scholarly journals TIR-only protein RBA1 recognizes a pathogen effector to regulate cell death inArabidopsis

2017 ◽  
Vol 114 (10) ◽  
pp. E2053-E2062 ◽  
Author(s):  
Marc T. Nishimura ◽  
Ryan G. Anderson ◽  
Karen A. Cherkis ◽  
Terry F. Law ◽  
Qingli L. Liu ◽  
...  
Keyword(s):  
Cell Death ◽  
Immune System ◽  
Pasteurella Multocida ◽  
Coiled Coil ◽  
Nucleotide Binding ◽  
Leucine Rich Repeat ◽  
Multidomain Structure ◽  
Pathogen Effector ◽  
Self Association ◽  
And Function

Detection of pathogens by plants is mediated by intracellular nucleotide-binding site leucine-rich repeat (NLR) receptor proteins. NLR proteins are defined by their stereotypical multidomain structure: an N-terminal Toll–interleukin receptor (TIR) or coiled-coil (CC) domain, a central nucleotide-binding (NB) domain, and a C-terminal leucine-rich repeat (LRR). The plant innate immune system contains a limited NLR repertoire that functions to recognize all potential pathogens. We isolated Response to the bacterial type III effector protein HopBA1 (RBA1), a gene that encodes a TIR-only protein lacking all other canonical NLR domains. RBA1 is sufficient to trigger cell death in response to HopBA1. We generated a crystal structure for HopBA1 and found that it has similarity to a class of proteins that includes esterases, the heme-binding protein ChaN, and an uncharacterized domain ofPasteurella multocidatoxin. Self-association, coimmunoprecipitation with HopBA1, and function of RBA1 require two previously identified TIR–TIR dimerization interfaces. Although previously described as distinct in other TIR proteins, in RBA1 neither of these interfaces is sufficient when the other is disrupted. These data suggest that oligomerization of RBA1 is required for function. Our identification of RBA1 demonstrates that “truncated” NLRs can function as pathogen sensors, expanding our understanding of both receptor architecture and the mechanism of activation in the plant immune system.

scholarly journals Dissection of Cell Death Induction by Wheat Stem Rust Resistance Protein Sr35 and Its Matching Effector AvrSr35

2020 ◽  
Vol 33 (2) ◽  
pp. 308-319 ◽  
Author(s):  
Stephen Bolus ◽  
Eduard Akhunov ◽  
Gitta Coaker ◽  
Jorge Dubcovsky
Keyword(s):  
Cell Death ◽  
Transient Expression ◽  
Stem Rust ◽  
Fluorescent Protein ◽  
Coiled Coil ◽  
Nucleotide Binding ◽  
Leucine Rich Repeat ◽  
Wheat Stem Rust ◽  
Pathogen Effector ◽  
Lrr Domain

Nucleotide-binding leucine-rich repeat receptors (NLRs) are the most abundant type of immune receptors in plants and can trigger a rapid cell-death (hypersensitive) response upon sensing pathogens. We previously cloned the wheat NLR Sr35, which encodes a coiled-coil (CC) NLR that confers resistance to the virulent wheat stem rust race Ug99. Here, we investigated Sr35 signaling after Agrobacterium-mediated transient expression in Nicotiana benthamiana. Expression of Sr35 in N. benthamiana leaves triggered a mild cell-death response, which is enhanced in the autoactive mutant Sr35 D503V. The N-terminal tagging of Sr35 with green fluorescent protein (GFP) blocked the induction of cell death, whereas a C-terminal GFP tag did not. No domain truncations of Sr35 generated cell-death responses as strong as the wild type, but a truncation including the NB-ARC (nucleotide binding adaptor) shared by APAF-1, R proteins, and CED-4 domains in combination with the D503V autoactive mutation triggered cell death. In addition, coexpression of Sr35 with the matching pathogen effector protein AvrSr35 resulted in robust cell death and electrolyte leakage levels that were similar to autoactive Sr35 and significantly higher than Sr35 alone. Coexpression of Sr35-CC-NB-ARC and AvrSr35 did not induce cell death, confirming the importance of the leucine-rich repeat (LRR) domain for AvrSr35 recognition. These findings were confirmed through Agrobacterium-mediated transient expression in barley. Taken together, these results implicate the CC-NB-ARC domains of Sr35 in inducing cell death and the LRR domain in AvrSr35 recognition. [Formula: see text] Copyright © 2020 The Author(s). This is an open access article distributed under the CC BY 4.0 International license .

scholarly journals The Coiled-Coil and Leucine-Rich Repeat Domain of the Potyvirus Resistance Protein Pvr4 Has a Distinct Role in Signaling and Pathogen Recognition

2018 ◽  
Vol 31 (9) ◽  
pp. 906-913 ◽  
Author(s):  
Saet-Byul Kim ◽  
Hye-Young Lee ◽  
Eun-Hye Choi ◽  
Eunsook Park ◽  
Ji-Hyun Kim ◽  
...  
Keyword(s):  
Cell Death ◽  
Coiled Coil ◽  
Mitogen Activated Protein Kinase ◽  
Protein Signaling ◽  
Death Domain ◽  
Leucine Rich Repeat ◽  
Domain Swap ◽  
Mitogen Activated Protein ◽  
And Function ◽  
Lrr Domain

