3s61

Publication Abstract from PubMed

The ornithine hydroxylase from Pseudomonas aeruginosa (PvdA) catalyzes the FAD dependent hydroxylation of the sidechain 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 electron donor and molecular oxygen. Class B enzymes include the well-studied flavin-containing monooxygenases and Baeyer-Villiger monoogenases. The first two structures of a class B N-hydroxylating monooxygenase were determined with the FAD in oxidized (1.9 A resolution) and reduced states (3.03 A). PvdA has the two expected Rossman-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 indicate 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.

Two structures of an N-hydroxylating flavoprotein monooxgenase: the ornithine hydroxylase from Pseudomonas aeruginosa.,Olucha J, Meneely KM, Chilton AS, Lamb AL J Biol Chem. 2011 Jul 13. PMID:21757711^[1]

From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine.