Physical and functional interaction of the Arabidopsis K+ channel AKT2 and phosphatase AtPP2CA
Physical and functional interaction of the Arabidopsis K+ channel AKT2 and phosphatase AtPP2CA
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DOI：
10.1105/tpc.000943
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发表时间：
2002-05-01
期刊：
影响因子：
11.6
通讯作者：
Thibaud, JB
中科院分区：
文献类型：
--
作者：
Chérel, I;Michard, E;Thibaud, JB
AKT 2 K+通道具有独特的功能特性，是迄今为止在拟南芥中唯一的弱内向整流器。该基因广泛表达，主要在韧皮部，但在叶表皮、叶肉和保卫细胞中也有较低水平的表达。脱落酸可上调AKT 2 mRNA水平。通过筛选双杂交cDNA文库，我们分离到一个蛋白磷酸酶2C（AtPP 2CA）参与脱落酸信号作为一个假定的合作伙伴AKT 2。我们通过体外结合研究进一步证实了相互作用。AtPP 2CA（β-葡萄糖醛酸酶报告基因）的表达表现出的模式在很大程度上重叠的AKT 2，并上调脱落酸。在COS细胞和非洲爪蟾卵母细胞中共表达AtPP 2CA和AKT 2，发现诱导AKT 2电流的抑制和通道内向整流的增加。定点突变和药理学分析表明，这种功能性相互作用涉及AtPP 2CA磷酸酶活性。AtPP 2CA对植物体内AKT 2活性的调节可以控制胁迫条件下K+的转运和膜极化。
The AKT2 K+ channel is endowed with unique functional properties, being the only weak inward rectifier characterized to date in Arabidopsis. The gene is expressed widely, mainly in the phloem but also at lower levels in leaf epiderm, mesophyll, and guard cells. The AKT2 mRNA level is upregulated by abscisic acid. By screening a two-hybrid cDNA library, we isolated a protein phosphatase 2C (AtPP2CA) involved in abscisic acid signaling as a putative partner of AKT2. We further confirmed the interaction by in vitro binding studies. The expression of AtPP2CA (beta-glucuronidase reporter gene) displayed a pattern largely overlapping that of AKT2 and was upregulated by abscisic acid. Coexpression of AtPP2CA with AKT2 in COS cells and Xenopus laevis oocytes was found to induce both an inhibition of the AKT2 current and an increase of the channel inward rectification. Site-directed mutagenesis and pharmacological analysis revealed that this functional interaction involves AtPP2CA phosphatase activity. Regulation of AKT2 activity by AtPP2CA in planta could allow the control of K+ transport and membrane polarization during stress situations.