Structure and expression of a laccase gene from the ligninolytic basidiomycete Ceriporiopsis subvermispora

A gene encoding laccase has been isolated from a genomic library of the whi te-rot basidiomycete Ceriporiopsis subvermispora constructed in Lambda GEM- ii. This gene (Cs-lcs1) contains an open reading frame of 2215 bp, encoding a mature protein of 499 amino acids with a 21-residue signal peptide. The protein sequence exhibits between 63 and 68% identity with laccases from ot her basidiomycetes and shares with all of them 10 conserved histidines and one cysteine involved in the coordination of copper atoms at the active sit e of the enzyme. The gene possesses ii introns, with splicing junctions and internal lariat formation sites adhering to the GT-AG and CTRAY rules, res pectively. The upstream region of Cs-lcsl contains a TATA box, two CAAT sit es, five putative metal response elements and a ACE1 element. In agreement with the presence of the latter element, transcription of Cs-lcsl is activa ted by copper and silver, as shown by Northern blot and reverse transcripti on followed by DNA amplification analyses. Based on Southern blot analysis, Cs-lcsl appears to be the only gene encoding laccase in C. subvermispora. (C) 1998 Elsevier Science B.V. All rights reserved.