254 results found
Chatterjee S, Lekmeechai S, Constantinou N, et al., 2021, The type III secretion system effector EspO of enterohaemorrhagic Escherichia coli inhibits apoptosis through an interaction with HAX-1, CELLULAR MICROBIOLOGY, Vol: 23, ISSN: 1462-5814
Chisenga CC, Bosomprah S, Simuyandi M, et al., 2021, Shigella-specific antibodies in the first year of life among Zambian infants: A longitudinal cohort study, PLOS ONE, Vol: 16, ISSN: 1932-6203
Mylona E, Sanchez Garrido J, Nguyen Hoang Thu T, et al., 2021, Very long O-antigen chains of Salmonella Paratyphi A inhibit inflammasome activation and pyroptotic cell death, Cellular Microbiology, Vol: 23, Pages: 1-14, ISSN: 1462-5814
Salmonella Paratyphi A (SPtA) remains one of the leading causes of enteric (typhoid) fever. Yet, despite the recent increased rate of isolation from patients in Asia, our understanding of its pathogenesis is incomplete. Here we investigated inflammasome activation in human macrophages infected with SPtA. We found that SPtA induces GSDMD‐mediated pyroptosis via activation of caspase‐1, caspase‐4 and caspase‐8. Although we observed no cell death in the absence of a functional Salmonella pathogenicity island‐1 (SPI‐1) injectisome, HilA‐mediated overexpression of the SPI‐1 regulon enhances pyroptosis. SPtA expresses FepE, an LPS O‐antigen length regulator, which induces the production of very long O‐antigen chains. Using a ΔfepE mutant we established that the very long O‐antigen chains interfere with bacterial interactions with epithelial cells and impair inflammasome‐mediated macrophage cell death. Salmonella Typhimurium (STm) serovar has a lower FepE expression than SPtA, and triggers higher pyroptosis, conversely, increasing FepE expression in STm reduced pyroptosis. These results suggest that differential expression of FepE results in serovar‐specific inflammasome modulation, which mirrors the pro‐ and anti‐inflammatory strategies employed by STm and SPtA, respectively. Our studies point towards distinct mechanisms of virulence of SPtA, whereby it attenuates inflammasome‐mediated detection through the elaboration of very long LPS O‐polysaccharides.
Ruano-Gallego D, Sanchez-Garrido J, Kozik Z, et al., 2021, Type III secretion system effectors form robust and flexible intracellular virulence networks, SCIENCE, Vol: 371, Pages: 1122-+, ISSN: 0036-8075
Zheng W, Peña A, Ilangovan A, et al., 2021, Cryoelectron-microscopy structure of the enteropathogenic Escherichia coli type III secretion system EspA filament., Proceedings of the National Academy of Sciences of USA, Vol: 118, ISSN: 0027-8424
Enteropathogenic Escherichia coli (EPEC) and enterohemorrhagic Escherichia coli (EHEC) utilize a macromolecular type III secretion system (T3SS) to inject effector proteins into eukaryotic cells. This apparatus spans the inner and outer bacterial membranes and includes a helical needle protruding into the extracellular space. Thus far observed only in EPEC and EHEC and not found in other pathogenic Gram-negative bacteria that have a T3SS is an additional helical filament made by the EspA protein that forms a long extension to the needle, mediating both attachment to eukaryotic cells and transport of effector proteins through the intestinal mucus layer. Here, we present the structure of the EspA filament from EPEC at 3.4 Å resolution. The structure reveals that the EspA filament is a right-handed 1-start helical assembly with a conserved lumen architecture with respect to the needle to ensure the seamless transport of unfolded cargos en route to the target cell. This functional conservation is despite the fact that there is little apparent overall conservation at the level of sequence or structure with the needle. We also unveil the molecular details of the immunodominant EspA epitope that can now be exploited for the rational design of epitope display systems.
