title: Cr(II) reactivity of taurine/alpha-ketoglutarate dioxygenase.
abstract: The interaction of CrII with taurine/alpha-ketoglutarate (alphaKG) dioxygenase (TauD) was examined. CrII replaces FeII and binds stoichiometrically with alphaKG to the FeII/alphaKG binding site of the protein, with additional CrII used to generate a chromophore attributed to a CrIII-semiquinone in a small percentage of the sample. Formation of the latter oxygen-sensitive species requires the dihydroxyphenylalanine (DOPA) quinone form of Tyr-73. This preformed side chain is generated by intracellular self-hydroxylation of Tyr-73 to form DOPA, which is subsequently oxidized to the quinone. No chromophore is generated when using NaBH4-treated sample, protein isolated from anaerobically grown cells, inactive TauD variants that are incapable of self-hydroxylation, or the Y73F active mutant of TauD. A CrIII-DOPA semiquinone also was observed in the herbicide hydroxylase SdpA.
authors.affiliation: Department of Microbiology & Molecular Genetics, Michigan State University, East Lansing, Michigan 48824-4320, USA.
authors.forename: Piotr K
authors.initials: PK
authors.lastname: Grzyska
authors.forename: Robert P
authors.initials: RP
authors.lastname: Hausinger
mesh_terms: D001665:Binding Sites; D002384:Catalysis; D002857:Chromium / Q000737:chemistry* / Q000378:metabolism; D004295:Dihydroxyphenylalanine / Q000737:chemistry / Q000378:metabolism; D005296:Ferrous Compounds / Q000737:chemistry / Q000378:metabolism; D006899:Mixed Function Oxygenases / Q000235:genetics / Q000378:metabolism*; D015394:Molecular Structure; D014443:Tyrosine / Q000737:chemistry / Q000378:metabolism
chemical_list: D005296:Ferrous Compounds; D002857:Chromium; D014443:Tyrosine; D004295:Dihydroxyphenylalanine; D006899:Mixed Function Oxygenases; C433064:taurine-alpha-ketoglutarate dioxygenase