title: Structural characterization of heterodimeric laccases from Pleurotus ostreatus.
abstract: The subfamily of POXA3 laccase isoenzymes produced by the fungus Pleurotus ostreatus has been characterized as an example of the complexity and heterogeneity of fungal isoenzyme patterns. Two isoenzymes, POXA3a and POXA3b, were previously purified, exhibiting an unusual heterodimeric structure composed of a large (67 kDa) and a small (18 or 16 kDa) subunit. A unique gene encodes the large subunit of both POXA3a and POXA3b, but alternative splicing produces two variants--differing for an insertion of four amino acids--for each isoenzyme. Two genes encoding POXA3a and POXA3b small subunits have been identified, and the corresponding amino acid sequences show only two amino acid substitutions. The 18- and 16-kDa subunits of both POXA3a and POXA3b differ for N-glycosylation at Asn150 of the 16-kDa subunit. The POXA3 large subunit 3D model allows us to highlight peculiarities of this molecule with respect to the laccases whose 3D structures are known.
authors: Dipartimento di Chimica Organica e Biochimica, Università di Napoli "Federico II," Complesso Universitario Monte S. Angelo, via Cintia, Naples 80126, Italy. giardina@unina.it
authors: Paola
authors: P
authors: Giardina
authors: Flavia
authors: F
authors: Autore
authors: Vincenza
authors: V
authors: Faraco
authors: Giovanna
authors: G
authors: Festa
authors: Gianna
authors: G
authors: Palmieri
authors: Alessandra
authors: A
authors: Piscitelli
authors: Giovanni
authors: G
authors: Sannia
mesh_terms: D000595:Amino Acid Sequence; D019281:Dimerization; D042845:Laccase / Q000737:chemistry* / Q000235:genetics; D008969:Molecular Sequence Data; D020076:Pleurotus / Q000201:enzymology* / Q000235:genetics; D020836:Protein Structure, Quaternary; D019032:Spectrometry, Mass, Matrix-Assisted Laser Desorption-Ionization
chemical_list: D042845:Laccase