Disease relevance of Mbar_A2142

• The amino acid sequence of MtsB was homologous to the cobalamin-binding fragment of methionine synthase from Escherichia coli and possessed the signature residues involved in binding the corrinoid, including a histidyl residue which ligates cobalt [1].

High impact information on Mbar_A2142

• Its corrinoid cofactor at the top of the Rossmann domain reaches deeply into the funnel of MtaB, defining a region between zinc(II) and the corrinoid cobalt that must be the binding site for methanol [2].
• These results are most consistent with a model for the native methylthiol:coenzyme M methyltransferase in which MtsA mediates the methylation of corrinoid bound to MtsB with dimethylsulfide and subsequently demethylates MtsB-bound corrinoid with coenzyme M, possibly employing elements of the same methyltransferase active site for both reactions [3].
• Reconstitution of dimethylamine:coenzyme M methyl transfer with a discrete corrinoid protein and two methyltransferases purified from Methanosarcina barkeri [4].
• These results indicate MtbB1 demethylates dimethylamine and specifically methylates the corrinoid prosthetic group of MtbC, which is subsequently demethylated by MtbA to methylate coenzyme M during methanogenesis from dimethylamine [4].
• MtbB1 methylated either corrinoid bound to MtbC or free cob(I)alamin with dimethylamine, indicating MtbB1 carries an active site for dimethylamine demethylation and corrinoid methylation [4].

Biological context of Mbar_A2142

• Catalysis of acetyl-CoA cleavage and tetrahydrosarcinapterin methylation by a carbon monoxide dehydrogenase-corrinoid enzyme complex [5].

Associations of Mbar_A2142 with chemical compounds

• The activation mechanism is discussed within the context of a proposed model and compared to those described for other corrinoid-containing methyl group transferring proteins [6].
• These results show that MMCP is the major corrinoid protein for methanogenesis from monomethylamine detectable in extracts and that it interacts with two methyltransferases [7].
• The MtsA subunit of the methylthiol:coenzyme M methyltransferase of Methanosarcina barkeri catalyses both half-reactions of corrinoid-dependent dimethylsulfide: coenzyme M methyl transfer [3].
• This methyltransferase is the 480-kDa corrinoid protein previously identified by its methylation following inhibition of methyl-CoM reductase in otherwise methanogenic cell extracts [8].
• Sequence and transcript analysis of a novel Methanosarcina barkeri methyltransferase II homolog and its associated corrinoid protein homologous to methionine synthase [1].

Other interactions of Mbar_A2142

• Analyses during purification showed that catalytic activity was restricted exclusively to the fractions that contained the carbon monoxide dehydrogenase-corrinoid enzyme complex [5].

Analytical, diagnostic and therapeutic context of Mbar_A2142

• A corrinoid content of 0.9 +/- 0.1 mol B12/mol holoenzyme was calculated from HPLC analysis [9].
• Methanol:coenzyme M methyltransferase from Methanosarcina barkeri--identification of the active-site histidine in the corrinoid-harboring subunit MtaC by site-directed mutagenesis [10].

References