The pepper Pvr4 protein encoding coiled-coil (CC) nucleotide-binding (NB) leucine-rich repeat (LRR) (NLR) confer hypersensitive response (HR) to potyviruses, including Pepper mottle virus (PepMoV), by recognizing the viral avirulence protein NIb. To figure out the Pvr4-mediated HR mechanism, we analyzed signaling component genes and structure-function relationships of Pvr4, using chimeras and deletion mutants in Nicotiana benthamiana. Molecular chaperone components including HSP90, SGT1, and RAR1 were required, while plant hormones and mitogen-activated protein kinase signaling components had little effect on Pvr4-NIb-mediated HR cell death. Domain swap analyses indicated that the LRR domain of Pvr4 determines recognition of PepMoV-NIb. Our deletion analysis further revealed that the CC domain or CC-NBARC domain alone can trigger autoactive cell death in N. benthamiana. However, the fragments having only an LRR domain could suppress CC-NBARC domain-induced cell death in trans. Further, C-terminal truncation analysis of Pvr4 revealed that a minimum three of five LRR exons showing high similarity was essential for Pvr4 function. The LRR domain may maintain Pvr4 in an inactive state in the absence of NIb. These results provide further insight into the structure and function of NLR protein signaling in plants.

scholarly journals Coiled-coil and RPW8-type immune receptors function at the plasma membrane in a phospholipid dependent manner

2020 ◽  
Author(s):  
Svenja C. Saile ◽  
Frank M. Ackermann ◽  
Sruthi Sunil ◽  
Adam Bayless ◽  
Eva Stöbbe ◽  
...  
Keyword(s):  
Cell Death ◽  
Plasma Membrane ◽  
Coiled Coil ◽  
Dependent Manner ◽  
Leucine Rich Repeat ◽  
Cell Death Response ◽  
Infected Cells ◽  
Self Association ◽  
Phosphatidylinositol 4

AbstractActivation of intracellular nucleotide-binding leucine-rich repeat receptors (NLRs) results in immunity and a localized cell death response of infected cells. Cell death activity of many NLRs requires oligomerization and in some cases plasma membrane (PM) localization. However, the exact mechanisms underlying PM localization of NLRs lacking recognizable N- or C-terminal lipidation motifs or predicted transmembrane domains remains elusive. Here we show that the PM localization and stability of members of the RPW8-like coiled-coil (CCR) domain NLRs (RNLs) and a CC-type NLR (CNL) depend on the interaction with PM phospholipids. Depletion of phosphatidylinositol-4-phosphate (PI4P) from the PM led to a mislocalization of the analyzed NLRs and consequently inhibited their cell death activity. We further demonstrate activation-dependent self-association of cell death inducing RNLs. Our results provide new insights into the molecular mechanism of NLR PM localization and defines an important role of phospholipids for CNL and RNL activity during immunity.

The small molecule Zaractin activates ZAR1-mediated immunity in Arabidopsis

2021 ◽  
Vol 118 (47) ◽  
pp. e2116570118
Author(s):  
Derek Seto ◽  
Madiha Khan ◽  
D. Patrick Bastedo ◽  
Alexandre Martel ◽  
Trinh Vo ◽  
...  
Keyword(s):  
Immune System ◽  
Pseudomonas Syringae ◽  
Small Molecule ◽  
Nucleotide Binding ◽  
Infection Process ◽  
Effector Proteins ◽  
Cellular Proteins ◽  
Leucine Rich Repeat ◽  
Effector Triggered Immunity ◽  
Immune Pathway

Pathogenic effector proteins use a variety of enzymatic activities to manipulate host cellular proteins and favor the infection process. However, these perturbations can be sensed by nucleotide-binding leucine-rich-repeat (NLR) proteins to activate effector-triggered immunity (ETI). Here we have identified a small molecule (Zaractin) that mimics the immune eliciting activity of the Pseudomonas syringae type III secreted effector (T3SE) HopF1r and show that both HopF1r and Zaractin activate the same NLR-mediated immune pathway in Arabidopsis. Our results demonstrate that the ETI-inducing action of pathogenic effectors can be harnessed to identify synthetic activators of the eukaryotic immune system.

scholarly journals RicePi5-Mediated Resistance toMagnaporthe oryzaeRequires the Presence of Two Coiled-Coil–Nucleotide-Binding–Leucine-Rich Repeat Genes

Genetics ◽  
2009 ◽  
Vol 181 (4) ◽  
pp. 1627-1638 ◽  
Author(s):  
Sang-Kyu Lee ◽  
Min-Young Song ◽  
Young-Su Seo ◽  
Hye-Kyung Kim ◽  
Seho Ko ◽  
...  
Keyword(s):  
Coiled Coil ◽  
Nucleotide Binding ◽  
Leucine Rich Repeat
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