title: The reducing component BoxA of benzoyl-coenzyme A epoxidase from Azoarcus evansii is a [4Fe-4S] protein.
abstract: BoxA is the reductase component of the benzoyl-coenzyme A (CoA) oxidizing epoxidase enzyme system BoxAB. The enzyme catalyzes the key step of an hitherto unknown aerobic, CoA-dependent pathway of benzoate metabolism, which is the epoxidation of benzoyl-CoA to the non-aromatic 2,3-epoxybenzoyl-CoA. The function of BoxA is the transfer of two electrons from NADPH to the epoxidase component BoxB. We could show recently that BoxB is a diiron enzyme, whereas here we demonstrate that BoxA harbors an FAD and two [4Fe-4S] clusters per protein monomer. The characterization of BoxA was hampered by severe oxygen sensitivity; the cubane [4Fe-4S] clusters degrade already with traces of oxygen. Interestingly, the adventitiously formed [3Fe-4S] centers could be reconstituted in vitro by adding Fe(II) and sulfide to retrieve the native cubane centers. BoxA is the first example of a reductase of this type that has an FAD and two bacterial ferredoxin-type [4Fe-4S] clusters. In other cases within the catalytically versatile family of diiron enzymes, the related reductases have plant-type ferredoxin or Rieske-type [2Fe-2S] centers only.
authors.affiliation: Mikrobiologie, Fakultät Biologie, Schänzlestrasse 1, Universität Freiburg, Freiburg, Germany.
authors.forename: Liv J
authors.initials: LJ
authors.lastname: Rather
authors.forename: Eckhard
authors.initials: E
authors.lastname: Bill
authors.forename: Wael
authors.initials: W
authors.lastname: Ismail
authors.forename: Georg
authors.initials: G
authors.lastname: Fuchs
mesh_terms: D000214:Acyl Coenzyme A / Q000378:metabolism; D000595:Amino Acid Sequence; D020627:Azoarcus / Q000737:chemistry / Q000201:enzymology* / Q000378:metabolism; D002384:Catalysis; D020134:Catalytic Domain; D004578:Electron Spin Resonance Spectroscopy; D005296:Ferrous Compounds / Q000737:chemistry / Q000378:metabolism; D007501:Iron / Q000737:chemistry / Q000378:metabolism; D008954:Models, Biological; D008969:Molecular Sequence Data; D010084:Oxidation-Reduction; D010088:Oxidoreductases / Q000737:chemistry / Q000378:metabolism; D044925:Oxidoreductases Acting on CH-CH Group Donors / Q000737:chemistry* / Q000378:metabolism / Q000502:physiology*; D054730:Protein Interaction Domains and Motifs / Q000502:physiology; D013056:Spectrophotometry, Ultraviolet; D013455:Sulfur / Q000737:chemistry / Q000378:metabolism; D013457:Sulfur Compounds / Q000737:chemistry / Q000378:metabolism
chemical_list: D000214:Acyl Coenzyme A; D005296:Ferrous Compounds; D013457:Sulfur Compounds; C037817:benzoyl-coenzyme A; D013455:Sulfur; D007501:Iron; D010088:Oxidoreductases; C023111:epoxidase; D044925:Oxidoreductases Acting on CH-CH Group Donors; C109030:benzoyl-coenzyme A reductase (dearomatizing)