title: Microbial urate catabolism: characterization of HpyO, a non-homologous isofunctional isoform of the flavoprotein urate hydroxylase HpxO.
abstract: In aerobic cells, urate is oxidized to 5-hydroxyisourate by two distinct enzymes: a coenzyme-independent urate oxidase (EC 1.7.3.3) found in eukaryotes and bacteria like Bacillus subtilis and a prokaryotic flavoprotein urate hydroxylase (HpxO) originally found in some Klebsiella species. More cases of analogous or non-homologous isofunctional enzymes (NISE) for urate catabolism have been hypothesized by inspecting bacterial genomes. Here, we used a functional complementation approach in which a candidate gene for urate oxidation is integrated by homologous recombination in the Acinetobacter baylyi ADP1 genome at the locus of its original hpxO gene. Catabolism of urate was restored in A. baylyi ADP1 expressing a FAD-dependent protein from Xanthomonas campestris, representing a new urate hydroxylase family that we called HpyO. This enzyme was kinetically characterized and compared with other HpxO enzymes. In contrast to the latter, HpyO is a typical Michaelian enzyme. This work provides the first experimental evidences for the function of HpyO in bacterial urate catabolism and establishes it as a NISE of HpxO.
authors.affiliation: Commissariat à l'Energie Atomique et aux Energies Alternatives (CEA), DSV, Institut de Génomique (IG), UMR8030, Evry, France; Université d'Evry Val d'Essonne (UEVE), UMR8030, Evry, France; CNRS UMR 8030, 2 rue Gaston Crémieux, F-91057, Evry Cedex, France; Laboratoire SATIE, ENSC, Université de Cergy-Pontoise, CNRS UMR 8029, 5 mail Gay Lussac, F-95031, Neuville sur Oise cedex, France.
authors.forename: Magalie
authors.initials: M
authors.lastname: Michiel
authors.forename: Nadia
authors.initials: N
authors.lastname: Perchat
authors.forename: Alain
authors.initials: A
authors.lastname: Perret
authors.forename: Sabine
authors.initials: S
authors.lastname: Tricot
authors.forename: Aude
authors.initials: A
authors.lastname: Papeil
authors.forename: Marielle
authors.initials: M
authors.lastname: Besnard
authors.forename: Véronique
authors.initials: V
authors.lastname: de Berardinis
authors.forename: Marcel
authors.initials: M
authors.lastname: Salanoubat
authors.forename: Cécile
authors.initials: C
authors.lastname: Fischer