scholarly journals Conserved RxLR Effectors From Oomycetes Hyaloperonospora arabidopsidis and Phytophthora sojae Suppress PAMP- and Effector-Triggered Immunity in Diverse Plants

2018 ◽  
Vol 31 (3) ◽  
pp. 374-385 ◽  
Author(s):  
Devdutta Deb ◽  
Ryan G. Anderson ◽  
Theresa How-Yew-Kin ◽  
Brett M. Tyler ◽  
John M. McDowell
Keyword(s):  
Plant Pathogens ◽  
Phytophthora Species ◽  
Phytophthora Sojae ◽  
Effector Proteins ◽  
Host Cells ◽  
Rxlr Effectors ◽  
Genes Encoding ◽  
Effector Triggered Immunity ◽  
Hyaloperonospora Arabidopsidis ◽  
Diverse Plant

Effector proteins are exported to the interior of host cells by diverse plant pathogens. Many oomycete pathogens maintain large families of candidate effector genes, encoding proteins with a secretory leader followed by an RxLR motif. Although most of these genes are very divergent between oomycete species, several genes are conserved between Phytophthora species and Hyaloperonospora arabidopsidis, suggesting that they play important roles in pathogenicity. We describe a pair of conserved effector candidates, HaRxL23 and PsAvh73, from H. arabidopsidis and P. sojae respectively. We show that HaRxL23 is expressed early during infection of Arabidopsis. HaRxL23 triggers an ecotype-specific defense response in Arabidopsis, suggesting that it is recognized by a host surveillance protein. HaRxL23 and PsAvh73 can suppress pathogen-associated molecular pattern (PAMP)-triggered immunity (PTI) in Nicotiana benthamiana and effector-triggered immunity (ETI) in soybean. Transgenic Arabidopsis constitutively expressing HaRxL23 or PsAvh73 exhibit suppression of PTI and enhancement of bacterial and oomycete virulence. Together, our experiments demonstrate that these conserved oomycete RxLR effectors suppress PTI and ETI across diverse plant species.

scholarly journals Signatures of Adaptation to Obligate Biotrophy in the Hyaloperonospora arabidopsidis Genome

Science ◽  
2010 ◽  
Vol 330 (6010) ◽  
pp. 1549-1551 ◽  
Author(s):  
Laura Baxter ◽  
Sucheta Tripathy ◽  
Naveed Ishaque ◽  
Nico Boot ◽  
Adriana Cabral ◽  
...  
Keyword(s):  
Plant Pathogens ◽  
Inorganic Nitrogen ◽  
Living Plant ◽  
Rxlr Effectors ◽  
Fungal Plant Pathogens ◽  
Genes Encoding ◽  
Zoospore Formation ◽  
Hyaloperonospora Arabidopsidis ◽  
Obligate Biotrophs ◽  
Obligate Biotroph

Many oomycete and fungal plant pathogens are obligate biotrophs, which extract nutrients only from living plant tissue and cannot grow apart from their hosts. Although these pathogens cause substantial crop losses, little is known about the molecular basis or evolution of obligate biotrophy. Here, we report the genome sequence of the oomycete Hyaloperonospora arabidopsidis (Hpa), an obligate biotroph and natural pathogen of Arabidopsis thaliana. In comparison with genomes of related, hemibiotrophic Phytophthora species, the Hpa genome exhibits dramatic reductions in genes encoding (i) RXLR effectors and other secreted pathogenicity proteins, (ii) enzymes for assimilation of inorganic nitrogen and sulfur, and (iii) proteins associated with zoospore formation and motility. These attributes comprise a genomic signature of evolution toward obligate biotrophy.

scholarly journals Interaction of Phytophthora sojae Effector Avr1b With E3 Ubiquitin Ligase GmPUB1 Is Required for Recognition by Soybeans Carrying Phytophthora Resistance Rps1-b and Rps1-k Genes

2021 ◽  
Vol 12 ◽  
Author(s):  
Shan Li ◽  
Regina Hanlon ◽  
Hua Wise ◽  
Narinder Pal ◽  
Hargeet Brar ◽  
...  
Keyword(s):  
Cell Death ◽  
Phytophthora Sojae ◽  
Effector Proteins ◽  
Host Cells ◽  
Bimolecular Fluorescence Complementation ◽  
Yeast Two Hybrid ◽  
Synonymous Mutations ◽  
Rxlr Effectors ◽  
C Terminus ◽  
Two Hybrid

