Alternative complex formation of the Ca-regulated protein kinase CIPK1 controls abscisic acid-dependent and independent stress responses in Arabidopsis.
Intracellular release of calcium ions belongs to the earliest events in cellular stress perception. The molecular mechanisms integrating signals from different environmental cues and translating them into an optimized response are largely unknown. We report here the functional characterization of CIPK1, a protein kinase interacting strongly with the calcium sensors CBL1 and CBL9. Comparison of the expression patterns indicates that the three proteins execute their functions in the same tissues. Physical interaction of CIPK1 with CBL1 and CBL9 targets the kinase to the plasma membrane. We show that, similarly to loss of CBL9 function, mutation of either CBL1 or CIPK1 renders plants hypersensitive to osmotic stress. Remarkably, in contrast to the cbl1 mutant and similarly to the cbl9 mutant, loss of CIPK1 function impairs abscisic acid (ABA) responsiveness. We therefore suggest that, by alternative complex formation with either CBL1 or CBL9, the kinase CIPK1 represents a convergence point for ABA-dependent and ABA-independent stress responses. Based on our genetic, physiological and protein-protein interaction data, we propose a general model for information processing in calcium-regulated signalling networks.
D'Angelo
Cecilia
C
Molekulare Entwicklungsbiologie der Pflanzen, Institut für Botanik und Botanischer Garten, Universität Münster, Schlossplatz 4, 48149 Münster, Germany.
Weinl
Stefan
S
Batistic
Oliver
O
Pandey
Girdhar K
GK
Cheong
Yong Hwa
YH
Schültke
Stefanie
S
Albrecht
Veronica
V
Ehlert
Britta
B
Schulz
Burkhard
B
Harter
Klaus
K
Luan
Sheng
S
Bock
Ralph
R
Kudla
Jörg
J
D000040:Abscisic Acid / Q000378:metabolism*; D017360:Arabidopsis / Q000201:enzymology* / Q000235:genetics / Q000378:metabolism; D029681:Arabidopsis Proteins / Q000235:genetics / Q000378:metabolism*; D020013:Calcium Signaling; D002135:Calcium-Binding Proteins / Q000235:genetics / Q000378:metabolism; D002462:Cell Membrane / Q000378:metabolism; D015870:Gene Expression; D009997:Osmotic Pressure; D017346:Protein Serine-Threonine Kinases / Q000235:genetics / Q000378:metabolism*
D029681:Arabidopsis Proteins; C514582:CBL9 protein, Arabidopsis; D002135:Calcium-Binding Proteins; C483419:calcineurin B-like protein 1, Arabidopsis; D000040:Abscisic Acid; C507144:CIPK1 protein, Arabidopsis; D017346:Protein Serine-Threonine Kinases