Reaction: 2 CO2 + 2 reduced ferredoxin [iron-sulfur] cluster + CoB + CoM + 2 H+ = 2 formate + 2 oxidized ferredoxin [iron-sulfur] cluster + CoM-S-S-CoB
Glossary: coenzyme B = CoB = N-(7-mercaptoheptanoyl)threonine 3-O-phosphate = N-(7-thioheptanoyl)-3-O-phosphothreonine
coenzyme M = CoM = 2-sulfanylethane-1-sulfonate = 2-mercaptoethanesulfonate (deprecated)
CoM-S-S-CoB = CoB-CoM heterodisulfide = N-{7-[(2-sulfoethyl)dithio]heptanoyl}-O3-phospho-L-threonine
Systematic name: coenzyme B,coenzyme M,ferredoxin:formate oxidoreductase
Comments: The enzyme is found in formate-oxidizing CO2-reducing methanogenic archaea such as Methanococcus maripaludis. It consists of a cytoplasmic complex of HdrABC reductase and formate dehydrogenase. Electron pairs donated by formate dehydrogenase are transferred to the HdrA subunit of the reductase, where they are bifurcated, reducing both ferredoxin and CoB-CoM heterodisulfide. cf. EC 1.8.7.3, ferredoxin:CoB-CoM heterodisulfide reductase, EC 1.8.98.4, coenzyme F420:CoB-CoM heterodisulfide,ferredoxin reductase, EC 1.8.98.5, H2:CoB-CoM heterodisulfide,ferredoxin reductase, and EC 1.8.98.1, dihydromethanophenazine:CoB-CoM heterodisulfide reductase.
Links to other databases: BRENDA, EXPASY, KEGG, MetaCyc, CAS registry number:
References:
1. Costa, K.C., Wong, P.M., Wang, T., Lie, T.J., Dodsworth, J.A., Swanson, I., Burn, J.A., Hackett, M. and Leigh, J.A. Protein complexing in a methanogen suggests electron bifurcation and electron delivery from formate to heterodisulfide reductase. Proc. Natl Acad. Sci. USA 107 (2010) 11050-11055. [PMID: 20534465]
2. Costa, K.C., Lie, T.J., Xia, Q. and Leigh, J.A. VhuD facilitates electron flow from H2 or formate to heterodisulfide reductase in Methanococcus maripaludis. J. Bacteriol. 195 (2013) 5160-5165. [PMID: 24039260]