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Publication Abstract from PubMed

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 alpha and two beta of 19 and 38kDa, respectively. Both the two subunits fold as a cupin, but that of the small alpha subunit lacks a competent metal binding pocket. Two tetramers are present in the asymmetric unit. Each of the four beta subunits in the asymmetric unit binds one Fe(II) ion. The iron ion in each beta 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.

The crystal structures of native hydroquinone 1,2-dioxygenase from Sphingomonas sp. TTNP3 and of substrate and inhibitor complexes.,Ferraroni M, Da Vela S, Kolvenbach BA, Corvini PF, Scozzafava A Biochim Biophys Acta. 2017 May;1865(5):520-530. doi:, 10.1016/j.bbapap.2017.02.013. Epub 2017 Feb 20. PMID:28232026^[1]

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