Mechanisms controlling the plasma membrane targeting and the nanodomain organization of the plant SPFH protein HIR2

SUMMARY Plasma membranes (PM) contain myriads of diverse nanodomains that correspond to nanometric scale structures enriched in specific lipids and proteins acting as signaling/regulation hubs involved in diverse biological processes. So far, how PM nanodomains are formed and maintained in plant cells remains largely unknown. We sought to address this question using HIR2, a plant‐specific Stomatin/Prohibitin/Flotillin/HflK/C (SPFH) domain‐containing protein that arranges in PM nanodomains, as a model. We revealed that the mono S‐acylation of Arabidopsis HIR2 either on C6 or on C7 was required for the localization of HIR2 in the PM. In addition, using state‐of‐the‐art microscopy techniques, we provided evidence that the lipid composition in sterols and very long chain fatty acids of the PM influenced HIR2 nanodomain organization. Interestingly, we highlighted that the oligomerization of HIR2 through its C‐terminal domain is essential for its organization in nanodomains and to ensure HIR2 lateral stability in the PM. HIR proteins are involved in plant immunity, and we revealed here that HIR2 nanodomain organization is required to boost the apoplastic reactive oxygen species burst induced by the bacterial peptide flg22. Overall, we propose that HIR2 nanodomain organization is a complex mechanism relying on different parameters and is essential for HIR2 function.