2-M acts specifically in metabolism of methanol, but does not substitute for MT2-A in conversion of monomethylamine or dimethylamine. Nevertheless, both isozymes are capable of supporting the conversion of trimethylamine
conversions of monomethylamine and dimethylamine to CH3-SCoM are dependent upon MT2-A, and are not supported by MT2-M. In contrast, MT2-M acts specifically in metabolism of methanol, but does not substitute for MT2-A in conversion of monomethylamine or dimethylamine. Nevertheless, both isozymes are capable of supporting the conversion of trimethylamine
Zn21 or Co21 are required for MtaA activity, Zn2+ can be replaced by Co2+ but not by Mg2+, the kinetics of activation by Co2+ being similarily slow. About 1 mol of transition metal is bound per mol of protein. The role of the transition metal in MtaA is to lower the microscopic pKa of the thiol group of coenzyme M by coordination to the zinc, and thus to increase its nucleophilicity for methyl group attack, pKZn2+ of MtaA is over 15
the demethylation of cob(I)inamide reaction is inhibited by imidazole. Imidazole does not inhibit methyltransfer from methylcob(III)alamin to coenzyme M at 10 mM
MtaB plus methanol positively affect the catalytic efficiency of MtaA. activation of MtaA by MtaB is methanol-dependent. Methylation of cob(I)inamide with methanol is dependent on imidazole but not on the demethylation of methylcob(III)inamide with coenzyme M. The demethylation reaction is even inhibited by imidazole
MtaB plus methanol positively affect the catalytic efficiency of MtaA. activation of MtaA by MtaB is methanol-dependent. Methylation of cob(I)inamide with methanol is dependent on imidazole but not on the demethylation of methylcob(III)inamide with coenzyme M. The demethylation reaction is even inhibited by imidazole
Euchromatic histone methyltransferase 2 inhibitor, BIX-01294, sensitizes human promyelocytic leukemia HL-60 and NB4 cells to growth inhibition and differentiation.
MtaA kinetics, overview. Demethylation of methylcob(III)alamin catalysed by MtaA alone exhibit apparent Km for cob(I)alamin and methylcob(III)alamin of above 1 mm
MtaA with substrate methylcob(III)inamide, 50 mM methylcob(III)inamide as substrate show an activity of 8 U/mg, approximately 40fold higher than with 50 mM methylcob(III)-alamin, pH 7.0, 37°C
specific MT1/corrinoid pairs have been identified for methanol (MtaC, MtaB), trimethylamine (MttC, MttB), dimethylamine (MtbC, MtbB), methylamine (MtmC, MtmB) and methylsulfide (MtsA, MtsB). MT2 proteins are somewhat less specific with MtaA being used for methanol, and poorly for trimethylamine showing 5% of the methanol-dependent activity, and an enzyme designated MtbA, EC 2.1.1.1247, being used for all three methylamines. The MtsA protein apparently catalyses both MT1 and MT2 reactions in the activation of dimethylsulfide
all combinations of MtaC, MtaB, and MtaA can form functional methanol-specific methyltransferase 1/2, MT1/MT2, complexes. Substrate-dependent, posttranscriptional regulation of mtaCBA operons, overview
methanol catabolism in Methanosarcina species requires the concerted effort of methanol:5-hydroxybenzimidazolylcobamide methyltransferase, MtaB, a corrinoid-containing methyl-accepting protein, MtaC, and Co-methyl-5-hydroxybenzimidazolylcobamide:2-mercapto-ethanesulfonic acid methyltransferase, MtaA
methyl-coenzyme M formation from coenzyme M and methanol in Methanosarcina barkeri is catalysed by an enzyme system composed of three polypeptides MtaA, MtaB and MtaC, the latter of which harbours a corrinoid prosthetic group. We report here that MtaC can be substituted by free cob(I)alamin which is methylated with methanol in an MtaB-catalysed reaction and demethylated with coenzyme M in an MtaA-catalysed reaction
the enzyme system catalyzing the formation of methyl-coenzyme M from methanol and coenzyme M in Methanosarcina barkeri is composed of the three different polypeptides MtaA, MtaB and MtaC of which MtaC harbors a corrinoid prosthetic group
the enzyme system from Methanosarcina barkeri is composed of two methyltransferases, transferase MT1, which is composed of a 50-kDa subunit, MtaB, and a 27-kDa corrinoid-harbouring subunit, MtaC, catalyzes the methylation of free cob(1)alamin with methanol, EC 2.1.1.90, and transferase MT2 catalyzes the transfer of the methyl group from CH,-MT1 to coenzyme M. Instead of CH,-MTI, MtaA can also use free methylcobalamin as the methyl donor. MtaC with its supernucleophilic cobamide prosthetic group accepts the methyl group from methanol and passes it to coenzyme M, MtaB activates methanol for nucleophilic attack by the cob(1)amide, and MtaA activates coenzyme M for nucleophilic attack of the methyl group of the methylcobamide
