Fig. 2

Phylogenetic analysis of representative laccases from plants, fungi, insects and bacteria. Laccases are encoded by multigene family, for example, the Arabidopsis genome encodes 17 laccases, and the number of identified laccase genes in Trametes villosa and Nephotettix cincticeps is 5 and 3, respectively. Laccases from plants, fungi, insects and bacteria are clustered separately in the phylogenetic tree for each taxon, but share conserved copper binding sites. The amino acids potentially involved in copper binding include ten histidines and one cysteine (in red), with numbers 1, 2 and 3 corresponding to the Cu1, Cu2 and Cu3 ions. An axial ligand of methionine, leucine, or phenylalanine (in bold) was indicated. The bootstrap consensus tree was constructed by MEGA with the Neighbor-Joining method. Database accession numbers of laccase sequences are listed in Additional file 1: Table S1