title: Crystallization and preliminary X-ray crystallographic analysis of the small subunit of the heterodimeric laccase POXA3b from Pleurotus ostreatus.
abstract: Laccases are multicopper oxidases of great biotechnological potential. While laccases are generally monomeric glycoproteins, the white-rot fungus Pleurotus ostreatus produces two closely related heterodimeric isoenzymes composed of a large subunit, homologous to the other fungal laccases, and a small subunit. The sequence of the small subunit does not show significant homology to any other protein or domain of known function and consequently its function is unknown. The highest similarity to proteins of known structure is to a putative enoyl-CoA hydratase/isomerase from Acinetobacter baumannii, which shows an identity of 27.8%. Diffraction-quality crystals of the small subunit of the heterodimeric laccase POXA3b (sPOXA3b) from P. ostreatus were obtained using the sitting-drop vapour-diffusion method at 294 K from a solution consisting of 1.8 M sodium formate, 0.1 M Tris-HCl pH 8.5. The crystals belonged to the tetragonal space group P4(1)2(1)2 or P4(3)2(1)2, with unit-cell parameters a = 126.6, c = 53.9 Å. The asymmetric unit contains two molecules related by a noncrystallographic twofold axis. A complete data set extending to a maximum resolution of 2.5 Å was collected at 100 K using a wavelength of 1.140 Å.
authors.affiliation: Dipartimento di Chimica `Ugo Schiff', Università di Firenze, Via della Lastruccia 3, 50019 Sesto Fiorentino (FI), Italy.
authors.forename: Marta
authors.initials: M
authors.lastname: Ferraroni
authors.affiliation: Dipartimento di Chimica `Ugo Schiff', Università di Firenze, Via della Lastruccia 3, 50019 Sesto Fiorentino (FI), Italy.
authors.forename: Andrea
authors.initials: A
authors.lastname: Scozzafava
authors.affiliation: Laboratoire Biosciences, Institut des Sciences Moléculaires de Marseille, Université Aix-Marseille, ISM2 CNRS UMR 6263, Marseille CEDEX 20, France.
authors.forename: Sana
authors.initials: S
authors.lastname: Ullah
authors.affiliation: Laboratoire Biosciences, Institut des Sciences Moléculaires de Marseille, Université Aix-Marseille, ISM2 CNRS UMR 6263, Marseille CEDEX 20, France.
authors.forename: Thierry
authors.initials: T
authors.lastname: Tron
authors.affiliation: Dipartimento di Scienze Chimiche, Università di Napoli `Federico II', Via Cintia 4, 80126 Naples, Italy.
authors.forename: Alessandra
authors.initials: A
authors.lastname: Piscitelli
authors.affiliation: Dipartimento di Scienze Chimiche, Università di Napoli `Federico II', Via Cintia 4, 80126 Naples, Italy.
authors.forename: Giovanni
authors.initials: G
authors.lastname: Sannia
mesh_terms: D000595:Amino Acid Sequence; D020134:Catalytic Domain; D003300:Copper / Q000378:metabolism; D003460:Crystallization; D018360:Crystallography, X-Ray; D042845:Laccase / Q000737:chemistry*; D008969:Molecular Sequence Data; D020076:Pleurotus / Q000201:enzymology*; D055503:Protein Multimerization; D017433:Protein Structure, Secondary; D021122:Protein Subunits / Q000737:chemistry*
chemical_list: D021122:Protein Subunits; D003300:Copper; D042845:Laccase
keywords: POXA3b; Pleurotus ostreatus; laccase isoenzymes; multicopper oxidases