Crystal structure of a laccase from Melanocarpus albomyces with an intact trinuclear copper site.
We have crystallized the ascomycete laccase from Melanocarpus albomyces with all four coppers present and determined the crystal structure at 2.4 A resolution. The enzyme is heavily glycosylated and consists of three cupredoxin-like domains, similar to those found in the Cu-depleted basidiomycete laccase from Coprinus cinereus. However, there are significant differences in the loops forming the substrate-binding pocket. In addition, the crystal structure of the M. albomyces laccase revealed elongated electron density between all three coppers in the trinuclear copper site, suggesting that an oxygen molecule binds with a novel geometry. This oxygen, required in the reaction, may enter the trinuclear site through the tunnel, which is open in the structure of the C. cinereus laccase. In contrast, the C-terminus on the M. albomyces laccase forms a plug that blocks this access.
Hakulinen
Nina
N
Department of Chemistry, University of Joensuu, PO BOX 111, FIN-80101, Joensuu, Finland.
Kiiskinen
Laura-Leena
LL
Kruus
Kristiina
K
Saloheimo
Markku
M
Paananen
Arja
A
Koivula
Anu
A
Rouvinen
Juha
J
D000595:Amino Acid Sequence; D001665:Binding Sites; D020134:Catalytic Domain; D003300:Copper / Q000737:chemistry; D003302:Coprinus / Q000201:enzymology / Q000235:genetics; D018360:Crystallography, X-Ray; D042845:Laccase; D008958:Models, Molecular; D008969:Molecular Sequence Data; D010088:Oxidoreductases / Q000737:chemistry* / Q000235:genetics; D010100:Oxygen / Q000737:chemistry; D011487:Protein Conformation; D017386:Sequence Homology, Amino Acid; D020037:Sordariales / Q000201:enzymology* / Q000235:genetics; D013045:Species Specificity; D055672:Static Electricity
D003300:Copper; D010088:Oxidoreductases; D042845:Laccase; D010100:Oxygen