Shanghai Key Laboratory of Bio-energy Crops, Center of Plant Science, School of Life Sciences, Shanghai University, Shanghai 200444, China.
J Agric Food Chem. 2024 Oct 30;72(43):23908-23916. doi: 10.1021/acs.jafc.4c07925. Epub 2024 Oct 17.
To successfully colonize legume root nodules, rhizobia must effectively evade host-generated reactive oxygen species (ROS). LsrB, a redox regulator from , is essential for symbiosis with alfalfa (). The three cysteine residues in LsrB's substrate domain play distinct roles in activating downstream redox genes. The study found that LsrB's substrate-binding domain, dependent on the cysteine residue Cys146, is involved in oxidized glutathione (GSSG) resistance and alfalfa nodulation symbiosis. LsrB homologues from other rhizobia, with Cys172/Cys238 or Cys146, enhance GSSG resistance and complement mutant's symbiotic nodulation. Substituting amino acids in LsrB with Cys restores mutant phenotypes. The deletion mutant shows increased sensitivity to NCR247, suggesting an interaction with host plant-derived NCRs in alfalfa nodules. Our findings reveal that the key cysteine residue in the LsrB's substrate domain is vital for rhizobium-legume symbiosis.
为了成功定殖豆科植物根瘤，根瘤菌必须有效地逃避宿主产生的活性氧（ROS）。来自 的氧化还原调节剂 LsrB 对于与紫花苜蓿（）共生至关重要。LsrB 底物结构域中的三个半胱氨酸残基在激活下游氧化还原基因方面发挥着不同的作用。研究发现，LsrB 的底物结合域依赖于半胱氨酸残基 Cys146，参与氧化型谷胱甘肽（GSSG）抗性和紫花苜蓿结瘤共生。其他根瘤菌的 LsrB 同源物，带有 Cys172/Cys238 或 Cys146，增强了 GSSG 抗性并补充了 突变体的共生结瘤。用半胱氨酸取代 LsrB 中的氨基酸恢复了 突变体的表型。 缺失突变体对 NCR247 的敏感性增加，表明其与紫花苜蓿根瘤中宿主植物衍生的 NCRs 相互作用。我们的研究结果表明，LsrB 底物结构域中的关键半胱氨酸残基对根瘤菌-豆科植物共生至关重要。
