The EspF Effector, a Bacterial Pathogen's Swiss Army Knife

ABSTRACT Central to the pathogenesis of many bacterial pathogens is the ability to deliver effector proteins directly into the cells of their eukaryotic host. EspF is one of many effector proteins exclusive to the attaching and effacing pathogen family that includes enteropathogenic (EPEC) and enterohemorrhagic (EHEC) Escherichia coli. Work in recent years has revealed EspF to be one of the most multifunctional effector proteins known, with defined roles in several host cellular processes, including disruption of the epithelial barrier, antiphagocytosis, microvillus effacement, host membrane remodelling, modulation of the cytoskeleton, targeting and disruption of the nucleolus, intermediate filament disruption, cell invasion, mitochondrial dysfunction, apoptosis, and inhibition of several important epithelial transporters. Surprisingly, despite this high number of functions, EspF is a relatively small effector protein, and recent work has begun to decipher the molecular events that underlie its multifunctionality. This review focuses on the activities of EspF within the host cell and discusses recent findings and molecular insights relating to the virulence functions of this fascinating bacterial effector.

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Distribution of espI among clinical enterohaemorrhagic and enteropathogenic Escherichia coli isolates

Journal of Medical Microbiology ◽

10.1099/jmm.0.45684-0 ◽

2004 ◽

Vol 53 (11) ◽

pp. 1145-1149 ◽

Cited By ~ 29

Author(s):

Rosanna Mundy ◽

Claire Jenkins ◽

Jun Yu ◽

Henry Smith ◽

Gad Frankel

Keyword(s):

Escherichia Coli ◽

Type Iii Secretion ◽

Severe Disease ◽

Pathogenicity Island ◽

Effector Proteins ◽

Effector Protein ◽

Enteropathogenic Escherichia Coli ◽

Type Iii Effector ◽

Type Iii

Enterohaemorrhagic (EHEC) and enteropathogenic (EPEC) Escherichia coli are important diarrhoeagenic pathogens; infection is dependent on translocation of a number of type III effector proteins. Until recently all the known effectors were encoded on the LEE pathogenicity island, which also encodes the adhesin intimin and the type III secretion apparatus. Recently, a novel non-LEE effector protein, EspI/NleA, which is required for full virulence in vivo and is encoded on a prophage, was identified. The aim of this study was to determine the distribution of espI among clinical EHEC and EPEC isolates. espI was detected in 86 % and 53 % of LEE+ EHEC and EPEC strains, respectively. Moreover, the espI gene was more commonly found in patients suffering from a more severe disease.

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Tricellular Tight Junction Protein Tricellulin Is Targeted by the Enteropathogenic Escherichia coli Effector EspG1, Leading to Epithelial Barrier Disruption

Infection and Immunity ◽

10.1128/iai.00700-16 ◽

2016 ◽

Vol 85 (1) ◽

Cited By ~ 6

Author(s):

Vijay Morampudi ◽

Franziska A. Graef ◽

Martin Stahl ◽

Udit Dalwadi ◽

Victoria S. Conlin ◽

...

Keyword(s):

Escherichia Coli ◽

Tight Junction ◽

Significant Loss ◽

Effector Proteins ◽

Epithelial Barrier ◽

Tight Junction Proteins ◽

Barrier Dysfunction ◽

Barrier Disruption ◽

Junction Protein ◽

Junction Proteins

ABSTRACT Enteropathogenic Escherichia coli (EPEC)-induced diarrhea is often associated with disruption of intestinal epithelial tight junctions. Although studies have shown alterations in the expression and localization of bicellular tight junction proteins during EPEC infections, little is known about whether tricellular tight junction proteins (tTJs) are affected. Using Caco-2 cell monolayers, we investigated if EPEC is capable of targeting the tTJ protein tricellulin. Our results demonstrated that at 4 h postinfection, EPEC induced a significant reduction in tricellulin levels, accompanied by a significant loss of transepithelial resistance (TEER) and a corresponding increase in paracellular permeability. Conversely, cells overexpressing tricellulin were highly resistant to EPEC-induced barrier disruption. Confocal microscopy revealed the distribution of tricellulin into the plasma membrane of infected epithelial cells and confirmed the localization of EPEC aggregates in close proximity to tTJs. Moreover, infections with EPEC strains lacking genes encoding specific type III secreted effector proteins demonstrated a crucial role for the effector EspG1 in modulating tricellulin expression. Complementation studies suggest that the EspG-induced depletion of tricellulin is microtubule dependent. Overall, our results show that EPEC-induced epithelial barrier dysfunction is mediated in part by EspG1-induced microtubule-dependent depletion of tricellulin.

