Methyl-coenzyme M reductase, ferredoxin-like fold (IPR009024)
Short name: Me_CoM_Rdtase_Fd-like_fold
- Methyl-coenzyme M reductase, gamma subunit (IPR003178)
- Methyl-coenzyme M reductase, alpha subunit, N-terminal (IPR003183)
- Methyl-coenzyme M reductase, alpha subunit, N-terminal subdomain 1 (IPR015811)
- Methyl-coenzyme M reductase, alpha subunit, N-terminal subdomain 2 (IPR015823)
- Methyl-coenzyme M reductase, beta subunit, N-terminal (IPR022680)
- Methyl-coenzyme M reductase, gamma subunit superfamily (IPR036994)
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:18.104.22.168), 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].
This superfamily represents a domain with a ferredoxin-like fold decorated with additional secondary structures that is found in all three subunits, alpha, beta and gamma. This fold consists of an alpha/beta sandwich with an anti-parallel beta-sheet with a duplicated beta-alpha-beta topology [PMID: 11491299].
- SSF55088 (SSF55088)