CLONING AND SEQUENCING OF A LACCASE GENE FROM THE LIGNIN-DEGRADING BASIDIOMYCETE PLEUROTUS-OSTREATUS

The gene (pox1) encoding a phenol oxidase from Pleurotus ostreatus, a lignin-degrading basidiomycete, was cloned and sequenced, and the corr esponding pox1 cDNA was also synthesized and sequenced. The isolated g ene consists of 2,592 bp, with the coding sequence being interrupted b y 19 introns and flanked by an upstream region in which putative CAAT and TATA consensus sequences could be identified at positions -174 and -84, respectively. The isolation of a second cDNA (pox2 cDNA), showin g 84% similarity, and of the corresponding truncated genomic clones de monstrated the existence of a multigene family coding for isoforms of laccase in P. ostreatus. PCR amplifications of specific regions on the DNA of isolated monokaryons proved that the two genes are not allelic forms. The POX1 amino acid sequence deduced was compared with those o f other known laccases from different fungi.