Poster
Hannah Lena Weber, MSc (she/her/hers)
PhD student
ZMBP, University of Tübingen
Tuebingen, Baden-Wurttemberg, Germany
Alexandra Ehinger
ZMBP, University of Tübingen
Tübingen, Baden-Wurttemberg, Germany
Sven zur Oven-Krockhaus
Institute of Physical and Theoretical Chemistry, University of Tübingen
Tübingen, Baden-Wurttemberg, Germany
Julien Gronnier
Technical University of Munich
Freising, Bayern, Germany
Cyril Zipfel
Institute of Plant and Microbial Biology, University of Zurich / The Sainsbury Laboratory
Zurich, Zurich, Switzerland
Klaus Harter
ZMBP, University of Tübingen
Tübingen, Baden-Wurttemberg, Germany
Birgit Kemmerling
ZMBP, University of Tübingen
Tübingen, Baden-Wurttemberg, Germany
Receptor-like-kinases (RLKs) at the plasma membrane are organized in distinct domains, but the organizing mechanisms are not yet fully understood. We identified HYPERSENSITIVE INDUCED REACTION 2 (HIR2) as an interactor of various RLKs, such as BRI1-ASSOCIATED RECEPTOR KINASE (BAK1) and BAK1-INTERACTING RECEPTOR (BIR2). HIR2 belongs to the stomatin/prohibitin/flotillin/HflKC (SPFH) protein family, which are thought to act as scaffold proteins at membranes. Recent cryo-EM studies resolved the structure of two SPFH proteins, HflKC and flotillin. They form large, ring-like oligomers capable of capturing their cargo and compartmentalizing membranes. HIR2, despite lacking a transmembrane region, localizes to the plasma membrane. We found that myristoylation sites, potential palmitoylation sites, and a hydrophobic stretch at the N-terminus are essential for its localization. AlphaFold predictions revealed ring-like HIR2 oligomeric structures analogous to those observed in bacterial HflKC and animal flotillin. Blue-native PAGE confirmed HIR2’s ability to form large complexes in planta. Given HIR2’s interaction with RLKs, we hypothesized that it might provide a platform for their signal transduction. Indeed, single-particle tracking Photoactivated Localization Microscopy (sptPALM) revealed that loss of HIR2 alters RLK dynamics and clustering behavior, highlighting its unprecedented role in plant membrane architecture and molecular signaling.