scholarly journals Mapping of Shigella flexneri’s tissue distribution and type III secretion apparatus activity during infection of the large intestine of guinea pigs

2019 ◽  
Vol 77 (7) ◽  
Author(s):  
Giulia Nigro ◽  
Ellen T Arena ◽  
Martin Sachse ◽  
Maryse Moya-Nilges ◽  
Benoit S Marteyn ◽  
...  
Keyword(s):  
Lamina Propria ◽  
Type Iii Secretion ◽  
Guinea Pigs ◽  
Fluorescent Protein ◽  
Host Cells ◽  
Post Challenge ◽  
Type Iii ◽  
Shigella Spp ◽  
Green Fluorescent

ABSTRACT Shigella spp. are bacterial pathogens that invade the human colonic mucosa using a type III secretion apparatus (T3SA), a proteinaceous device activated upon contact with host cells. Active T3SAs translocate proteins that carve the intracellular niche of Shigella spp. Nevertheless, the activation state of the T3SA has not been addressed in vivo. Here, we used a green fluorescent protein transcription-based secretion activity reporter (TSAR) to provide a spatio-temporal description of S. flexneri T3SAs activity in the colon of Guinea pigs. First, we observed that early mucus release is triggered in the vicinity of luminal bacteria with inactive T3SA. Subsequent mucosal invasion showed bacteria with active T3SA associated with the brush border, eventually penetrating into epithelial cells. From 2 to 8 h post-challenge, the infection foci expanded, and these intracellular bacteria displayed homogeneously high-secreting activity, while extracellular foci within the lamina propria featured bacteria with low secretion activity. We also found evidence that within lamina propria macrophages, bacteria reside in vacuoles instead of accessing the cytosol. Finally, bacteria were cleared from tissues between 8 and 24 h post-challenge, highlighting the hit-and-run colonization strategy of Shigella. This study demonstrates how genetically encoded reporters can contribute to deciphering pathogenesis in vivo.

scholarly journals A C-Terminal Domain Targets the Pseudomonas aeruginosa Cytotoxin ExoU to the Plasma Membrane of Host Cells

2006 ◽  
Vol 74 (5) ◽  
pp. 2552-2561 ◽  
Author(s):  
Shira D. P. Rabin ◽  
Jeffrey L. Veesenmeyer ◽  
Kathryn T. Bieging ◽  
Alan R. Hauser
Keyword(s):  
Pseudomonas Aeruginosa ◽  
Cell Death ◽  
Plasma Membrane ◽  
Hela Cells ◽  
Type Iii Secretion ◽  
Fluorescent Protein ◽  
Host Cells ◽  
Type Iii ◽  
C Terminus ◽  
Green Fluorescent

ABSTRACT ExoU, a phospholipase injected into host cells by the type III secretion system of Pseudomonas aeruginosa, leads to rapid cytolytic cell death. Although the importance of ExoU in infection is well established, the mechanism by which this toxin kills host cells is less clear. To gain insight into how ExoU causes cell death, we examined its subcellular localization following transfection or type III secretion/translocation into HeLa cells. Although rapid cell lysis precluded visualization of wild-type ExoU by fluorescence microscopy, catalytically inactive toxin was readily detected at the periphery of HeLa cells. Biochemical analysis confirmed that ExoU was targeted to the membrane fraction of transfected cells. Visualization of ExoU peptides fused with green fluorescent protein indicated that the domain responsible for this targeting was in the C terminus of ExoU, between residues 550 and 687. Localization to the plasma membrane occurred within 1 h of expression, which is consistent with the kinetics of cytotoxicity. Together, these results indicate that a domain between residues 550 and 687 of ExoU targets this toxin to the plasma membrane, a process that may be important in cytotoxicity.

scholarly journals Pseudomonas syringae HrpP Is a Type III Secretion Substrate Specificity Switch Domain Protein That Is Translocated into Plant Cells but Functions Atypically for a Substrate-Switching Protein

