scholarly journals The Pleiades cluster of fungal effector genes inhibit host defenses

2019 ◽  
Author(s):  
Fernando Navarrete ◽  
Nenad Grujic ◽  
Alexandra Stirnberg ◽  
David Aleksza ◽  
Michelle Gallei ◽  
...  
Keyword(s):  
Plant Pathogens ◽  
Functional Characterization ◽  
Rapid Evolution ◽  
Effector Proteins ◽  
Host Defenses ◽  
E3 Ligases ◽  
Effector Genes ◽  
Ros Burst ◽  
Molecular Patterns

SummaryBiotrophic plant pathogens secrete effector proteins to manipulate the host physiology. Effectors suppress defenses and induce an environment favorable to disease development. Sequence-based prediction of effector function is difficulted by their rapid evolution rate. In the maize pathogen Ustilago maydis, effector-coding genes frequently organize in clusters. Here we describe the functional characterization of the pleiades, a cluster of ten symplastic effectors. Deletion of the pleiades leads to strongly impaired virulence and accumulation of reactive oxygen species (ROS) in infected tissue. Eight of the Pleiades suppress the production of ROS upon perception of pathogen associated molecular patterns (PAMPs). Although genetically redundant, the Pleiades target different host components. The paralogs Taygeta1 and Merope1 suppress ROS production in either the cytoplasm or nucleus, respectively. Merope1 targets and promotes the autoubiquitination activity of RFI2, a conserved family of E3 ligases that regulates the production of PAMP-triggered ROS burst and influences flowering time in plants.

scholarly journals The Pleiades are a cluster of fungal effectors that inhibit host defenses

2021 ◽  
Vol 17 (6) ◽  
pp. e1009641
Author(s):  
Fernando Navarrete ◽  
Nenad Grujic ◽  
Alexandra Stirnberg ◽  
Indira Saado ◽  
David Aleksza ◽  
...  
Keyword(s):  
Plant Pathogens ◽  
Functional Characterization ◽  
Rapid Evolution ◽  
Effector Proteins ◽  
In Planta ◽  
E3 Ligases ◽  
Effector Genes ◽  
Ros Burst ◽  
Molecular Patterns

Biotrophic plant pathogens secrete effector proteins to manipulate the host physiology. Effectors suppress defenses and induce an environment favorable to disease development. Sequence-based prediction of effector function is impeded by their rapid evolution rate. In the maize pathogen Ustilago maydis, effector-coding genes frequently organize in clusters. Here we describe the functional characterization of the pleiades, a cluster of ten effector genes, by analyzing the micro- and macroscopic phenotype of the cluster deletion and expressing these proteins in planta. Deletion of the pleiades leads to strongly impaired virulence and accumulation of reactive oxygen species (ROS) in infected tissue. Eight of the Pleiades suppress the production of ROS upon perception of pathogen associated molecular patterns (PAMPs). Although functionally redundant, the Pleiades target different host components. The paralogs Taygeta1 and Merope1 suppress ROS production in either the cytoplasm or nucleus, respectively. Merope1 targets and promotes the auto-ubiquitination activity of RFI2, a conserved family of E3 ligases that regulates the production of PAMP-triggered ROS burst in plants.

scholarly journals Identification of divergent type VI secretion effectors using a conserved chaperone domain

2015 ◽  
Vol 112 (29) ◽  
pp. 9106-9111 ◽  
Author(s):  
Xiaoye Liang ◽  
Richard Moore ◽  
Mike Wilton ◽  
Megan J. Q. Wong ◽  
Linh Lam ◽  
...  
Keyword(s):  
Functional Characterization ◽  
Large Family ◽  
Effector Proteins ◽  
Gram Negative Bacteria ◽  
Type Vi Secretion System ◽  
Gram Negative ◽  
Effector Genes ◽  
Type Vi Secretion ◽  
Bacterial Fitness

The type VI secretion system (T6SS) is a lethal weapon used by many bacteria to kill eukaryotic predators or prokaryotic competitors. Killing by the T6SS results from repetitive delivery of toxic effectors. Despite their importance in dictating bacterial fitness, systematic prediction of T6SS effectors remains challenging due to high effector diversity and the absence of a conserved signature sequence. Here, we report a class of T6SS effector chaperone (TEC) proteins that are required for effector delivery through binding to VgrG and effector proteins. The TEC proteins share a highly conserved domain (DUF4123) and are genetically encoded upstream of their cognate effector genes. Using the conserved TEC domain sequence, we identified a large family of TEC genes coupled to putative T6SS effectors in Gram-negative bacteria. We validated this approach by verifying a predicted effector TseC in Aeromonas hydrophila. We show that TseC is a T6SS-secreted antibacterial effector and that the downstream gene tsiC encodes the cognate immunity protein. Further, we demonstrate that TseC secretion requires its cognate TEC protein and an associated VgrG protein. Distinct from previous effector-dependent bioinformatic analyses, our approach using the conserved TEC domain will facilitate the discovery and functional characterization of new T6SS effectors in Gram-negative bacteria.

