NITROGEN REGULATION OF LIGNIN PEROXIDASE GENE-TRANSCRIPTION

Western blot (immunoblot) analysis with a polyclonal antibody to ligni n peroxidase (LIP) isozyme H8 from the white rot basidiomycete Phanero chaete chrysosporium demonstrates that LiP protein is detectable in th e extracellular media of 5- and 6-day-old nitrogen-limited, but not ni trogen-sufficient, cultures. Northern (RNA) blot analysis demonstrates that lip mRNA is detectable from 5- and 6-day old cells grown in nitr ogen-limited, but not nitrogen-sufficient, cultures. These results ind icate that LIP expression is regulated at the level of gene transcript ion by nutrient nitrogen. Since lignin degradation by P. chrysosporium is derepressed by nitrogen starvation, it appears that lignin degrada tion and LIP expression are coordinately regulated in this organism. T hese results contradict a recent report which concluded that LiP prote in expression is not regulated by nutrient nitrogen (C. G. Johnston an d S. D. Aust, Biochem. Biophys. Res. Commun. 200:108-112, 1994).