2009 ◽  
Vol 191 (9) ◽  
pp. 3120-3131 ◽  
Author(s):  
Joanne E. Morello ◽  
Alan Collmer
Keyword(s):  
Substrate Specificity ◽  
Pseudomonas Syringae ◽  
Type Iii Secretion ◽  
Fluorescent Protein ◽  
Plant Cells ◽  
Effector Proteins ◽  
Type Iii ◽  
Native Promoter ◽  
C Terminus ◽  
Green Fluorescent

ABSTRACT Pseudomonas syringae delivers virulence effector proteins into plant cells via an Hrp1 type III secretion system (T3SS). P. syringae pv. tomato DC3000 HrpP has a C-terminal, putative T3SS substrate specificity switch domain, like Yersinia YscP. A ΔhrpP DC3000 mutant could not cause disease in tomato or elicit a hypersensitive response (HR) in tobacco, but the HR could be restored by expression of HrpP in trans. Though HrpP is a relatively divergent protein in the T3SS of different P. syringae pathovars, hrpP from P. syringae pv. syringae 61 and P. syringae pv. phaseolicola 1448A restored HR elicitation and pathogenicity to DC3000 ΔhrpP. HrpP was translocated into Nicotiana benthamiana cells via the DC3000 T3SS when expressed from its native promoter, but it was not secreted in culture. N- and C-terminal truncations of HrpP were tested for their ability to be translocated and to restore HR elicitation activity to the ΔhrpP mutant. No N-terminal truncation completely abolished translocation, implying that HrpP has an atypical T3SS translocation signal. Deleting more than 20 amino acids from the C terminus abolished the ability to restore HR elicitation. HrpP fused to green fluorescent protein was no longer translocated but could restore HR elicitation activity to the ΔhrpP mutant, suggesting that translocation is not essential for the function of HrpP. No T3SS substrates were detectably secreted by DC3000 ΔhrpP except the pilin subunit HrpA, which unexpectedly was secreted poorly. HrpP may function somewhat differently than YscP because the P. syringae T3SS pilus likely varies in length due to differing plant cell walls.

scholarly journals Characterization of the Yersinia enterocolitica Type III Secretion ATPase YscN and Its Regulator, YscL

2006 ◽  
Vol 188 (10) ◽  
pp. 3525-3534 ◽  
Author(s):  
Bill Blaylock ◽  
Kelly E. Riordan ◽  
Dominique M. Missiakas ◽  
Olaf Schneewind
Keyword(s):  
Yersinia Enterocolitica ◽  
Type Iii Secretion ◽  
Atp Hydrolysis ◽  
Biochemical Properties ◽  
Host Cells ◽  
Gram Negative Bacteria ◽  
Type Iii ◽  
Bacterial Proteins

ABSTRACT Type III secretion is a mechanism used by a broad range of gram-negative bacteria to neutralize eukaryotic defenses by enabling translocation of bacterial proteins directly into the cytoplasm of host cells. The bacterial energy source for secretion is ATP, which is consumed by an ATPase that couples ATP hydrolysis to the unfolding of secreted proteins and the dissociation of their chaperones just prior to secretion. By studying the biochemical properties of YscN and YscL of Yersinia enterocolitica, we have characterized them as the ATPase and ATPase regulator, respectively, of the type III secretion system of this organism. In vivo, YscL and YscN interact with each other, and the overexpression of glutathione S-transferase-YscL abolishes secretion and down-regulates the expression of secretion apparatus components.

scholarly journals Antibodies Inhibiting the Type III Secretion System of Gram-Negative Pathogenic Bacteria

Antibodies ◽  
2020 ◽  
Vol 9 (3) ◽  
pp. 35
Author(s):  
Julia A. Hotinger ◽  
Aaron E. May
Keyword(s):  
Type Iii Secretion ◽  
Pathogenic Bacteria ◽  
Type Iii Secretion System ◽  
The United States ◽  
Secretion System ◽  
Effector Proteins ◽  
Host Cells ◽  
Gram Negative ◽  
Type Iii ◽  
Shigella Spp