scholarly journals Leaping into the Unknown World of Sporisorium scitamineum Candidate Effectors

2020 ◽  
Vol 6 (4) ◽  
pp. 339
Author(s):  
Natália Sousa Teixeira-Silva ◽  
Patrícia Dayane Carvalho Schaker ◽  
Hugo Vianna Silva Rody ◽  
Thiago Maia ◽  
Christopher M. Garner ◽  
...  
Keyword(s):  
Plant Cell Wall ◽  
Expression Profiles ◽  
Functional Characterization ◽  
Subcellular Location ◽  
Sporisorium Scitamineum ◽  
Effector Genes ◽  
Molecular Events ◽  
Phosphatase 2A ◽  
Set Up

Sporisorium scitamineum is a biotrophic fungus causing sugarcane smut disease. In this study, we set up a pipeline and used genomic and dual transcriptomic data previously obtained by our group to identify candidate effectors of S. scitamineum and their expression profiles in infected smut-resistant and susceptible sugarcane plants. The expression profile of different genes after infection in contrasting sugarcane genotypes assessed by RT-qPCR depended on the plant genotypes and disease progression. Three candidate effector genes expressed earlier only in resistant plants, four expressed in both genotypes, and three later in susceptible plants. Ten genes were cloned and transiently expressed in N. benthamiana leaves to determine their subcellular location, while four localized in more than one compartment. Two candidates, g3890 having a nucleoplasmic and mitochondrial location and g5159 targeting the plant cell wall, were selected to obtain their possible corresponding host targets using co-immunoprecipitation (CoIP) experiments and mass spectrometry. Various potential interactors were identified, including subunits of the protein phosphatase 2A and an endochitinase. We investigated the presence of orthologs in sugarcane and using transcriptome data present their expression profiles. Orthologs of sugarcane shared around 70% similarity. Identifying a set of putative fungal effectors and their plant targets provides a valuable resource for functional characterization of the molecular events leading to smut resistance in sugarcane plants and uncovers further opportunities for investigation.

scholarly journals Functional Characterization of EscK (Orf4), a Sorting Platform Component of the Enteropathogenic Escherichia coli Injectisome

2016 ◽  
Vol 199 (1) ◽  
Author(s):  
Eduardo Soto ◽  
Norma Espinosa ◽  
Miguel Díaz-Guerrero ◽  
Meztlli O. Gaytán ◽  
José L. Puente ◽  
...  
Keyword(s):  
Escherichia Coli ◽  
Type Iii Secretion ◽  
Diarrheal Disease ◽  
Functional Characterization ◽  
Type Iii Secretion System ◽  
Secretion System ◽  
Effector Proteins ◽  
Content Type ◽  
Enterocyte Effacement

ABSTRACT The type III secretion system (T3SS) is a supramolecular machine used by many bacterial pathogens to translocate effector proteins directly into the eukaryotic host cell cytoplasm. Enteropathogenic Escherichia coli (EPEC) is an important cause of infantile diarrheal disease in underdeveloped countries. EPEC virulence relies on a T3SS encoded within a chromosomal pathogenicity island known as the locus of enterocyte effacement (LEE). In this work, we pursued the functional characterization of the LEE-encoded protein EscK (previously known as Orf4). We provide evidence indicating that EscK is crucial for efficient T3S and belongs to the SctK (OrgA/YscK/MxiK) protein family, whose members have been implicated in the formation of a sorting platform for secretion of T3S substrates. Bacterial fractionation studies showed that EscK localizes to the inner membrane independently of the presence of any other T3SS component. Combining yeast two-hybrid screening and pulldown assays, we identified an interaction between EscK and the C-ring/sorting platform component EscQ. Site-directed mutagenesis of conserved residues revealed amino acids that are critical for EscK function and for its interaction with EscQ. In addition, we found that T3S substrate overproduction is capable of compensating for the absence of EscK. Overall, our data suggest that EscK is a structural component of the EPEC T3SS sorting platform, playing a central role in the recruitment of T3S substrates for boosting the efficiency of the protein translocation process. IMPORTANCE The type III secretion system (T3SS) is an essential virulence determinant for enteropathogenic Escherichia coli (EPEC) colonization of intestinal epithelial cells. Multiple EPEC effector proteins are injected via the T3SS into enterocyte cells, leading to diarrheal disease. The T3SS is encoded within a genomic pathogenicity island termed the locus of enterocyte effacement (LEE). Here we unravel the function of EscK, a previously uncharacterized LEE-encoded protein. We show that EscK is central for T3SS biogenesis and function. EscK forms a protein complex with EscQ, the main component of the cytoplasmic sorting platform, serving as a docking site for T3S substrates. Our results provide a comprehensive functional analysis of an understudied component of T3SSs.

