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Literature summary extracted from

  • Sauer, K.; Thauer, R.K.
    Methanol:coenzyme M methyltransferase from Methanosarcina barkeri - substitution of the corrinoid harbouring subunit MtaC by free cob(I)alamin (1999), Eur. J. Biochem., 261, 674-681.
    View publication on PubMed

Activating Compound

EC Number Activating Compound Comment Organism Structure
2.1.1.246 methanol 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 Methanosarcina barkeri
2.1.1.246 MtaB 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 Methanosarcina barkeri
2.1.1.246 Ti(III) citrate increases the specific activity of MtaA by 60% and decreases the apparent Km for methylcob(III)-alamin from 0.003 mM to below 0.001 mM Methanosarcina barkeri

Cloned(Commentary)

EC Number Cloned (Comment) Organism
2.1.1.246 gene mtaA, expression of His-tagged MtaA in Escherichia coli strain M15 Methanosarcina barkeri

Inhibitors

EC Number Inhibitors Comment Organism Structure
2.1.1.246 imidazole 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 Methanosarcina barkeri

KM Value [mM]

EC Number KM Value [mM] KM Value Maximum [mM] Substrate Comment Organism Structure
2.1.1.246 additional information
-
 additional information 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 Methanosarcina barkeri

Metals/Ions

EC Number Metals/Ions Comment Organism Structure
2.1.1.246 Co2+ Zn2+ can be substituted by Co2+ Methanosarcina barkeri
2.1.1.246 Zn2+ Mta contains 1 mol Zn2+ per mol of enzyme, Zn2+ can be substituted by Co2+ Methanosarcina barkeri

Natural Substrates/ Products (Substrates)

EC Number Natural Substrates Organism Comment (Nat. Sub.) Natural Products Comment (Nat. Pro.) Rev. Reac.
2.1.1.246 a [methyl-Co(III) methanol-specific corrinoid protein] + coenzyme M Methanosarcina barkeri
-
 methyl-CoM + a [Co(I) methanol-specific corrinoid protein]
-
 r

Organism

EC Number Organism UniProt Comment Textmining
2.1.1.246 Methanosarcina barkeri
-
 gene mtaA
-

Purification (Commentary)

EC Number Purification (Comment) Organism
2.1.1.246 recombinant His-tagged MtaA from Escherichia coli strain M15 by nickel affinity and anion exchange chromatography to homogeneity Methanosarcina barkeri

Specific Activity [micromol/min/mg]

EC Number Specific Activity Minimum [µmol/min/mg] Specific Activity Maximum [µmol/min/mg] Comment Organism
2.1.1.246 0.2
-
 MtaA with substrate methylcob(III)-alamin, pH 7.0, 37°C Methanosarcina barkeri
2.1.1.246 8
-
 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 Methanosarcina barkeri

Substrates and Products (Substrate)

EC Number Substrates Comment Substrates Organism Products Comment (Products) Rev. Reac.
2.1.1.246 a [methyl-Co(III) methanol-specific corrinoid protein] + coenzyme M
-
 Methanosarcina barkeri methyl-CoM + a [Co(I) methanol-specific corrinoid protein]
-
 r
2.1.1.246 additional information 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 Methanosarcina barkeri ?
-
 ?

Synonyms

EC Number Synonyms Comment Organism
2.1.1.246 methanol:coenzyme M methyltransferase
-
 Methanosarcina barkeri
2.1.1.246 MT2
-
 Methanosarcina barkeri
2.1.1.246 mtaA
-
 Methanosarcina barkeri

Temperature Optimum [°C]

EC Number Temperature Optimum [°C] Temperature Optimum Maximum [°C] Comment Organism
2.1.1.246 37
-
 assay at Methanosarcina barkeri

pH Optimum

EC Number pH Optimum Minimum pH Optimum Maximum Comment Organism
2.1.1.246 7
-
 assay at Methanosarcina barkeri

General Information

EC Number General Information Comment Organism
2.1.1.246 metabolism 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 Methanosarcina barkeri
2.1.1.246 physiological function 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 Methanosarcina barkeri