Hopkins EGD, Frankel G, 2021, Overview of the Effect of Citrobacter rodentium Infection on Host Metabolism and the Microbiota., Methods Mol Biol, Vol: 2291, Pages: 399-418
Citrobacter rodentium is a natural enteric mouse pathogen that models human intestinal diseases, such as pathogenic E. coli infections, ulcerative colitis, and colon cancer. Upon reaching the monolayer of intestinal epithelial cells (IECs) lining the gut, a complex web of interactions between the host, the pathogen, and the microbiota ensues. A number of studies revealed surprisingly rapid changes in IEC bioenergetics upon infection, involving a switch from oxidative phosphorylation to aerobic glycolysis, leading to mucosal oxygenation and subsequent changes in microbiota composition. Microbiome studies have revealed a bloom in Enterobacteriaceae during C. rodentium infection in both resistant (i.e., C57BL/6) and susceptible (i.e., C3H/HeN) strains of mice concomitant with a depletion of butyrate-producing Clostridia. The emerging understanding that dysbiosis of cholesterol metabolism is induced by enteric infection further confirms the pivotal role immunometabolism plays in disease outcome. Inversely, the host and microbiota also impact upon the progression of infection, from the susceptibility of the distal colon to C. rodentium colonization to clearance of the pathogen, both via opsonization from the host adaptive immune system and out competition by the resident microbiota. Further complicating this compendium of interactions, C. rodentium exploits microbiota metabolites to fine-tune virulence gene expression and promote colonization. This chapter summarizes the current knowledge of the myriad of pathogen-host-microbiota interactions that occur during the progression of C. rodentium infection in mice and the broader implications of these findings on our understanding of enteric disease.
Zheng W, Pena A, Low WW, et al., 2020, Cryoelectron-Microscopic Structure of the pKpQIL Conjugative Pili from Carbapenem-Resistant Klebsiella pneumoniae, STRUCTURE, Vol: 28, Pages: 1321-+, ISSN: 0969-2126
Zhong Q, Roumeliotis T, Kozik Z, et al., 2020, Clustering of Tir during enteropathogenic E. coli infection triggers calcium influx-dependent pyroptosis in intestinal epithelial cells, PLoS Biology, Vol: 18, ISSN: 1544-9173
Clustering of the enteropathogenic Escherichia coli (EPEC) type III secretion system (T3SS) effector translocated intimin receptor (Tir) by intimin leads to actin polymerisation and pyroptotic cell death in macrophages. The effect of Tir clustering on the viability of EPEC-infected intestinal epithelial cells (IECs) is unknown. We show that EPEC induces pyroptosis in IECs in a Tir-dependent but actin polymerisation-independent manner, which was enhanced by priming with interferon gamma (IFNγ). Mechanistically, Tir clustering triggers rapid Ca2+ influx, which induces lipopolysaccharide (LPS) internalisation, followed by activation of caspase-4 and pyroptosis. Knockdown of caspase-4 or gasdermin D (GSDMD), translocation of NleF, which blocks caspase-4 or chelation of extracellular Ca2+, inhibited EPEC-induced cell death. IEC lines with low endogenous abundance of GSDMD were resistant to Tir-induced cell death. Conversely, ATP-induced extracellular Ca2+ influx enhanced cell death, which confirmed the key regulatory role of Ca2+ in EPEC-induced pyroptosis. We reveal a novel mechanism through which infection with an extracellular pathogen leads to pyroptosis in IECs.
