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Identification of Small Molecule-binding Proteins in a Native Cellular Environment by Live-cell Photoaffinity Labeling
Published on: September 20, 2016
Subcellular targets and recognition mechanism of Ralstonia solanacearum effector RipE1
Dimitra Tsakiri1, Konstantinos Kotsaridis1, Vassiliki A Michalopoulou1,2
1Department of Biology, University of Crete, 714 09 Heraklion, Crete, Greece.
Abstract:
Some plant NLRs carry unusual integrated protein domains (IDs) that mimic host targets of pathogen effectors. RipE1 is a core Ralstonia solanacearum Type III effector with a predicted cysteine protease activity that activates defense responses in resistant plants. In this study, we used a library of NLR-IDs as an investigative tool to screen for potential host-cell targets of RipE1. Based on these findings and the effector's localization, we identified two plant membrane trafficking components as RipE1's subcellular targets. Depending on its protease activity, RipE1 promotes the degradation of both exocyst complex subunit Exo70B1 and its known interactor RPM1-interacting protein-4 (RIN4), a known plant immunity regulator. RipE1 protease activity is recognized by the RIN4-guarding NLR Pseudomonas tomato race 1 (Ptr1) in Nicotiana benthamiana. Overall, the data presented here, along with the existing literature, suggest a possible link between RipE1 activity upon the host secretion machinery and its NLR-mediated recognition.
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