Pathogenic bacteria are a global health threat, with over 2 million infections caused by Gram-negative bacteria every year in the United States. This problem is exacerbated by the increase in resistance to common antibiotics that are routinely used to treat these infections, creating an urgent need for innovative ways to treat and prevent virulence caused by these pathogens. Many Gram-negative pathogenic bacteria use a type III secretion system (T3SS) to inject toxins and other effector proteins directly into host cells. The T3SS has become a popular anti-virulence target because it is required for pathogenesis and knockouts have attenuated virulence. It is also not required for survival, which should result in less selective pressure for resistance formation against T3SS inhibitors. In this review, we will highlight selected examples of direct antibody immunizations and the use of antibodies in immunotherapy treatments that target the bacterial T3SS. These examples include antibodies targeting the T3SS of Pseudomonas aeruginosa, Yersinia pestis, Escherichia coli, Salmonella enterica, Shigella spp., and Chlamydia trachomatis.

scholarly journals Yersinia pestis YopK Inhibits Bacterial Adhesion to Host Cells by Binding to the Extracellular Matrix Adaptor Protein Matrilin-2

2017 ◽  
Vol 85 (8) ◽  
Author(s):  
Yafang Tan ◽  
Wanbing Liu ◽  
Qingwen Zhang ◽  
Shiyang Cao ◽  
Haihong Zhao ◽  
...  
Keyword(s):  
Extracellular Matrix ◽  
Hela Cells ◽  
Bacterial Adhesion ◽  
Type Iii Secretion ◽  
Fluorescent Protein ◽  
Adaptor Protein ◽  
Innate Immune ◽  
Host Cells ◽  
Content Type ◽  
Green Fluorescent

ABSTRACT Pathogenic yersiniae harbor a type III secretion system (T3SS) that injects Yersinia outer protein (Yop) into host cells. YopK has been shown to control Yop translocation and prevent inflammasome recognition of the T3SS by the innate immune system. Here, we demonstrate that YopK inhibits bacterial adherence to host cells by binding to the extracellular matrix adaptor protein matrilin-2 (MATN2). YopK binds to MATN2, and deleting amino acids 91 to 124 disrupts binding of YopK to MATN2. A yopK null mutant exhibits a hyperadhesive phenotype, which could be responsible for the established Yop hypertranslocation phenotype of yopK mutants. Expression of YopK, but not YopKΔ91–124, in a yopK mutant restored the wild-type phenotypes of adhesion and Yop translocation, suggesting that binding to MATN2 might be essential for YopK to inhibit bacterial adhesion and negatively regulate Yop translocation. A green fluorescent protein (GFP)-YopK fusion specifically binds to the endogenous MATN2 on the surface of HeLa cells, whereas GFP-YopKΔ91–124 cannot. Addition of purified YopK protein during infection decreased adhesion of Y. pestis to HeLa cells, while YopKΔ91–124 protein showed no effect. Taking these results together, we propose a model that the T3SS-secreted YopK hinders bacterial adhesion to HeLa cells by binding to MATN2, which is ubiquitously exposed on eukaryotic cells.

scholarly journals Interaction of Pasteurella multocida with Free-Living Amoebae

2005 ◽  
Vol 71 (9) ◽  
pp. 5458-5464 ◽  
Author(s):  
Matthew J. Hundt ◽  
Carmel G. Ruffolo
Keyword(s):  
Pasteurella Multocida ◽  
Fluorescent Protein ◽  
Host Cells ◽  
Free Living ◽  
Fowl Cholera ◽  
Transmission Electron ◽  
Membrane Bound ◽  
Green Fluorescent ◽  
First Time

ABSTRACT Pasteurella multocida is a highly infectious, facultative intracellular bacterium which causes fowl cholera in birds. This study reports, for the first time, the observed interaction between P. multocida and free-living amoebae. Amoebal trophozoites were coinfected with fowl-cholera-causing P. multocida strain X-73 that expressed the green fluorescent protein (GFP). Using confocal fluorescence microscopy, GFP expressing X-73 was located within the trophozoite. Transmission electron microscopy of coinfection preparations revealed clusters of intact X-73 cells in membrane-bound vacuoles within the trophozoite cytoplasm. A coinfection assay employing gentamicin to kill extracellular bacteria was used to assess the survival and replication of P. multocida within amoebae. In the presence of amoebae, the number of recoverable intracellular X-73 cells increased over a 24-h period; in contrast, X-73 cultured alone in assay medium showed a consistent decline in growth. Cytotoxicity assays and microscopy showed that X-73 was able to lyse and exit the amoebal cells approximately 18 h after coinfection. The observed interaction between P. multocida and amoebae can be considered as an infective process as the bacterium was able to invade, survive, replicate, and lyse the amoebal host. This raises the possibility that similar interactions occur in vivo between P. multocida and host cells. Free-living amoebae are ubiquitous within water and soil environments, and P. multocida has been observed to survive within these same ecosystems. Thus, our findings suggest that the interaction between P. multocida and amoebae may occur within the natural environment.

