title: X-ray structure of Escherichia coli pyridoxine 5'-phosphate oxidase complexed with pyridoxal 5'-phosphate at 2.0 A resolution.
abstract: Escherichia coli pyridoxine 5'-phosphate oxidase catalyzes the terminal step in the biosynthesis of pyridoxal 5'-phosphate by the FMN oxidation of pyridoxine 5'-phosphate forming FMNH(2) and H(2)O(2). Recent studies have shown that in addition to the active site, pyridoxine 5'-phosphate oxidase contains a non-catalytic site that binds pyridoxal 5'-phosphate tightly. The crystal structure of pyridoxine 5'-phosphate oxidase from E. coli with one or two molecules of pyridoxal 5'-phosphate bound to each monomer has been determined to 2.0 A resolution. One of the pyridoxal 5'-phosphate molecules is clearly bound at the active site with the aldehyde at C4' of pyridoxal 5'-phosphate near N5 of the bound FMN. A protein conformational change has occurred that partially closes the active site. The orientation of the bound pyridoxal 5'-phosphate suggests that the enzyme catalyzes a hydride ion transfer between C4' of pyridoxal 5'-phosphate and N5 of FMN. When the crystals are soaked with excess pyridoxal 5'-phosphate an additional molecule of this cofactor is also bound about 11 A from the active site. A possible tunnel exists between the two sites so that pyridoxal 5'-phosphate formed at the active site may transfer to the non-catalytic site without passing though the solvent.
authors.affiliation: Institute for Structural Biology and Drug Discovery, and Department of Biochemistry, Virginia Commonwealth University, Richmond, VA 23219, USA. msafo@hsc.vcu.edu
authors.forename: M K
authors.initials: MK
authors.lastname: Safo
authors.forename: F N
authors.initials: FN
authors.lastname: Musayev
authors.forename: M L
authors.initials: ML
authors.lastname: di Salvo
authors.forename: V
authors.initials: V
authors.lastname: Schirch
mesh_terms: D001665:Binding Sites; D003460:Crystallization; D018360:Crystallography, X-Ray; D019281:Dimerization; D004926:Escherichia coli / Q000201:enzymology*; D005486:Flavin Mononucleotide / Q000378:metabolism; D006860:Hydrogen Bonding; D008024:Ligands; D008958:Models, Molecular; D020836:Protein Structure, Quaternary; D017433:Protein Structure, Secondary; D011732:Pyridoxal Phosphate / Q000031:analogs & derivatives / Q000737:chemistry / Q000378:metabolism*; D011734:Pyridoxaminephosphate Oxidase / Q000737:chemistry* / Q000378:metabolism*; D014867:Water / Q000378:metabolism
chemical_list: D008024:Ligands; D014867:Water; D011732:Pyridoxal Phosphate; D005486:Flavin Mononucleotide; D011734:Pyridoxaminephosphate Oxidase; C024593:pyridoxine 5-phosphate