Studies on Molecular Basis for Reactive Nitrogen Metabolism in Plants

植物活性氮代谢的分子基础研究

基本信息

批准号：
15570038
负责人：
SAKAMOTO Atsushi
金额：
$ 2.24万
依托单位：
HIROSHIMA UNIVERSITY
依托单位国家：
日本
项目类别：
Grant-in-Aid for Scientific Research (C)
财政年份：
2003
资助国家：
日本
起止时间：
2003 至 2004
项目状态：
已结题

项目摘要

(1)Arabidopsis 2-Cys Peroxiredoxin as Metabolic Enzyme for Reactive Nitrogen SpeciesPurified recombinant proteins of a thiol-dependent peroxidase called 2-Cys peroxiredoxin (2CPRX) from Arabidopsis were shown to metabolically scavenge peroxynitrite, a reactive nitrogen species (RNS) known as a potent oxidizing and nitrating agent. The Arabidopsis 2CPRX cDNA was functionally able to complement the hypersensitivity of a yeast mutant to nitrite-derived RNS. These results demonstrated a new role of plant 2CPRX as a critical determinant of the resistance to RNS, and support the existence of a plant enzymatic basis for RNS metabolism.(2)Functional relevance of Arabidopsis Non-Symbiotic Hemoglobin to Reactive Nitrogen SpeciesPlants ubiquitously contain non-symbiotic hemoglobins whose physiological role remains obscure. Purified recombinant proteins of an Arabidopsis non-symbiotic hemoglobin (AtGLB1) were shown to possess peroxidase-like activity that can oxidize nitrite as electron donor to f … More orm nitrogen dioxide radicals. AtGLB1 mRNA significantly accumulated in Arabidopsis seedlings that had been exposed to nitrite. These results support the physiological relevance of the function of AtGLB1 to nitrite and nitrite-derived RNS, and suggest a new possible route for RNS production in plants, apart from nitric-oxide (NO) biogenesis.(3)Plant-Physiological Impact of Molecular-Genetic Alteration in S-Nitrosothiol MetabolismS-Nitrosothiols (RSNO), a major form of RNS, are NO-adducts of thiol compounds such as S-nitrosoglutathione (GSNO) that is a representative RSNO with biological relevance. Overexpression of Arabidopsis GSNO reductase (GSNOR), the only known plant enzyme possibly involved in RSNO metabolism, led to a significant RSNO reduction in transgenic Arabidopsis. In contrast, knocking out the GSNOR gene resulted in RSNO over-accumulation. Metabolic studies of NO_2 assimilation in transgenic Arabidopsis overexpressing GSNOR suggested the existence of a crosstalk between RNS metabolism and the primary nitrogen assimilation. These results strongly indicate GSNOR as a key enzyme in RSNO metabolism and its potential importance in plant nitrogen metabolism. Less

（1）拟南芥含有反应性氮的反应性氮的拟南芥依赖性蛋白质的拟南芥重组蛋白，称为2-Cys过氧化物氧化毒素（2CPRX），从拟南芥中表现出称为2-Cys的过氧化物毒素（2CPRX），显示出代谢性的氧化剂，一种反应性的nitrite（Repoxynitrite）（Reactive nitrite（Recative nitrite））代理人。拟南芥2CPRX cDNA在功能上能够补充酵母突变体对亚硝酸盐衍生的RN的超敏反应。这些结果表明，植物2CPRX是对RN耐药性的关键决定剂的新作用，并支持植物酶基础的RNS代谢基础的存在。（2）拟南芥非生物血红蛋白的功能相关性与无效性氮种类无与伦比的物理作用，其物理性血压素的功能相关性。拟南芥非对称血红蛋白（ATGLB1）的纯化的重组蛋白显示出潜在的过氧化物酶样活性，可以将氧化物亚硝酸盐作为f…f…更多ORM氮二氧化物自由基的电子供体。 ATGLB1 mRNA在暴露于亚硝酸盐的拟南芥幼苗中显着加速。 These results support the physical relevance of the function of AtGLB1 to nitrite and nitrite-derived RNS, and suggest a new possible route for RNS production in Plants, apart from nitric-oxide (NO) biogenesis.(3)Plant-Physiological Impact of Molecular-Genetic Alteration in S-Nitrosothiol MetabolismS-Nitrosothiol (RSNO), a major form of RNS, are无硫醇化合物（例如S-硝基谷硫硫代（GSNO））是具有生物学相关性的RSNO的硫醇化合物。拟南芥GSNO还原酶（GSNOR）的过表达，这是唯一可能参与RSNO代谢的植物酶，导致转基因拟南芥的RSNO显着降低。相比之下，淘汰GSNOR基因会导致RSNO过度累积。转基因拟南芥中过表达GSNOR中NO_2同化的代谢研究表明，RNS代谢与主要的氮同化之间存在串扰。这些结果强烈表明GSNOR是RSNO代谢的关键酶及其在植物氮代谢中的潜在重要性。较少的