A helper NLR targets organellar membranes to trigger immunity

Ibrahim, T.; Yuen, E. L. H.; Wang, H.-Y.; King, F. J.; Toghani, A.; Kourelis, J.; Vuolo, C.; Adamkova, V.; Castel, B.; Jones, J. D.; Wu, C.-H.; Kamoun, S.; Bozkurt, T. O.

doi:10.1101/2024.09.19.613839

bioRxiv · 10.1101/2024.09.19.613839

A helper NLR targets organellar membranes to trigger immunity

Ibrahim, T.·Yuen, E. L. H.·Wang, H.-Y.·King, F. J.·Toghani, A.·Kourelis, J.·Vuolo, C.·Adamkova, V.·Castel, B.·Jones, J. D.·Wu, C.-H.·Kamoun, S.·Bozkurt, T. O.

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Abstract

Upon activation, plant NLR immune receptors are known to assemble into oligomeric resistosomes that insert into the plasma membrane, forming Ca2+-permeable channels and triggering immunity. Here, we show that the RPW8-like coiled-coil (CCR-) NLR NRG1 primarily targets organelles instead of the plasma membrane. Unlike canonical CC-NLRs, activated NRG1 accumulates at the chloroplast envelope and channels stromal Ca2+ into the cytosol. AlphaFold modeling of the NRG1 resistosome reveals an unusually long N-terminal membrane-insertion structure that would span the double chloroplast membranes. Nanobody-mediated relocalization shows functional membrane specificity: chloroplast trapping abolishes activity of the canonical helper CC-NLR NRC4 but not NRG1. NRG1 orthologs, from non-flowering lineages to angiosperms, target chloroplasts, suggesting that organelle-centered defense dates back to at least [~]360 million years. We propose that coiled-coil NLR diversification has enabled compartment-specific immune signaling to capture diverse Ca2+ stores.

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Ibrahim, T., Yuen, E. L. H., Wang, H.-Y., King, F. J., Toghani, A., Kourelis, J., Vuolo, C., Adamkova, V., Castel, B., Jones, J. D., Wu, C.-H., Kamoun, S., Bozkurt, T. O.. 2024-09-22. A helper NLR targets organellar membranes to trigger immunity. https://doi.org/10.1101/2024.09.19.613839

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