Isozymes of lignin peroxidase and manganese(II) peroxidase from the white-rot basidiomycete Trametes versicolor. II. Partial sequences, peptide maps, and amino acid and carbohydrate compositions.

The basidiomycete Trametes versicolor, a white-rot fungus and potent degrader of lignin, produces multiple forms of extracellular peroxidases. Nine of these forms, six lignin peroxidases and three manganese(II) peroxidases, purified as described in the preceding paper, were characterized by amino-terminal sequencing, amino acid analyses, carbohydrate analyses, or peptide mapping. For two of the lignin peroxidase forms, tryptic peptides were isolated and sequenced to an extent corresponding to about 40 and 30%, respectively, of the primary structure. Eight of the nine peroxidases investigated were found to possess unique amino-terminal regions. A comparison of the sequences shows 57% of the residues to be identical, indicating a common ancestry for the lignin peroxidase and the manganese(II) peroxidase. The degree of identity among the five lignin peroxidases is about 80% and among the three manganese(II) peroxidases about 70%. Pairwise comparisons of the sequences disclosed that some of the lignin peroxidases are very closely related, either identical or differing only in a single amino acid residue of the thirty-five investigated. These close relationships are also supported by peptide mapping and by similarities in amino acid compositions. Tyr is absent in all isozymes. Lignin and manganese(II) peroxidases showed the presence of glucosamine and mannose in an amount corresponding to 3 to 6% of the molecular mass of the proteins. The carbohydrate compositions are compatible with the presence of 1, 2, and 3 sites of N-glycosylation. The results obtained strongly suggest that the complexity in the peroxidase pattern displayed by the fungus (T. Johansson and P.O. Nyman, Arch. Biochem. Biophys. 300, 49-56, 1993) can largely be accounted for by a heterogeneity at the gene level, probably in the form of multiple structural genes. Two recently published genes from genomic clones of T. versicolor are identical in sequence to two of the lignin peroxidases characterized here.