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Legionella pneumophila targets autophagosomes and promotes host autophagy during late infection

10.1101/2021.07.08.451723 ◽

2021 ◽

Author(s):

Rebecca R. Noll ◽

Colleen M. Pike ◽

Stephanie S. Lehman ◽

Chad Williamson ◽

Ramona Neunuebel

Keyword(s):

Legionella Pneumophila ◽

Bacterial Pathogen ◽

Nutrient Release ◽

Effector Proteins ◽

Type Iv Secretion ◽

Host Cells ◽

Effector Protein ◽

Wild Type ◽

Cellular Processes ◽

Type Iv

Autophagy is a fundamental eukaryotic process that mediates clearance of unwanted molecules and facilitates nutrient release. The bacterial pathogen Legionella pneumophila establishes an intracellular niche within phagocytes by manipulating host cellular processes, such as autophagy. Effector proteins translocated by L. pneumophila's Dot/Icm type IV secretion system have been shown to suppress autophagy. However evidence suggests that overall inhibition of autophagy may be detrimental to the bacterium. As autophagy contributes to cellular homeostasis and nutrient acquisition, L. pneumophila may translocate effectors that promote autophagy for these benefits. Here, we show that effector protein Lpg2411 binds phosphatidylinositol-3-phosphate lipids and preferentially binds autophagosomes. Translocated Lpg2411 accumulates late during infection and co-localizes with the autophagy receptor p62 and ubiquitin. Furthermore, autophagy is inhibited to a greater extent in host cells infected with a mutant strain lacking Lpg2411 compared to those infected with wild-type L. pneumophila, indicating that Lpg2411 stimulates autophagy to support the bacterium's intracellular lifestyle.

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Novel Effector Protein EspY3 of Type III Secretion System from Enterohemorrhagic Escherichia coli Is Localized in Actin Pedestals

Microorganisms ◽

10.3390/microorganisms6040112 ◽

2018 ◽

Vol 6 (4) ◽

pp. 112 ◽

Cited By ~ 2

Author(s):

Mariano Larzábal ◽

Wanderson Marques Da Silva ◽

Nahuel Riviere ◽

Ángel Cataldi

Keyword(s):

Escherichia Coli ◽

Type Iii Secretion ◽

Type Iii Secretion System ◽

Secretion System ◽

Effector Proteins ◽

Enterohemorrhagic Escherichia Coli ◽

Effector Protein ◽

Type Iii ◽

T3ss Effector ◽

Intestinal Enterocytes

Enterohemorrhagic Escherichia coli (EHEC) and enteropathogenic Escherichia coli (EPEC) are attaching and effacing (A/E) pathogens, which translocate effector proteins to intestinal enterocytes through a type III secretion system (T3SS). T3SS and most of its effector proteins are encoded in a pathogenicity island called LEE. Recently, new effectors have been located outside the LEE. This study aimed to characterize EspY3, a novel non-LEE encoded T3SS effector of EHEC. EspY3 shares homology with SopD and PipB2 effector proteins of Salmonella’s T3SS-1 and T3SS-2, respectively. The presence of recombinant EspY3 in the supernatant samples demonstrated that EspY3 was secreted by the T3SS of EHEC and EPEC. Through infection assays, we demonstrated the translocation of EspY3 into Caco-2 cells by T3SS of EPEC. The subcellular localization of EspY3 was determined in the pedestal region, where its presence generates a significant increase in the size of the pedestals area. The EspY3 effector induced the elongation of polymerized actin pedestals in infected Caco-2 by EPEC. This study confirmed that EspY3 is part of the repertoire of T3SS effectors of EHEC O157:H7, and that it participates in modeling cellular actin during the infection.

