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

Eui Hwan Chung, Luis Da Cunha, Ai Jiuan Wu, Zhiyong Gao, Karen Cherkis, Ahmed J. Afzal, David MacKey, Jeffery L. Dangl

Research output: Contribution to journalArticle

Abstract

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.

Original languageEnglish (US)
Pages (from-to)125-136
Number of pages12
JournalCell Host and Microbe
Volume9
Issue number2
DOIs
StatePublished - Feb 17 2011

ASJC Scopus subject areas

  • Parasitology
  • Microbiology
  • Virology

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