The enzyme, which catalyses the transfer of a methyl group from methylamine to a methylamine-specific corrinoid protein (MtmC), is involved in methanogenesis from methylamine. The enzyme contains the unusual amino acid pyrrolysine . Methylation of the corrinoid protein requires the central cobalt to be in the Co(I) state. During methylation the cobalt is oxidized to the Co(III) state. The methylated corrinoid protein is substrate for EC 2.1.1.247, methylated methylamine-specific corrinoid protein:coenzyme M methyltransferase.
The enzyme, which catalyses the transfer of a methyl group from methylamine to a methylamine-specific corrinoid protein (MtmC), is involved in methanogenesis from methylamine. The enzyme contains the unusual amino acid pyrrolysine [3]. Methylation of the corrinoid protein requires the central cobalt to be in the Co(I) state. During methylation the cobalt is oxidized to the Co(III) state. The methylated corrinoid protein is substrate for EC 2.1.1.247, methylated methylamine-specific corrinoid protein:coenzyme M methyltransferase.
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
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
a 60-kDa monomeric iron sulfur protein, is a protein required for reductive activation of corrinoid-dependent methylamine methyltransferase reactions in methanogenic archaea, it is required for in vitro ATP-dependent reductive activation of methylamine:CoM methyl transfer mediating the ATP-dependent reductive activation of Co(II) corrinoid to the Co(I) state for the monomethylamine corrinoid protein, MtmC, overview. RamA affects both lag times and rates during assay of MMA:CoM methyl transfer
archaeal methane formation from methylamines is initiated by distinct methyltransferases with specificity for monomethylamine, dimethylamine, or trimethylamine. Each methylamine methyltransferase methylates a cognate corrinoid protein, which is subsequently demethylated by a second methyltransferase to form methyl-coenzyme M, the direct methane precursor
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
when growing on trimethylamine, nitrogen fixation does not occur in the cells, indicating that ammonium released during trimethylamine degradation is sufficient to serve as a nitrogen source and represses nif gene induction, transcriptional regulation of soluble methyltransferases, which catalyze the initial step of methylamine consumption by methanogenesis, in response to different carbon and nitrogen sources, overview. Regulation of soluble methyltransferases in response to different nitrogen and carbon sources, overview
when growing on trimethylamine, nitrogen fixation does not occur in the cells, indicating that ammonium released during trimethylamine degradation is sufficient to serve as a nitrogen source and represses nif gene induction, transcriptional regulation of soluble methyltransferases, which catalyze the initial step of methylamine consumption by methanogenesis, in response to different carbon and nitrogen sources, overview. Regulation of soluble methyltransferases in response to different nitrogen and carbon sources, overview
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
the MMAMT polypeptide is rate-limiting for methyl transfer until at a 2fold molar excess over monomethylamine corrinoid protein, MMCP. MMAMT and MMCP form a complex. MMCP is the major corrinoid protein for methanogenesis from monomethylamine
single in-frame amber UAG codons are found in the genes encoding MtmB, MtbB, or MttB, the methyltransferases initiating methane formation from monomethylamine, dimethylamine, or trimethylamine, respectively, in certain Archaea. The amber codon codes for pyrrolysine, the 22nd genetically encoded amino acid found in nature
single in-frame amber UAG codons are found in the genes encoding MtmB, MtbB, or MttB, the methyltransferases initiating methane formation from monomethylamine, dimethylamine, or trimethylamine, respectively, in certain Archaea. The amber codon codes for pyrrolysine, the 22nd genetically encoded amino acid found in nature
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
single in-frame amber UAG codons are found in the genes encoding MtmB, MtbB, or MttB, the methyltransferases initiating methane formation from monomethylamine, dimethylamine, or trimethylamine, respectively, in certain Archaea. The amber codon codes for pyrrolysine, the 22nd genetically encoded amino acid found in nature
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
native MtmB from monomethylamine-grown cells, by two different steps of anionexchange chromatography, followed by gel filtration and another step of anion exchange chromatography to near homogeneity
native MtmB from monomethylamine-grown cells, by two different steps of anionexchange chromatography, followed by gel filtration and another step of anion exchange chromatography to near homogeneity, co-purification with the monomethylamine-specific corrinoid protein MtmC
gene mtmB, DNA and amino acid sequence determination and analysis, genetic organization, the open reading frame of mtmB is interrupted by a single in-frame, midframe, UAG codon. A mechanism that circumvents UAG-directed termination of translation must operate during expression of mtmB in this methanogen. Analysis of the clustered genes encoding the methyltransferases of methanogenesis from monomethylamine and determination of transcript start sites. Cloning and expression of MtmB in Escherichia coli strain DH5alpha
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
gene mtmB1and mtmB2C2, operon encoding MMA methylamine methyltransferase, quantitative RT-PCR expression analysis, comparison with other methylamine methyltransferases, overview. Transcriptional regulation of genes encoding methylamine methyltransferases in cells growing on Ttrimethyamine or methanol in the presence of ammonium, overview
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EXPRESSION
ORGANISM
UNIPROT
LITERATURE
transcription of the mtmB1C1 operon is not affected by the nitrogen source but appears to be increased when trimethylamine is the sole carbon and energy source. Under nitrogen limitation, a 543fold up-regulation of the mtmB2C2 operon encoding MMA methyltransferase 2 is obtained when methanol was used as carbon source, whereas transcription of the homologous mtmB1C1 operon occurs at a constant level independently of the nitrogen source
transcription of the mtmB1C1 operon is not affected by the nitrogen source but appears to be increased when trimethylamine is the sole carbon and energy source. Under nitrogen limitation, a 543fold up-regulation of the mtmB2C2 operon encoding MMA methyltransferase 2 is obtained when methanol was used as carbon source, whereas transcription of the homologous mtmB1C1 operon occurs at a constant level independently of the nitrogen source
transcription of the mtmB1C1 operon is not affected by the nitrogen source but appears to be increased when trimethylamine is the sole carbon and energy source. Under nitrogen limitation, a 543fold up-regulation of the mtmB2C2 operon encoding MMA methyltransferase 2 is obtained when methanol was used as carbon source, whereas transcription of the homologous mtmB1C1 operon occurs at a constant level independently of the nitrogen source