9405978 Gold The lignin degradative system (LDS) of the white rot basidiomycetous fungus Phanerochaete chrysosporium is capable of degrading the plant cell wall polymer, lignin, and a range of aromatic pollutants. The major components of this nonspecific oxidative system are two extracellular heme-containing peroxidases, manganese peroxidase (MnP) and lignin peroxidase (LiP). The LDS is expressed during secondary metabolic growth, the onset of which is triggered by limiting nutrient nitrogen. MnP expression also is regulated at the level of gene transcription by Mn ion and by heat shock and chemical stress. The primary goal of the project is to elucidate on the molecular level these specific mechanisms of mnp gene transcription. Mn, heat shock and H2O2 regulation of individual mnp genes will be analyzed under conditions of nitrogen and carbon limitation. Site-directed mutagenesis, deletion analysis and synthetic promoter elements are being used to identify the cis-acting sequences required for Mn and heat shock regulation. DNaseI footprinting and gel mobility shift assays will be used to assay putative DNA-binding transcription factors. Mn and heat shock-induced mnp mRNAs will be compared and the possibility of a post-transcriptionial Mn requirement will be examined. %%% The lignin degradative system (LDS) of the fungus Phanerochaete chrysosporium is capable of degrading the plant cell wall polymer, lignin, and a range of aromatic pollutants. The primary goal of this project is to determine what causes the genes for the enzymes involved in this degradation to be turned on and off. This work may ultimately help in the removal of pollutants from the environment.
