Accumulating evidence suggests that hydrogen sulfide (H2S) is a gaseous signaling molecule that regulates diverse cellular signaling pathways through persulfidation, which involves the post translational modification (PTM) of specific cysteine residues to form persulfides. However, the mechanisms that underlie this important redox-based PTM remain poorly understood in higher plants. We have, therefore, analyzed how protein persulfidation acts as a specific and reversible signaling mechanism during the plant abscisic acid (ABA) response. Here we show that ABA stimulates the persulfidation of L-cysteine desulfhydrase 1 (DES1), an important endogenous H2S enzyme, at Cys44 and Cys205 in a redox-dependent manner. Moreover, sustainable H2S accumulation drives persulfidation of the NADPH oxidase respiratory burst oxidase homolog protein D (RBOHD) at Cys825 and Cys890, which enhance its ability to produce reactive oxygen species. Physiologically, S-persulfidation-induced RBOHD activity is relevant to ABA-induced stomatal closure. Together, these processes form a negative feedback loop that fine-tunes guard cell redox homeostasis and ABA signaling. These findings not only expand our current knowledge of H2S function in the context of guard cell ABA signaling, but also demonstrate the presence of a rapid signal integration mechanism involving specific and reversible redox-based PTMs that occur in response to changing environmental conditions.

越来越多的证据表明，硫化氢（H2S）是一种气体信号分子，通过过硫化作用来调节多种细胞信号传导途径，这涉及特定半胱氨酸残基的翻译后修饰（PTM）以形成过硫化物。但是，这种基于氧化还原的重要PTM的机理在高等植物中仍然知之甚少。因此，我们已经分析了蛋白质过硫化如何在植物脱落酸（ABA）反应期间作为一种特定且可逆的信号转导机制起作用。在这里，我们显示ABA以氧化还原依赖性方式刺激Cys44和Cys205的L-半胱氨酸脱硫酶1（DES1）（一种重要的内源H2S酶）的过硫化作用。此外，可持续的H2S积累会驱动Cys825和Cys890上NADPH氧化酶呼吸爆发氧化酶同源蛋白D（RBOHD）的过硫化，从而增强其产生活性氧的能力。在生理上，S-过硫化诱导的RBOHD活性与ABA诱导的气孔关闭有关。这些过程共同形成一个负反馈回路，可微调保卫细胞氧化还原稳态和ABA信号传导。这些发现不仅扩展了我们目前在保卫细胞ABA信号传导方面对H2S功能的了解，而且还证明了快速信号整合机制的存在，该机制涉及响应于变化的环境条件而发生的特定且可逆的基于氧化还原的PTM。S-过硫化诱导的RBOHD活性与ABA诱导的气孔关闭有关。这些过程共同形成一个负反馈回路，可微调保卫细胞氧化还原稳态和ABA信号传导。这些发现不仅扩展了我们目前在保卫细胞ABA信号传导方面对H2S功能的了解，而且还证明了快速信号整合机制的存在，该机制涉及响应于变化的环境条件而发生的特定且可逆的基于氧化还原的PTM。S-过硫化诱导的RBOHD活性与ABA诱导的气孔关闭有关。这些过程共同形成一个负反馈回路，可微调保卫细胞氧化还原稳态和ABA信号传导。这些发现不仅扩展了我们目前在保卫细胞ABA信号传导方面对H2S功能的了解，而且还证明了快速信号整合机制的存在，该机制涉及响应于变化的环境条件而发生的特定且可逆的基于氧化还原的PTM。