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首页> 外文期刊>Trends in Plant Science >Response to Zemojtel et al: Plant nitric oxide synthase: AtNOS1 is just the beginning
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Response to Zemojtel et al: Plant nitric oxide synthase: AtNOS1 is just the beginning

机译：对Zemojtel等人的回应：植物一氧化氮合酶：AtNOS1仅仅是开始

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In plants, nitric oxide synthase (NOS) activity has been detected in several plant species when mammalian NOS inhibitors have been used to inhibit NO production [1]. One of the most frustrating aspects of research on NOS-dependent NO biosynthesis in plants is that although NOS activity has been detected in plants, no gene or protein with a sequence similar to mammalian NOS has been found in the sequenced Arabidopsis genome. These findings indicate that plants have a different NOS enzyme. AtNOS1 was first identified during a search for an Arabidopsis homologous protein with a sequence similarity to a distinct NOS that was characterized in the nervous system of the snail Helix pomatia. The snail NOS gene encodes a 60 kDa protein with no sequence homology to mammalian NOS isoforms and, when expressed in Escherichia coli, increases NO synthesis in crude extracts [2]. The role of AtNOS1 in NO biosynthesis in vivo was examined in a homozygous mutant line, Atnos1, and was measured with 4,5-diaminofluorescein diacetate (DAF-2 DA) dye. NO levels were found to be much lower in roots of Atnos1 mutant plants compared with wild type when grown on plates or treated with abscisic acid (ABA). More importantly, NOS activity in protein extracts from the mutant leaves was only 20% of the activity in wild-type extracts [3]. Other laboratories have confirmed these findings - they have reported that Atnos1 is 20% of the wild-type level of NO measured using NO-specific electrodes [4] and using 4-amino-5-methylamino-2',7'-difluorofluorescein (DAF-FM) fluorescence in Arabidopsis leaves [5]. In addition, the Atnos1 mutant shows a dramatic increase in susceptibility to the bacterial pathogen Pseudomonas syringae [5] and reduced NO production in response to ABA [6]. Theseresults show that AtNOS1 is an important source of NO, needed not only for signaling but also for plant defense responses.
机译：在植物中，当使用哺乳动物NOS抑制剂抑制NO产生时，已经在几种植物中检测到一氧化氮合酶（NOS）活性[1]。植物中依赖NOS的NO生物合成研究中最令人沮丧的方面之一是，尽管已在植物中检测到NOS活性，但在测序的拟南芥基因组中未发现与哺乳动物NOS序列相似的基因或蛋白质。这些发现表明植物具有不同的NOS酶。首先在寻找拟南芥同源蛋白期间发现了AtNOS1，该蛋白与在蜗牛螺旋果树的神经系统中表征的独特NOS具有相似的序列相似性。蜗牛的NOS基因编码一个60 kDa的蛋白质，与哺乳动物的NOS亚型没有序列同源性，当在大肠杆菌中表达时，会增加粗提物中的NO合成[2]。在纯合突变体Atnos1中检查了AtNOS1在体内NO生物合成中的作用，并用4,5-二氨基荧光素二乙酸酯（DAF-2 DA）染料进行了测定。当在平板上生长或用脱落酸（ABA）处理时，与野生型相比，Atnos1突变植物的根中未发现NO水平低得多。更重要的是，突变叶蛋白质提取物中的NOS活性仅为野生型提取物中NOS活性的20％[3]。其他实验室也证实了这些发现-他们报告说Atnos1是使用NO特异性电极[4]和使用4-amino-5-methylamino-2'，7'-difluorofluorescein（4）测定的野生型NO的20％。拟南芥叶片中的DAF-FM）荧光[5]。此外，Atnos1突变体对细菌病原体丁香假单胞菌的敏感性显着提高[5]，并且对ABA的响应降低了NO的产生[6]。这些结果表明，AtNOS1是重要的NO来源，不仅需要信号传导，而且还需要植物防御反应。

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