scholarly journals Analysis of intraspecies diversity reveals a subset of highly variable plant immune receptors and predicts their binding sites

2021 ◽  
Author(s):  
Judith Van Dingenen
Keyword(s):  
Interleukin 1 ◽  
Nucleotide Binding ◽  
Coiled Coils ◽  
Leucine Rich Repeat ◽  
Signal Transducers ◽  
Receptor Oligomerization ◽  
Continuous Generation ◽  
Pathogen Recognition Receptors ◽  
Intraspecies Diversity ◽  
Lrr Domain

Abstract Plants have two kinds of pathogen recognition receptors: extracellular receptor like kinases and proteins (RLKs and RLPs) and intracellular Nucleotide-Binding Leucine Rich Repeat (NLR) receptors. NLRs comprise three main domains: a central Nucleotide Binding domain (NB-ARC) that mediates receptor oligomerization upon activation, a C-terminal Leucine Rich Repeat (LRR) domain that defines receptor specificity and an N-terminal domain that mediates immunity. Based on the latter domain, the NLRs are subdivided into three monophyletic groups: RNLs (Resistance to Powdery Mildew8), CNLs (Coiled-Coils) and TNLs (Toll/Interleukin-1 Receptor homology). NLRs can be sensors or signal transducers. As sensors, NLRs can recognize pathogens by directly binding the effectors, by recognizing the effector’s action on other proteins, or by recognition of modifications to a non-canonical NLR domain. Continuous generation of NLR diversity is required to keep up with a range of rapidly evolving pathogens.

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 Arabidopsis TIR-NB-LRR Gene RAC1 Confers Resistance to Albugo candida (White Rust) and Is Dependent on EDS1 but not PAD4

2004 ◽  
Vol 17 (7) ◽  
pp. 711-719 ◽  
Author(s):  
Mohammad H. Borhan ◽  
Eric B. Holub ◽  
Jim L. Beynon ◽  
Kevin Rozwadowski ◽  
S. Roger Rimmer
Keyword(s):  
Positional Cloning ◽  
Rust Resistance ◽  
Interleukin 1 ◽  
Dominant Gene ◽  
Leucine Rich Repeat ◽  
Albugo Candida ◽  
White Rust ◽  
Candida Isolate ◽  
Turn Structure ◽  
Lrr Domain

Resistance to Albugo candida isolate Acem1 is conferred by a dominant gene, RAC1, in accession Ksk-1 of Arabidopsis thaliana. This gene was isolated by positional cloning and is a member of the Drosophila toll and mammalian interleukin-1 receptor (TIR) nucleotide-binding site leucine-rich repeat (NB-LRR) class of plant resistance genes. Strong identity of the TIR and NB domains was observed between the predicted proteins encoded by the Ksk-1 allele and the allele from an Acem1-susceptible accession Columbia (Col) (99 and 98%, respectively). However, major differences between the two predicted proteins occur within the LRR domain and mainly are confined to the β-strand/β-turn structure of the LRR. Both proteins contain 14 imperfect repeats. RAC1-mediated resistance was analyzed further using mutations in defense regulation, including: pad4-1, eds1-1, and NahG, in the presence of the RAC1 allele from Ksk-1. White rust resistance was completely abolished by eds1-1 but was not affected by either pad4-1 or NahG.

scholarly journals Integrity of the post-LRR domain is required for TNLs’ function

2020 ◽  
Author(s):  
Simon Bernard Saucet ◽  
Daniel Esmenjaud ◽  
Cyril Van Ghelder
Keyword(s):  
Amino Acids ◽  
Interleukin 1 ◽  
Defense Responses ◽  
Effector Proteins ◽  
Domain Specificity ◽  
Leucine Rich Repeat ◽  
Pathogen Effector ◽  
Tir Domains ◽  
Conserved Amino Acids ◽  
Lrr Domain

Plants trigger appropriate defense responses notably through intracellular nucleotide-binding (NB) and leucine-rich repeat (LRR) containing receptor genes (NLRs) that detect secreted pathogen effector proteins. In NLR resistance genes, the toll/interleukin-1 receptor (TIR)-NB-LRRs (TNLs) are an important subfamily out of which approximately half members carry a post-LRR (PL) domain of unknown role. We first investigated the requirement of the PL domain for TNL–mediated immune response by mutating the most conserved amino acids across PL domains of Arabidopsis thaliana TNLs. We identified several amino acids in the PL domain of RPS4 required for its ability to trigger a hypersensitive response to AvrRps4 in N. tabacum transient assay. Mutating the corresponding amino acids within the PL domain of the tobacco TNL gene N also affected its function. Consequently, our results indicate that the integrity of the PL domain at conserved positions is crucial for at least two unrelated TNLs. We then tested the PL domain specificity for function by swapping PL domains between the paralogs RPS4 and RPS4B. Our results suggest that the PL domain is involved in their TNL pair specificity, ‘off state’ stability and NLR complex activation. Considering genetically paired Arabidopsis TNLs, we finally compared the PL and TIR domains of their sensor and executor sequences, respectively. While TIR and PL domains from executors present complete motifs, sensors showed a lack of conservation with degenerated motifs. We provide here a first contribution to the functional analysis of the PL domain in order to decipher its role for TNLs’ function.

scholarly journals Resistance protein Pit interacts with the GEF OsSPK1 to activate OsRac1 and trigger rice immunity