Slater S, Frankel G, 2020, Advances and challenges in studying type III secretion effectors of attaching and effacing pathogens, Frontiers in Cellular and Infection Microbiology, Vol: 10, Pages: 1-7, ISSN: 2235-2988
Sanchez Garrido J, Slater SL, Clements A, et al., 2020, Vying for the control of inflammasomes: the cytosolic frontier of enteric bacterial pathogen - host interactions, Cellular Microbiology, Vol: 22, Pages: 1-19, ISSN: 1462-5814
Enteric pathogen-host interactions occur at multiple interfaces,includingthe intestinal epitheliumand deeper organsof the immune system. Microbial ligands and activities are detected by host sensorsthat elicit a range of immune responses. Membrane-bound Toll-Like Receptors (TLRs) and cytosolic inflammasomepathways are key signal transducers that trigger production of pro-inflammatory molecules such as cytokines and chemokinesand regulate cell deathin response to infection. In recent years, the inflammasomes have emerged as a key frontier in the tusslebetween bacterial pathogens and the host. Inflammasomes are complexes that activate caspase-1and are regulated by related caspases, such as caspase-11, -4, -5 and -8.Importantly, enteric bacterial pathogens can actively engage or evade inflammasome signalling systems. Extracellular, vacuolar and cytosolic bacteria have developed divergent strategies to subvert inflammasomes. While some pathogens take advantage of inflammasomeactivation(e.g. Listeria monocytogenes, Helicobacter pylori), others(e.g. E. coli, Salmonella, Shigella, Yersinia sp.) deploy a range of virulence factors, mainly type 3 secretion system (T3SS) effectors, that subvert or inhibit inflammasomes. In this review we focus on inflammasomepathwaysand their immune functions and discuss how enteric bacterial pathogens interact with them.These studies have not only shed light on the inflammasome-mediated immunity, but also the exciting area of mammalian cytosolic immune
Carson D, Barry R, Eve GD H, et al., 2020, Citrobacter rodentium induces rapid and unique metabolic and inflammatory responses in mice suffering from severe disease, Cellular Microbiology, Vol: 22, Pages: 1-17, ISSN: 1462-5814
The mouse pathogen Citrobacter rodentium is used to model infections with enterohaemorrhagic and enteropathogenic Escherichia coli (EHEC and EPEC). Pathogenesis is commonly modelled in mice developing mild disease (e.g., C57BL/6). However, little is known about host responses in mice exhibiting severe colitis (e.g., C3H/HeN), which arguably provide a more clinically relevant model for human paediatric enteric infection. Infection of C3H/HeN mice with C. rodentium results in rapid colonic colonisation, coinciding with induction of key inflammatory signatures and colonic crypt hyperplasia. Infection also induces dramatic changes to bioenergetics in intestinal epithelial cells, with transition from oxidative phosphorylation (OXPHOS) to aerobic glycolysis and higher abundance of SGLT4, LDHA, and MCT4. Concomitantly, mitochondrial proteins involved in the TCA cycle and OXPHOS were in lower abundance. Similar to observations in C57BL/6 mice, we detected simultaneous activation of cholesterol biogenesis, import, and efflux. Distinctly, however, the pattern recognition receptors NLRP3 and ALPK1 were specifically induced in C3H/HeN. Using cell‐based assays revealed that C. rodentium activates the ALPK1/TIFA axis, which is dependent on the ADP‐heptose biosynthesis pathway but independent of the Type III secretion system. This study reveals for the first time the unfolding intestinal epithelial cells' responses during severe infectious colitis, which resemble EPEC human infections.
Barry R, Ruano-Gallego D, Radhakrishnan ST, et al., 2020, Faecal neutrophil elastase-antiprotease balance reflects colitis severity, Mucosal Immunology, Vol: 13, Pages: 322-333, ISSN: 1933-0219
Given the global burden of diarrheal diseases on healthcare it is surprising how little is known about the drivers of disease severity. Colitis caused by infection and inflammatory bowel disease (IBD) is characterised by neutrophil infiltration into the intestinal mucosa and yet our understanding of neutrophil responses during colitis is incomplete. Using infectious (Citrobacter rodentium) and chemical (dextran sulphate sodium; DSS) murine colitis models, as well as human IBD samples, we find that faecal neutrophil elastase (NE) activity reflects disease severity. During C. rodentium infection intestinal epithelial cells secrete the serine protease inhibitor SerpinA3N to inhibit and mitigate tissue damage caused by extracellular NE. Mice suffering from severe infection produce insufficient SerpinA3N to control excessive NE activity. This activity contributes to colitis severity as infection of these mice with a recombinant C. rodentium strain producing and secreting SerpinA3N reduces tissue damage. Thus, uncontrolled luminal NE activity is involved in severe colitis. Taken together, our findings suggest that NE activity could be a useful faecal biomarker for assessing disease severity as well as therapeutic target for both infectious and chronic inflammatory colitis.
