论文题目：Persulfidation of host NADPH oxidase RbohB by rhizobial 3-mercaptopyruvate sulfurtransferase maintains redox homeostasis and promotes symbiotic nodulation in soybean
论文作者：Weiqin Zhang, Wuyu Liu, Kai Wang, Huaping Cheng, Xiaoli Bai, Jianhua Zhang, Gehong Wei, Juan Chen
论文摘要：
Reactive oxygen species (ROS) play a crucial role in various stages of legume-rhizobium symbiosis, from initial nodulation signaling to nodule senescence. However, how rhizobial redox-related proteins regulate symbiotic nodulation in legumes remains largely unknown. By combining transcriptomics, proteomics, and biochemical and molecular genetics, we investigated the role of the Sinorhizobium fredii Q8 enzyme 3-mercaptopyruvate sulfurtransferase (3MST). Although 3MST was not the primary source of hydrogen sulfide (H2S) under our conditions, its absence significantly disrupted symbiotic nodule development, redox homeostasis, infection capacity, and nitrogen fixation efficiency in soybean. We identified host plasma membrane-localized NADPH oxidase (RbohB) as a pivotal regulator that activates immune responses during nodule development. Notably, 3MST localized to the nucleoid and cytoplasmic membrane and was secreted during nodulation, where it interacted with RbohB and persulfidated Cys791 to suppress NADPH oxidase activity. This 3MST-mediated regulation maintained symbiotic redox balance and promoted nodule development. Genetic analysis of soybean involving RbohB overexpression, RNA interference and site-directed mutagenesis at Cys791 supported the model, linking the 3MST-RbohB interaction to effective rhizobial colonization and improved plant growth. Collectively, our findings shed light on a rhizobium-host redox pathway in which a rhizobial sulfurtransferase modulates RbohB via persulfidation to promote nodulation.
活性氧（ROS）在豆科植物与根瘤菌共生的多个阶段中发挥关键作用，从结瘤初期的信号传导到根瘤衰老均不可或缺。然而，根瘤菌的氧化还原相关蛋白如何调控豆科植物的共生结瘤仍知之甚少。本研究结合转录组学、蛋白质组学以及生化与分子遗传学的方法，系统探讨了 Sinorhizobium fredii Q8中的3-巯基丙酮酸硫转移酶（3MST）的作用。结果表明，尽管在本研究条件下3MST并非硫化氢（H2S）的主要来源，但其缺失显著破坏了大豆的共生根瘤发育、氧化还原稳态、侵染能力以及固氮效率。本研究鉴定出宿主质膜定位的NADPH 氧化酶RbohB是结瘤发育过程中激活免疫反应的重要调控因子。值得注意的是，3MST定位于拟核和胞质膜，并在结瘤过程中被分泌，与RbohB相互作用并对其Cys791残基进行硫巯基化修饰，从而抑制NADPH氧化酶活性。这一调控机制有效维持了共生过程中的氧化还原平衡并促进根瘤发育。对大豆进行的遗传学分析，包括RbohB的过表达、RNA干扰及 Cys791位点的定点突变，进一步支持了该机制，揭示了3MST-RbohB相互作用在根瘤菌有效定殖与宿主生长促进中的作用。综上，本研究揭示了一条根瘤菌-宿主氧化还原通路，即根瘤菌来源的硫转移酶通过硫巯基化修饰调控RbohB，从而促进结瘤。本研究不仅深化了我们对共生固氮过程中氧化还原平衡调控的理解，也为提高豆科作物固氮效率提供了新的分子靶点。通过调控3MST的表达或活性，或者精确修饰RbohB的过硫化状态，有望开发出减少化肥依赖、提高作物产量的新策略。
论文链接：https://www.cell.com/molecular-plant/fulltext/S1674-2052(25)00319-3