scholarly journals Phytophthora infestans RXLR-WY effector AVR3a associates with a Dynamin-Related Protein involved in endocytosis of a plant pattern recognition receptor

2014 ◽  
Author(s):  
Angela Chaparro-Garcia ◽  
Simon Schwizer ◽  
Jan Sklenar ◽  
Kentaro Yoshida ◽  
Jorunn I. B. Bos ◽  
...  
Keyword(s):  
Pattern Recognition ◽  
Cell Death ◽  
Phytophthora Infestans ◽  
Plant Pathogens ◽  
Defense Responses ◽  
Effector Proteins ◽  
Related Protein ◽  
Receptor Mediated Endocytosis ◽  
Molecular Patterns ◽  
Basal Immunity

Perception of pathogen associated molecular patterns (PAMPs) by cell surface localized pattern recognition receptors (PPRs), activates plant basal defense responses in a process known as PAMP/PRR–triggered immunity (PTI). In turn, pathogens deploy effector proteins that interfere with different steps in PTI signaling. However, our knowledge of PTI suppression by filamentous plant pathogens, i.e. fungi and oomycetes, remains fragmentary. Previous work revealed that BAK1/SERK3, a regulatory receptor of several PRRs, contributes to basal immunity against the Irish potato famine pathogen Phytophthora infestans. Moreover BAK1/SERK3 is required for the cell death induced by P. infestans elicitin INF1, a protein with characteristics of PAMPs. The P. infestans host-translocated RXLR-WY effector AVR3a is known to supress INF1-mediated defense by binding the E3 ligase CMPG1. In contrast, AVR3aKI-Y147del, a deletion mutant of the C-terminal tyrosine of AVR3a, fails to bind CMPG1 and suppress INF1 cell death. Here we studied the extent to which AVR3a and its variants perturb additional BAK1/SERK3 dependent PTI responses using the plant PRR FLAGELLIN SENSING 2 (FLS2). We found that all tested variants of AVR3a, including AVR3aKI-Y147del, suppress early defense responses triggered by the bacterial flagellin-derived peptide flg22 and reduce internalization of activated FLS2 from the plasma membrane without disturbing its nonactivated localization. Consistent with this effect of AVR3a on FLS2 endocytosis, we discovered that AVR3a associates with the Dynamin-Related Protein DRP2, a plant GTPase implicated in receptor-mediated endocytosis. Interestingly, DRP2 is required for ligand-induced FLS2 internalization but does not affect internalization of the growth receptor BRASSINOSTEROID INSENSITIVE 1 (BRI1). Furthermore, overexpression of DRP2 suppressed accumulation of reactive oxygen species triggered by PAMP treatment. We conclude that AVR3a associates with a key cellular trafficking and membrane-remodeling complex involved in immune receptor-mediated endocytosis and signaling. AVR3a is a multifunctional effector that can suppress BAK1/SERK3 mediated immunity through at least two different pathways.

scholarly journals Functional Characterization of an Amaranth Natterin-4-Like-1 Gene in Arabidopsis thaliana

2022 ◽  
Vol 5 ◽  
Author(s):  
Gabriela Cabrales-Orona ◽  
Norma Martínez-Gallardo ◽  
John Paul Délano-Frier
Keyword(s):  
Arabidopsis Thaliana ◽  
Plant Pathogens ◽  
Functional Characterization ◽  
Water Deficit Stress ◽  
Photosynthetic Parameters ◽  
Grain Amaranth ◽  
Amaranthus Hypochondriacus ◽  
Defensive Function ◽  
Fungal Plant Pathogens

The functional characterization of an Amaranthus hypochondriacus Natterin-4-Like-1 gene (AhN4L-1) coding for an unknown function protein characterized by the presence of an aerolysin-like pore-forming domain in addition to two amaranthin-like agglutinin domains is herewith described. Natterin and nattering-like proteins have been amply described in the animal kingdom. However, the role of nattering-like proteins in plants is practically unknown. The results described in this study, obtained from gene expression data in grain amaranth and from AhN4L-1-overexpressing Arabidopsis thaliana plants indicated that this gene was strongly induced by several biotic and abiotic conditions in grain amaranth, whereas data obtained from the overexpressing Arabidopsis plants further supported the defensive function of this gene, mostly against bacterial and fungal plant pathogens. GUS and GFP AhN4L-1 localization in roots tips, leaf stomata, stamens and pistils also suggested a defensive function in these organs, although its participation in flowering processes, such as self-incompatibility and abscission, is also possible. However, contrary to expectations, the overexpression of this gene negatively affected the vegetative and reproductive growth of the transgenic plants, which also showed no increased tolerance to salinity and water-deficit stress. The latter despite the maintenance of significantly higher chlorophyll levels and photosynthetic parameters under intense salinity stress. These results are discussed in the context of the physiological roles known to be played by related lectins and AB proteins in plants.