Mullineaux-Sanders C, Sanchez-Garrido J, Hopkins EGD, et al., 2019, Citrobacter rodentium-host-microbiota interactions: immunity, bioenergetics and metabolism, NATURE REVIEWS MICROBIOLOGY, Vol: 17, Pages: 701-715, ISSN: 1740-1526
Wong JLC, Romano M, Kerry L, et al., 2019, OmpK36-mediated Carbapenem resistance attenuates ST258 Klebsiella pneumoniae in vivo, Nature Communications, Vol: 10, ISSN: 2041-1723
Carbapenem-resistance in Klebsiella pneumoniae (KP) sequence type ST258 is mediated by carbapenemases (e.g. KPC-2) and loss or modification of the major non-selective porins OmpK35 and OmpK36. However, the mechanism underpinning OmpK36-mediated resistance and consequences of these changes on pathogenicity remain unknown. By solving the crystal structure of a clinical ST258 OmpK36 variant we provide direct structural evidence of pore constriction, mediated by a di-amino acid (Gly115-Asp116) insertion into loop 3, restricting diffusion of both nutrients (e.g. lactose) and Carbapenems. In the presence of KPC-2 this results in a 16-fold increase in MIC to Meropenem. Additionally, the Gly-Asp insertion impairs bacterial growth in lactose-containing medium and confers a significant in vivo fitness cost in a murine model of ventilator-associated pneumonia. Our data suggest that the continuous selective pressure imposed by widespread Carbapenem utilisation in hospital settings drives the expansion of KP expressing Gly-Asp insertion mutants, despite an associated fitness cost.
Ruano-Gallego D, Yara DA, Di Ianni L, et al., 2019, A nanobody targeting the translocated intimin receptor inhibits the attachment of enterohemorrhagic E. coli to human colonic mucosa, PLOS PATHOGENS, Vol: 15, ISSN: 1553-7366
Mylona E, Frankel G, 2019, The S. Typhi effector StoD is an E3 ubiquitin ligase which binds K48- and K63-linked di-ubiquitin, Life Science Alliance, Vol: 2, ISSN: 2575-1077
Salmonella enterica (e.g., serovars Typhi and Typhimurium) relies on translocation of effectors via type III secretion systems (T3SS). Specialization of typhoidal serovars is thought to be mediated via pseudogenesis. Here, we show that the Salmonella Typhi STY1076/t1865 protein, named StoD, a homologue of the enteropathogenic Escherichia coli/enterohemorrhagic E. coli/Citrobacter rodentium NleG, is a T3SS effector. The StoD C terminus (StoD-C) is a U-box E3 ubiquitin ligase, capable of autoubiquitination in the presence of multiple E2s. The crystal structure of the StoD N terminus (StoD-N) at 2.5 Å resolution revealed a ubiquitin-like fold. In HeLa cells expressing StoD, ubiquitin is redistributed into puncta that colocalize with StoD. Binding assays showed that StoD-N and StoD-C bind the same exposed surface of the β-sheet of ubiquitin, suggesting that StoD could simultaneously interact with two ubiquitin molecules. Consistently, StoD interacted with both K63- (KD = 5.6 ± 1 μM) and K48-linked diubiquitin (KD = 15 ± 4 μM). Accordingly, we report the first S. Typhi–specific T3SS effector. We suggest that StoD recognizes and ubiquitinates pre-ubiquitinated targets, thus subverting intracellular signaling by functioning as an E4 enzyme.
