title: Phthalate dioxygenase reductase: a modular structure for electron transfer from pyridine nucleotides to [2Fe-2S].
abstract: Phthalate dioxygenase reductase (PDR) is a prototypical iron-sulfur flavoprotein (36 kilodaltons) that utilizes flavin mononucleotide (FMN) to mediate electron transfer from the two-electron donor, reduced nicotinamide adenine nucleotide (NADH), to the one-electron acceptor, [2Fe-2S]. The crystal structure of oxidized PDR from Pseudomonas cepacia has been analyzed at 2.0 angstrom resolution resolution; reduced PDR and pyridine nucleotide complexes have been analyzed at 2.7 angstrom resolution. NADH, FMN, and the [2Fe-2S] cluster, bound to distinct domains, are brought together near a central cleft in the molecule, with only 4.9 angstroms separating the flavin 8-methyl and a cysteine sulfur ligated to iron. The domains that bind FMN and [2Fe-2S] are packed so that the flavin ring and the plane of the [2Fe-2S] core are approximately perpendicular. The [2Fe-2S] group is bound by four cysteines in a site resembling that in plant ferredoxins, but its redox potential (-174 millivolts at pH 7.0) is much higher than the potentials of plant ferredoxins. Structural and sequence similarities assign PDR to a distinct family of flavoprotein reductases, all related to ferredoxin NADP(+)-reductase.
mesh_terms: D000595:Amino Acid Sequence; D001665:Binding Sites; D016956:Burkholderia cepacia / Q000201:enzymology; D004579:Electron Transport; D005486:Flavin Mononucleotide / Q000378:metabolism*; D007506:Iron-Sulfur Proteins / Q000737:chemistry* / Q000378:metabolism*; D008958:Models, Molecular; D008969:Molecular Sequence Data; D009243:NAD / Q000378:metabolism*; D010088:Oxidoreductases / Q000737:chemistry* / Q000378:metabolism; D011487:Protein Conformation; D017433:Protein Structure, Secondary; D017386:Sequence Homology, Amino Acid
chemical_list: D007506:Iron-Sulfur Proteins; D009243:NAD; D005486:Flavin Mononucleotide; D010088:Oxidoreductases; C049135:phthalate oxygenase reductase