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Poster

Session: Session 1 Presenting Authors at Posters (Evens)

P-436 - How to decode cellular signals: Investigating the biochemical mechanism-of-action of calcium-dependent protein kinases

Tuesday, July 15, 2025
09:55 - 11:30  
Location: Confex Hall 3
Structure Informed Synthetic Biology: From Design to Function

    Presenting Author(s)

  • KM

    Kamélia Maguemoun

    Queen's University
    Kingston, Ontario, Canada

    • Author(s)

  • AL

    Anja Liese

    Postdoc
    Leibniz Inst of Plant Biochemistry
    Halle, Sachsen-Anhalt, Germany

  • SM

    Susanne Matschi

    Postdoc
    Leibniz-Institute of Plant Biochemistry
    Halle, Sachsen-Anhalt, Germany

  • MB

    Melissa Bredow

    Department of Plant Pathology, Entomology and Microbiology, Iowa State University
    Ames, Iowa, United States

  • TR

    Tina Romeis

    Department Leader
    Leibniz-Institute of Plant Biochemistry
    Halle (Saale), Sachsen-Anhalt, Germany

  • JM

    Jacqueline Monaghan

    Queen's University
    Kingston, Ontario, Canada

Calcium (Ca²⁺) is a crucial signaling molecule that regulates plant growth and stress responses. Our research focuses on calcium-dependent protein kinases (CPKs), a group of Ca²⁺-binding proteins that decode and process Ca²⁺ signals with high specificity. Some CPKs integrate multiple signals, triggering distinct cellular responses. However, the mechanisms enabling this specificity remain unclear. Recent research suggests that phosphorylation plays a role in Ca²⁺ signal decoding. Arabidopsis thaliana AtCPK28 is an important negative regulator of biotic stress signaling, contributing to immune homeostasis. Our lab discovered that autophosphorylation of AtCPK28 at Ser318 primes its kinase domain for Ca²⁺ activation in vitro and is required for its function in immune signaling but not in stem elongation.  These findings indicate that phosphorylation may modulate Ca²⁺-dependent activation, and influence CPK subfunctionalization across stress pathways. Structural analysis reveals that these phosphorylation sites lie within or near the autoinhibitory junction (AIJ), a flexible regulatory region controlling transitions between active and inactive conformations. Comparative analysis across eukaryotic CPKs suggests that the AIJ contains key phosphorylatable sites, some linked to activation. We hypothesize that phosphorylation in this region enables CPKs to decode distinct Ca²⁺ signatures, mediating crosstalk between abiotic and biotic stress signaling.