Phytophthora sojae is an oomycete that causes stem and root rot disease in soybean. P. sojae delivers many RxLR effector proteins, including Avr1b, into host cells to promote infection. We show here that Avr1b interacts with the soybean U-box protein, GmPUB1-1, in yeast two-hybrid, pull down, and bimolecular fluorescence complementation (BIFC) assays. GmPUB1-1, and a homeologous copy GmPUB1-2, are induced by infection and encode 403 amino acid proteins with U-Box domains at their N-termini. Non-synonymous mutations in the Avr1b C-terminus that abolish suppression of cell death also abolished the interaction of Avr1b with GmPUB1-1, while deletion of the GmPUB1-1 C-terminus, but not the U box, abolished the interaction. BIFC experiments suggested that the GmPUB1-1-Avr1b complex is targeted to the nucleus. In vitro ubiquitination assays demonstrated that GmPUB1-1 possesses E3 ligase activity. Silencing of the GmPUB1 genes in soybean cotyledons resulted in loss of recognition of Avr1b by gene products encoded by Rps1-b and Rps1-k. The recognition of Avr1k (which did not interact with GmPUB1-1) by Rps1-k plants was not, however, affected following GmPUB1-1 silencing. Furthermore, over-expression of GmPUB1-1 in particle bombardment experiments triggered cell death suggesting that GmPUB1 may be a positive regulator of effector-triggered immunity. In a yeast two-hybrid system, GmPUB1-1 also interacted with a number of other RxLR effectors including Avr1d, while Avr1b and Avr1d interacted with a number of other infection-induced GmPUB proteins, suggesting that the pathogen uses a multiplex of interactions of RxLR effectors with GmPUB proteins to modulate host immunity.

scholarly journals Structural genomic applied on the rust fungus Melampsora larici-populina reveals two candidate effector proteins adopting cystine-knot and nuclear transport factor 2-like protein folds

2019 ◽  
Author(s):  
Karine de Guillen ◽  
Cécile Lorrain ◽  
Pascale Tsan ◽  
Philippe Barthe ◽  
Benjamin Petre ◽  
...  
Keyword(s):  
Plant Pathogens ◽  
Nuclear Transport ◽  
Sequence Similarity ◽  
Rust Fungus ◽  
Parasitic Infection ◽  
Effector Proteins ◽  
Host Cells ◽  
Dimensional Structure ◽  
Structural Genomic ◽  
Transport Factor

ABSTRACTRust fungi are plant pathogens that secrete an arsenal of effector proteins interfering with plant functions and promoting parasitic infection. Effectors are often species-specific, evolve rapidly, and display low sequence similarities with known proteins or domains. How rust fungal effectors function in host cells remains elusive, and biochemical and structural approaches have been scarcely used to tackle this question. In this study, we used a strategy based on recombinant protein production in Escherichia coli to study eleven candidate effectors of the leaf rust fungus Melampsora larici-populina. We successfully purified and solved the three-dimensional structure of two proteins, MLP124266 and MLP124017, using NMR spectroscopy. Although both proteins show no sequence similarity with known proteins, they exhibit structural similarities to knottin and nuclear transport factor 2-like proteins, respectively. Altogether, our findings show that sequence-unrelated effectors can adopt folds similar to known proteins, and encourage the use of biochemical and structural approaches to functionally characterize rust effector candidates.

scholarly journals Prediction and Characterization of RXLR Effectors in Pythium Species

2020 ◽  
Vol 33 (8) ◽  
pp. 1046-1058 ◽  
Author(s):  
Gan Ai ◽  
Kun Yang ◽  
Wenwu Ye ◽  
Yuee Tian ◽  
Yaxin Du ◽  
...  
Keyword(s):  
Genome Rearrangement ◽  
De Novo ◽  
Biological Control Agent ◽  
Protein Structures ◽  
Control Agent ◽  
Phytophthora Species ◽  
Host Cells ◽  
Pythium Species ◽  
Origin And Evolution ◽  
Rxlr Effectors

