Overexpression of the plasma membrane‐localized NDR1 protein results in enhanced bacterial disease resistance in Arabidopsis thaliana

Abstract

Previous studies have established that mutations in the NDR1 gene in Arabidopsis thaliana suppress the resistance response of three resistance proteins, RPS2, RPM1, and RPS5, to Pseudomonas syringae pv. tomato (Pst) strain DC3000 containing the cognate effector genes, avrRpt2, avrRpm1, and avrpPhB, respectively. NDR1 is a plasma membrane (PM)-localized protein, and undergoes several post-translational modifications including carboxy-terminal processing and N-linked glycosylation. Expression of NDR1 under the NDR1 native promoter complements the ndr1-1 mutation, while overexpression of NDR1 results in enhanced resistance to virulent Pst. Sequence analysis and mass spectrometry suggest that NDR1 is localized to the PM via a C-terminal glycosylphosphatidyl-inositol (GPI) anchor. GPI modification would potentially place NDR1 on the outer surface of the PM, perhaps allowing NDR1 to act as a transducer of pathogen signals and/or interact directly with the pathogen.

NDR1 Interaction with RIN4 Mediates the Differential Activation of Multiple Disease Resistance Pathways in Arabidopsis

“…As shown in Figure 2A, following transient coexpression of both genes for 40 h in N. benthamiana leaves by Agrobacterium infection, we observed that both HA:NDR1 and T7:RIN4 can be shown to associate in a series of coimmunoprecipitation experiments. Moreover, using HA:NDR1 epitope-tagged complemented ndr1-1 mutant Arabidopsis plants (Coppinger et al, 2004), we were successful in demonstrating a specific interaction between RIN4 and NDR1 ( Figure 2B). The in planta coimmunoprecipitation experiment validates our initial yeast two-hybrid results demonstrating that NDR1 and RIN4 physically associate in planta.…”

“…Our working hypothesis is that NDR1 assumes a double anchor membrane conformation: anchored at the N terminus by a transmembrane domain (residues 19 to 34) and at the C terminus by the addition of the GPI anchor (Coppinger et al, 2004). If our working model for NDR1's topology is correct, the 18 N-terminal amino acids of NDR1 are the only residues that lie within the cytoplasm and thus are positioned to interact with the cytoplasmically facing plasma membrane-localized RIN4.…”

“…The proposed topology of NDR1 within the plasma membrane suggests that an approximate 18-amino acid portion lies within the cytoplasm, while the remainder of the NDR1 protein resides on the outside surface (i.e., apoplast) of the plasma membrane (Coppinger et al, 2004). We set out to determine the domain architecture required for NDR1-RIN4 interaction and, moreover, to determine how this protein-protein interaction contributes to disease resistance signaling following P. syringae perception.…”

“…NDR1 was first identified in a genetic screen aimed at identifying genetic loci required for disease resistance signaling in Arabidopsis in response to infection by P. syringae (Century et al, 1995(Century et al, , 1997. NDR1 is a plasma membrane, glycophosphatidyl-inositol (GPI)-anchored protein required for the activation of disease resistance signaling mediated by members of the largest class of disease resistance proteins in Arabidopsis (Coppinger et al, 2004). Previous work addressed the genetic requirement for NDR1 in the activation of resistance signaling mediated by the coiled-coil (CC) NB-LRR class of resistance proteins; yet to date, the mechanism of NDR1 function in disease resistance signaling remains elusive (Century et al, 1995(Century et al, , 1997.…”

A Conserved Carboxylesterase Is a SUPPRESSOR OF AVRBST-ELICITED RESISTANCE inArabidopsis

“…NDR1 is a critical player in this pathway, as ndr1-1 sober1-1 double mutants were fully susceptible to Pst DC3000 AvrBsT HYB -HA infection. NDR1 is a plasma membrane glycophosphatidylinositol-anchored protein required for the activation of disease resistance signaling for a number of R proteins in Arabidopsis (Coppinger et al, 2004). Mutations in EDS1, PAD4, SID2, and NPR1 only partially compromised sober1-1 resistance, whereas a JAR1 mutant had no effect.…”