Goddard P, Sanchez Garrido J, Slater S, et al., 2019, Enteropathogenic E. coli stimulates effector-driven rapid caspase-4 activation in human macrophages, Cell Reports, Vol: 27, Pages: 1008-1017.e6, ISSN: 2211-1247
Microbial infections can stimulate the assembly of inflammasomes, which activate caspase-1. The gastrointestinal pathogen enteropathogenic Escherichia coli (EPEC) causes localized actin polymerization in host cells. Actin polymerization requires the binding of the bacterial adhesin intimin to Tir, which is delivered to host cells via a type 3 secretion system (T3SS). We show that EPEC induces T3SS-dependent rapid non-canonical NLRP3 inflammasome activation in human macrophages. Notably, caspase-4 activation by EPEC triggers pyroptosis and cytokine processing through the NLRP3-caspase-1 inflammasome. Mechanistically, caspase-4 activation requires the detection of LPS and EPEC-induced actin polymerization, either via Tir tyrosine phosphorylation and the phosphotyrosine-binding adaptor NCK or Tir and the NCK-mimicking effector TccP. An engineered E. coli K12 could reconstitute Tir-intimin signaling, which is necessary and sufficient for inflammasome activation, ruling out the involvement of other virulence factors. Our studies reveal a crosstalk between caspase-4 and caspase-1 that is cooperatively stimulated by LPS and effector-driven actin polymerization.
Hopkins E, Roumeliotis TI, Mullineaux-Sanders C, et al., 2019, Intestinal epithelial cells and the microbiome undergo swift reprogramming at the inception of colonic Citrobacter rodentium infection, mBio, Vol: 10, ISSN: 2150-7511
We used the mouse attaching and effacing (A/E) pathogen Citrobacter rodentium, which models the human A/E pathogens enteropathogenic Escherichia coli and enterohemorrhagic E. coli (EPEC and EHEC), to temporally resolve intestinal epithelial cell (IEC) responses and changes to the microbiome during in vivo infection. We found the host to be unresponsive during the first 3 days postinfection (DPI), when C. rodentium resides in the caecum. In contrast, at 4 DPI, the day of colonic colonization, despite only sporadic adhesion to the apex of the crypt, we observed robust upregulation of cell cycle and DNA repair processes, which were associated with expansion of the crypt Ki67-positive replicative zone, and downregulation of multiple metabolic processes (including the tricarboxylic acid [TCA] cycle and oxidative phosphorylation). Moreover, we observed dramatic depletion of goblet and deep crypt secretory cells and an atypical regulation of cholesterol homeostasis in IECs during early infection, with simultaneous upregulation of cholesterol biogenesis (e.g., 3-hydroxy-3-methylglutaryl–coenzyme A reductase [Hmgcr]), import (e.g., low-density lipoprotein receptor [Ldlr]), and efflux (e.g., AbcA1). We also detected interleukin 22 (IL-22) responses in IECs (e.g., Reg3γ) on the day of colonic colonization, which occurred concomitantly with a bloom of commensal Enterobacteriaceae on the mucosal surface. These results unravel a new paradigm in host-pathogen-microbiome interactions, showing for the first time that sensing a small number of pathogenic bacteria triggers swift intrinsic changes to the IEC composition and function, in tandem with significant changes to the mucosa-associated microbiome, which parallel innate immune responses.
