The protein kinase SOS2 activates the Arabidopsis H+/Ca2+ antiporter CAX1 to integrate calcium transport and salt tolerance
The protein kinase SOS2 activates the Arabidopsis H+/Ca2+ antiporter CAX1 to integrate calcium transport and salt tolerance
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DOI：
10.1074/jbc.m309084200
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发表时间：
2004-01-23
影响因子：
4.8
通讯作者：
Hirschi, KD
中科院分区：
文献类型：
--
作者：
Cheng, NH;Pittman, JK;Hirschi, KD
细胞内离子的调节是生长和适应不可或缺的组成部分。植物SOS 2蛋白激酶及其相关的Ca 2+传感器SOS 3已被证明可以调节质膜H+/ Na+反向转运蛋白SOS 1;然而，这些调节剂如何调节细胞内的Ca 2+水平却知之甚少。在这里，我们表明，SOS 2调节液泡H+/Ca 2+逆向转运蛋白CAX 1。使用酵母生长测定，SOS 2的共表达特异性激活CAX 1，而SOS 3没有。如果嵌合蛋白含有CAX 1的N末端，则CAX 1样嵌合转运蛋白被SOS 2激活。通过以剂量依赖性方式添加SOS 2蛋白，使来自CAX 1表达细胞的质膜具有H+/Ca 2+感受态。使用酵母双杂交测定，SOS 2与CAX 1的N末端相互作用。在这些酵母试验中，SOS 2对CAX 1的激活是不依赖于SOS 3的。在植物中，CAX 1的失调版本的高水平表达引起盐敏感性。这些研究结果表明，多功能的SOS 2和植物中的Ca 2+和Na+的稳态之间提供了一个机制的联系。
The regulation of ions within cells is an indispensable component of growth and adaptation. The plant SOS2 protein kinase and its associated Ca2+ sensor, SOS3, have been demonstrated to modulate the plasma membrane H+/ Na+ antiporter SOS1; however, how these regulators modulate Ca2+ levels within cells is poorly understood. Here we demonstrate that SOS2 regulates the vacuolar H+/Ca2+ antiporter CAX1. Using a yeast growth assay, co-expression of SOS2 specifically activated CAX1, whereas SOS3 did not. CAX1-like chimeric transporters were activated by SOS2 if the chimeric proteins contained the N terminus of CAX1. Vacuolar membranes from CAX1-expressing cells were made to be H+/Ca2+-competent by the addition of SOS2 protein in a dose-dependent manner. Using a yeast two-hybrid assay, SOS2 interacted with the N terminus of CAX1. In each of these yeast assays, the activation of CAX1 by SOS2 was SOS3-independent. In planta, the high level of expression of a deregulated version of CAX1 caused salt sensitivity. These findings suggest multiple functions for SOS2 and provide a mechanistic link between Ca2+ and Na+ homeostasis in plants.