Formylmethanofuran dehydrogenase, subunit B (IPR016457)

Short name: Formylmethanofuran_DH_bsu

Overlapping homologous superfamilies


Family relationships



Formylmethanofuran dehydrogenase (EC: is found in methanogenic and sulphate-reducing archaea. The enzyme contains molybdenum or tungsten, a molybdopterin guanine dinuceotide cofactor (MGD) and iron-sulphur clusters [PMID: 8125106]. It catalyses the reversible reduction of CO2 and methanofuran via N-carboxymethanofuran (carbamate) to N-formylmethanofuran, the first and second steps in methanogenesis from CO2 [PMID: 8575452, PMID: 9342247]. This reaction is important for the reduction of CO2 to methane, in autotrophic CO2 fixation, and in CO2 formation from reduced C1 units [PMID: 8954165]. The synthesis of formylmethanofuran is crucial for the energy metabolism of archaea. Methanogenic archaea derives the energy for autrophic growth from the reduction of CO2 with molecular hydrogen as the electron donor [PMID: 12492476]. The process of methanogenesis consists of a series of reduction reactions at which the one-carbon unit derived from CO2 is bound to C1 carriers.

There are two isoenzymes of formylmethanofuran dehydrogenase: a tungsten-containing isoenzyme (Fwd) and a molybdenum-containing isoenzyme (Fmd). The tungsten isoenzyme is constitutively transcribed, whereas transcription of the molybdenum operon is induced by molybdate [PMID: 9818358]. The archaean Methanobacterium thermoautotrophicum contains a 4-subunit (FwdA, FwdB, FwdC, FwdD) tungsten formylmethanofuran dehydrogenase and a 3-subunit (FmdA, FmdB, FmdC) molybdenum formylmethanofuran dehydrogenase [PMID: 8954165].

This entry represents subunit B (FmdB and FwdB) of formylmethanofuran dehydrogenase. The other subunits are subunit A (IPR012027), subunit C (IPR017550), subunit D (IPR012040), subunit E (IPR026328) and subunit F. Some organisms also encode a fusion of the C and D subunits (IPR012048). Formylmethanofuran dehydrogenase catalyzes the first step in methane formation from CO2 in methanogenic archaea and some eubacteria. Members in this entry belong to the molybdopterin_binding (MopB) superfamily of proteins [PMID: 8954165].

GO terms

Biological Process

GO:0015948 methanogenesis

Molecular Function

GO:0018493 formylmethanofuran dehydrogenase activity

Cellular Component

No terms assigned in this category.

Contributing signatures

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