RXLR effectors, a class of secreted proteins that are transferred into host cells to manipulate host immunity, have been reported to widely exist in oomycetes, including those from genera Phytophthora, Hyaloperonospora, Albugo, and Saprolegnia. However, in Pythium species, no RXLR effector has yet been characterized, and the origin and evolution of such virulent effectors are still unknown. Here, we developed a modified regular expression method for de novo identification of RXLRs and characterized 359 putative RXLR effectors in nine Pythium species. Phylogenetic analysis revealed that all oomycetous RXLRs formed a single superfamily, suggesting that they might have a common ancestor. RXLR effectors from Pythium and Phytophthora species exhibited similar sequence features, protein structures, and genome locations. In particular, there were significantly more RXLR proteins in the mosquito biological control agent P. guiyangense than in the other eight Pythium species, and P. guiyangense RXLRs might be the result of gene duplication and genome rearrangement events, as indicated by synteny analysis. Expression pattern analysis of RXLR-encoding genes in the plant pathogen P. ultimum detected transcripts of the majority of the predicted RXLR genes, with some RXLR effectors induced in infection stages and one RXLR showing necrosis-inducing activity. Furthermore, all predicted RXLR genes were cloned from two biocontrol agents, P. oligandrum and P. periplocum, and three of the RXLR genes were found to induce a defense response in Nicotiana benthamiana. Taken together, our findings represent the first evidence of RXLR effectors in Pythium species, providing valuable information on their evolutionary patterns and the mechanisms of their interactions with diverse hosts.

scholarly journals RIPK1-dependent apoptosis bypasses pathogen blockade of innate signaling to promote immune defense

2017 ◽  
Vol 214 (11) ◽  
pp. 3171-3182 ◽  
Author(s):  
Lance W. Peterson ◽  
Naomi H. Philip ◽  
Alexandra DeLaney ◽  
Meghan A. Wynosky-Dolfi ◽  
Kendra Asklof ◽  
...  
Keyword(s):  
Cell Death ◽  
Kinase Activity ◽  
Cytokine Production ◽  
Mapk Signaling ◽  
Immune Defense ◽  
Effector Proteins ◽  
Host Cells ◽  
Effector Triggered Immunity ◽  
Induced Apoptosis

Many pathogens deliver virulence factors or effectors into host cells in order to evade host defenses and establish infection. Although such effector proteins disrupt critical cellular signaling pathways, they also trigger specific antipathogen responses, a process termed “effector-triggered immunity.” The Gram-negative bacterial pathogen Yersinia inactivates critical proteins of the NF-κB and MAPK signaling cascade, thereby blocking inflammatory cytokine production but also inducing apoptosis. Yersinia-induced apoptosis requires the kinase activity of receptor-interacting protein kinase 1 (RIPK1), a key regulator of cell death, NF-κB, and MAPK signaling. Through the targeted disruption of RIPK1 kinase activity, which selectively disrupts RIPK1-dependent cell death, we now reveal that Yersinia-induced apoptosis is critical for host survival, containment of bacteria in granulomas, and control of bacterial burdens in vivo. We demonstrate that this apoptotic response provides a cell-extrinsic signal that promotes optimal innate immune cytokine production and antibacterial defense, demonstrating a novel role for RIPK1 kinase–induced apoptosis in mediating effector-triggered immunity to circumvent pathogen inhibition of immune signaling.

scholarly journals Characterization of Enteropathogenic Escherichia coli Mutants That Fail To Disrupt Host Cell Spreading and Attachment to Substratum

2006 ◽  
Vol 74 (2) ◽  
pp. 839-849 ◽  
Author(s):  
Chen Nadler ◽  
Yulia Shifrin ◽  
Shani Nov ◽  
Simi Kobi ◽  
Ilan Rosenshine
Keyword(s):  
Escherichia Coli ◽  
Host Cell ◽  
Protein Production ◽  
Response Regulator ◽  
Constitutive Expression ◽  
Effector Proteins ◽  
Host Cells ◽  
Expression Vectors ◽  
Cell Functions ◽  
Genes Encoding

