EC 1.17.98.5

Reaction: formate + 2 H⁺ = CO₂ + H₂

Other name(s): HCDR

Systematic name: formate:proton oxidoreductase

Comments: The enzyme, originally characterized from the acetogenic bacterium Acetobacterium woodii, catalyses the reduction of CO₂ to formate with electrons provided by the oxidation of molecular hydrogen. It consists of two catalytic subunits - a hydrogenase and a formate dehydrogenase, which are connected by two types of electron transfer subunits. The enzyme forms membrane-anchored nanowires in which the electron-transfer subunits oligomerize through their C-terminal helices to form the backbone of the filament. The rapid electron transfer via the filaments enhances the activity of the enzyme, resulting in a very high catalytic turnover rate. While the reaction is similar to that catalysed by the formate hydrogenlyase complex, which is formed by EC 1.17.98.4, formate dehydrogenase (hydrogenase), and EC 1.12.7.2, ferredoxin hydrogenase, this enzyme is not biased towards formate oxidation, and does not require ferredoxin in order to complete the reaction (although it is able to use reduced ferredoxin instead of dihydrogen for the reduction of CO2).

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

References:

1. Schuchmann, K. and Muller, V. Direct and reversible hydrogenation of CO₂ to formate by a bacterial carbon dioxide reductase. Science 342 (2013) 1382-1385. [PMID: 24337298]

2. Schuchmann, K., Vonck, J. and Muller, V. A bacterial hydrogen-dependent CO₂ reductase forms filamentous structures. FEBS J. 283 (2016) 1311-1322. [PMID: 26833643]

3. Schwarz, F.M., Schuchmann, K. and Muller, V. Hydrogenation of CO₂ at ambient pressure catalyzed by a highly active thermostable biocatalyst. Biotechnol. Biofuels 11 (2018) 237. [PMID: 30186365]

4. Dietrich, H.M., Righetto, R.D., Kumar, A., Wietrzynski, W., Trischler, R., Schuller, S.K., Wagner, J., Schwarz, F.M., Engel, B.D., Muller, V. and Schuller, J.M. Membrane-anchored HDCR nanowires drive hydrogen-powered CO₂ fixation. Nature 607 (2022) 823-830. [PMID: 35859174]