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Cell Host Microbe. 2014 Oct 8;16(4):484-94. doi: 10.1016/j.chom.2014.09.004.

A plant phosphoswitch platform repeatedly targeted by type III effector proteins regulates the output of both tiers of plant immune receptors.

Author information

1
Department of Biology, University of North Carolina, Chapel Hill, Chapel Hill, NC 27599, USA.
2
Department of Biology, University of North Carolina, Chapel Hill, Chapel Hill, NC 27599, USA; Curriculum in Genetics and Molecular Biology, University of North Carolina, Chapel Hill, Chapel Hill, NC 27599, USA; Carolina Center for Genome Sciences, University of North Carolina, Chapel Hill, Chapel Hill, NC 27599, USA; Department of Microbiology and Immunology, University of North Carolina, Chapel Hill, Chapel Hill, NC 27599, USA; Howard Hughes Medical Institute, University of North Carolina, Chapel Hill, Chapel Hill, NC 27599, USA. Electronic address: dangl@email.unc.edu.

Abstract

Plants detect microbes via two functionally interconnected tiers of immune receptors. Immune detection is suppressed by equally complex pathogen mechanisms. The small plasma-membrane-tethered protein RIN4 negatively regulates microbe-associated molecular pattern (MAMP)-triggered responses, which are derepressed upon bacterial flagellin perception. We demonstrate that recognition of the flagellin peptide MAMP flg22 triggers accumulation of RIN4 phosphorylated at serine 141 (pS141) that mediates derepression of several immune outputs. RIN4 is targeted by four bacterial type III effector proteins, delivered temporally after flagellin perception. Of these, AvrB acts with a host kinase to increase levels of RIN4 phosphorylated at threonine 166 (pT166). RIN4 pT166 is epistatic to RIN4 pS141. Thus, AvrB contributes to virulence by enhancing "rerepression" of immune system outputs. Our results explain the evolution of independent effectors that antagonize accumulation of RIN4 pS141 and of a specific plant intracellular NLR protein, RPM1, which is activated by AvrB-mediated accumulation of RIN4 pT166.

PMID:
25299334
DOI:
10.1016/j.chom.2014.09.004
[Indexed for MEDLINE]
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