ABSTRACT Upon infection of host cells, enteropathogenic Escherichia coli (EPEC) delivers a set of effector proteins into the host cell cytoplasm via the type III secretion system (TTSS). The effectors subvert various host cell functions. We found that EPEC interferes with the spreading and ultimately with the attachment of suspended fibroblasts or epithelial cells, and we isolated mini-Tn10kan insertion mutants that failed to similarly affect host cells. In most mutants, the insertion sites were mapped to genes encoding TTSS components, including cesD, escC, escJ, escV, espD, sepL, espB, and escF. Other mutants contained insertions in micC or upstream of bfpP, yehL, or ydeP. The insertion upstream of ydeP was associated with a reduction in TTSS protein production and was studied further. To determine whether the apparent repression was due to constitutive expression of the downstream encoded genes, ydeP and ydeO expression vectors were constructed. Expression of recombinant YdeP, YdeO, or EvgA, a positive regulator of both ydeP and ydeO, repressed TTSS protein production. Our results suggest that upon activation of the EvgAS two-component system, EvgA (the response regulator) activates both ydeP and ydeO expression and that YdeP and YdeO act conjointly, directly or indirectly repressing expression of the TTSS genes.

scholarly journals YopJ Family Effectors Promote Bacterial Infection through a Unique Acetyltransferase Activity

2016 ◽  
Vol 80 (4) ◽  
pp. 1011-1027 ◽  
Author(s):  
Ka-Wai Ma ◽  
Wenbo Ma
Keyword(s):  
Plant Pathogens ◽  
Molecular Mechanisms ◽  
Bacterial Species ◽  
Cysteine Proteases ◽  
Catalytic Triad ◽  
Effector Proteins ◽  
Host Cells ◽  
Target Proteins ◽  
Acetyltransferase Activity ◽  
Type Iii

SUMMARYGram-negative bacterial pathogens rely on the type III secretion system to inject virulence proteins into host cells. These type III secreted “effector” proteins directly manipulate cellular processes to cause disease. Although the effector repertoires in different bacterial species are highly variable, theYersiniaouter protein J (YopJ) effector family is unique in that its members are produced by diverse animal and plant pathogens as well as a nonpathogenic microsymbiont. All YopJ family effectors share a conserved catalytic triad that is identical to that of the C55 family of cysteine proteases. However, an accumulating body of evidence demonstrates that many YopJ effectors modify their target proteins in hosts by acetylating specific serine, threonine, and/or lysine residues. This unique acetyltransferase activity allows the YopJ family effectors to affect the function and/or stability of their targets, thereby dampening innate immunity. Here, we summarize the current understanding of this prevalent and evolutionarily conserved type III effector family by describing their enzymatic activities and virulence functions in animals and plants. In particular, the molecular mechanisms by which representative YopJ family effectors subvert host immunity through posttranslational modification of their target proteins are discussed.

scholarly journals Putative LysM Effectors Contribute to Fungal Lifestyle

2021 ◽  
Vol 22 (6) ◽  
pp. 3147
Author(s):  
Marta Suarez-Fernandez ◽  
Ana Aragon-Perez ◽  
Luis Vicente Lopez-Llorca ◽  
Federico Lopez-Moya
Keyword(s):  
Plant Pathogens ◽  
Fungal Endophytes ◽  
Alpha Helix ◽  
Pathogenic Fungi ◽  
Nematophagous Fungus ◽  
Effector Proteins ◽  
Evolutionary Divergence ◽  
Plant Host ◽  
Gene Encoding ◽  
Genes Encoding

Fungal LysM effector proteins can dampen plant host–defence responses, protecting hyphae from plant chitinases, but little is known on these effectors from nonpathogenic fungal endophytes. We found four putative LysM effectors in the genome of the endophytic nematophagous fungus Pochonia chlamydosporia (Pc123). All four genes encoding putative LysM effectors are expressed constitutively by the fungus. Additionally, the gene encoding Lys1—the smallest one—is the most expressed in banana roots colonised by the fungus. Pc123 Lys1, 2 and 4 display high homology with those of other strains of the fungus and phylogenetically close entomopathogenic fungi. However, Pc123 Lys3 displays low homology with other fungi, but some similarities are found in saprophytes. This suggests evolutionary divergence in Pc123 LysM effectors. Additionally, molecular docking shows that the NAcGl binding sites of Pc123 Lys 2, 3 and 4 are adjacent to an alpha helix. Putative LysM effectors from fungal endophytes, such as Pc123, differ from those of plant pathogenic fungi. LysM motifs from endophytic fungi show clear conservation of cysteines in Positions 13, 51 and 63, unlike those of plant pathogens. LysM effectors could therefore be associated with the lifestyle of a fungus and give us a clue of how organisms could behave in different environments.

