Fungal effector Ecp6 outcompetes host immune receptor for chitin binding through intrachain LysM dimerization

Sánchez‐Vallet, Andrea; Saleem-Batcha, Raspudin; Kombrink, Anja; Hansen, Guido; Valkenburg, D.J.; Thomma, B.P.H.J.; Mesters, J.R.

doi:10.7554/elife.00790

Cited by 220 publications

(259 citation statements)

References 45 publications

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“…A recent study revealed that intermolecular dimerization of Arabidopsis thaliana CERK1, the chitin elicitor receptor kinase with three LysM motifs, is crucial for binding chitin oligosaccharides and its signaling function . Ecp6, the ortholog of Slp1 in the fungal pathogen Cladosporium fulvum (de Jonge et al, 2010), also has three LysM motifs that form intrachain LysM dimers to provide a groove for chitin binding (Sánchez-Vallet et al, 2013). To further determine how N-glycosylation affects the chitin binding activity of Slp1, it will be important to compare differences in the crystal structure of Slp1 between N-glycosylated and nonglycosylated Slp1.…”

Section: Discussionmentioning

confidence: 99%

N-Glycosylation of Effector Proteins by an α-1,3-Mannosyltransferase Is Required for the Rice Blast Fungus to Evade Host Innate Immunity

et al. 2014

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Plant pathogenic fungi deploy secreted effectors to suppress plant immunity responses. These effectors operate either in the apoplast or within host cells, so they are putatively glycosylated, but the posttranslational regulation of their activities has not been explored. In this study, the ASPARAGINE-LINKED GLYCOSYLATION3 (ALG3)-mediated N-glycosylation of the effector, Secreted LysM Protein1 (Slp1), was found to be essential for its activity in the rice blast fungus Magnaporthe oryzae. ALG3 encodes an a-1,3-mannosyltransferase for protein N-glycosylation. Deletion of ALG3 resulted in the arrest of secondary infection hyphae and a significant reduction in virulence. We observed that Dalg3 mutants induced massive production of reactive oxygen species in host cells, in a similar manner to Dslp1 mutants, which is a key factor responsible for arresting infection hyphae of the mutants. Slp1 sequesters chitin oligosaccharides to avoid their recognition by the rice (Oryza sativa) chitin elicitor binding protein CEBiP and the induction of innate immune responses, including reactive oxygen species production. We demonstrate that Slp1 has three N-glycosylation sites and that simultaneous Alg3-mediated N-glycosylation of each site is required to maintain protein stability and the chitin binding activity of Slp1, which are essential for its effector function. These results indicate that Alg3-mediated N-glycosylation of Slp1 is required to evade host innate immunity.

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Section: Discussionmentioning

confidence: 99%

N-Glycosylation of Effector Proteins by an α-1,3-Mannosyltransferase Is Required for the Rice Blast Fungus to Evade Host Innate Immunity

et al. 2014

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“…Avr4 is a chitin-binding protein that protects the fungus from plant chitinases, and it is recognised by the Hcr9-4D LRR-RLP gene located at the Cf-4 locus (Thomas et al 1997; Van Den Burg et al 2006). Ecp6, a LysM protein, also binds to chitin oligomers released by the action of host chitinases, which in turn minimises recognition by the host (Sánchez-Vallet et al 2013). Reduced effector expression was proposed to contribute to the reduced virulence of cfwor1 mutants (Okmen et al 2014).…”

Section: Fungal Potential Against Host Immune Systemmentioning

confidence: 99%

Chitin and chitin-related compounds in plant–fungal interactions

Pusztahelyi

2018

Mycology

145

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Chitin is the second abundant polysaccharide in the world after cellulose. It is a vital structural component of the fungal cell wall but not for plants. In plants, fungi are recognised through the perception of conserved microbe-associated molecular patterns (MAMPs) to induce MAMP-triggered immunity (MTI). Chitin polymers and their modified form, chitosan, induce host defence responses in both monocotyledons and dicotyledons. The plants’ response to chitin, chitosan, and derived oligosaccharides depends on the acetylation degree of these compounds which indicates possible biocontrol regulation of plant immune system. There has also been a considerable amount of recent research aimed at elucidating the roles of chitin hydrolases in fungi and plants as chitinase production in plants is not considered solely as an antifungal resistance mechanism. We discuss the importance of chitin forms and chitinases in the plant–fungal interactions and their role in persistent and possible biocontrol.Abbreviations ET, ethylene; GAP, GTPase-activating protein; GEF, GDP/GTP exchange factor; JA, jasmonic acid; LysM, lysin motif; MAMP, microbe-associated molecular pattern; MTI, MAMP-triggered immunity; NBS, nucleotide-binding site; NBS-LRR, nucleotide-binding site leucine-rich repeats; PM, powdery mildew; PR, pathogenesis-related; RBOH, respiratory burst oxidase homolog; RLK, receptor-like kinase; RLP, receptor-like protein; SA, salicylic acid; TF, transcription factor.

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“…Thus, adapted pathogens must overcome PTI in order to grow and to cause disease. A common mechanism for PTI suppression is the secretion of pathogen proteins, called effectors, into the apoplast or inside host cells (Dou and Zhou, 2012;Sánchez-Vallet et al, 2013). Plants also can recognize specific intracellular pathogen effectors using resistance proteins and induce effectortriggered immunity (ETI; Chiang and Coaker, 2015).…”

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confidence: 99%

A Cysteine-Rich Protein Kinase Associates with a Membrane Immune Complex and the Cysteine Residues Are Required for Cell Death

et al. 2016

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Membrane-localized proteins perceive and respond to biotic and abiotic stresses. We performed quantitative proteomics on plasma membrane-enriched samples from Arabidopsis (Arabidopsis thaliana) treated with bacterial flagellin. We identified multiple receptor-like protein kinases changing in abundance, including cysteine (Cys)-rich receptor-like kinases (CRKs) that are up-regulated upon the perception of flagellin. CRKs possess extracellular Cys-rich domains and constitute a gene family consisting of 46 members in Arabidopsis. The single transfer DNA insertion lines CRK28 and CRK29, two CRKs induced in response to flagellin perception, did not exhibit robust alterations in immune responses. In contrast, silencing of multiple bacterial flagellin-induced CRKs resulted in enhanced susceptibility to pathogenic Pseudomonas syringae, indicating functional redundancy in this large gene family. Enhanced expression of CRK28 in Arabidopsis increased disease resistance to P. syringae. Expression of CRK28 in Nicotiana benthamiana induced cell death, which required intact extracellular Cys residues and a conserved kinase active site. CRK28-mediated cell death required the common receptor-like protein kinase coreceptor BAK1. CRK28 associated with BAK1 as well as the activated FLAGELLIN-SENSING2 (FLS2) immune receptor complex. CRK28 self-associated as well as associated with the closely related CRK29. These data support a model where Arabidopsis CRKs are synthesized upon pathogen perception, associate with the FLS2 complex, and coordinately act to enhance plant immune responses.

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Fungal effector Ecp6 outcompetes host immune receptor for chitin binding through intrachain LysM dimerization

Cited by 220 publications

References 45 publications

N-Glycosylation of Effector Proteins by an α-1,3-Mannosyltransferase Is Required for the Rice Blast Fungus to Evade Host Innate Immunity

N-Glycosylation of Effector Proteins by an α-1,3-Mannosyltransferase Is Required for the Rice Blast Fungus to Evade Host Innate Immunity

Chitin and chitin-related compounds in plant–fungal interactions

A Cysteine-Rich Protein Kinase Associates with a Membrane Immune Complex and the Cysteine Residues Are Required for Cell Death

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