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Legionella pneumophila LegC7 effector protein drives aberrant ER:endosome fusion in yeast

10.1101/2020.11.20.391441 ◽

2020 ◽

Author(s):

Nathan K. Glueck ◽

Kevin M. O’Brien ◽

Vincent J. Starai

Keyword(s):

Membrane Trafficking ◽

Legionella Pneumophila ◽

Molecular Mechanisms ◽

Bacterial Pathogen ◽

Severe Form ◽

Effector Proteins ◽

Effector Protein ◽

Host Membrane ◽

Membrane Tethering

AbstractLegionella pneumophila is a facultative intracellular bacterial pathogen, causing the severe form of pneumonia known as Legionnaires’ disease. Legionella actively alters host organelle trafficking through the activities of ‘effector’ proteins secreted via a TypeIVB secretion system, in order to construct the bacteria-laden Legionella-containing vacuole (LCV) and prevent lysosomal degradation. The LCV is derived from membrane derived from host ER, secretory vesicles, and phagosomes, although the precise molecular mechanisms that drive its synthesis remain poorly understood. In an effort to characterize the in vivo activity of the LegC7/YlfA SNARE-like effector protein from Legionella in the context of eukaryotic membrane trafficking in yeast, we find that LegC7 interacts with the Emp46p/Emp47p ER-to-Golgi glycoprotein cargo adapter complex, alters ER morphology, and induces aberrant ER:endosome fusion, as measured by visualization of ER cargo degradation, reconstitution of split-GFP proteins, and enhanced oxidation of the ER lumen. LegC7-dependent toxicity, disruption of ER morphology, and ER:endosome fusion events were dependent upon endosomal VPS class C tethering complexes and the endosomal t-SNARE, Pep12p. This work establishes a model in which LegC7 functions to recruit host ER material to the bacterial phagosome during infection by inducing membrane fusion, potentially through interaction with host membrane tethering complexes and/or cargo adapters.

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Host autophagy machinery is diverted to the pathogen interface to mediate focal defense responses against the Irish potato famine pathogen

eLife ◽

10.7554/elife.37476 ◽

2018 ◽

Vol 7 ◽

Cited By ~ 23

Author(s):

Yasin F Dagdas ◽

Pooja Pandey ◽

Yasin Tumtas ◽

Nattapong Sanguankiattichai ◽

Khaoula Belhaj ◽

...

Keyword(s):

Plant Immunity ◽

Defense Responses ◽

Effector Proteins ◽

Plant Colonization ◽

Effector Protein ◽

Selective Autophagy ◽

Host Membrane ◽

Complex Functions ◽

Potato Famine ◽

Irish Potato Famine

During plant cell invasion, the oomycete Phytophthora infestans remains enveloped by host-derived membranes whose functional properties are poorly understood. P. infestans secretes a myriad of effector proteins through these interfaces for plant colonization. Recently we showed that the effector protein PexRD54 reprograms host-selective autophagy by antagonising antimicrobial-autophagy receptor Joka2/NBR1 for ATG8CL binding (Dagdas et al., 2016). Here, we show that during infection, ATG8CL/Joka2 labelled defense-related autophagosomes are diverted toward the perimicrobial host membrane to restrict pathogen growth. PexRD54 also localizes to autophagosomes across the perimicrobial membrane, consistent with the view that the pathogen remodels host-microbe interface by co-opting the host autophagy machinery. Furthermore, we show that the host-pathogen interface is a hotspot for autophagosome biogenesis. Notably, overexpression of the early autophagosome biogenesis protein ATG9 enhances plant immunity. Our results implicate selective autophagy in polarized immune responses of plants and point to more complex functions for autophagy than the widely known degradative roles.

