title: The oxygen-tolerant and NAD+-dependent formate dehydrogenase from Rhodobacter capsulatus is able to catalyze the reduction of CO2 to formate.
abstract: The formate dehydrogenase from Rhodobacter capsulatus (RcFDH) is an oxygen-tolerant protein with an (αβγ)2 subunit composition that is localized in the cytoplasm. It belongs to the group of metal and NAD(+)-dependent FDHs with the coordination of a molybdenum cofactor, four [Fe4S4] clusters and one [Fe2S2] cluster associated with the α-subunit, one [Fe4S4] cluster and one FMN bound to the β-subunit, and one [Fe2S2] cluster bound to the γ-subunit. RcFDH was heterologously expressed in Escherichia coli and characterized. Cofactor analysis showed that the bis-molybdopterin guanine dinucleotide cofactor is bound to the FdsA subunit containing a cysteine ligand at the active site. A turnover rate of 2189 min(-1) with formate as substrate was determined. The back reaction for the reduction of CO2 was catalyzed with a k(cat) of 89 min(-1). The preference for formate oxidation shows an energy barrier for CO2 reduction of the enzyme. Furthermore, the FMN-containing and [Fe4S4]-containing β-subunit together with the [Fe2S2]-containing γ-subunit forms a diaphorase unit with activities for both NAD(+) reduction and NADH oxidation. In addition to the structural genes fdsG, fdsB, and fdsA, the fds operon in R. capsulatus contains the fdsC and fdsD genes. Expression studies showed that RcFDH is only active when both FdsC and FdsD are present. Both proteins are proposed to be involved in bis-molybdopterin guanine dinucleotide modification and insertion into RcFDH.
authors.affiliation: Department of Molecular Enzymology, Institute of Biochemistry and Biology, University of Potsdam, Germany.
authors.forename: Tobias
authors.initials: T
authors.lastname: Hartmann
authors.forename: Silke
authors.initials: S
authors.lastname: Leimkühler
mesh_terms: D002245:Carbon Dioxide / Q000737:chemistry* / Q000378:metabolism; D002384:Catalysis; D004926:Escherichia coli / Q000201:enzymology / Q000235:genetics; D005560:Formate Dehydrogenases / Q000737:chemistry / Q000378:metabolism*; D005561:Formates / Q000378:metabolism*; D006150:Guanine Nucleotides / Q000378:metabolism; D009243:NAD / Q000378:metabolism*; D009245:NADH Dehydrogenase / Q000378:metabolism; D009876:Operon; D010084:Oxidation-Reduction; D010100:Oxygen / Q000378:metabolism*; D060066:Protein Interaction Maps; D055503:Protein Multimerization; D011622:Pterins / Q000378:metabolism; D016354:Rhodobacter capsulatus / Q000201:enzymology*; D020349:Surface Plasmon Resonance
chemical_list: D005561:Formates; D006150:Guanine Nucleotides; D011622:Pterins; D009243:NAD; C063761:molybdopterin guanine dinucleotide; D002245:Carbon Dioxide; D005560:Formate Dehydrogenases; D009245:NADH Dehydrogenase; D010100:Oxygen
keywords: FMN; FeS cluster; formate dehydrogenase; molybdenum cofactor (Moco)-binding chaperone; molybdoenzyme