Arabidopsis K＋ transporter I （AKT1） participates in K＋ uptake in roots, especially under Iow-K conditions. We recently identified a Ca2＋ signaling pathway consisting of multiple calcineurin B-like calcium sensors...Arabidopsis K＋ transporter I （AKT1） participates in K＋ uptake in roots, especially under Iow-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 fur- ther insights into the signaling network consisting of CBL-CIPK-PP2C interactions in the activation of the AKT1 channel.展开更多
基金This work is supported by the National Science Foundation (to SL)，the WCU program National Research Foundation,Korea
文摘Arabidopsis K＋ transporter I （AKT1） participates in K＋ uptake in roots, especially under Iow-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 fur- ther insights into the signaling network consisting of CBL-CIPK-PP2C interactions in the activation of the AKT1 channel.