2018 ◽  
Vol 115 (49) ◽  
pp. E11551-E11560 ◽  
Author(s):  
Qiong Wang ◽  
Yuying Li ◽  
Kazuya Ishikawa ◽  
Ken-ichi Kosami ◽  
Kazumi Uno ◽  
...  
Keyword(s):  
Molecular Mechanisms ◽  
Interleukin 1 ◽  
Domain Architecture ◽  
Nucleotide Binding ◽  
Small Gtpase ◽  
Leucine Rich Repeat ◽  
Nucleotide Exchange ◽  
Downstream Signaling

Resistance (R) genes encode intracellular nucleotide-binding/leucine-rich repeat-containing (NLR) family proteins that serve as critical plant immune receptors to induce effector-triggered immunity (ETI). NLR proteins possess a tripartite domain architecture consisting of an N-terminal variable region, a central nucleotide-binding domain, and a C-terminal leucine-rich repeat. N-terminal coiled-coil (CC) or Toll-interleukin 1 receptor (TIR) domains of R proteins appear to serve as platforms to trigger immune responses, because overexpression of the CC or TIR domain of some R proteins is sufficient to induce an immune response. Because direct downstream signaling molecules of R proteins remain obscure, the molecular mechanisms by which R proteins regulate downstream signaling are largely unknown. We reported previously that a rice R protein named Pit triggers ETI through a small GTPase, OsRac1, although how Pit activates OsRac1 is unclear. Here, we identified OsSPK1, a DOCK family guanine nucleotide exchange factor, as an interactor of Pit and activator for OsRac1. OsSPK1 contributes to signaling by two disease-resistance genes, Pit and Pia, against the rice blast fungus Magnaporthe oryzae and facilitates OsRac1 activation in vitro and in vivo. The CC domain of Pit is required for its binding to OsSPK1, OsRac1 activation, and the induction of cell death. Overall, we conclude that OsSPK1 is a direct and key signaling target of Pit-mediated immunity. Our results shed light on how R proteins trigger ETI through direct downstream molecules.

scholarly journals TIR signaling promotes the interactions between EDS1/PAD4 and ADR1-L1 and oligomerization of ADR1-L1

2021 ◽  
Author(s):  
Zhongshou Wu ◽  
Lei Tian ◽  
Xueru Liu ◽  
Yuelin Zhang ◽  
Xin Li
Keyword(s):  
Cell Death ◽  
Disease Resistance ◽  
Immune Activation ◽  
Disease Susceptibility ◽  
Interleukin 1 ◽  
Family Members ◽  
Nucleotide Binding ◽  
Leucine Rich Repeat ◽  
Downstream Signaling ◽  
Biochemical Mechanisms

Both plants and animals use nucleotide-binding leucine-rich repeat (NLR) immune receptors to perceive pathogens and trigger immunity. Toll/interleukin-1 receptor (TIR)-type plant NLRs (TNLs) require the lipase-like protein family members Enhanced Disease Susceptibility 1 (EDS1)/ Phytoalexin Deficient 4 (PAD4)/ Senescence-Associated Gene 101 (SAG101) and helper NLRs (hNLRs) for downstream signaling, the biochemical mechanisms of which remain unclear. Here, we report that TIR signaling promotes the association of EDS1 and PAD4 with hNLR ACTIVATED DISEASE RESISTANCE 1-Like 1 (ADR1-L1), and the oligomerization of ADR1-L1s for downstream immune activation and cell death.

scholarly journals Nucleotide-Binding Leucine-Rich Repeat Genes CsRSF1 and CsRSF2 Are Positive Modulators in the Cucumis sativus Defense Response to Sphaerotheca fuliginea

2021 ◽  
Vol 22 (8) ◽  
pp. 3986
Author(s):  
Xue Wang ◽  
Qiumin Chen ◽  
Jingnan Huang ◽  
Xiangnan Meng ◽  
Na Cui ◽  
...  
Keyword(s):  
Cell Membrane ◽  
Defense Response ◽  
Nucleotide Binding ◽  
Plant Defense Response ◽  
Sphaerotheca Fuliginea ◽  
Leucine Rich Repeat ◽  
Transcript Levels ◽  
Yield And Quality ◽  
Leucine Rich Repeats ◽  
Exogenous Substances

Cucumber powdery mildew caused by Sphaerotheca fuliginea is a leaf disease that seriously affects cucumber’s yield and quality. This study aimed to report two nucleotide-binding site-leucine-rich repeats (NBS-LRR) genes CsRSF1 and CsRSF2, which participated in regulating the resistance of cucumber to S. fuliginea. The subcellular localization showed that the CsRSF1 protein was localized in the nucleus, cytoplasm, and cell membrane, while the CsRSF2 protein was localized in the cell membrane and cytoplasm. In addition, the transcript levels of CsRSF1 and CsRSF2 were different between resistant and susceptible cultivars after treatment with exogenous substances, such as abscisic acid (ABA), methyl jasmonate (MeJA), salicylic acid (SA), ethephon (ETH), gibberellin (GA) and hydrogen peroxide (H2O2). The expression analysis showed that the transcript levels of CsRSF1 and CsRSF2 were correlated with plant defense response against S. fuliginea. Moreover, the silencing of CsRSF1 and CsRSF2 impaired host resistance to S. fuliginea, but CsRSF1 and CsRSF2 overexpression improved resistance to S. fuliginea in cucumber. These results showed that CsRSF1 and CsRSF2 genes positively contributed to the resistance of cucumber to S. fuliginea. At the same time, CsRSF1 and CsRSF2 genes could also regulate the expression of defense-related genes. The findings of this study might help enhance the resistance of cucumber to S. fuliginea.

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