A novel chloride channel in Vicia faba guard cell vacuoles activated by the serine/threonine kinase, CDPK
A novel chloride channel in Vicia faba guard cell vacuoles activated by the serine/threonine kinase, CDPK
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DOI：
10.1002/j.1460-2075.1996.tb01047.x
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发表时间：
1996-12-02
期刊：
影响因子：
11.4
通讯作者：
Schroeder, JI
中科院分区：
文献类型：
--
作者：
Pei, ZM;Ward, JM;Schroeder, JI
高等植物中的钙依赖性蛋白激酶 (CDPK) 含有 C 端钙调蛋白样调节结构域。关于生理学 CDPK 靶点知之甚少，激酶活性和多种 Ca2+ 依赖性信号通路均与气孔保卫细胞运动的控制有关。为了确定 CDPK 或其他蛋白激酶是否在保卫细胞信号传导中发挥作用，在膜片钳实验中将纯化和重组的激酶应用于蚕豆保卫细胞液泡。 CDPK 激活保卫细胞中的新型液泡氯 (VCL) 和苹果酸电导，激活依赖于 Ca2+ 和 ATP。此外，使用不依赖 Ca2+ 的、组成型活性 CDPK* 突变体，在不存在 Ca2+ 的情况下发生 VCL 激活。蛋白激酶A的激活较弱（与CDPK相比为22%）。当前整个液泡记录的反转随着 Cl- 的能斯特势而变化，并在谷氨酸中消失。单通道记录显示 CDPK 激活的 34 +/- 5 pS Cl 通道。 VCL 通道在生理电位下被激活，使 Cl- 摄取到液泡中，VCL 通道可能提供以前未识别的但必要的途径，用于将阴离子摄取到气孔打开所需的液泡中。在红甜菜液泡中也观察到了 CDPK 激活的 VCL 电流，表明这些通道可能为激酶依赖性阴离子吸收提供更通用的机制。
Calcium-Dependent Protein Kinases (CDPKs) in higher plants contain a C-terminal calmodulin-like regulatory domain. Little is known regarding physiological CDPK targets, Both kinase activity and multiple Ca2+-dependent signaling pathways have been implicated in the control of stomatal guard cell movements, To determine whether CDPK or other protein kinases could have a role in guard cell signaling, purified and recombinant kinases were applied to Vicia faba guard cell vacuoles during patch-clamp experiments. CDPK activated novel vacuolar chloride (VCL) and malate conductances in guard cells, Activation was dependent on both Ca2+ and ATP, Furthermore, VCL activation occurred in the absence of Ca2+ using a Ca2+-independent, constitutively active, CDPK* mutant. Protein kinase A showed weaker activation (22% as compared with CDPK). Current reversals in whole vacuole recordings shifted with the Nernst potential for Cl- and vanished in glutamate. Single channel recordings showed a CDPK-activated 34 +/- 5 pS Cl- channel. VCL channels were activated at physiological potentials enabling Cl- uptake into vacuoles, VCL channels may provide a previously unidentified, but necessary, pathway for anion uptake into vacuoles required for stomatal opening. CDPK-activated VCL currents were also observed in red beet vacuoles suggesting that these channels may provide a more general mechanism for kinase-dependent anion uptake.