Abstract
Cytoplasmic plant immune receptors recognize specific pathogen effector proteins and initiate effector-triggered immunity. In Arabidopsis, the immune receptors RPS4 and RRS1 are both required to activate defense to three different pathogens. We show that RPS4 and RRS1 physically associate. Crystal structures of the N-terminal Toll-interleukin-1 receptor/resistance (TIR) domains of RPS4 and RRS1, individually and as a heterodimeric complex (respectively at 2.05, 1.75, and 2.65 angstrom resolution), reveal a conserved TIR/TIR interaction interface. We show that TIR domain heterodimerization is required to form a functional RRS1/RPS4 effector recognition complex. The RPS4 TIR domain activates effector-independent defense, which is inhibited by the RRS1 TIR domain through the heterodimerization interface. Thus, RPS4 and RRS1 function as a receptor complex in which the two components play distinct roles in recognition and signaling.
Publication types
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Research Support, Non-U.S. Gov't
MeSH terms
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Agrobacterium / physiology
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Amino Acid Motifs
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Arabidopsis / chemistry
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Arabidopsis / immunology*
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Arabidopsis / microbiology
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Arabidopsis Proteins / chemistry*
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Arabidopsis Proteins / genetics
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Arabidopsis Proteins / metabolism
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Bacterial Proteins / immunology
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Bacterial Proteins / metabolism
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Cell Death
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Crystallography, X-Ray
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Immunity, Innate
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Models, Molecular
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Mutation
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Nicotiana / genetics
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Nicotiana / immunology
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Nicotiana / metabolism
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Nicotiana / microbiology
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Plant Diseases / immunology
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Plant Diseases / microbiology
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Plant Leaves / microbiology
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Plant Proteins / chemistry*
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Plant Proteins / genetics
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Plant Proteins / metabolism
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Plants, Genetically Modified
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Protein Interaction Domains and Motifs
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Protein Multimerization
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Protein Structure, Secondary
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Protein Structure, Tertiary
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Receptors, Immunologic / chemistry*
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Receptors, Immunologic / genetics
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Receptors, Immunologic / metabolism
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Signal Transduction
Substances
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Arabidopsis Proteins
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AvrRps4 protein, Pseudomonas syringae
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Bacterial Proteins
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Plant Proteins
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RRS1 protein, Arabidopsis
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Receptors, Immunologic
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rps4 protein, plant
Associated data
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PDB/4C6R
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PDB/4C6S
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PDB/4C6T