Phosphorylation of SOS3-LIKE CALCIUM BINDING PROTEIN8 by SOS2 Protein Kinase Stabilizes Their Protein Complex and Regulates Salt Tolerance in Arabidopsis
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>Phosphorylation of SOS3-LIKE CALCIUM BINDING PROTEIN8 by SOS2 Protein Kinase Stabilizes Their Protein Complex and Regulates Salt Tolerance in Arabidopsis
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Phosphorylation of SOS3-LIKE CALCIUM BINDING PROTEIN8 by SOS2 Protein Kinase Stabilizes Their Protein Complex and Regulates Salt Tolerance in Arabidopsis
n nnnThe Salt Overly Sensitive (SOS) pathway plays an important rolein the regulation of Na+/K+ ion homeostasis and salt tolerancein Arabidopsis thaliana. Previously, we reported that the calciumbinding proteins SOS3 and SOS3-LIKE CALCIUM BINDING PROTEIN8(SCaBP8) nonredundantly activate the protein kinase SOS2. Here,we show that SOS2 phosphorylates SCaBP8 at its C terminus butdoes not phosphorylate SOS3. In vitro, SOS2 phosphorylationof SCaBP8 was enhanced by the bimolecular interaction of SOS2and SCaBP8 and did not require calcium ions. In vivo, this phosphorylationwas induced by salt stress, occurred at the membrane, stabilizedthe SCaBP8-SOS2 interaction, and enhanced plasma membrane Na+/H+exchange activity. When a Ser at position 237 in the SCaBP8protein (the SOS2 phosphorylation target) was mutated to Ala,SCaBP8 was no longer phosphorylated by SOS2 and the mutant proteincould not fully rescue the salt-sensitive phenotype of the scabp8mutant. By contrast, when Ser-237 was mutated to Asp to mimicthe charge of a phosphorylated Ser residue, the mutant proteinrescued the scabp8 salt sensitivity. These data demonstratethat calcium sensor phosphorylation is a critical componentof SOS pathway regulation of salt tolerance in Arabidopsis.展开▼
机译:ABSTRACTn FONT> TH> TR> TABLE> n
n TOP n <字体颜色= 464c53>抽象 FONT> n 介绍 n 结果 n 讨论 n 方法 n 参考文献 n FONT> TH> TR> TABLE> n nnn盐分过度敏感(SOS)途径在t中起着重要的作用 SUP>拟南芥中Na + SUP> / K + SUP>离子稳态和耐盐性 SUP>的调节。以前,我们报道了钙 SUP>结合蛋白SOS3和SOS3-Like钙结合蛋白8 SUP>(SCaBP8)非冗余地激活了蛋白激酶SOS2。在这里, SUP>我们显示SOS2在其C末端使SCaBP8磷酸化,但 SUP>却没有将SOS3磷酸化。在体外,SOS2 SUP>和SCaBP8的双分子相互作用增强了SCaBP8的SOS2磷酸化 SUP>,并且不需要钙离子。在体内,这种磷酸化 SUP>是由盐胁迫诱导的,发生在膜上,稳定了 SUP> SCaBP8-SOS2的相互作用,并增强了质膜Na + SUP> / H + SUP> SUP>交换活动。当SCaBP8 SUP>蛋白(SOS2磷酸化目标)中第237位的Ser突变为Ala时, SUP> SCaBP8不再被SOS2磷酸化,突变蛋白 < / SUP>无法完全挽救 scabp8 I> SUP>突变体的盐敏感性表型。相反,当Ser-237突变为Asp以模仿磷酸化Ser残基的电荷时,突变蛋白 SUP>降低了 scabp8 I>的盐敏感性。这些数据证明 SUP>,钙传感器磷酸化是拟南芥 I>中耐盐性的SOS途径调控盐耐受性的关键组成部分。 SUP>
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