A novel NADPH thioredoxin reductase, localized in the chloroplast, which deficiency causes hypersensitivity to abiotic stress in Arabidopsis thaliana
A novel NADPH thioredoxin reductase, localized in the chloroplast, which deficiency causes hypersensitivity to abiotic stress in Arabidopsis thaliana
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DOI：
10.1074/jbc.m404696200
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发表时间：
2004-10-15
影响因子：
4.8
通讯作者：
Cejudo, FJ
中科院分区：
文献类型：
--
作者：
Serrato, AJ;Pérez-Ruiz, JM;Cejudo, FJ
植物含有三个硫氧还蛋白系统。叶绿体硫氧还蛋白通过铁氧还蛋白-硫氧还蛋白还原酶还原，而细胞质和线粒体硫氧还蛋白通过NADPH硫氧还蛋白还原酶（NTR）还原。植物、低等真核生物和细菌的NTR具有较高的相似性，与哺乳动物的NTR不同。在这里，我们描述了来自水稻的OsNTRC基因编码一个新的NTR，在C端有一个硫氧还蛋白样结构域，因此，一个假定的NTR/硫氧还蛋白系统在一个多肽中。在其他植物和蓝藻中发现了同源基因，但在细菌、酵母或哺乳动物中没有发现。在大肠杆菌中以his标记多肽的形式表达全长OsNTRC和截断NTR和硫氧还蛋白结构域的构建体，并构建了与OsNTRC酶特异性交叉反应的多克隆抗体。体外活性分析表明，OsNTRC是一种具有NTR和硫氧还蛋白活性的双功能酶，但不是NTR/硫氧还蛋白系统。虽然OsNTRC基因在水稻幼苗的根和芽中表达，但该蛋白仅在芽和成熟叶片中发现。此外，分离实验表明，OsNTRC定位于叶绿体。拟南芥NTRC敲除突变体表现出生长抑制和对甲基紫菌、干旱和盐胁迫的超敏反应。这些结果表明NTRC基因参与了植物抗氧化应激的保护。
Plants contain three thioredoxin systems. Chloroplast thioredoxins are reduced by ferredoxin-thioredoxin reductase, whereas the cytosolic and mitochondrial thioredoxins are reduced by NADPH thioredoxin reductase (NTR). There is high similarity among NTRs from plants, lower eukaryotes, and bacteria, which are different from mammal NTR. Here we describe the OsNTRC gene from rice encoding a novel NTR with a thioredoxin-like domain at the C terminus, hence, a putative NTR/thioredoxin system in a single polypeptide. Orthologous genes were found in other plants and cyanobacteria, but not in bacteria, yeast, or mammals. Full-length OsNTRC and constructs with truncated NTR and thioredoxin domains were expressed in Escherichia coli as His-tagged polypeptides, and a polyclonal antibody specifically cross-reacting with the OsNTRC enzyme was raised. An in vitro activity assay showed that OsNTRC is a bifunctional enzyme with both NTR and thioredoxin activity but is not an NTR/thioredoxin system. Although the OsNTRC gene was expressed in roots and shoots of rice seedlings, the protein was exclusively found in shoots and mature leaves. Moreover, fractionation experiments showed that OsNTRC is localized to the chloroplast. An Arabidopsis NTRC knock-out mutant showed growth inhibition and hypersensitivity to methyl viologen, drought, and salt stress. These results suggest that the NTRC gene is involved in plant protection against oxidative stress.