Arabidopsis SENESCENCE-ASSOCIATED GENE101 Stabilizes and Signals within an ENHANCED DISEASE SUSCEPTIBILITY1 Complex in Plant Innate Immunity

• Published in: The Plant cell 2005-09, Vol.17 (9), p.2601-2613
• Main Authors: Feys, Bart J, Wiermer, Marcel, Bhat, Riyaz A, Moisan, Lisa J, Medina-Escobar, Nieves, Neu, Christina, Cabral, Adriana, Parker, Jane E
• Format: Article
• Language: English
• Subjects: Amino Acid Sequence; amino acid sequences; Arabidopsis - anatomy & histology; Arabidopsis - genetics; Arabidopsis - metabolism; Arabidopsis Proteins - genetics; Arabidopsis Proteins - metabolism; Arabidopsis thaliana; bacterial diseases of plants; binding proteins; blight; Carboxylic Ester Hydrolases - genetics; Carboxylic Ester Hydrolases - metabolism; Cytosol; disease resistance; DNA-Binding Proteins - genetics; DNA-Binding Proteins - metabolism; Energy transfer; Epidermal cells; Fluorescence; Fractionation; fungal diseases of plants; Gels; genes; Immunity, Innate - physiology; Invasive plants; Leaves; Molecular Sequence Data; Multiprotein Complexes; nucleotide sequences; Parasitism; Pathogens; Peronospora parasitica; Phenotype; Plant cells; Plant interaction; Plant Leaves - chemistry; plant pathogenic bacteria; plant proteins; Plants, Genetically Modified; protein-protein interactions; Proteins; Pseudomonas syringae pv. tomato; resistance mechanisms; Seedlings - cytology; Seedlings - metabolism; Seedlings - microbiology; Sequence Alignment; signal transduction; Signal Transduction - physiology
• ISSN: 1040-4651; 1532-298X; 1532-298X
• DOI: 10.1105/tpc.105.033910

Plant innate immunity against invasive biotrophic pathogens depends on the intracellular defense regulator ENHANCED DISEASE SUSCEPTIBILITY1 (EDS1). We show here that Arabidopsis thaliana EDS1 interacts in vivo with another protein, SENESCENCE-ASSOCIATED GENE101 (SAG101), discovered through a proteomic approach to identify new EDS1 pathway components. Together with PHYTOALEXIN-DEFICIENT4 (PAD4), a known EDS1 interactor, SAG101 contributes intrinsic and indispensable signaling activity to EDS1-dependent resistance. The combined activities of SAG101 and PAD4 are necessary for programmed cell death triggered by the Toll-Interleukin-1 Receptor type of nucleotide binding/leucine-rich repeat immune receptor in response to avirulent pathogen isolates and in restricting the growth of normally virulent pathogens. We further demonstrate by a combination of cell fractionation, coimmunoprecipitation, and fluorescence resonance energy transfer experiments the existence of an EDS1-SAG101 complex inside the nucleus that is molecularly and spatially distinct from EDS1-PAD4 associations in the nucleus and cytoplasm. By contrast, EDS1 homomeric interactions were detected in the cytoplasm but not inside the nucleus. These data, combined with evidence for coregulation between individual EDS1 complexes, suggest that dynamic interactions of EDS1 and its signaling partners in multiple cell compartments are important for plant defense signal relay.