Arabidopsis HYPERSENSITIVE INDUCED REACTION 2 affects plasma membrane receptor pathways and organization

Weber, H.; Ehinger, A.; Kolb, D.; Fallahzadeh-Mamaghani, V.; Halter, T.; Franz-Wachtel, M.; zur Oven-Krockhaus, S.; Gronnier, J.; Zipfel, C.; Harter, K.; Kemmerling, B.

doi:10.1101/2025.04.11.648320

bioRxiv · 10.1101/2025.04.11.648320

Arabidopsis HYPERSENSITIVE INDUCED REACTION 2 affects plasma membrane receptor pathways and organization

Weber, H.·Ehinger, A.·Kolb, D.·Fallahzadeh-Mamaghani, V.·Halter, T.·Franz-Wachtel, M.·zur Oven-Krockhaus, S.·Gronnier, J.·Zipfel, C.·Harter, K.·Kemmerling, B.

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Abstract

The distribution of proteins across the plasma membrane is not uniform; however, the principles governing their organization remain not fully understood. Hypersensitive-induced reaction (HIR) proteins are plant-specific members of the stomatin/prohibitin/flotillin/HflK/C (SPFH) family that have been shown to influence membrane organization. Arabidopsis thaliana HIR2 interacts with multiple plasma membrane proteins, including receptor kinases such as BAK1-INTERACTING RECEPTORS 2 and 3 (BIR2 and 3), BRI1-ASSOCIATED KINASE 1 (BAK1), FLAGELLIN SENSING 2 (FLS2), and BRASSINOSTEROID INSENSITIVE 1 (BRI1). These interactions connect HIR2 to BAK1-mediated signaling pathways, as evidenced by impaired growth and immunity phenotypes in hir2 mutants. HIR2 is anchored to the inner leaflet of the plasma membrane through a hydrophobic interaction domain and S-acylation. Using single-particle tracking photoactivated localization microscopy (sptPALM), we showed that HIR2 affects receptor kinase dynamics and clustering, suggesting a role in spatially coordinating receptor complex activities. Structural modeling with AlphaFold 3 predicts a multimeric circular cup-like assembly for HIR2, consistent with high molecular weight complexes identified through blue native polyacrylamide gel electrophoresis. These findings indicate that HIR2 forms a discrete membrane compartment, providing a novel structural framework for spatial membrane organization and thereby modulating the function of membrane-resident receptors.

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Weber, H., Ehinger, A., Kolb, D., Fallahzadeh-Mamaghani, V., Halter, T., Franz-Wachtel, M., zur Oven-Krockhaus, S., Gronnier, J., Zipfel, C., Harter, K., Kemmerling, B.. 2025-04-14. Arabidopsis HYPERSENSITIVE INDUCED REACTION 2 affects plasma membrane receptor pathways and organization. https://doi.org/10.1101/2025.04.11.648320

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