title: The crystal structure of Pseudomonas putida azoreductase - the active site revisited.
abstract: The enzymatic degradation of azo dyes begins with the reduction of the azo bond. In this article, we report the crystal structures of the native azoreductase from Pseudomonas putida MET94 (PpAzoR) (1.60 Å), of PpAzoR in complex with anthraquinone-2-sulfonate (1.50 Å), and of PpAzoR in complex with Reactive Black 5 dye (1.90 Å). These structures reveal the residues and subtle changes that accompany substrate binding and release. Such changes highlight the fine control of access to the catalytic site that is required by the ping-pong mechanism, and in turn the specificity offered by the enzyme towards different substrates. The topology surrounding the active site shows novel features of substrate recognition and binding that help to explain and differentiate the substrate specificity observed among different bacterial azoreductases.
authors.affiliation: Macromolecular Crystallography Unit, Instituto de Tecnologia Química e Biológica, Universidade Nova de Lisboa, Oeiras, Portugal.
authors.forename: Ana Maria D
authors.initials: AM
authors.lastname: Gonçalves
authors.forename: Sónia
authors.initials: S
authors.lastname: Mendes
authors.forename: Daniele
authors.initials: D
authors.lastname: de Sanctis
authors.forename: Lígia O
authors.initials: LO
authors.lastname: Martins
authors.forename: Isabel
authors.initials: I
authors.lastname: Bento
mesh_terms: D000595:Amino Acid Sequence; D001391:Azo Compounds / Q000378:metabolism*; D002384:Catalysis; D020134:Catalytic Domain; D003460:Crystallization; D018360:Crystallography, X-Ray; D005486:Flavin Mononucleotide / Q000378:metabolism; D007700:Kinetics; D008969:Molecular Sequence Data; D009247:NADH, NADPH Oxidoreductases / Q000737:chemistry* / Q000378:metabolism; D009601:Nitroreductases; D011487:Protein Conformation; D016958:Pseudomonas putida / Q000201:enzymology*; D013379:Substrate Specificity
chemical_list: D001391:Azo Compounds; D005486:Flavin Mononucleotide; D009247:NADH, NADPH Oxidoreductases; D009601:Nitroreductases; C021106:azoreductase
keywords: azo dyes; azoreductase; crystal structure; quinone reductase; quinones