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

Plant J. 2013 Apr;74(2):258-66. doi: 10.1111/tpj.12123. Epub 2013 Feb 13.

Abstract

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.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Arabidopsis / genetics
  • Arabidopsis / metabolism*
  • Arabidopsis Proteins / genetics
  • Arabidopsis Proteins / metabolism*
  • Calcium-Binding Proteins / genetics
  • Calcium-Binding Proteins / metabolism*
  • Immunoprecipitation
  • Patch-Clamp Techniques
  • Polymerase Chain Reaction
  • Potassium / metabolism*
  • Potassium Channels / genetics
  • Potassium Channels / metabolism*
  • Protein Binding
  • Protein Serine-Threonine Kinases / genetics
  • Protein Serine-Threonine Kinases / metabolism
  • Two-Hybrid System Techniques

Substances

  • Arabidopsis Proteins
  • CBL10 protein, Arabidopsis
  • Calcium-Binding Proteins
  • Potassium Channels
  • AKT1 protein, Arabidopsis
  • CIPK23 protein, Arabidopsis
  • Protein Serine-Threonine Kinases
  • Potassium