Department of Molecular and Cell Biology, Pennsylvania State University, University Park 16802.
Two cDNA clones encoding lignin peroxidase isozymes from Phanerochaete chrysosporium have been isolated and characterized. One of the clones, lambda ML-4, encodes isozyme H8 as does the previously reported clone lambda ML-1 [Tien, M. and Tu, C.-P.D. Nature 326 (1987) 520-523; 328, 742]. Our data are consistent with lambda ML-1 and lambda ML-4 being allelic variants. The other clone, lambda ML-5, encodes a homologous isozyme. We have also isolated the genomic clone corresponding to lambda ML-4 cDNA. Conserved residues thought to be essential for peroxidase function were identified in the predicted amino acid sequences of both cDNA clones. Northern blot analyses indicate that these isozymes are expressed during secondary metabolism, appearing on day 4 of growth and increasing on days 5 and 6.