Discovery of a new metal and NAD⁺-dependent formate dehydrogenase from Clostridium ljungdahlii

Over the next decades, with the growing concern of rising atmospheric carbon dioxide (CO₂) levels, the importance of investigating new approaches for its reduction becomes crucial. Reclamation of CO₂ for conversion into biofuels represents an alternative and attractive production method that has been studied in recent years, now with enzymatic methods gaining more attention. Formate dehydrogenases (FDHs) are NAD(P)H-dependent oxidoreductases that catalyze the conversion of formate into CO₂ and have been extensively used for cofactor recycling in chemoenzymatic processes. A new FDH from <i>Clostridium ljungdahlii</i> (<i>Cl</i>FDH) has been recently shown to possess activity in the reverse reaction: the mineralization of CO₂ into formate. In this study, we show the successful homologous expression of <i>Cl</i>FDH in <i>Escherichia coli</i>. Biochemical and kinetic characterization of the enzyme revealed that this homologue also demonstrates activity toward CO₂ reduction. Structural analysis of the enzyme through homology modeling is also presented.