Salt stress triggers phosphorylation of the Arabidopsis vacuolar K+ channel TPK1 by calcium-dependent protein kinases (CDPKs)
- Author(s)
- Andreas Latz, Norbert Mehlmer, Simone Zapf, Thomas D Mueller, Bernhard Wurzinger, Barbara Pfister, Edina Csaszar, Rainer Hedrich, Markus Teige, Dirk Becker
- Abstract
14-3-3 proteins play an important role in the regulation of many cellular processes. The Arabidopsis vacuolar two-pore K(+) channel 1 (TPK1) interacts with the 14-3-3 protein GRF6 (GF14-λ). Upon phosphorylation of the putative binding motif in the N-terminus of TPK1, GRF6 binds to TPK1 and activates the potassium channel. In order to gain a deeper understanding of this 14-3-3-mediated signal transduction, we set out to identify the respective kinases, which regulate the phosphorylation status of the 14-3-3 binding motif in TPK1. Here, we report that the calcium-dependent protein kinases (CDPKs) can phosphorylate and thereby activate the 14-3-3 binding motif in TPK1. Focusing on the stress-activated kinase CPK3, we visualized direct and specific interaction of TPK1 with the kinase at the tonoplast in vivo. In line with its proposed role in K(+) homeostasis, TPK1 phosphorylation was found to be induced by salt stress in planta, and both cpk3 and tpk1 mutants displayed salt-sensitive phenotypes. Molecular modeling of the TPK1-CPK3 interaction domain provided mechanistic insights into TPK1 stress-regulated phosphorylation responses and pinpointed two arginine residues in the N-terminal 14-3-3 binding motif in TPK1 critical for kinase interaction. Taken together, our studies provide evidence for an essential role of the vacuolar potassium channel TPK1 in salt-stress adaptation as a target of calcium-regulated stress signaling pathways involving Ca(2+), Ca(2+)-dependent kinases, and 14-3-3 proteins.
- Organisation(s)
- Department of Biochemistry and Cell Biology
- External organisation(s)
- Julius-Maximilians-Universität Würzburg, Ludwig-Maximilians-Universität München, King Saud University
- Journal
- Molecular Plant
- Volume
- 6
- Pages
- 1274-1289
- No. of pages
- 16
- ISSN
- 1674-2052
- DOI
- https://doi.org/10.1093/mp/sss158
- Publication date
- 12-2012
- Peer reviewed
- Yes
- Austrian Fields of Science 2012
- 106002 Biochemistry, 106052 Cell biology
- Keywords
- Portal url
- https://ucris.univie.ac.at/portal/en/publications/salt-stress-triggers-phosphorylation-of-the-arabidopsis-vacuolar-k-channel-tpk1-by-calciumdependent-protein-kinases-cdpks(af02fdf7-33f9-44f5-89a3-abcb5bd1741c).html