Levanova N, Mattheis C, Carson D, et al., 2019, The Legionella effector LtpM is a new type of phosphoinositide-activated glucosyltransferase, JOURNAL OF BIOLOGICAL CHEMISTRY, Vol: 294, Pages: 2862-2879
Gomez-Valero L, Rusniok C, Carson D, et al., 2019, More than 18,000 effectors in the Legionella genus genome provide multiple, independent combinations for replication in human cells, PROCEEDINGS OF THE NATIONAL ACADEMY OF SCIENCES OF THE UNITED STATES OF AMERICA, Vol: 116, Pages: 2265-2273, ISSN: 0027-8424
Frankel G, Schroeder GN, 2019, The Galleria mellonella Infection Model for Investigating the Molecular Mechanisms of Legionella Virulence., Methods Mol Biol, Vol: 1921, Pages: 333-346
Legionella species evolved virulence factors to exploit protozoa as replicative niches in the environment. Cell culture infection models demonstrated that many of these factors also enable the bacteria to thrive in human macrophages; however, these models do not recapitulate the complex interactions between macrophages, lung epithelial, and additional immune cells, which are crucial to control bacterial infections. Thus, suitable infection models are required to understand which bacterial factors are important to trigger disease. Guinea pigs and, most frequently, mice have been successfully used as mammalian model hosts; however, ethical and economic considerations impede their use in high-throughput screening studies of Legionella isolates or small molecule inhibitors.Here, we describe the larvae of the lepidopteran Galleria mellonella as insect model of Legionella pathogenesis. Larvae can be obtained from commercial suppliers in large numbers, maintained without the need of specialized equipment, and infected by injection. Although lacking the complexity of a mammalian immune system, the larvae mount humoral and cellular immune responses to infection. L. pneumophila strain 130b and other prototype isolates withstand these responses and use the Defective in organelle trafficking/Intracellular multiplication (Dot/Icm) type IV secretion system (T4SS ) to inject effectors enabling survival and replication in hemocytes, insect phagocytes, ultimately leading to the death of the larvae. Differences in virulence between L. pneumophila isolates or gene deletion mutants can be analyzed using indicators of larval health and immune induction, such as pigmentation, mobility, histopathology, and survival. Bacterial replication can be measured by plating hemolymph or by immunofluorescence microscopy of isolated circulating hemocytes from infected larvae. Combined, these straightforward experimental readouts make G. mellonella larvae a versatile model host to rapidly assess the v
So EC, Mousnier A, Frankel G, et al., 2019, Determination of In Vivo Interactomes of Dot/Icm Type IV Secretion System Effectors by Tandem Affinity Purification., Methods Mol Biol, Vol: 1921, Pages: 289-303
The Dot/Icm type IV secretion system (T4SS) is essential for the pathogenesis of Legionella species and translocates a multitude of effector proteins into host cells. The identification of host cell targets of these effectors is often critical to unravel their roles in controlling the host. Here we describe a method to characterize the protein complexes associated with effectors in infected host cells. To achieve this, Legionella expressing an effector of interest fused to a Bio-tag, a combination of hexahistidine tags and a specific recognition sequence for the biotin ligase BirA, are used to infect host cells expressing BirA, which leads to biotinylation of the translocated effector. Following chemical cross-linking, effector interactomes are isolated by tandem affinity purification employing metal affinity and NeutrAvidin resins and identified by western blotting or mass spectrometry.
Connolly JPR, Slater SL, O'Boyle N, et al., 2018, Host-associated niche metabolism controls enteric infection through fine-tuning the regulation of type 3 secretion, Nature Communications, Vol: 9, ISSN: 2041-1723
Niche-adaptation of a bacterial pathogen hinges on the ability to recognize the complexity of signals from the environment and integrate that information with the regulation of genes critical for infection. Here we report the transcriptome of the attaching and effacing pathogen Citrobacter rodentium during infection of its natural murine host. Pathogen gene expression in vivo was heavily biased towards the virulence factor repertoire and was found to be co-ordinated uniquely in response to the host. Concordantly, we identified the host-specific induction of a metabolic pathway that overlapped with the regulation of virulence. The essential type 3 secretion system and an associated suite of distinct effectors were found to be modulated co-ordinately through a unique mechanism involving metabolism of microbiota-derived 1,2-propanediol, which dictated the ability to colonize the host effectively. This study provides novel insights into how host-specific metabolic adaptation acts as a cue to fine-tune virulence.
