Specific threonine phosphorylation of a host target by two unrelated type III effectors activates a host innate immune receptor in plants

The Arabidopsis NB-LRR immune receptor RPM1 recognizes the Pseudomonas syringae type III effectors AvrB or AvrRpm1 to mount an immune response. Although neither effector is itself a kinase, AvrRpm1 and AvrB are known to target Arabidopsis RIN4, a negative regulator of basal plant defense, for phosph...

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Bibliographic Details
Published in:Cell host & microbe 2011-02, Vol.9 (2), p.125-136
Main Authors: Chung, Eui-Hwan, da Cunha, Luis, Wu, Ai-Jiuan, Gao, Zhiyong, Cherkis, Karen, Afzal, Ahmed J, Mackey, David, Dangl, Jeffery L
Format: Article
Language:English
Subjects:
Arabidopsis - genetics
Arabidopsis - immunology
Arabidopsis - metabolism
Arabidopsis - microbiology
Arabidopsis Proteins - chemistry
Arabidopsis Proteins - genetics
Arabidopsis Proteins - immunology
Arabidopsis Proteins - metabolism
Bacterial Proteins - genetics
Bacterial Proteins - metabolism
Carrier Proteins - chemistry
Carrier Proteins - genetics
Carrier Proteins - metabolism
Host-Pathogen Interactions
Phosphorylation
Plant Diseases - immunology
Plant Diseases - microbiology
Protein Binding
Protein Structure, Tertiary
Pseudomonas syringae - genetics
Pseudomonas syringae - metabolism
Threonine - metabolism
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Summary:The Arabidopsis NB-LRR immune receptor RPM1 recognizes the Pseudomonas syringae type III effectors AvrB or AvrRpm1 to mount an immune response. Although neither effector is itself a kinase, AvrRpm1 and AvrB are known to target Arabidopsis RIN4, a negative regulator of basal plant defense, for phosphorylation. We show that RIN4 phosphorylation activates RPM1. RIN4(142-176) is necessary and, with appropriate localization sequences, sufficient to support effector-triggered RPM1 activation, with the threonine residue at position 166 being critical. Phosphomimic substitutions at T166 cause effector-independent RPM1 activation. RIN4 T166 is phosphorylated in vivo in the presence of AvrB or AvrRpm1. RIN4 mutants that lose interaction with AvrB cannot be coimmunoprecipitated with RPM1. This defines a common interaction platform required for RPM1 activation by phosphorylated RIN4 in response to pathogenic effectors. Conservation of an analogous threonine across all RIN4-like proteins suggests a key function for this residue beyond the regulation of RPM1.
ISSN:1931-3128
1934-6069
DOI:10.1016/j.chom.2011.01.009