Regulation of Manganese Peroxidase Gene Expression

锰过氧化物酶基因表达的调控

• 批准号: 9723725
• 负责人: Michael Gold
• 金额: $ 31.5万
• 依托单位: Oregon Health & Science University
• 依托单位国家: 美国
• 项目类别: Continuing Grant
• 财政年份: 1997
• 资助国家: 美国
• 起止时间: 1997-09-15 至 2002-12-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=9723725&HistoricalAwards=false
• 关键词: Regulation; Manganese; Peroxidase; Gene; Expression

Gold 9723725 The lignin degradative system (LDS) of the white-rot basidiomycetous fungus Phanerochaete chrysosporium degrades the plant cell wall polymer, lignin, and a wide range of aromatic pollutants. The major extracellular components of this nonspecific oxidative system are two 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 the depletion of nutrient nitrogen. MnP expression also is regulated at the level of gene transcription by Mn ion, by heat shock, and by oxidative stress. The primary goal of this project is to elucidate these specific mechanisms of mnp gene transcription at the molecular level. New mnp promoter-gene reporter constructs will be used to examine the regulation of individual mnp genes by nitrogen, Mn, and heat shock. The cis-acting promoter sequences involved in mnp regulation using site-directed mutagenesis of putative metal response elements, promoter deletion analysis, and synthetic promoter elements will be identified. The putative Mn-responsive transcription factor will be identified and purified, and genes encoding the Mn-responsive and heat shock transcription factors will be cloned. Finally, the post-transcriptional requirements for MnP synthesis will be examined further. Lignin is the second most abundant natural polymer, constituting 15-30% of woody plant cell walls, and forming a matrix that surrounds the cellulose in wood. Thus, the degradation of lignin is a significant step in the global carbon cycle. Furthermore, lignin presents a major obstacle to the industrial utilization of cellulose. White-rot fungi are the only organisms which can completely degrade lignin to carbon dioxide and water. The best studied of these fungi, Phanerochaete chrysosporium, efficiently degrades lignin and a wide range of environmental pollutants. P. chrysosporium and other lignin-degrading fungi secrete the enzyme manganese peroxidase (Mn P). This enzyme oxidizes manganese ion (Mn) which, in turn, depolymerizes lignin. The production of MnP is regulated at the level of the gene by the depletion of nutrient nitrogen, by the availability of Mn, and by temperature and chemical stresses. The goal of this research is to understand, at the molecular level, the mechanisms by which each of these factors control MnP production. This is the first example of Mn regulation of gene expression to be studied at the molecular level.

金9723725白腐担子菌真菌黄孢原毛革菌的木质素降解系统（LDS）降解植物细胞壁聚合物、木质素和广泛的芳香族污染物。 这种非特异性氧化系统的主要细胞外组分是两种含血红素的过氧化物酶，锰过氧化物酶（MnP）和木质素过氧化物酶（LiP）。 LDS在次级代谢生长期间表达，其开始由营养氮的消耗触发。 锰磷酸酶的表达也受到锰离子、热休克和氧化应激在基因转录水平上的调节。 本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。 新的mnp启动子基因报告构建体将被用来检查个别mnp基因的氮，锰和热休克的调节。 使用定点诱变推定的金属反应元件，启动子缺失分析，和合成启动子元件参与mnp调控的顺式作用启动子序列将被确定。 将鉴定和纯化推定的Mn响应性转录因子，并克隆编码Mn响应性转录因子和热休克转录因子的基因。 最后，将进一步研究MNP合成的转录后要求。 木质素是第二丰富的天然聚合物，占木本植物细胞壁的15-30%，并形成围绕木材中纤维素的基质。 因此，木质素的降解是全球碳循环中的重要一步。 此外，木质素是纤维素工业利用的主要障碍。 白腐真菌是唯一能将木质素完全降解为二氧化碳和水的生物。 这些真菌中研究得最好的是黄孢原毛平革菌，它能有效地降解木质素和各种环境污染物。 黄孢原毛平革菌和其它木质素降解真菌分泌锰过氧化物酶（Mn P）。 这种酶氧化锰离子（Mn），锰离子又解聚木质素。 锰过氧化物酶的产生在基因水平上受营养氮的消耗、锰的利用率以及温度和化学胁迫的调节。 本研究的目标是在分子水平上了解这些因素中的每一个控制MnP产生的机制。 这是锰调控基因表达的第一个例子，在分子水平上进行研究。