Nitrogen regulation of lignin peroxidase gene transcription

Western blot (immunoblot) analysis with a polyclonal antibody to lignin peroxidase (LiP) isozyme H8 from the white rot basidiomycete Phanerochaete chrysosporium demonstrates that LiP protein is detectable in the extracellular media of 5- and 6-day-old nitrogen-limited, but not nitrogen-sufficient, cultures. Northern (RNA) blot analysis demonstrates that lip mRNA is detectable from 5- and 6-day old cells grown in nitrogen-limited, but not nitrogen-sufficient, cultures. These results indicate that LiP expression is regulated at the level of gene transcription by nutrient nitrogen. Since lignin degradation by P. chrysosporium is derepressed by nitrogen starvation, it appears that lignin degradation and LiP expression are coordinately regulated in this organism. These results contradict a recent report which concluded that LiP protein expression is not regulated by nutrient nitrogen (C. G. Johnston and S. D. Aust, Biochem. Biophys. Res. Commun. 200:108-112, 1994).