Alternative complex formation of the Ca2+-regulated protein kinase CIPK1 controls abscisic acid-dependent and independent stress responses in Arabidopsis

Authors

  • Cecilia D'Angelo,

    1. Molekulare Entwicklungsbiologie der Pflanzen, Institut für Botanik und Botanischer Garten, Universität Münster, Schlossplatz 4, 48149 Münster, Germany,
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    • These authors contributed equally to this work.

  • Stefan Weinl,

    1. Molekulare Entwicklungsbiologie der Pflanzen, Institut für Botanik und Botanischer Garten, Universität Münster, Schlossplatz 4, 48149 Münster, Germany,
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    • These authors contributed equally to this work.

  • Oliver Batistic,

    1. Molekulare Entwicklungsbiologie der Pflanzen, Institut für Botanik und Botanischer Garten, Universität Münster, Schlossplatz 4, 48149 Münster, Germany,
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    • These authors contributed equally to this work.

  • Girdhar K. Pandey,

    1. Department of Plant and Microbial Biology, University of California, Berkeley, CA 94720, USA,
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  • Yong Hwa Cheong,

    1. Department of Plant and Microbial Biology, University of California, Berkeley, CA 94720, USA,
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  • Stefanie Schültke,

    1. Molekulare Entwicklungsbiologie der Pflanzen, Institut für Botanik und Botanischer Garten, Universität Münster, Schlossplatz 4, 48149 Münster, Germany,
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  • Veronica Albrecht,

    1. Institut für Pflanzenwissenschaften, Universitätsstr. 2, CH-8092 Zürich, Switzerland,
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  • Britta Ehlert,

    1. Max-Planck-Institut für Molekulare Pflanzenphysiologie, Am Mühlenberg 1, 14476 Potsdam-Golm, Germany,
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  • Burkhard Schulz,

    1. Purdue University, Department of Horticulture and Landscape Architecture, West Lafayette, IN 47907, USA, and
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  • Klaus Harter,

    1. Zentrum für Molekularbiologie der Pflanzen/Pflanzenphysiologie, Universität Tübingen, Auf der Morgenstelle 1, 72076 Tübingen, Germany
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  • Sheng Luan,

    1. Department of Plant and Microbial Biology, University of California, Berkeley, CA 94720, USA,
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  • Ralph Bock,

    1. Max-Planck-Institut für Molekulare Pflanzenphysiologie, Am Mühlenberg 1, 14476 Potsdam-Golm, Germany,
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  • Jörg Kudla

    Corresponding author
    1. Molekulare Entwicklungsbiologie der Pflanzen, Institut für Botanik und Botanischer Garten, Universität Münster, Schlossplatz 4, 48149 Münster, Germany,
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*(fax +49 251 83 23311; e-mail jkudla@uni-muenster.de).

Summary

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.

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