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Cell Host Microbe. 2011 Feb 17;9(2):125-36. doi: 10.1016/j.chom.2011.01.009.

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

Author information

1
Department of Biology, University of North Carolina, Chapel Hill, 27599, USA.

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.

PMID:
21320695
PMCID:
PMC3061827
DOI:
10.1016/j.chom.2011.01.009
[Indexed for MEDLINE]
Free PMC Article

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