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 (Comment) | Organism |
---|---|
gene mtaA, expression of His-tagged MtaA in Escherichia coli strain M15 | Methanosarcina barkeri |
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 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 | 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 | 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 | UniProt | Comment | Textmining |
---|---|---|---|
Methanosarcina barkeri | - |
gene mtaA | - |
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 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 | 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 | Comment | Organism |
---|---|---|
methanol:coenzyme M methyltransferase | - |
Methanosarcina barkeri |
MT2 | - |
Methanosarcina barkeri |
mtaA | - |
Methanosarcina barkeri |
Temperature Optimum [°C] | Temperature Optimum Maximum [°C] | Comment | Organism |
---|---|---|---|
37 | - |
assay at | Methanosarcina barkeri |
pH Optimum Minimum | pH Optimum Maximum | Comment | Organism |
---|---|---|---|
7 | - |
assay at | Methanosarcina barkeri |
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 |