Photorespiratory hydrogen peroxide (H2 O2 ) plays key roles in pathogenesis responses by triggering the salicylic acid (SA) pathway in Arabidopsis. However, factors linking intracellular H2 O2 to activation of the SA pathway remain elusive. In this work, the catalase-deficient Arabidopsis mutant, cat2, was exploited to elucidate the impact of S-nitrosoglutathione reductase 1 (GSNOR1) on H2 O2 -dependent signalling pathways. Introducing the gsnor1-3 mutation into the cat2 background increased S-nitrosothiol levels and abolished cat2-triggered cell death, SA accumulation, and associated gene expression but had little additional effect on the major components of the ascorbate-glutathione system or glycolate oxidase activities. Differential transcriptome profiles between gsnor1-3 and cat2 gsnor1-3 together with damped ROS-triggered gene expression in cat2 gsnor1-3 further indicated that GSNOR1 acts to mediate the SA pathway downstream of H2 O2 . Up-regulation of GSNOR activity was compromised in cat2 cad2 and cat2 pad2 mutants in which glutathione accumulation was genetically prevented. Experiments with purified recombinant GSNOR revealed that the enzyme is posttranslationally regulated by direct denitrosation in a glutathione-dependent manner. Together, our findings identify GSNOR1-controlled nitrosation as a key factor in activation of the SA pathway by H2 O2 and reveal that glutathione is required to maintain this biological function.

中文翻译：

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谷胱甘肽依赖的GSNOR1的亚硝化促进H2 O2下游的氧化信号传导。

光呼吸过氧化氢（H2 O2）通过触发拟南芥中的水杨酸（SA）途径在发病机理中起关键作用。但是，将细胞内H2 O2与SA途径活化相关联的因素仍然难以捉摸。在这项工作中，利用过氧化氢酶缺陷的拟南芥突变体cat2来阐明S-亚硝基谷胱甘肽还原酶1（GSNOR1）对H2 O2依赖性信号通路的影响。将gsnor1-3突变引入cat2背景可增加S-亚硝基硫醇水平，并消除cat2触发的细胞死亡，SA积累和相关基因表达，但对抗坏血酸-谷胱甘肽系统或乙醇酸氧化酶活性的主要成分几乎没有附加影响。gsnor1-3和cat2 gsnor1-3之间的差异转录组谱以及cat2 gsnor1-3中受ROS触发的阻尼基因表达进一步表明GSNOR1发挥了介导H2 O2下游的SA途径的作用。GSNOR活性的上调在cat2 cad2和cat2 pad2突变体中受到损害，在突变体中，谷胱甘肽的积累被遗传地阻止了。使用纯化的重组GSNOR进行的实验表明，该酶在谷胱甘肽依赖性方式下被直接脱氮后翻译后调控。总之，我们的发现将GSNOR1控制的亚硝化确定为H2 O2激活SA途径的关键因素，并揭示了维持这种生物学功能需要谷胱甘肽。GSNOR活性的上调在cat2 cad2和cat2 pad2突变体中受到损害，在突变体中，谷胱甘肽的积累被遗传地阻止了。使用纯化的重组GSNOR进行的实验表明，该酶在谷胱甘肽依赖性方式下被直接脱氮后翻译后调控。总之，我们的发现将GSNOR1控制的亚硝化确定为H2 O2激活SA途径的关键因素，并揭示了维持这种生物学功能需要谷胱甘肽。GSNOR活性的上调在cat2 cad2和cat2 pad2突变体中受到损害，在这些突变体中，谷胱甘肽的积累被遗传地阻止了。使用纯化的重组GSNOR进行的实验表明，该酶在谷胱甘肽依赖性方式下被直接脱氮后翻译后调控。总之，我们的发现将GSNOR1控制的亚硝化确定为H2 O2激活SA途径的关键因素，并揭示了维持这种生物学功能需要谷胱甘肽。