scholarly journals Design of a new effector recognition specificity in a plant NLR immune receptor by molecular engineering of its integrated decoy domain

2021 ◽  
Author(s):  
Stella Cesari ◽  
Yuxuan Xi ◽  
Nathalie Declerck ◽  
Véronique Chalvon ◽  
Léa Mammri ◽  
...  
Keyword(s):  
Immune Responses ◽  
Crop Protection ◽  
Molecular Engineering ◽  
Future Research ◽  
Pathogen Effectors ◽  
Recognition Specificity ◽  
Heterologous System ◽  
Binding Surface ◽  
Engineering Strategy ◽  
Effector Recognition

SUMMARYPlant nucleotide-binding and leucine-rich repeat domain proteins (NLRs) are immune sensors that specifically recognize pathogen effectors and induce immune responses. Designing artificial NLRs with new effector recognition specificities is a promising prospect for sustainable, knowledge-driven crop protection. However, such strategies are hampered by the complexity of NLR function. Here, we tested whether molecular engineering of the integrated decoy domain (ID) of an NLR could extend its recognition spectrum to a new effector. To this aim, we relied on the detailed molecular knowledge of the recognition of distinct Magnaporthe oryzae MAX (Magnaporthe AVRs and ToxB-like) effectors by the rice NLRs RGA5 and Pikp-1. For both NLRs, effector recognition involves physical binding to their HMA (Heavy Metal-Associated) IDs. However, AVR-PikD, the effector recognized by Pikp-1, binds to a completely different surface of the HMA domain compared to AVR-Pia and AVR1-CO39, recognized by RGA5. By introducing into the HMA domain of RGA5 the residues of the Pikp-1 HMA domain involved in AVR-PikD binding, we created a high-affinity binding surface for this new effector. In the Nicotiana benthamiana heterologous system, RGA5 variants carrying this engineered binding surface still recognize AVR-Pia and AVR1-CO39, but also perceive the new ligand, AVR-PikD, resulting in the activation of immune responses. Therefore, our study provides a proof of concept for the design of new effector recognition specificities in NLRs through molecular engineering of IDs. However, it pinpoints significant knowledge gaps that limit the full deployment of this NLR-ID engineering strategy and provides hypotheses for future research on this topic.

scholarly journals The allelic rice immune receptor Pikh confers extended resistance to strains of the blast fungus through a single polymorphism in the effector binding interface

2020 ◽  
Author(s):  
Juan Carlos De la Concepcion ◽  
Josephine H. R. Maidment ◽  
Apinya Longya ◽  
Gui Xiao ◽  
Marina Franceschetti ◽  
...  
Keyword(s):  
Immune Responses ◽  
Rice Blast ◽  
Immune Recognition ◽  
Immune Receptor ◽  
Immune Receptors ◽  
Pathogen Effectors ◽  
Binding Interface ◽  
Recognition Specificity ◽  
Blast Fungus ◽  
Effector Recognition

AbstractArms race co-evolution drives rapid adaptive changes in pathogens and in the immune systems of their hosts. Plant intracellular NLR immune receptors detect effectors delivered by pathogens to promote susceptibility, activating an immune response that halts colonization. As a consequence, pathogen effectors evolve to escape immune recognition and are highly variable. In turn, NLR receptors are one of the most diverse protein families in plants, and this variability underpins differential recognition of effector variants. The molecular mechanisms underlying natural variation in effector recognition by NLRs are starting to be elucidated. The rice NLR pair Pik-1/Pik-2 recognizes AVR-Pik effectors from the blast fungus Magnaporthe oryzae, triggering immune responses that limit rice blast infection. Allelic variation in a heavy metal associated (HMA) domain integrated in the receptor Pik-1 confers differential binding to AVR-Pik variants, determining resistance specificity. Previous mechanistic studies uncovered how a Pik allele, Pikm, has extended recognition to effector variants through a specialized HMA/AVR-Pik binding interface. Here, we reveal the mechanistic basis of extended recognition specificity conferred by another Pik allele, Pikh. A single residue in Pikh-HMA increases binding to AVR-Pik variants, leading to an extended effector response in planta. The crystal structure of Pikh-HMA in complex with an AVR-Pik variant confirmed that Pikh and Pikm use a similar molecular mechanism to extend their pathogen recognition profile. This study shows how different NLR receptor alleles functionally converge to extend recognition specificity to pathogen effectors.Author SummaryPlant pathogens constantly evolve to overcome immune defences and successfully colonize hosts, resulting in some of the most devastating diseases that affect global food production. To defend themselves, plants have evolved a sophisticated immune system that recognizes the presence of different pathogens and triggers immune responses to stop their spread. How plant immune receptors achieve extended recognition to specific pathogen strains and the molecular details of this recognition are just starting to be understood.In this study, we characterize how an allele of a rice immune receptor achieves a broad-spectrum recognition to effectors from the rice blast fungus. We found that this receptor has evolved a single change that alters the way it binds to different effector variants. This change increases binding affinity to these variants and this is ultimately translated to immune recognition. Interestingly, a different rice immune receptor allele also achieves broad-spectrum effector recognition in a similar way. Therefore, different immune receptor alleles can converge on a similar mechanism to achieve extended recognition to pathogen effectors.This knowledge has the potential to help to the rational design of plant immune receptors with bespoke resistance to some of the most destructive pathogens. A long-term goal in plant biotechnology.

