Regulation of Manganese Peroxidase Gene Expression

9405978金白腐担子菌黄孢原毛平革菌的木质素降解系统能够降解植物细胞壁聚合物、木质素和一系列芳香污染物。这个非特异性氧化系统的主要成分是两种胞外含血红素的过氧化物酶，即锰过氧化物酶(MNP)和木质素过氧化物酶(LIP)。LDS在次生代谢期表达，次生代谢期由限制营养氮启动。此外，锰离子、热激和化学胁迫也在基因转录水平上调控着MNP的表达。该项目的主要目标是在分子水平上阐明MNP基因转录的这些特定机制。在氮和碳限制的条件下，分析了锰、热激和H_2O_2对单个MNP基因的调控。定点突变、缺失分析和合成启动子元件正被用于鉴定锰和热休克调节所需的顺式作用序列。DNaseI足迹和凝胶迁移率改变分析将被用来检测可能的DNA结合转录因子。将比较锰和热休克诱导的锰核糖核酸，并研究转录后锰需求的可能性。黄孢原毛平革菌的木质素降解系统(LDS)能够降解植物细胞壁聚合物、木质素和一系列芳香污染物。这个项目的主要目标是确定是什么导致参与这种降解的酶的基因被打开和关闭。这项工作最终可能有助于消除环境中的污染物。

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.