Calcineurin B-like protein CBL10 directly interacts with AKT1 and modulates K+ homeostasis in Arabidopsis

Authors

  • Xiao-Ling Ren,

    1. State Key Laboratory of Plant Physiology and Biochemistry, National Plant Gene Research Centre (Beijing), College of Biological Sciences, China Agricultural University, Beijing, China
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    • These authors contributed equally to this work.
  • Guo-Ning Qi,

    1. State Key Laboratory of Plant Physiology and Biochemistry, National Plant Gene Research Centre (Beijing), College of Biological Sciences, China Agricultural University, Beijing, China
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    • These authors contributed equally to this work.
  • Han-Qian Feng,

    1. State Key Laboratory of Plant Physiology and Biochemistry, National Plant Gene Research Centre (Beijing), College of Biological Sciences, China Agricultural University, Beijing, China
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    • These authors contributed equally to this work.
  • Shuai Zhao,

    1. State Key Laboratory of Plant Physiology and Biochemistry, National Plant Gene Research Centre (Beijing), College of Biological Sciences, China Agricultural University, Beijing, China
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  • Shuang-Shuang Zhao,

    1. Key Laboratory of Plant Stress, Life Science College, Shandong Normal University, Jinan, China
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  • Yi Wang,

    1. State Key Laboratory of Plant Physiology and Biochemistry, National Plant Gene Research Centre (Beijing), College of Biological Sciences, China Agricultural University, Beijing, China
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  • Wei-Hua Wu

    Corresponding author
    • State Key Laboratory of Plant Physiology and Biochemistry, National Plant Gene Research Centre (Beijing), College of Biological Sciences, China Agricultural University, Beijing, China
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For correspondence (e-mail wuwh@public3.bta.net.cn).

Summary

Potassium transporters and channels play crucial roles in K+ uptake and translocation in plant cells. These roles are essential for plant growth and development. AKT1 is an important K+ channel in Arabidopsis roots that is involved in K+ uptake. It is known that AKT1 is activated by a protein kinase CIPK23 interacting with two calcineurin B-like proteins CBL1/CBL9. The present study showed that another calcineurin B-like protein (CBL10) may also regulate AKT1 activity. The CBL10-over-expressing lines showed a phenotype as sensitive as that of the akt1 mutant under low-K+ conditions. In addition, the K+ content of both CBL10-over-expressing lines and akt1 mutant plants were significantly reduced compared with wild-type plants. Moreover, CBL10 directly interacted with AKT1, as verified in yeast two-hybrid, BiFC and co-immunoprecipitation experiments. The results of electrophysiological analysis in both Xenopus oocytes and Arabidopsis root cell protoplasts demonstrated that CBL10 impairs AKT1-mediated inward K+ currents. Furthermore, the results from the yeast two-hybrid competition assay indicated that CBL10 may compete with CIPK23 for binding to AKT1 and negatively modulate AKT1 activity. The present study revealed a CBL-interacting protein kinase-independent regulatory mechanism of calcineurin B-like proteins in which CBL10 directly regulates AKT1 activity and affects ion homeostasis in plant cells.

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