scholarly journals Recent Advances in Effector-Triggered Immunity in Plants: New Pieces in the Puzzle Create a Different Paradigm

2021 ◽  
Vol 22 (9) ◽  
pp. 4709
Author(s):  
Quang-Minh Nguyen ◽  
Arya Bagus Boedi Iswanto ◽  
Geon Hui Son ◽  
Sang Hee Kim
Keyword(s):  
Host Plants ◽  
Crop Protection ◽  
Innate Immune ◽  
Leucine Rich Repeat ◽  
Resistance Proteins ◽  
Pathogen Effectors ◽  
Innate Immune Signaling ◽  
Current Perspective ◽  
Effector Triggered Immunity ◽  
Effector Recognition

Plants rely on multiple immune systems to protect themselves from pathogens. When pattern-triggered immunity (PTI)—the first layer of the immune response—is no longer effective as a result of pathogenic effectors, effector-triggered immunity (ETI) often provides resistance. In ETI, host plants directly or indirectly perceive pathogen effectors via resistance proteins and launch a more robust and rapid defense response. Resistance proteins are typically found in the form of nucleotide-binding and leucine-rich-repeat-containing receptors (NLRs). Upon effector recognition, an NLR undergoes structural change and associates with other NLRs. The dimerization or oligomerization of NLRs signals to downstream components, activates “helper” NLRs, and culminates in the ETI response. Originally, PTI was thought to contribute little to ETI. However, most recent studies revealed crosstalk and cooperation between ETI and PTI. Here, we summarize recent advancements in our understanding of the ETI response and its components, as well as how these components cooperate in the innate immune signaling pathways. Based on up-to-date accumulated knowledge, this review provides our current perspective of potential engineering strategies for crop protection.

scholarly journals Pathogen effector recognition-dependent association of NRG1 with EDS1 and SAG101 in TNL receptor immunity

2021 ◽  
Vol 12 (1) ◽  
Author(s):  
Xinhua Sun ◽  
Dmitry Lapin ◽  
Joanna M. Feehan ◽  
Sara C. Stolze ◽  
Katharina Kramer ◽  
...  
Keyword(s):  
Disease Susceptibility ◽  
Nucleotide Binding ◽  
Molecular Evidence ◽  
Pathogen Effectors ◽  
Pathogen Effector ◽  
Family Protein ◽  
Activated State ◽  
Defence Signalling ◽  
Effector Recognition ◽  
Dependent Interaction

