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Literature summary for 2.1.1.248 extracted from
- Function of genetically encoded pyrrolysine in corrinoid-dependent methylamine methyltransferases (2004), Curr. Opin. Chem. Biol., 8, 484-491.
Cloned(Commentary)
| Cloned (Comment) | Organism |
|---|---|
| gene mtmB1, DNA and amino acid sequence determination and analysis, UAG is not the stop codon in the encoding gene, no UAG modification. The mtmB1 amber codon encodes pyrrolysine in UAG, crystal structure of MtmB reveals lysine, but with epsilonN in amide linkage with (4R,5R)-4 substituted-pyrroline-5-carboxylate | Methanosarcina barkeri |
Crystallization (Commentary)
| Crystallization (Comment) | Organism |
|---|---|
| two crystal forms of MtmB obtained from solutions containing NaCl or (NH4)2SO4. In the NaCl crystal form, the pyrroline is unmodified at the C-2 position. The second crystal form is a mixture of two pyrrolysine states. Crystal structure analysis, overview | Methanosarcina barkeri |
Molecular Weight [Da]
| Molecular Weight [Da] | Molecular Weight Maximum [Da] | Comment | Organism |
|---|---|---|---|
| 50000 | - |
3 * 50000 | Methanosarcina barkeri |
Natural Substrates/ Products (Substrates)
| Natural Substrates | Organism | Comment (Nat. Sub.) | Natural Products | Comment (Nat. Pro.) | Rev. | Reac. |
|---|---|---|---|---|---|---|
| methylamine + a [Co(I) methylamine-specific corrinoid protein] | Methanosarcina barkeri | - |
a [methyl-Co(III) methylamine-specific corrinoid protein] + ammonia | - |
? |  |
Organism
| Organism | UniProt | Comment | Textmining |
|---|---|---|---|
| Methanosarcina barkeri | O30642 | gene mtmB1 | - |
Substrates and Products (Substrate)
| Substrates | Comment Substrates | Organism | Products | Comment (Products) | Rev. | Reac. |
|---|---|---|---|---|---|---|
| methylamine + a [Co(I) methylamine-specific corrinoid protein] | - |
Methanosarcina barkeri | a [methyl-Co(III) methylamine-specific corrinoid protein] + ammonia | - |
? | |
| methylamine + a [Co(I) methylamine-specific corrinoid protein] | the methylamine-specific corrinoid protein MtmC cycles between methyl-Co(III)- and Co(I)-MtmC during catalysis. Methanogen methylotrophic corrinoid proteins such as MtmC are methylated in the Co(I) state, forming a hexacoordinate methyl-Co(III) species whose demethylation regenerates Co (I) corrinoid. Pyrrolysine in MtmB mediates methylation of MtmC | Methanosarcina barkeri | a [methyl-Co(III) methylamine-specific corrinoid protein] + ammonia | - |
? | |
| additional information | model for MtmB methylation of Co(I) corrinoid cofactor with monomethylamine. Y335 and Q333 are proposed to assist in the initial MtmB binding of monomethylamine and positioning such that electrophilic attack of the C-2 atom on the lone electron pair of the nitrogen of unionized monomethylamine occurs. The residues can also serve to H-bond with the ammonia released from the pyrroline ring, enhancing the equilibrium between 2-aminopyrrolysine and pyrrolysine in the direction of product removal from the enzyme, model of pyrrolysine function | Methanosarcina barkeri | ? | - |
? | |
Subunits
| Subunits | Comment | Organism |
|---|---|---|
| homotrimer | 3 * 50000 | Methanosarcina barkeri |
| More | tertiary structures of MtmB and its substrate, MtmC | Methanosarcina barkeri |
Synonyms
| Synonyms | Comment | Organism |
|---|---|---|
| MMA methyltransferase | - |
Methanosarcina barkeri |
| MtmB | - |
Methanosarcina barkeri |
General Information
| General Information | Comment | Organism |
|---|---|---|
| metabolism | biochemistry of methane formation by Methanosarcina species from monomethylamine, dimethylamine, and trimethylamine: methanogenesis from these substrates is initiated by three methyltransferases that specifically methylate their cognate corrinoid proteins with one of these methylamines, cf. EC 2.1.1.250 and EC 2.1.1.249, overview | Methanosarcina barkeri |
| additional information | the enzyme contains pyrrolysine at the UAG posotion, crystal structure of MtmB reveals lysine, but with epsilonN in amide linkage with (4R,5R)-4 substituted-pyrroline-5-carboxylate | Methanosarcina barkeri |
| physiological function | the enzyme is involved in the corrinoid-dependent demethylation of methylamines, which are used for coenzyme M methylation, homology modeling of MtmC, the methylamine-specific corrinoid protein. Pyrrolysine in MtmB mediates methylation of MtmC | Methanosarcina barkeri |
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