title: The crystal structures of native hydroquinone 1,2-dioxygenase from Sphingomonas sp. TTNP3 and of substrate and inhibitor complexes.
abstract: The crystal structure of hydroquinone 1,2-dioxygenase, a Fe(II) ring cleaving dioxygenase from Sphingomonas sp. strain TTNP3, which oxidizes a wide range of hydroquinones to the corresponding 4-hydroxymuconic semialdehydes, has been solved by Molecular Replacement, using the coordinates of PnpCD from Pseudomonas sp. strain WBC-3. The enzyme is a heterotetramer, constituted of two subunits α and two β of 19 and 38kDa, respectively. Both the two subunits fold as a cupin, but that of the small α subunit lacks a competent metal binding pocket. Two tetramers are present in the asymmetric unit. Each of the four β subunits in the asymmetric unit binds one Fe(II) ion. The iron ion in each β subunit is coordinated to three protein residues, His258, Glu264, and His305 and a water molecule. The crystal structures of the complexes with the substrate methylhydroquinone, obtained under anaerobic conditions, and with the inhibitors 4-hydroxybenzoate and 4-nitrophenol were also solved. The structures of the native enzyme and of the complexes present significant differences in the active site region compared to PnpCD, the other hydroquinone 1,2-dioxygenase of known structure, and in particular they show a different coordination at the metal center.
authors.affiliation: Dipartimento di Chimica "Ugo Schiff", Università di Firenze, Via della Lastruccia 3, I-50019, Sesto Fiorentino, FI, Italy. Electronic address: marta.ferraroni@unifi.it.
authors.forename: Marta
authors.initials: M
authors.lastname: Ferraroni
authors.affiliation: Dipartimento di Chimica "Ugo Schiff", Università di Firenze, Via della Lastruccia 3, I-50019, Sesto Fiorentino, FI, Italy. Electronic address: stefanodavela@gmail.com.
authors.forename: Stefano
authors.initials: S
authors.lastname: Da Vela
authors.affiliation: Institute for Ecopreneurship, School of Life Sciences, University of Applied Sciences and Arts Northwestern Switzerland, Gründenstrasse 40, 4132 Muttenz, Switzerland. Electronic address: boris.kolvenbach@fhnw.ch.
authors.forename: Boris A
authors.initials: BA
authors.lastname: Kolvenbach
authors.affiliation: Institute for Ecopreneurship, School of Life Sciences, University of Applied Sciences and Arts Northwestern Switzerland, Gründenstrasse 40, 4132 Muttenz, Switzerland. Electronic address: philippe.corvini@fhnw.ch.
authors.forename: Philippe F X
authors.initials: PFX
authors.lastname: Corvini
authors.affiliation: Dipartimento di Chimica "Ugo Schiff", Università di Firenze, Via della Lastruccia 3, I-50019, Sesto Fiorentino, FI, Italy. Electronic address: andrea.scozzafava@unifi.it.
authors.forename: Andrea
authors.initials: A
authors.lastname: Scozzafava
mesh_terms: D000595:Amino Acid Sequence; D001665:Binding Sites; D020134:Catalytic Domain; D018360:Crystallography, X-Ray; D049308:Dioxygenases / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism; D006873:Hydroquinones / Q000737:chemistry*; D007501:Iron / Q000737:chemistry*; D009596:Nitrophenols / Q000737:chemistry; D010226:Parabens / Q000737:chemistry; D011487:Protein Conformation; D017386:Sequence Homology, Amino Acid; D020578:Sphingomonas / Q000201:enzymology*
chemical_list: D006873:Hydroquinones; D009596:Nitrophenols; D010226:Parabens; D007501:Iron; D049308:Dioxygenases; C038193:4-hydroxybenzoic acid; C031927:hydroquinone; C024836:4-nitrophenol
keywords: Crystallography; Cupin superfamily; Dioxygenase; Metal binding motif; Ring cleaving