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Mitotic Arrest-Deficient 2 Like 2 (MAD2L2) Interacts with Escherichia coli Effector Protein EspF

Life ◽

10.3390/life11090971 ◽

2021 ◽

Vol 11 (9) ◽

pp. 971

Author(s):

Amin Tahoun ◽

Hanem El-Sharkawy ◽

Samar M. Moustafa ◽

Lina Jamil M. Abdel-Hafez ◽

Ashraf Albrakati ◽

...

Keyword(s):

Escherichia Coli ◽

Mitotic Arrest ◽

Effector Proteins ◽

Host Protein ◽

Effector Protein ◽

Cellular Interactions ◽

Virulence Determinants ◽

E Coli ◽

Worldwide Distribution ◽

Localization Sequence

Enteropathogenic (EPEC) and Enterohemorrhagic (EHEC) Escherichia coli are considered emerging zoonotic pathogens of worldwide distribution. The pathogenicity of the bacteria is conferred by multiple virulence determinants, including the locus of enterocyte effacement (LEE) pathogenicity island, which encodes a type III secretion system (T3SS) and effector proteins, including the multifunctional secreted effector protein (EspF). EspF sequences differ between EPEC and EHEC serotypes in terms of the number and residues of SH3-binding polyproline-rich repeats and N-terminal localization sequence. The aim of this study was to discover additional cellular interactions of EspF that may play important roles in E coli colonization using the Yeast two-hybrid screening system (Y2H). Y2H screening identified the anaphase-promoting complex inhibitor Mitotic Arrest-Deficient 2 Like 2 (MAD2L2) as a host protein that interacts with EspF. Using LUMIER assays, MAD2L2 was shown to interact with EspF variants from EHEC O157:H7 and O26:H11 as well as EPEC O127:H6. MAD2L2 is targeted by the non-homologous Shigella effector protein invasion plasmid antigen B (IpaB) to halt the cell cycle and limit epithelial cell turnover. Therefore, we postulate that interactions between EspF and MAD2L2 serve a similar function in promoting EPEC and EHEC colonization, since cellular turnover is a key method for bacteria removal from the epithelium. Future work should investigate the biological importance of this interaction that could promote the colonization of EPEC and EHEC E. coli in the host.

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Salmonella Host Cell Invasion Emerged by Acquisition of a Mosaic of Separate Genetic Elements, IncludingSalmonella Pathogenicity Island 1 (SPI1), SPI5, and sopE2

Journal of Bacteriology ◽

10.1128/jb.183.7.2348-2358.2001 ◽

2001 ◽

Vol 183 (7) ◽

pp. 2348-2358 ◽

Cited By ~ 91

Author(s):

Susanne Mirold ◽

Kristin Ehrbar ◽

Astrid Weissmüller ◽

Rita Prager ◽

Helmut Tschäpe ◽

...

Keyword(s):

Host Cell ◽

Cell Invasion ◽

Common Ancestor ◽

Pathogenicity Island ◽

Effector Proteins ◽

Effector Protein ◽

Last Common Ancestor ◽

Host Cell Invasion ◽

Genetic Elements ◽

Type Iii

ABSTRACT Salmonella spp. possess a conserved type III secretion system encoded within the pathogenicity island 1 (SPI1; centisome 63), which mediates translocation of effector proteins into the host cell cytosol to trigger responses such as bacterial internalization. Several translocated effector proteins are encoded in other regions of the Salmonella chromosome. It remains unclear how this complex chromosomal arrangement of genes for the type III apparatus and the effector proteins emerged and how the different effector proteins cooperate to mediate virulence. By Southern blotting, PCR, and phylogenetic analyses of highly diverseSalmonella spp., we show here that effector protein genes located in the core of SPI1 are present in allSalmonella lineages. Surprisingly, the same holds true for several effector protein genes located in distant regions of theSalmonella chromosome, namely, sopB(SPI5, centisome 20), sopD (centisome 64), andsopE2 (centisomes 40 to 42). Our data demonstrate thatsopB, sopD, and sopE2, along with SPI1, were already present in the last common ancestor of all contemporary Salmonella spp. Analysis ofSalmonella mutants revealed that host cell invasion is mediated by SopB, SopE2, and, in the case of Salmonella enterica serovar Typhimurium SL1344, by SopE: a sopB sopE sopE2-deficient triple mutant was incapable of inducing membrane ruffling and was >100-fold attenuated in host cell invasion. We conclude that host cell invasion emerged early during evolution by acquisition of a mosaic of genetic elements (SPI1 itself, SPI5 [sopB], and sopE2) and that the last common ancestor of all contemporary Salmonella spp. was probably already invasive.

