Nitric Oxide (NO) Production by Plant Nitrate Reductase

植物硝酸还原酶产生一氧化氮 (NO)

基本信息

批准号：
12660048
负责人：
YAMASAKI Hideo
金额：
$ 0.64万
依托单位：
University of the Ryukyus
依托单位国家：
日本
项目类别：
Grant-in-Aid for Scientific Research (C)
财政年份：
2000
资助国家：
日本
起止时间：
2000 至 2002
项目状态：
已结题

来源：
https://kaken.nii.ac.jp/grant/KAKENHI-PROJECT-12660048/
关键词：
nitric oxide nitrate reductase nitrogen assimilation reactive oxygen reactive nitrogen peroxynitrite NOS plant 植物生理ストレス NO 気孔シグナル伝達バイアグラ酸化的ストレス

项目摘要

Nitric oxide (NO) is an important molecule that is involved in diverse physiological functions of living organisms. It has been shown that NO can produced endogenously by NO synthase (NOS, EC 1.14.13.39) in vertebrate, invertebrates and bacteria. In contrast, the mechanism for enzymatic NO production in plants and algae is still in debate. Until recently, NOS had been presumed as the only enzyme that could produce NO in plant cells. Despite many efforts to identify a gene and protein similar to mammalian-type NOS, however, there has been no substantial evidence to conclude the presence of such NOS in plants. We have proposed an alternative NO production mechanism for plants. Nitrate reductase (NR) is a well-known protein for plant biologists because it is a key enzyme of nitrate assimilation metabolism. The enzyme normally catalyzes the reduction of nitrate to form nitrite using NAD(P)H. we have shown that the enzyme is capable of further reducing the product nitrite to produce NO as the result. Importantly, NO can be subsequently converted to peroxynitrite, the most toxic active nitrogen, under aerobic conditions. Although we cannot exclude a possibility for discovering a new type NOS that is unique to plants, it is now evident that plants do produce NO by the distinct mechanism from animals. These findings, the classical enzyme possessing unexplored important functions, offers us a new opportunity to re-consider and re-investigate plant biology with integrated knowledge in terms of "NO".

一氧化氮（NO）是一种重要的分子，参与生物体的多种生理功能。研究表明，脊椎动物、无脊椎动物和细菌中的NO合酶（NOS，EC 1.14.13.39）可以内源性产生NO。相比之下，植物和藻类中酶促产生一氧化氮的机制仍存在争议。直到最近，NOS 还被认为是植物细胞中唯一能产生 NO 的酶。尽管为鉴定与哺乳动物型NOS相似的基因和蛋白质做出了许多努力，然而，还没有实质性证据表明植物中存在这种NOS。我们为植物提出了一种替代的 NO 生产机制。硝酸盐还原酶（NR）是植物生物学家熟知的蛋白质，因为它是硝酸盐同化代谢的关键酶。该酶通常利用 NAD(P)H 催化硝酸盐还原形成亚硝酸盐。我们已经证明，该酶能够进一步还原亚硝酸盐产物，从而产生 NO。重要的是，在有氧条件下，NO 随后可以转化为过氧亚硝酸盐，这是毒性最强的活性氮。虽然我们不能排除发现植物特有的新型 NOS 的可能性，但现在很明显，植物确实通过与动物不同的机制产生 NO。这些发现，经典酶具有未被探索的重要功能，为我们提供了一个新的机会，以“NO”的综合知识重新思考和研究植物生物学。