title: Two structures of an N-hydroxylating flavoprotein monooxygenase: ornithine hydroxylase from Pseudomonas aeruginosa.
abstract: The ornithine hydroxylase from Pseudomonas aeruginosa (PvdA) catalyzes the FAD-dependent hydroxylation of the side chain amine of ornithine, which is subsequently formylated to generate the iron-chelating hydroxamates of the siderophore pyoverdin. PvdA belongs to the class B flavoprotein monooxygenases, which catalyze the oxidation of substrates using NADPH as the electron donor and molecular oxygen. Class B enzymes include the well studied flavin-containing monooxygenases and Baeyer-Villiger monooxygenases. The first two structures of a class B N-hydroxylating monooxygenase were determined with FAD in oxidized (1.9 Å resolution) and reduced (3.03 Å resolution) states. PvdA has the two expected Rossmann-like dinucleotide-binding domains for FAD and NADPH and also a substrate-binding domain, with the active site at the interface between the three domains. The structures have NADP(H) and (hydroxy)ornithine bound in a solvent-exposed active site, providing structural evidence for substrate and co-substrate specificity and the inability of PvdA to bind FAD tightly. Structural and biochemical evidence indicates that NADP(+) remains bound throughout the oxidative half-reaction, which is proposed to shelter the flavin intermediates from solvent and thereby prevent uncoupling of NADPH oxidation from hydroxylated product formation.
authors.affiliation: Department of Molecular Biosciences, University of Kansas, Lawrence, Kansas 66045, USA.
authors.forename: Jose
authors.initials: J
authors.lastname: Olucha
authors.forename: Kathleen M
authors.initials: KM
authors.lastname: Meneely
authors.forename: Annemarie S
authors.initials: AS
authors.lastname: Chilton
authors.forename: Audrey L
authors.initials: AL
authors.lastname: Lamb
mesh_terms: D002384:Catalysis; D020134:Catalytic Domain; D018360:Crystallography, X-Ray; D005182:Flavin-Adenine Dinucleotide; D006899:Mixed Function Oxygenases / Q000737:chemistry*; D009249:NADP; D009952:Ornithine; D010084:Oxidation-Reduction; D010105:Oxygenases / Q000737:chemistry*; D011487:Protein Conformation; D011550:Pseudomonas aeruginosa / Q000201:enzymology*; D013379:Substrate Specificity
chemical_list: D005182:Flavin-Adenine Dinucleotide; D009249:NADP; D009952:Ornithine; D006899:Mixed Function Oxygenases; D010105:Oxygenases; C524418:ornithine hydroxylase, Pseudomonas aeruginosa; C020066:dimethylaniline monooxygenase (N-oxide forming)