title: Separable fragments and membrane tethering of Arabidopsis RIN4 regulate its suppression of PAMP-triggered immunity.
abstract: RPM1-interacting protein 4 (RIN4) is a multifunctional Arabidopsis thaliana protein that regulates plant immune responses to pathogen-associated molecular patterns (PAMPs) and bacterial type III effector proteins (T3Es). RIN4, which is targeted by multiple defense-suppressing T3Es, provides a mechanistic link between PAMP-triggered immunity (PTI) and effector-triggered immunity and effector suppression of plant defense. Here we report on a structure-function analysis of RIN4-mediated suppression of PTI. Separable fragments of RIN4, including those produced when the T3E AvrRpt2 cleaves RIN4 and each containing a plant-specific nitrate-induced (NOI) domain, suppress PTI. The N-terminal and C-terminal NOIs each contribute to PTI suppression and are evolutionarily conserved. Native RIN4 is anchored to the plasma membrane by C-terminal acylation. Nonmembrane-tethered derivatives of RIN4 activate a cell death response in wild-type Arabidopsis and are hyperactive PTI suppressors in a mutant background that lacks the cell death response. Our results indicate that RIN4 is a multifunctional suppressor of PTI and that a virulence function of AvrRpt2 may include cleaving RIN4 into active defense-suppressing fragments.
authors: Department of Horticulture and Crop Science, Ohio State University, Columbus, Ohio 43210, USA.
authors: Ahmed J
authors: AJ
authors: Afzal
authors: Luis
authors: L
authors: da Cunha
authors: David
authors: D
authors: Mackey
mesh_terms: D000595:Amino Acid Sequence; D017360:Arabidopsis / Q000235:genetics / Q000276:immunology* / Q000378:metabolism; D029681:Arabidopsis Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D001426:Bacterial Proteins / Q000276:immunology / Q000378:metabolism; D002352:Carrier Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D016923:Cell Death; D002462:Cell Membrane / Q000378:metabolism; D018506:Gene Expression Regulation, Plant / Q000502:physiology; D047908:Intracellular Signaling Peptides and Proteins; D008954:Models, Biological; D008969:Molecular Sequence Data; D010802:Phylogeny; D010935:Plant Diseases / Q000276:immunology* / Q000382:microbiology; D057865:Plant Immunity / Q000276:immunology*; D018515:Plant Leaves; D030821:Plants, Genetically Modified; D017434:Protein Structure, Tertiary; D044224:Pseudomonas syringae / Q000254:growth & development / Q000276:immunology / Q000472:pathogenicity*; D051192:Receptors, Pattern Recognition / Q000378:metabolism; D014774:Virulence
chemical_list: D029681:Arabidopsis Proteins; D001426:Bacterial Proteins; D002352:Carrier Proteins; D047908:Intracellular Signaling Peptides and Proteins; C453279:RIN4 protein, Arabidopsis; D051192:Receptors, Pattern Recognition; C420919:avrRpt2 protein, Pseudomonas syringae