scholarly journals In Vitro Translocation Experiments with RxLR-Reporter Fusion Proteins of Avr1b from Phytophthora sojae and AVR3a from Phytophthora infestans Fail to Demonstrate Specific Autonomous Uptake in Plant and Animal Cells

2013 ◽  
Vol 26 (5) ◽  
pp. 528-536 ◽  
Author(s):  
Stephan Wawra ◽  
Armin Djamei ◽  
Isabell Albert ◽  
Thorsten Nürnberger ◽  
Regine Kahmann ◽  
...  
Keyword(s):  
Fusion Proteins ◽  
Fluorescent Protein ◽  
Phytophthora Sojae ◽  
Host Cells ◽  
Eukaryotic Cells ◽  
Large Set ◽  
Animal Cells ◽  
Reporter Protein ◽  
Rxlr Effectors ◽  
Translocation Experiments

Plant-pathogenic oomycetes have a large set of secreted effectors that can be translocated into their host cells during infection. One group of these effectors are the RxLR effectors for which it has been shown, in a few cases, that the RxLR motif is important for their translocation. It has been suggested that the RxLR-leader sequences alone are enough to translocate the respective effectors into eukaryotic cells through binding to surface-exposed phosphoinositol-3-phosphate. These conclusions were primary based on translocation experiments conducted with recombinant fusion proteins whereby the RxLR leader of RxLR effectors (i.e., Avr1b from Phytophthora sojae) were fused to the green fluorescent protein reporter-protein. However, we failed to observe specific cellular uptake for a comparable fusion protein where the RxLR leader of the P. infestans AVR3a was fused to monomeric red fluorescent protein. Therefore, we reexamined the ability of the reported P. sojae AVR1b RxLR leader to enter eukaryotic cells. Different relevant experiments were performed in three independent laboratories, using fluorescent reporter fusion constructs of AVR3a and Avr1b proteins in a side-by-side comparative study on plant tissue and human and animal cells. We report that we were unable to obtain conclusive evidence for specific RxLR-mediated translocation.

scholarly journals Structural genomics applied to the rust fungus Melampsora larici-populina reveals two candidate effector proteins adopting cystine knot and NTF2-like protein folds

2019 ◽  
Vol 9 (1) ◽  
Author(s):  
Karine de Guillen ◽  
Cécile Lorrain ◽  
Pascale Tsan ◽  
Philippe Barthe ◽  
Benjamin Petre ◽  
...  
Keyword(s):  
Plant Pathogens ◽  
Sequence Similarity ◽  
Rust Fungus ◽  
Parasitic Infection ◽  
Three Dimensional ◽  
Effector Proteins ◽  
Host Cells ◽  
Dimensional Structure ◽  
Small Proteins ◽  
Wide Range

AbstractRust fungi are plant pathogens that secrete an arsenal of effector proteins interfering with plant functions and promoting parasitic infection. Effectors are often species-specific, evolve rapidly, and display low sequence similarities with known proteins. How rust fungal effectors function in host cells remains elusive, and biochemical and structural approaches have been scarcely used to tackle this question. In this study, we produced recombinant proteins of eleven candidate effectors of the leaf rust fungus Melampsora larici-populina in Escherichia coli. We successfully purified and solved the three-dimensional structure of two proteins, MLP124266 and MLP124017, using NMR spectroscopy. Although both MLP124266 and MLP124017 show no sequence similarity with known proteins, they exhibit structural similarities to knottins, which are disulfide-rich small proteins characterized by intricate disulfide bridges, and to nuclear transport factor 2-like proteins, which are molecular containers involved in a wide range of functions, respectively. Interestingly, such structural folds have not been reported so far in pathogen effectors, indicating that MLP124266 and MLP124017 may bear novel functions related to pathogenicity. Our findings show that sequence-unrelated effectors can adopt folds similar to known proteins, and encourage the use of biochemical and structural approaches to functionally characterize effector candidates.

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