State Key Laboratory of Plant Environmental Resilience, Frontiers Science Center for Molecular Design Breeding, College of Biological Sciences, China Agricultural University, Beijing, China.
DP Technology, Beijing, China.
Nat Plants. 2023 Nov;9(11):1915-1923. doi: 10.1038/s41477-023-01550-6. Epub 2023 Oct 26.
The plasma membrane Na/H exchanger Salt Overly Sensitive 1 (SOS1) is crucial for plant salt tolerance. Unlike typical sodium/proton exchangers, SOS1 contains a large cytoplasmic domain (CPD) that regulates Na/H exchange activity. However, the underlying modulation mechanism remains unclear. Here we report the structures of SOS1 from Arabidopsis thaliana in two conformations, primarily differing in CPD flexibility. The CPD comprises an interfacial domain, a cyclic nucleotide-binding domain-like domain (CNBD-like domain) and an autoinhibition domain. Through yeast cell-based Na tolerance test, we reveal the regulatory role of the interfacial domain and the activation role of the CNBD-like domain. The CPD forms a negatively charged cavity that is connected to the ion binding site. The transport of Na may be coupled with the conformational change of CPD. These findings provide structural and functional insight into SOS1 activity regulation.
质膜 Na+/H+ 交换体盐过度敏感 1（SOS1）对于植物的耐盐性至关重要。与典型的钠离子/质子交换器不同，SOS1 含有一个调节 Na+/H+交换活性的大细胞质结构域（CPD）。然而，其潜在的调节机制尚不清楚。在这里，我们报告了拟南芥 SOS1 的两种构象的结构，主要区别在于 CPD 的灵活性。CPD 由界面域、环核苷酸结合域样结构域（CNBD 样结构域）和自动抑制结构域组成。通过酵母细胞耐钠测试，我们揭示了界面域的调节作用和 CNBD 样结构域的激活作用。CPD 形成一个带负电荷的空腔，与离子结合位点相连。Na 的转运可能与 CPD 的构象变化偶联。这些发现为 SOS1 活性调节提供了结构和功能方面的见解。
