Molecular cloning and nucleotide sequence of the protyrosinase gene, melO, from Aspergillus oryzae and expression of the gene in yeast cells.

The coding region of the protyrosinase gene, melO, from Aspergillus oryzae occupies 1671 base pairs of the genomic DNA and is separated into two exons by one intron. The full-length cDNA of the melO gene was cloned. Analysis of the 1617 base pairs nucleotide sequence revealed a single open reading frame coding 539 amino acid residues. The cDNA has been expressed in yeast cells. The predicted protein product derived from the melO gene is identified by Western blotting and activity determination. The predicted amino acid sequence of the gene product was compared with that of Neurospora crassa tyrosinase. A coupled pair of three histidine residues in the tyrosinase was assumed to correspond to Cu(II) ligands in the homologous tyrosinases from Streptomyces glaucescens and Homo sapiens.