Deciphering RLP44-linked LRR-receptor dynamics and signalling specificity at the plasma membrane

• Applicants: Professor Dr. Klaus Harter; Professor Dr. Sebastian Wolf
• Subject Area: Plant Cell and Developmental Biology
• Term: from 2015 to 2025
• Project identifier: Deutsche Forschungsgemeinschaft (DFG) - Project number 278516350

• Final Report Year: 2024

Final Report Abstract

The presented research findings explore the role of RLP44, a plant receptor protein, in signal transduction in plants. RLP44 interacts with various receptors, such as the PSK receptor (PSKR1) and the brassinosteroid receptor (BRI1). These interactions activate their respective signaling pathways through the formation of a complex with the co-receptor BAK1. It was found that these signaling pathways compete for RLP44, which was confirmed through genetic and biochemical analyses. These discoveries align with the concept that plasma membrane receptors form dynamic and flexible networks to respond to external stimuli. A central focus of the research was understanding how specific responses are achieved amidst the multitude of potential receptor interactions. It was shown that post-translational modifications, such as phosphorylation of RLP44, play a role in the specificity of these interactions. Phosphorylation affects both the function of RLP44 in the BR signaling pathway and its subcellular localization, while it plays no role in the PSK signaling pathway. Another important aspect was the investigation of the spatial organization of receptor complexes in the plasma membrane. Using techniques such as spectral FRET and FRET-FLIM, it was demonstrated that RLP44, BRI1, and BAK1 form specific ternary protein complexes within defined nanodomains of the plasma membrane. This research emphasizes the well-defined organization of receptor protein clusters, even when they share common proteins like BAK1. The advancement of microscopy techniques, particularly super-resolution microscopy (sptPALM), enabled the study of nanoscale organization and dynamics of proteins in the plasma membrane. These developments have led to a more precise analysis of the association and organization of protein complexes in living plant cells. Additionally, it was shown that the binding of RLP44 to de-methylesterified pectin in the cell wall is essential for its function in the BR signaling pathway. This binding influences the subcellular localization of RLP44 and regulates its availability for complex formation with other receptors. In summary, these findings contribute to a better understanding of complex signaling networks and the role of cell wall interactions in plant cells.

Publications

• A Mutant Allele Uncouples the Brassinosteroid-Dependent and Independent Functions of BRASSINOSTEROID INSENSITIVE 1. Plant Physiology, 182(1), 669-678.
  Holzwart, Eleonore; Wanke, Friederike; Glöckner, Nina; Höfte, Herman; Harter, Klaus & Wolf, Sebastian
  
• Phosphorylation-dependent routing of RLP44 towards brassinosteroid or phytosulfokine signalling. Journal of Cell Science, 134(20).
  Garnelo, Gómez Borja; Holzwart, Eleonore; Shi, Chaonan; Lozano-Durán, Rosa & Wolf, Sebastian
  
• Computational modeling and quantitative physiology reveal central parameters for brassinosteroid-regulated early cell physiological processes linked to elongation growth of the Arabidopsis root. eLife, 11.
  Großeholz, Ruth; Wanke, Friederike; Rohr, Leander; Glöckner, Nina; Rausch, Luiselotte; Scholl, Stefan; Scacchi, Emanuele; Spazierer, Amelie-Jette; Shabala, Lana; Shabala, Sergey; Schumacher, Karin; Kummer, Ursula & Harter, Klaus
  
• Deciphering RLP44-linked LRR receptor dynamics and signaling specificity at the plasma membrane. 5th ZMBP Summer Academy in Plant Molecular Biology, Wildberg
  Rohr L.; zur Oven-Krockhaus, S.; Keck J.; Rausch L.; Wolf S & Harter K.
  
• Three-Fluorophore FRET Enables the Analysis of Ternary Protein Association in Living Plant Cells. Plants, 11(19), 2630.
  Glöckner, Nina; zur Oven-Krockhaus, Sven; Rohr, Leander; Wackenhut, Frank; Burmeister, Moritz; Wanke, Friederike; Holzwart, Eleonore; Meixner, Alfred J.; Wolf, Sebastian & Harter, Klaus
  
• BRASSINOSTEROID INSENSITIVE1 internalization can occur independent of ligand binding. Plant Physiology, 192(1), 65-76.
  Neubus, Claus Lucas Alves; Liu, Derui; Hohmann, Ulrich; Vukašinović, Nemanja; Pleskot, Roman; Liu, Jing; Schiffner, Alexei; Jaillais, Yvon; Wu, Guang; Wolf, Sebastian; Van Damme, Daniël; Hothorn, Michael & Russinova, Eugenia
  
• OneFlowTraX: a user-friendly software for super-resolution analysis of single-molecule dynamics and nanoscale organization. Frontiers in Plant Science, 15.
  Rohr, Leander; Ehinger, Alexandra; Rausch, Luiselotte; Glöckner, Burmeister Nina; Meixner, Alfred J.; Gronnier, Julien; Harter, Klaus; Kemmerling, Birgit & zur, Oven-Krockhaus Sven
  
• Simultaneous and Dynamic Super-Resolution Imaging of Two Proteins inArabidopsis thalianausing dual-color sptPALM.
  Rohr, Leander; Ehinger, Alexandra; Burmeister, Nina Glöckner; Meixner, Alfred J.; Kemmerling, Birgit; Harter, Klaus & Oven-Krockhaus, Sven zur