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Effect of Escherichia Coli Infection on Metabolism of Dietary Protein in Intestine

Current Protein and Peptide Science ◽

10.2174/1389203720666191113144049 ◽

2020 ◽

Vol 21 (8) ◽

pp. 772-776

Author(s):

Xiao-Pei Peng ◽

Wei Ding ◽

Jian-Min Ma ◽

Jie Zhang ◽

Jian Sun ◽

...

Keyword(s):

Escherichia Coli ◽

Intestinal Tract ◽

Effector Proteins ◽

Physical Injury ◽

Dietary Proteins ◽

Pathogenic Role ◽

E Coli ◽

Low Protein ◽

Pathogenic Escherichia Coli ◽

Escherichia Coli Infection

Dietary proteins are linked to the pathogenic Escherichia coli (E. coli) through the intestinal tract, which is the site where both dietary proteins are metabolized and pathogenic E. coli strains play a pathogenic role. Dietary proteins are degraded by enzymes in the intestine lumen and their metabolites are transferred into enterocytes to be further metabolized. Seven diarrheagenic E. coli pathotypes have been identified, and they damage the intestinal epithelium through physical injury and effector proteins, which lead to inhibit the digestibility and absorption of dietary proteins in the intestine tract. But the increased tryptophan (Trp) content in the feed, low-protein diet or milk fractions supplementation is effective in preventing and controlling infections by pathogenic E. coli in the intestine.

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The Epichloë festucae Antifungal Protein Efe-AfpA Is Also a Possible Effector Protein Required for the Interaction of the Fungus with its Host Grass Festuca rubra subsp. rubra

Microorganisms ◽

10.3390/microorganisms9010140 ◽

2021 ◽

Vol 9 (1) ◽

pp. 140

Author(s):

Ruying Wang ◽

Simin Luo ◽

Bruce B. Clarke ◽

Faith C. Belanger

Keyword(s):

Disease Resistance ◽

Insect Resistance ◽

Effector Proteins ◽

Antifungal Protein ◽

Grass Species ◽

Effector Protein ◽

Festuca Rubra ◽

Symbiotic Interaction ◽

Red Fescue ◽

Epichloë Festucae

Strong creeping red fescue (Festuca rubra subsp. rubra) is a commercially important low-maintenance turfgrass and is often naturally infected with the fungal endophyte Epichloë festucae. Epichloë spp. are endophytes of several cool-season grass species, often conferring insect resistance to the grass hosts due to the production of toxic alkaloids. In addition to insect resistance, a unique feature of the strong creeping red fescue/E. festucae symbiosis is the endophyte-mediated disease resistance to the fungal pathogen Clarireedia jacksonii, the causal agent of dollar spot disease. Such disease resistance is not a general feature of other grass/ Epichloë interactions. E. festucae isolates infecting red fescue have an antifungal protein gene Efe-afpA, whereas most other Epichloë spp. do not have a similar gene. The uniqueness of this gene suggests it may, therefore, be a component of the unique disease resistance seen in endophyte-infected red fescue. Here, we report the generation of CRISPR-Cas9 Efe-afpA gene knockouts with the goal of determining if absence of the protein in endophyte-infected Festuca rubra leads to disease susceptibility. However, it was not possible to infect plants with the knockout isolates, although infection was possible with the wild type E. festucae and with complemented isolates. This raises the interesting possibility that, in addition to having antifungal activity, the protein is required for the symbiotic interaction. The antifungal protein is a small secreted protein with high expression in planta relative to its expression in culture, all characteristics consistent with effector proteins. If Efe-AfpA is an effector protein it must be specific to certain interactions, since most Epichloë spp. do not have such a gene in their genomes.

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