Molecular characterization of the phenol oxidase (pox2) gene from the ligninolytic fungus Pleurotus ostreatus.

The gene (pox2) encoding a phenol oxidase from Pleurotus ostreatus, a lignin-degrading basidiomycete, was sequenced and the corresponding pox2-cDNA was also synthesized, cloned and sequenced. The isolated gene consisted of 2674 bp, with the coding sequence interrupted by 19 introns and flanked by an upstream region in which the putative metal-responsive elements (MREs) were determined in the promoter region (849 bp), where MRE 1, 2, 3 and 4 were located in positions -20, -60, -236 and -297. A functional TATA consensus sequence was recognized in position -85, while CAAT and its inversion consensus sequences were recognized in positions -284, -554, -689 and -752. The putative GC box consensus sequences were recognized in positions -181 and -460, and xenobiotic-responsive elements in positions -107, -277 and -390. The isolation of a second cDNA (pox2-cDNA), the nucleotide sequence of pox2, was found to contain an ORF of 1665 bp capable of coding for a protein of 533 amino acid residues. Northern blot analysis revealed that strong transcriptional induction was observed in the copper-supplemented cultures for the pox2 gene.