AbstractPlants utilise intracellular nucleotide-binding, leucine-rich repeat (NLR) immune receptors to detect pathogen effectors and activate local and systemic defence. NRG1 and ADR1 “helper” NLRs (RNLs) cooperate with enhanced disease susceptibility 1 (EDS1), senescence-associated gene 101 (SAG101) and phytoalexin-deficient 4 (PAD4) lipase-like proteins to mediate signalling from TIR domain NLR receptors (TNLs). The mechanism of RNL/EDS1 family protein cooperation is not understood. Here, we present genetic and molecular evidence for exclusive EDS1/SAG101/NRG1 and EDS1/PAD4/ADR1 co-functions in TNL immunity. Using immunoprecipitation and mass spectrometry, we show effector recognition-dependent interaction of NRG1 with EDS1 and SAG101, but not PAD4. An EDS1-SAG101 complex interacts with NRG1, and EDS1-PAD4 with ADR1, in an immune-activated state. NRG1 requires an intact nucleotide-binding P-loop motif, and EDS1 a functional EP domain and its partner SAG101, for induced association and immunity. Thus, two distinct modules (NRG1/EDS1/SAG101 and ADR1/EDS1/PAD4) mediate TNL receptor defence signalling.

N-Acetyl Galactosamine Targeting: Paving the Way for Clinical Application of Nucleotide Medicines in Cardiovascular Diseases

2021 ◽  
Author(s):  
Erik A.L. Biessen ◽  
Theo J.C. Van Berkel
Keyword(s):  
Immune Responses ◽  
Targeted Delivery ◽  
Antisense Oligonucleotides ◽  
Sugar Metabolism ◽  
Innate Immune ◽  
Future Research ◽  
Clinical Use ◽  
Innate Immune Responses ◽  
Chemically Modified ◽  
Intrinsic Capacity

While the promise of oligonucleotide therapeutics, such as (chemically modified) ASO (antisense oligonucleotides) and short interfering RNAs, is undisputed from their introduction onwards, their unfavorable pharmacokinetics and intrinsic capacity to mobilize innate immune responses, were limiting widespread clinical use. However, these major setbacks have been tackled by breakthroughs in chemistry, stability and delivery. When aiming an intervention hepatic targets, such as lipid and sugar metabolism, coagulation, not to mention cancer and virus infection, introduction of N-acetylgalactosamine aided targeting technology has advanced the field profoundly and by now a dozen of N-acetylgalactosamine therapeutics for these indications have been approved for clinical use or have progressed to clinical trial stage 2 to 3 testing. This technology, in combination with major advances in oligonucleotide stability allows safe and durable intervention in targets that were previously deemed undruggable, such as Lp(a) and PCSK9, at high efficacy and specificity, often with as little as 2 doses per year. Their successful use even the most visionary would not have predicted 2 decades ago. Here, we will review the evolution of N-acetylgalactosamine technology. We shall outline their fundamental design principles and merits, and their application for the delivery of oligonucleotide therapeutics to the liver. Finally, we will discuss the perspectives of N-acetylgalactosamine technology and propose directions for future research in receptor targeted delivery of these gene medicines.

scholarly journals The allelic rice immune receptor Pikh confers extended resistance to strains of the blast fungus through a single polymorphism in the effector binding interface

2021 ◽  
Vol 17 (3) ◽  
pp. e1009368
Author(s):  
Juan Carlos De la Concepcion ◽  
Josephine H. R. Maidment ◽  
Apinya Longya ◽  
Gui Xiao ◽  
Marina Franceschetti ◽  
...  
Keyword(s):  
Molecular Mechanisms ◽  
Allelic Variation ◽  
Immune Recognition ◽  
In Planta ◽  
Pathogen Effectors ◽  
Binding Interface ◽  
Recognition Specificity ◽  
Blast Fungus ◽  
Resistance Specificity ◽  
Mechanistic Basis

Arms race co-evolution drives rapid adaptive changes in pathogens and in the immune systems of their hosts. Plant intracellular NLR immune receptors detect effectors delivered by pathogens to promote susceptibility, activating an immune response that halts colonization. As a consequence, pathogen effectors evolve to escape immune recognition and are highly variable. In turn, NLR receptors are one of the most diverse protein families in plants, and this variability underpins differential recognition of effector variants. The molecular mechanisms underlying natural variation in effector recognition by NLRs are starting to be elucidated. The rice NLR pair Pik-1/Pik-2 recognizes AVR-Pik effectors from the blast fungus Magnaporthe oryzae, triggering immune responses that limit rice blast infection. Allelic variation in a heavy metal associated (HMA) domain integrated in the receptor Pik-1 confers differential binding to AVR-Pik variants, determining resistance specificity. Previous mechanistic studies uncovered how a Pik allele, Pikm, has extended recognition to effector variants through a specialized HMA/AVR-Pik binding interface. Here, we reveal the mechanistic basis of extended recognition specificity conferred by another Pik allele, Pikh. A single residue in Pikh-HMA increases binding to AVR-Pik variants, leading to an extended effector response in planta. The crystal structure of Pikh-HMA in complex with an AVR-Pik variant confirmed that Pikh and Pikm use a similar molecular mechanism to extend their pathogen recognition profile. This study shows how different NLR receptor alleles functionally converge to extend recognition specificity to pathogen effectors.