scholarly journals Functional Characterization of Key Residues in Regulatory Proteins HrpG and HrpV of Pseudomonas syringae pv. tomato DC3000

2017 ◽  
Vol 30 (8) ◽  
pp. 656-665 ◽  
Author(s):  
Milija Jovanovic ◽  
Christopher Waite ◽  
Ellen James ◽  
Nicholas Synn ◽  
Timothy Simpson ◽  
...  
Keyword(s):  
Pseudomonas Syringae ◽  
Plant Pathogens ◽  
Functional Characterization ◽  
Direct Interaction ◽  
Negative Control ◽  
Effector Proteins ◽  
Tomato Dc3000 ◽  
Sequence Alignments ◽  
Group I ◽  
Σ Factor

The plant pathogen Pseudomonas syringae pv. tomato DC3000 uses a type III secretion system (T3SS) to transfer effector proteins into the host. The expression of T3SS proteins is controlled by the HrpL σ factor. Transcription of hrpL is σ54-dependent and bacterial enhancer-binding proteins HrpR and HrpS coactivate the hrpL promoter. The HrpV protein imposes negative control upon HrpR and HrpS through direct interaction with HrpS. HrpG interacts with HrpV and relieves such negative control. The sequence alignments across Hrp group I-type plant pathogens revealed conserved HrpV and HrpG amino acids. To establish structure–function relationships in HrpV and HrpG, either truncated or alanine substitution mutants were constructed. Key functional residues in HrpV and HrpG are found within their C-terminal regions. In HrpG, L101 and L105 are indispensable for the ability of HrpG to directly interact with HrpV and suppress HrpV-dependent negative regulation of HrpR and HrpS. In HrpV, L108 and G110 are major determinants for interactions with HrpS and HrpG. We propose that mutually exclusive binding of HrpS and HrpG to the same binding site of HrpV governs a transition from negative control to activation of the HrpRS complex leading to HrpL expression and pathogenicity of P. syringae.

Functional characterization of the SIZ/PIAS-type SUMO E3 ligases, OsSIZ1 and OsSIZ2 in rice

2010 ◽  
Vol 33 (11) ◽  
pp. 1923-1934 ◽  
Author(s):  
HYEONG CHEOL PARK ◽  
HUN KIM ◽  
SUNG CHEOL KOO ◽  
HEE JIN PARK ◽  
MI SUN CHEONG ◽  
...  
Keyword(s):  
Functional Characterization ◽  
E3 Ligases

scholarly journals Positively selected effector genes and their contribution to virulence in the smut fungus Sporisorium reilianum

2017 ◽  
Author(s):  
Gabriel Schweizer ◽  
Karin Münch ◽  
Gertrud Mannhaupt ◽  
Jan Schirawski ◽  
Regine Kahmann ◽  
...  
Keyword(s):  
Positive Selection ◽  
Plant Pathogens ◽  
Molecular Mechanisms ◽  
Large Fraction ◽  
Gene Families ◽  
Effector Proteins ◽  
Smut Fungi ◽  
Formae Speciales ◽  
Effector Genes ◽  
Sporisorium Reilianum

AbstractPlants and fungi display a broad range of interactions in natural and agricultural ecosystems ranging from symbiosis to parasitism. These ecological interactions result in coevolution between genes belonging to different partners. A well-understood example are secreted fungal effector proteins and their host targets, which play an important role in pathogenic interactions. Biotrophic smut fungi (Basidiomycota) are well-suited to investigate the evolution of plant pathogens, because several reference genomes and genetic tools are available for these species. Here, we used the genomes of Sporisorium reilianum f. sp. zeae and S. reilianum f. sp. reilianum, two closely related formae speciales infecting maize and sorghum, respectively, together with the genomes of Ustilago hordei, Ustilago maydis and Sporisorium scitamineum to identify and characterize genes displaying signatures of positive selection. We identified 154 gene families having undergone positive selection during species divergence in at least one lineage, among which 77% were identified in the two investigated formae speciales of S. reilianum. Remarkably, only 29% of positively selected genes encode predicted secreted proteins. We assessed the contribution to virulence of nine of these candidate effector genes in S. reilianum f. sp. zeae by deleting individual genes, including a homologue of the effector gene pit2 previously characterized in U. maydis. Only the pit2 deletion mutant was found to be strongly reduced in virulence. Additional experiments are required to understand the molecular mechanisms underlying the selection forces acting on the other candidate effector genes, as well as the large fraction of positively selected genes encoding predicted cytoplasmic proteins.

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