IUBMB Enzyme Nomenclature


Accepted name: methylated-thiol—coenzyme M methyltransferase

Reaction: methanethiol + CoM = methyl-CoM + hydrogen sulfide (overall reaction)
(1a) methanethiol + a [Co(I) methylated--thiol-specific corrinoid protein] = a [methyl-Co(III) methylated-thiol-specific corrinoid protein] + hydrogen sulfide
(1b) a [methyl-Co(III) methylated-thiol-specific corrinoid protein] + coenzyme M = methyl-CoM + a [Co(I) methylated-thiol-specific corrinoid protein]

Glossary: CoM = coenzyme M = 2-sulfanylethane-1-sulfonate = 2-mercaptoethanesulfonate (deprecated)

Other name(s): mtsA (gene name)

Systematic name: methylated-thiol:coenzyme M methyltransferase

Comments: The enzyme, which is involved in methanogenesis from methylated thiols, such as methane thiol, dimethyl sulfide, and 3-S-methylmercaptopropionate, catalyses two successive steps - the transfer of a methyl group from the substrate to the cobalt cofactor of a methylated-thiol-specific corrinoid protein (MtsB), and the subsequent transfer of the methyl group from the corrinoid protein to coenzyme M. With most other methanogenesis substrates this process is carried out by two different enzymes (for example, EC, methanol—corrinoid protein Co-methyltransferase, and EC, methylated methanol-specific corrinoid protein:coenzyme M methyltransferase). The cobalt is oxidized during methylation from the Co(I) state to the Co(III) state, and is reduced back to the Co(I) form during demethylation.

Links to other databases: BRENDA, EXPASY, KEGG, Metacyc, CAS registry number:


1. Paul, L. and Krzycki, J.A. Sequence and transcript analysis of a novel Methanosarcina barkeri methyltransferase II homolog and its associated corrinoid protein homologous to methionine synthase. J. Bacteriol. 178 (1996) 6599-6607. [PMID: 8932317]

2. Tallant, T.C. and Krzycki, J.A. Methylthiol:coenzyme M methyltransferase from Methanosarcina barkeri, an enzyme of methanogenesis from dimethylsulfide and methylmercaptopropionate. J. Bacteriol. 179 (1997) 6902-6911. [PMID: 9371433]

3. Tallant, T.C., Paul, L. and Krzycki, J.A. The MtsA subunit of the methylthiol:coenzyme M methyltransferase of Methanosarcina barkeri catalyses both half-reactions of corrinoid-dependent dimethylsulfide: coenzyme M methyl transfer. J. Biol. Chem. 276 (2001) 4485-4493. [PMID: 11073950]

[EC created 2012]

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