scholarly journals In vivo administration of anti-HIV hyper-immune eggs induces anti-anti-idiotypic antibodies against HIV gp120 peptides (fragments 308-331 and 421-438) and against HIV gp41 peptide (fragment 579-601) which have demonstrable protective capacity

2021 ◽  
Author(s):  
Angel Justiz-Vaillant ◽  
Belkis Ferrer-Cosme ◽  
Monica Fisher Smikle ◽  
Oliver Pérez
Keyword(s):  
Immune Responses ◽  
Hiv Infections ◽  
Egg Yolk ◽  
Laboratory Animals ◽  
Future Research ◽  
Protective Capacity ◽  
Antigen Binding Site ◽  
Hiv Antigen ◽  
Gp41 Peptide

AbstractIsolation of antibodies from the egg yolk of chickens is of particular interest as a source of specific antibodies for oral administration to prevent infections and use them as immunodiagnostic reagents. The use of birds in antibody production results in a reduction in the use of laboratory animals. Immunized chickens produce larger quantities of antibodies (2000 mg IgY/month) than rodents (200 mg IgG/month) in the laboratory. According to Jerne’s network theory, it is possible to produce an antibody against the antigen-binding site of another antibody. This study assessed the hypothesis that immunization with viral peptides (immunogens) could provide a potent immune response that could be evaluated in chicken eggs. Human immunodeficiency virus 1(HIV-1) is used as an immunogen. The second hypothesis was that an orally administered antibody stimulates the production of a complementary antibody, the so-called anti-idiotypic antibody, which can potentially be therapeutical. This study reports and analyzes the use of eggs as therapeutic agents. We wanted to test the hypothesis that feeding chicks with hyperimmune eggs stimulates the production of anti-anti-idiotypic antibodies that neutralize the original HIV antigen fragments 308-331 or 421-438 of gp120 or fragment 579-601 of gp41. Future research could entail an anti-idiotype strategy for prophylactic vaccines. It is vital to note that it may need an anti-idiotype response to prime immunity against an HIV viral epitope, which may be used as a secondary element. The use of anti-idiotype immune responses in infected individuals may shift the balance of the immune system, allowing the organism to manage HIV infection. Therefore, it may be an avenue for immunotherapy to improve the fight against HIV infections. However, more studies and clinical trials are required to demonstrate similar human immune responses as observed in birds.

scholarly journals Cell Line Platforms Support Research into Arthropod Immunity

Insects ◽  
2021 ◽  
Vol 12 (8) ◽  
pp. 738
Author(s):  
Cynthia L. Goodman ◽  
David S. Kang ◽  
David Stanley
Keyword(s):  
Immune Responses ◽  
Cell Line ◽  
Cell Lines ◽  
Cost Effective ◽  
Future Research ◽  
Innate Immune Responses ◽  
Pathogenic Viruses ◽  
Future Research Directions ◽  
Bacteria And Fungi ◽  
Robust Systems

Innate immune responses are essential to maintaining insect and tick health and are the primary defense against pathogenic viruses, bacteria, and fungi. Cell line research is a powerful method for understanding how invertebrates mount defenses against pathogenic organisms and testing hypotheses on how these responses occur. In particular, immortal arthropod cell lines are valuable tools, providing a tractable, high-throughput, cost-effective, and consistent platform to investigate the mechanisms underpinning insect and tick immune responses. The research results inform the controls of medically and agriculturally important insects and ticks. This review presents several examples of how cell lines have facilitated research into multiple aspects of the invertebrate immune response to pathogens and other foreign agents, as well as comments on possible future research directions in these robust systems.