Development and validation of fourLeishmaniaspecies constitutively expressing GFP protein. A model for drug discovery and disease pathogenesis studies

Parasitology ◽  
2013 ◽  
Vol 141 (4) ◽  
pp. 501-510 ◽  
Author(s):  
ASHA PARBHU PATEL ◽  
ANDREW DEACON ◽  
GIULIA GETTI
Keyword(s):  
Leishmania Major ◽  
Fluorescent Protein ◽  
Protein A ◽  
Host Cells ◽  
Mammalian Host ◽  
Disease Pathogenesis ◽  
Compound Libraries ◽  
Green Fluorescent

SUMMARYGreen fluorescent protein (GFP)-parasite transfectants have been widely used as a tool for studying disease pathogenesis in several protozoan models and their application in drug screening assays has increased rapidly. In the past decade, the expression of GFP has been established in severalLeishmaniaspecies, mostly forin vitrostudies. The current work reports generation of four transgenic parasites constitutively expressing GFP (Leishmania mexicana, Leishmania aethiopica, Leishmania tropicaandLeishmania major) and their validation as a representative model of infection. This is the first report where stable expression of GFP has been achieved inL. aethiopicaandL. tropica. Integration of GFP was accomplished through homologous recombination of the expression construct, pRib1.2αNEOαGFP downstream of the 18S rRNA promoter in all species. A homogeneous and high level expression of GFP was detected in both the promastigote and the intracellular amastigote stages. All transgenic species showed the same growth pattern, ability to infect mammalian host cells and sensitivity to reference drugs as their wild type counterparts. All four transgenicLeishmaniaare confirmed as models forin vitroand possiblyin vivoinfections and represent an ideal tool for medium throughput testing of compound libraries.

scholarly journals Impact of Type III Secretion Effectors and of Phenoxyacetamide Inhibitors of Type III Secretion on Abscess Formation in a Mouse Model of Pseudomonas aeruginosa Infection

2017 ◽  
Vol 61 (11) ◽  
Author(s):  
Bryan J. Berube ◽  
Katherine R. Murphy ◽  
Matthew C. Torhan ◽  
Nicholas O. Bowlin ◽  
John D. Williams ◽  
...  
Keyword(s):  
Pseudomonas Aeruginosa ◽  
Mouse Model ◽  
Type Iii Secretion ◽  
Abscess Formation ◽  
Host Cells ◽  
Block Type ◽  
Content Type ◽  
Type Iii

ABSTRACT Pseudomonas aeruginosa is a leading cause of intra-abdominal infections, wound infections, and community-acquired folliculitis, each of which may involve macro- or microabscess formation. The rising incidence of multidrug resistance among P. aeruginosa isolates has increased both the economic burden and the morbidity and mortality associated with P. aeruginosa disease and necessitates a search for novel therapeutics. Previous work from our group detailed novel phenoxyacetamide inhibitors that block type III secretion and injection into host cells in vitro. In this study, we used a mouse model of P. aeruginosa abscess formation to test the in vivo efficacy of these compounds against the P. aeruginosa type III secretion system (T3SS). Bacteria used the T3SS to intoxicate infiltrating neutrophils to establish abscesses. Despite this antagonism, sufficient numbers of functioning neutrophils remained for proper containment of the abscesses, as neutrophil depletion resulted in an increased abscess size, the formation of dermonecrotic lesions on the skin, and the dissemination of P. aeruginosa to internal organs. Consistent with the specificity of the T3SS-neutrophil interaction, P. aeruginosa bacteria lacking a functional T3SS were fully capable of causing abscesses in a neutropenic host. Phenoxyacetamide inhibitors attenuated abscess formation and aided in the immune clearance of the bacteria. Finally, a P. aeruginosa strain resistant to the phenoxyacetamide compound was fully capable of causing abscess formation even in the presence of the T3SS inhibitors. Together, our results further define the role of type III secretion in murine abscess formation and demonstrate the in vivo efficacy of phenoxyacetamide inhibitors in P. aeruginosa infection.

