Institute of Biochemical Plant Pathology, Helmholtz Zentrum München, German Research Center for Environmental Health, D-85764 Neuherberg, Germany.
Plant Cell. 2010 Aug;22(8):2894-907. doi: 10.1105/tpc.109.066464. Epub 2010 Aug 17.
The role of reactive oxygen and nitrogen species in local and systemic defense reactions is well documented. NPR1 and TGA1 are key redox-controlled regulators of systemic acquired resistance in plants. NPR1 monomers interact with the reduced form of TGA1, which targets the activation sequence-1 (as-1) element of the promoter region of defense proteins. Here, we report the effect of the physiological nitric oxide donor S-nitrosoglutathione on the NPR1/TGA1 regulation system in Arabidopsis thaliana. Using the biotin switch method, we demonstrate that both NPR1 and TGA1 are S-nitrosylated after treatment with S-nitrosoglutathione. Mass spectrometry analyses revealed that the Cys residues 260 and 266 of TGA1 are S-nitrosylated and S-glutathionylated even at GSNO concentrations in the low micromolar range. Furthermore, we showed that S-nitrosoglutathione protects TGA1 from oxygen-mediated modifications and enhances the DNA binding activity of TGA1 to the as-1 element in the presence of NPR1. In addition, we observed that the translocation of NPR1 into the nucleus is promoted by nitric oxide. Taken together, our results suggest that nitric oxide is a redox regulator of the NPR1/TGA1 system and that they underline the importance of nitric oxide in the plant defense response.
活性氧和氮物种在局部和全身防御反应中的作用已有充分的文献记载。NPR1 和 TGA1 是植物系统获得性抗性中关键的氧化还原调控因子。NPR1 单体与 TGA1 的还原形式相互作用，TGA1 靶向防御蛋白启动子区域的激活序列-1(as-1)元件。在这里，我们报告了生理一氧化氮供体 S-亚硝基谷胱甘肽对拟南芥 NPR1/TGA1 调控系统的影响。使用生物素开关法，我们证明 S-亚硝基谷胱甘肽处理后，NPR1 和 TGA1 都被 S-亚硝基化。质谱分析表明，TGA1 的 Cys 残基 260 和 266 即使在 GSNO 浓度处于低微摩尔范围内时，也被 S-亚硝基化和 S-谷胱甘肽化。此外，我们表明 S-亚硝基谷胱甘肽在存在 NPR1 的情况下保护 TGA1 免受氧介导的修饰，并增强 TGA1 与 as-1 元件的 DNA 结合活性。此外，我们观察到一氧化氮促进 NPR1 向核内易位。总之，我们的结果表明，一氧化氮是 NPR1/TGA1 系统的氧化还原调节剂，它们强调了一氧化氮在植物防御反应中的重要性。