a positive effect of MtaA on the catalytic efficiency of MtaB is specific for MtaA. In the absence of MtaA no effect is observed, while in the presence of MtaA the formation of methylcob(III)alamin from methanol and cob(I)alamin is apparently inhibited by coenzyme M, probably because under these conditions MtaA actively catalyses the demethylation of methylcob(III)alamin. MtaB plus methanol positively affect the catalytic efficiency of MtaA
the methyltransferase designated MtaA together with the proteins MtaB and MtaC mediate the formation of methyl-coenzyme M from methanol and coenzyme M. MtaC is a 28-kDa corrinoid protein, MtaB, EC 2.1.1.90, catalyzes the methylation of MtaC and MtaA catalyzes the demethylation of methylated MtaC
methanol:coenzyme M methyltransferase is an enzyme complex composed of three subunits, MtaA, MtaB, and MtaC, found in methanogenic archaea and is needed for their growth on methanol ultimately producing methane. MtaABC catalyzes the energetically favorable methyl transfer from methanol to coenzyme M to form methyl coenzyme M, an important reaction for possible production of methanol from the anaerobic oxidation of methane
MtaC and MtaB form a tight complex and the encoding genes form a transcription unit, whereas MtaA purifies separately and its encoding gene is located separately
the enzyme system catalyzing the formation of methyl-coenzyme M from methanol and coenzyme M in Methanosarcina barkeri is composed of the three different polypeptides MtaA, MtaB and MtaC of which MtaC harbors a corrinoid prosthetic group
site-directed mutagenesis, mutation of the residue involved in zinc coordination in MtaA results in reduced zinc content and reduced activity compared to the wild-type enzyme
site-directed mutagenesis, mutation of the residue involved in zinc coordination in MtaA results in reduced zinc content and reduced activity compared to the wild-type enzyme
site-directed mutagenesis, mutation of the residue involved in zinc coordination in MtaA results in reduced zinc content and reduced activity compared to the wild-type enzyme
site-directed mutagenesis, mutation of the residue involved in zinc coordination in MtaA results in reduced zinc content and reduced activity compared to the wild-type enzyme
site-directed mutagenesis, mutation of the residue involved in zinc coordination in MtaA results in reduced zinc content and reduced activity compared to the wild-type enzyme
site-directed mutagenesis, mutation of the residue involved in zinc coordination in MtaA results in reduced zinc content and reduced activity compared to the wild-type enzyme
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CLONED (Commentary)
ORGANISM
UNIPROT
LITERATURE
gene mtaA, DNA and amino acid sequence determination and analysis, gene mtaA is monocislronically transcribed, transcription of the gene is positively controlled by the growth substrate rnethanol, overexpression of the His6-tagged enzyme in Escherichia coli strain M15
genes mtaA1 and mtaA2, overexpression of N-terminally His6-tagged mtaA1 in Escherichia coli strain BL21(DE3), strains carrying various combinations of mtaC, mtaB, and mtaA expressed from the strong, tetracycline-regulated PmcrB(tetO1) promoter exhibit similar growth characteristics on methanol, showing that all combinations of MtaC, MtaB, and MtaA can form functional MT1/MT2 complexes. Variations in activity correlate with differences in protein abundance, despite the fact that all the encoding genes are expressed from the same promoter, overview. The mtaCBA transcripts show different stabilities, which are strongly influenced by the growth substrate, quantitative expression and activity analysis, overview
demonstration of an in vitro ability of MtaABC to produce methanol may ultimately enable the anaerobic oxidation of methane to produce methanol and from methanol alternative fuel or fuel-precursor molecules
Methanol:coenzyme M methyltransferase from Methanosarcina barkeri. Zinc dependence and thermodynamics of the methanol:cob(I)alamin methyltransferase reaction
Methylcobalamin:coenzyme M methyltransferase isoenzymes MtaA and MtbA from Methanosarcina barkeri: Cloning, sequencing and differential transcription of the encoding genes, and functional overexpression of the mtaA gene in Escherichia coli
Methanol:coenzyme M methyltransferase from Methanosarcina barkeri - identification of the active-site histidine in the corrinoid-harboring subunit MtaC by site-directed mutagenesis
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
Genomic and proteomic analyses reveal multiple homologs of genes encoding enzymes of the methanol:coenzyme M methyltransferase system that are differentially expressed in methanol- and acetate-grown Methanosarcina thermophila