Methyl-coenzyme M reductase, protein D (IPR003901)

Short name: Me_CoM_Rdtase_D

Overlapping homologous superfamilies


Family relationships



Methyl-coenzyme M reductase (MCR) catalyses the reduction of methyl-coenzyme M (CH3-SCoM) and coenzyme B (HS-CoB) to methane and the corresponding heterosulphide CoM-S-S-CoB (EC:, the final step in methane biosynthesis. This reaction proceeds under anaerobic conditions by methanogenic Archaea [PMID: 16260307], and requires a nickel-porphinoid prosthetic group, coenzyme F430, which is in the EPR-detectable Ni(I) oxidation state in the active enzyme. Studies on a catalytically inactive enzyme aerobically co-crystallized with coenzyme M displayed a fully occupied coenzyme M-binding site with no alternate conformations. The binding of coenzyme M appears to induce specific conformational changes that suggests a molecular mechanism by which the enzyme ensures that methyl-coenzyme M enters the substrate channel prior to coenzyme B, as required by the active-site geometry [PMID: 11491299].

MCR is a hexamer composed of 2 alpha, 2 beta, and 2 gamma subunits with two identical nickel porphinoid active sites, which form two long active site channels with F430 embedded at the bottom [PMID: 9367957, PMID: 16234924].

Genes encoding the beta (mcrB) and gamma (mcrG) subunits of MCR are separated by two open reading frames coding for two proteins C and D [PMID: 3170483, PMID: 8863453]. The function of proteins C and D is unknown. This entry represents protein D.

GO terms

Biological Process

GO:0015948 methanogenesis

Molecular Function

No terms assigned in this category.

Cellular Component

No terms assigned in this category.

Contributing signatures

Signatures from InterPro member databases are used to construct an entry.