scholarly journals The Tubulin-Like RepX Protein Encoded by the pXO1 Plasmid Forms Polymers In Vivo in Bacillus anthracis

2009 ◽  
Vol 191 (8) ◽  
pp. 2493-2500 ◽  
Author(s):  
Parvez Akhtar ◽  
Syam P. Anand ◽  
Simon C. Watkins ◽  
Saleem A. Khan
Keyword(s):  
Bacillus Anthracis ◽  
Cell Morphology ◽  
Fluorescent Protein ◽  
Host Cells ◽  
E Coli ◽  
Green Fluorescent ◽  
Related Proteins ◽  
Polymeric Structures

ABSTRACT Bacillus anthracis contains two megaplasmids, pXO1 and pXO2, that are critical for its pathogenesis. Stable inheritance of pXO1 in B. anthracis is dependent upon the tubulin/FtsZ-like RepX protein encoded by this plasmid. Previously, we have shown that RepX undergoes GTP-dependent polymerization in vitro. However, the polymerization properties and localization pattern of RepX in vivo are not known. Here, we utilize a RepX-green fluorescent protein (GFP) fusion to show that RepX forms foci and three distinct forms of polymeric structures in B. anthracis in vivo, namely straight, curved, and helical filaments. Polymerization of RepX-GFP as well as the nature of polymers formed were dependent upon concentration of the protein inside the B. anthracis cells. RepX predominantly localized as polymers that were parallel to the length of the cell. RepX also formed polymers in Escherichia coli in the absence of other pXO1-encoded products, showing that in vivo polymerization is an inherent property of the protein and does not require either the pXO1 plasmid or proteins unique to B. anthracis. Overexpression of RepX did not affect the cell morphology of B. anthracis cells, whereas it drastically distorted the cell morphology of E. coli host cells. We discuss the significance of our observations in view of the plasmid-specific functions that have been proposed for RepX and related proteins encoded by several megaplasmids found in members of the Bacillus cereus group of bacteria.

scholarly journals Dual perspective proteomics infectome profiling discovers Salmonella type III secretion system effector functions in macrophages

2021 ◽  
Author(s):  
Jennifer Geddes-McAlister ◽  
A. Sukumaran ◽  
S. L. Vogt ◽  
J. L. Roland ◽  
S. E. Woodward ◽  
...  
Keyword(s):  
Type Iii Secretion ◽  
Bacterial Pathogens ◽  
Host Cells ◽  
Secretion Systems ◽  
Specific Expression ◽  
Type Iii ◽  
Cell Functions ◽  
Serovar Typhimurium ◽  
Dual Perspective

Intracellular bacterial pathogens have evolved sophisticated infection strategies, including the release and secretion of virulence factors to interfere with host cell functions and to perturb immune responses. For Salmonella enterica serovar Typhimurium (S. Typhimurium), the type III secretion systems encoded on Salmonella pathogenicity islands (SPI) 1 and 2 mediates invasion of the bacterium into innate immune cells and regulates bacterial replication and survival within the hostile environment of the host, respectively. Here, we explore the temporal and strain-specific dual perspective response of both the host and pathogen during cellular infection via quantitative proteomics. We report time- and pathogenicity island-specific expression and secretion of infection-associated proteins (i.e., SL1344_1263, SL1344_3112, SL1344_1563, and YnhG) and regulated immune response proteins in macrophage, including Cd86, Cd40, Casp4, C3, IL-1?, and Cd69). Through intracellular macrophage and in vivo murine models of infection, we reveal a role in virulence for three of the bacterial proteins (SL1344_1263, SL1344_1563, and YnhG), defining their importance as novel T3SS effectors. We characterize the temporal intra- and extracellular production of the effectors and identify their interaction networks in host cells, representing inhibitory and stimulatory pathways mounted by invading bacterial pathogens.

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