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Literature summary for 2.1.1.246 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

Activating Compound Comment Organism Structure
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
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
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)

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

Inhibitors

Inhibitors Comment Organism Structure
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]

KM Value [mM] KM Value Maximum [mM] Substrate Comment Organism Structure
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

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

Natural Substrates/ Products (Substrates)

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

Organism

Organism UniProt Comment Textmining
Methanosarcina barkeri
-
gene mtaA
-

Purification (Commentary)

Purification (Comment) Organism
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]

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

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

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

Temperature Optimum [°C]

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

pH Optimum

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

General Information

General Information Comment Organism
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
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