Berger CN, Crepin VF, Roumeliotis TI, et al., 2018, The Citrobacter rodentium type III secretion system effector EspO affects mucosal damage repair and antimicrobial responses, PLOS PATHOGENS, Vol: 14, ISSN: 1553-7366
Johnson R, Mylona E, Frankel G, 2018, Typhoidal Salmonella: Distinctive virulence factors and pathogenesis, CELLULAR MICROBIOLOGY, Vol: 20, ISSN: 1462-5814
Slater SL, Sagfors AM, Pollard DJ, et al., 2018, The Type III Secretion System of Pathogenic Escherichia coli, Editors: Frankel, Ron, Publisher: SPRINGER INTERNATIONAL PUBLISHING AG, Pages: 51-72
Pollard D, Berger CN, So E, et al., 2018, Broad spectrum regulation of non receptor tyrosine kinases by the bacterial ADP ribosyltransferase EspJ, mBio, Vol: 9, ISSN: 2150-7511
Tyrosine phosphorylation is key for signal transduction fromexogenousstimuli, including the defence against pathogens. Conversely, pathogens cansubvert protein phosphorylation to control hostimmune responsesand facilitateinvasionanddissemination. The bacterial 23effectorsEspJand SeoC areinjected into host cellsthough a type III secretion system by enteropathogenic and enterohaemorrhagic Escherichia coli(EPEC and EHEC), Citrobacter rodentiumand Salmonellaentericawhere they inhibit Src kinase bycoupledamidation andADP-ribosylation. C. rodentium, which is used tomodel EPEC and EHEC infections in human, is a mouse pathogen triggeringcolonic crypt hyperplasia (CCH) and colitis. Enumeration of bacterial shedding and CCH confirmed that EspJ affects neither tolerance nor resistance to infection. However, comparing the proteomes of intestinal epithelial cells isolated from mice infected with wildtype C.rodentiumor C. rodentiumencoding catalyticallyinactive EspJrevealed that EspJ-induced ADP-ribosylationregulatesmultiple non-receptor tyrosine kinasesin vivo. Investigating the substrate repertoire of EspJ revealed that in HeLa and A549 Src and Csk were significantly targeted; in polarised Caco2 cells EspJ targeted Src and Csk and the Src family kinase (SFK) Yes1, while in differentiated Thp1 EspJ modifiedCsk, the SFKs Hck and Lyn, the Tec family kinases Tec and Btk, and the adapter tyrosine kinase Syk. Furthermore, Abl (HeLa and Caco2) and Lyn (Caco2) were enriched specifically in the EspJ-containing samples. Biochemical assays revealed that EspJ, the only bacterial ADP-ribosyltransferase which targets mammalian kinases,controls immune responses andthe Src/Csk signalling axis.
Baumann D, Salia H, Greune L, et al., 2018, Multitalented EspB of enteropathogenic Escherichia coli (EPEC) enters cells autonomously and induces programmed cell death in human monocytic THP-1 cells, INTERNATIONAL JOURNAL OF MEDICAL MICROBIOLOGY, Vol: 308, Pages: 387-404, ISSN: 1438-4221
Mullineaux-Sanders C, Suez J, Elinav E, et al., 2018, Sieving through gut models of colonization resistance, NATURE MICROBIOLOGY, Vol: 3, Pages: 132-140, ISSN: 2058-5276
Mullineaux-Sanders C, Colins JW, Ruano-Gallego D, et al., 2017, Citrobacter rodentium relies on commensals for colonization of the colonic mucosa, Cell Reports, Vol: 21, Pages: 3381-3389, ISSN: 2211-1247
We investigated the role of commensals at the peak of infection with the colonic mouse pathogen Citrobacter rodentium. Bioluminescent and kanamycin (Kan)-resistant C. rodentium persisted avirulently in the cecal lumen of mice continuously treated with Kan. A single Kan treatment was sufficient to displace C. rodentium from the colonic mucosa, a phenomenon not observed following treatment with vancomycin (Van) or metronidazole (Met). Kan, Van, and Met induce distinct dysbiosis, suggesting C. rodentium relies on specific commensals for colonic colonization. Expression of the master virulence regulator ler is induced in germ-free mice, yet C. rodentium is only seen in the cecal lumen. Moreover, in conventional mice, a single Kan treatment was sufficient to displace C. rodentium constitutively expressing Ler from the colonic mucosa. These results show that expression of virulence genes is not sufficient for colonization of the colonic mucosa and that commensals are essential for a physiological infection course.
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