Endosomal signaling of the tomato leucine-rich repeat receptor-like protein LeEix2.

Extracellular leucine-rich repeat (LRR) receptor-like proteins (RLPs) represent a unique class of cell-surface receptors, as they lack a functional cytoplasmic domain. Our knowledge of how RLPs that do not contain a kinase or Toll domain function is very limited. The tomato RLP receptor LeEix2 signals to induce defense responses mediated by the fungal protein ethylene-inducing xylanase (EIX). The movement of FYVE-positive endosomes before and after EIX application was examined using spinning disc confocal microscopy. We found that while FYVE-positive endosomes generally observe a random movement pattern, following EIX application a subpopulation of FYVE-positive endosomes follow a directional movement pattern. Further, cellular endosomes travel greater distances at higher speeds following EIX application. Time-course experiments conducted with specific inhibitors demonstrate the involvement of endosomal signaling in EIX-triggered defense responses. Abolishing the existence of endosomes or the endocytic event prevented EIX-induced signaling. Endocytosis/endosome inhibitors, such as Dynasore or 1-butanol, inhibit EIX-induced signaling. Moreover, treatment with Endosidin1, which inhibits an early step in plasma membrane/endosome trafficking, enhances the induction of defense responses by EIX. Our data indicate a distinct endosomal signaling mechanism for induction of defense responses in this RLP system. © 2011 The Authors. The Plant Journal © 2011 Blackwell Publishing Ltd.

Citation

Miya Sharfman, Maya Bar, Marcelo Ehrlich, Silvia Schuster, Shiri Melech-Bonfil, Ran Ezer, Guido Sessa, Adi Avni. Endosomal signaling of the tomato leucine-rich repeat receptor-like protein LeEix2. The Plant journal : for cell and molecular biology. 2011 Nov;68(3):413-23

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PMID: 21736652

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