Lignin Peroxidase GeneFamily ofPhanerochaete chrysosporium: Complex Regulation byCarbonandNitrogen Limitation andIdentification ofaSecond Dimorphic Chromosome

Lignin peroxidases (LiP) ofPhanerochaete chrysosporium areencoded byafamily ofsixclosely related genes. FiveLiPgenes havebeenlocalized tothesamedimorphic chromosome. Inthis investigation, relative transcript levels oftheLiPgenes weredetermined. Transcripts oftheLiPA,LiPB, and0282genes wereatsimilar levels inbothcarbon- andnitrogen-limited cultures. Incontrast, transcription oftheGLG5,V4,andGLG4genes wasdramatically altered byculture conditions. Undercarbon-limited conditions, GLG4transcripts were,by far, themostabundant. Southern blotanalyses ofclamped homogeneous field gels wereusedtomaptheGLG4 genetoadimorphic chromosome separate fromtheother LiPgenes. Lignin depolymerization iscatalyzed byextracellular en- zymesofwhiterotbasidiomycetes suchasPhanerochaete chrysosporium (19). Majorcomponents ofthissystem in- clude lignin peroxidase (LiP), manganese-dependent perox-