Department of Plant and Microbial Biology, University of California, Berkeley, CA 94720, USA.
Mol Plant. 2011 May;4(3):527-36. doi: 10.1093/mp/ssr031. Epub 2011 May 18.
Arabidopsis K+ transporter 1 (AKT1) participates in K+ uptake in roots, especially under low-K conditions. We recently identified a Ca²⁺ signaling pathway consisting of multiple calcineurin B-like calcium sensors (CBLs) and multiple target kinases (CBL-interacting protein kinases or CIPKs) that phosphorylate and activate AKT1, whereas a specific PP2C-type phosphatase inactivates CIPK-dependent AKT1 activity. In this study, we analyzed the interactions between PP2Cs and the CBL-CIPK pathway and found previously unsuspected mechanisms underlying the CBL-CIPK-PP2C signaling processes. The interaction between the CIPKs and PP2Cs involves the kinase domain of the CIPK component, in addition to the protein phosphatase interacting motif (PPI) in the regulatory domain. Furthermore, specific CBLs physically interact with and inactivate PP2C phosphatases to recover the CIPK-dependent AKT1 channel activity. These findings provide further insights into the signaling network consisting of CBL-CIPK-PP2C interactions in the activation of the AKT1 channel.
拟南芥钾离子转运蛋白 1（AKT1）参与根部钾离子的摄取，特别是在低钾条件下。我们最近鉴定了一个由多个钙调素 B 样钙传感器（CBLs）和多个靶标激酶（CBL 相互作用蛋白激酶或 CIPKs）组成的钙信号通路，该通路磷酸化并激活 AKT1，而一种特定的 PP2C 型磷酸酶使 CIPK 依赖的 AKT1 活性失活。在这项研究中，我们分析了 PP2Cs 和 CBL-CIPK 途径之间的相互作用，并发现了 CBL-CIPK-PP2C 信号转导过程中以前未被怀疑的机制。CIPKs 和 PP2Cs 之间的相互作用除了调节域中的蛋白磷酸酶相互作用基序（PPI）外，还涉及 CIPK 成分的激酶结构域。此外，特定的 CBL 与 PP2C 磷酸酶相互作用并使其失活，以恢复 CIPK 依赖的 AKT1 通道活性。这些发现为 AKT1 通道激活过程中由 CBL-CIPK-PP2C 相互作用组成的信号网络提供了进一步的见解。