scholarly journals Dynamic accumulation of a helper NLR at the plant-pathogen interface underpins pathogen recognition

2021 ◽  
Author(s):  
Cian Duggan ◽  
Eleonora Moratto ◽  
Zachary Savage ◽  
Eranthika Hamilton ◽  
Hiroaki Adachi ◽  
...  
Keyword(s):  
Plasma Membrane ◽  
Immune Responses ◽  
Subcellular Localization ◽  
Plant Pathogen ◽  
Coiled Coil ◽  
Dynamic Changes ◽  
Pathogen Effectors ◽  
Mediate Response ◽  
Potato Famine ◽  
Irish Potato Famine

Plants employ sensor-helper pairs of NLR immune receptors to recognize pathogen effectors and activate immune responses. Yet the subcellular localization of NLRs pre- and post- activation during pathogen infection remains poorly known. Here we show that NRC4, from the 'NRC' solanaceous helper NLR family, undergoes dynamic changes in subcellular localization by shuttling to and from the plant-pathogen haustorium interface established during infection by the Irish potato famine pathogen Phytophthora infestans. Specifically, prior to activation, NRC4 accumulates at the extra-haustorial membrane (EHM), presumably to mediate response to perihaustorial effectors, that are recognized by NRC4-dependent sensor NLRs. However not all NLRs accumulate at the EHM, as the closely related helper NRC2, and the distantly related ZAR1, did not accumulate at the EHM. NRC4 required an intact N- terminal coiled coil domain to accumulate at the EHM, whereas the functionally conserved MADA motif implicated in cell death activation and membrane insertion was dispensable for this process. Strikingly, a constitutively autoactive NRC4 mutant did not accumulate at the EHM and showed punctate distribution that mainly associated with the plasma membrane, suggesting that post-activation, NRC4 probably undergoes a conformation switch to form clusters that do not preferentially associate with the EHM. When NRC4 is activated by a sensor NLR during infection however, NRC4 formed puncta mainly at the EHM and to a lesser extent at the plasma membrane. We conclude that following activation at the EHM, NRC4 may spread to other cellular membranes from its primary site of activation to trigger immune responses.

scholarly journals Recent Advances in Engineered Nanoparticles for RNAi-Mediated Crop Protection Against Insect Pests

2021 ◽  
Vol 3 ◽  
Author(s):  
Charlotte E. Pugsley ◽  
R. E. Isaac ◽  
Nicholas J. Warren ◽  
Olivier J. Cayre
Keyword(s):  
Nucleic Acid ◽  
Insect Pests ◽  
Research Effort ◽  
Insect Pest ◽  
Crop Protection ◽  
Mrna Degradation ◽  
Engineered Nanoparticles ◽  
Future Research ◽  
Therapeutic Applications ◽  
Rnai Response

Since the discovery of RNA interference (RNAi) in the nematode worm Caenorhabditis elegans in 1998 by Fire and Mello et al., strides have been made in exploiting RNAi for therapeutic applications and more recently for highly selective insect pest control. Although triggering mRNA degradation in insects through RNAi offers significant opportunities in crop protection, the application of environmental naked dsRNA is often ineffective in eliciting a RNAi response that results in pest lethality. There are many possible reasons for the failed or weak induction of RNAi, with predominant causes being the degradation of dsRNA in the formulated pesticide, in the field or in the insect once ingested, poor cuticular and oral uptake of the nucleic acid and sometimes the lack of an innate strong systemic RNAi response. Therefore, in the last 10 years significant research effort has focused on developing methods for the protection and delivery of environmental dsRNA to enable RNAi-induced insect control. This review focuses on the design and synthesis of vectors (vehicles that are capable of carrying and protecting dsRNA) that successfully enhance mRNA degradation via the RNAi machinery. The majority of solutions exploit the ability of charged polymers, both synthetic and natural, to complex with dsRNA, but alternative nanocarriers such as clay nanosheets and liposomal vesicles have also been developed. The various challenges of dsRNA delivery and the obstacles in the development of well-designed nanoparticles that act to protect the nucleic acid are highlighted. In addition, future research directions for improving the efficacy of RNA-mediated crop protection are anticipated with inspiration taken from polymeric architectures constructed for RNA-based therapeutic applications.

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