Department of Agriculture, Forestry and Bioresources, Seoul National University, Seoul, Korea.
Department of Applied Biosciences, Kyungpook National University, Daegu, Korea.
Plant Biol (Stuttg). 2024 Oct;26(6):1079-1087. doi: 10.1111/plb.13711. Epub 2024 Aug 23.
OsS1Fa1, a homologue of spinach S1Fa, is a small protein in rice that contains four distinct conserved motifs and participates in drought tolerance. However, the biological functions of these conserved motifs have not been characterized to date. Therefore, we investigated the roles of these conserved domains in the localization and cellular function of OsS1Fa1. We analysed the subcellular localization of OsS1Fa1 using confocal laser scanning microscopy (CLSM), following particle bombardment and bacterial infiltration. An E. coli in vivo reconstituted sumoylation assay was conducted to investigate sumoylation of OsS1Fa1. We characterized the function of the transmembrane domain of OsS1Fa1 in drought tolerance using transgenic Arabidopsis plants. Fluorescence analysis showed that OsS1Fa1 localized to the nuclear and cytoplasmic membranes. Mutation and cell fractionation analyses revealed that the membrane localization domain determined the subcellular localization of OsS1Fa1. The rice homologue OsS1Fa2 and Arabidopsis orthologs AtS1Fa1, AtS1Fa2, and AtS1Fa3 also exhibited similar localization patterns as OsS1Fa1. Sumoylation analysis demonstrated that OsS1Fa1 was conjugated with the small ubiquitin-related modifier (SUMO). Transgenic analysis showed that overexpression of OsS1Fa1(TMm1), a mutant form of the transmembrane domain of OsS1Fa1, in Arabidopsis did not enhance drought stress tolerance, whereas OsS1Fa1 overexpression improved the drought tolerance of transgenic Arabidopsis. Our data indicate that rice and Arabidopsis S1Fa1 proteins localize in the nuclear and cytoplasmic membranes, and that transmembrane domain determines subcellular localization and plays an important role in drought stress tolerance.
OsS1Fa1，菠菜 S1Fa 的同源物，是水稻中的一种小蛋白，含有四个不同的保守基序，参与耐旱性。然而，这些保守基序的生物学功能尚未得到表征。因此，我们研究了这些保守结构域在 OsS1Fa1 定位和细胞功能中的作用。我们使用共焦激光扫描显微镜（CLSM）分析了 OsS1Fa1 的亚细胞定位，随后进行了粒子轰击和细菌渗透。进行了大肠杆菌体内重新组装的 SUMOylation 测定，以研究 OsS1Fa1 的 SUMOylation。我们使用转基因拟南芥植物表征了 OsS1Fa1 跨膜结构域在耐旱性中的功能。荧光分析表明，OsS1Fa1 定位于核和细胞质膜。突变和细胞分级分析表明，膜定位域决定了 OsS1Fa1 的亚细胞定位。水稻同源物 OsS1Fa2 和拟南芥同源物 AtS1Fa1、AtS1Fa2 和 AtS1Fa3 也表现出与 OsS1Fa1 相似的定位模式。SUMOylation 分析表明，OsS1Fa1 与小泛素相关修饰物（SUMO）缀合。转基因分析表明，在拟南芥中过表达 OsS1Fa1(TMm1)，即 OsS1Fa1 跨膜结构域的突变形式，不会增强干旱胁迫耐受性，而 OsS1Fa1 的过表达提高了转基因拟南芥的耐旱性。我们的数据表明，水稻和拟南芥 S1Fa1 蛋白定位于核和细胞质膜，跨膜结构域决定亚细胞定位，并在耐旱性中发挥重要作用。
