scholarly journals EseE of Edwardsiella tarda Augments Secretion of Translocon Protein EseC and Expression of theescC-eseEOperon

2016 ◽  
Vol 84 (8) ◽  
pp. 2336-2344 ◽  
Author(s):  
Jia Yi ◽  
Shui Bing Xiao ◽  
Zhi Xiong Zeng ◽  
Jin Fang Lu ◽  
Lu Yi Liu ◽  
...  
Keyword(s):  
Gel Filtration ◽  
Host Cells ◽  
Edwardsiella Tarda ◽  
Supernatant Fraction ◽  
Bacterial Cells ◽  
Bacterial Survival ◽  
Content Type ◽  
Chaperone Protein ◽  
Pulldown Assay ◽  
Novel Protein

Edwardsiella tardais an important Gram-negative pathogen that employs a type III secretion system (T3SS) to deliver effectors into host cells to facilitate bacterial survival and replication. These effectors are translocated into host cells through a translocon complex composed of three secreted proteins, namely, EseB, EseC, and EseD. The secretion of EseB and EseD requires a chaperone protein called EscC, whereas the secretion of EseC requires the chaperone EscA. In this study, we identified a novel protein (EseE) that also regulates the secretion of EseC. AneseEdeletion mutant secreted much less EseC into supernatants, accompanied by increased EseC levels within bacterial cells. We also demonstrated that EseE interacted directly with EseC in a pulldown assay. Interestingly, EseC, EseE, and EscA were able to form a ternary complex, as revealed by pulldown and gel filtration assays. Of particular importance, the deletion ofeseEresulted in decreased levels of EseB and EseD proteins in both the bacterial pellet and supernatant fraction. Furthermore, real-time PCR assays showed that EseE positively regulated the transcription of the translocon operonescC-eseE, comprisingescC,eseB,escA,eseC,eseD, andeseE. These effects of EseE on the translocon components/operon appeared to have a functional consequence, since the ΔeseEstrain was outcompeted by wild-typeE. tardain a mixed infection in blue gourami fish. Collectively, our results demonstrate that EseE not only functions as a chaperone for EseC but also acts as a positive regulator controlling the expression of the translocon operonescC-eseE, thus contributing to the pathogenesis ofE. tardain fish.

scholarly journals Chlamydia trachomatis Cellular Exit Alters Interactions with Host Dendritic Cells

2017 ◽  
Vol 85 (5) ◽  
Author(s):  
Ashley M. Sherrid ◽  
Kevin Hybiske
Keyword(s):  
Dendritic Cells ◽  
Dendritic Cell ◽  
Chlamydia Trachomatis ◽  
Innate Immune ◽  
Host Cells ◽  
Bacterial Survival ◽  
Content Type ◽  
Innate Immune Signaling ◽  
Host Membrane ◽  
Membrane Bound

ABSTRACT The strategies utilized by pathogens to exit host cells are an area of pathogenesis which has received surprisingly little attention, considering the necessity of this step for infections to propagate. Even less is known about how exit through these pathways affects downstream host-pathogen interactions and the generation of an immune response. Chlamydia trachomatis exits host epithelial cells through two equally active mechanisms: lysis and extrusion. Studies have characterized the outcome of interactions between host innate immune cells, such as dendritic cells and macrophages, and free, extracellular Chlamydia bacteria, such as those resulting from lysis. Exit via extrusion generates a distinct, host-membrane-bound compartment of Chlamydia separate from the original infected cell. In this study, we assessed the effect of containment within extrusions upon the interaction between Chlamydia and host dendritic cells. Extrusion dramatically affected the outcome of Chlamydia-dendritic cell interactions for both the bacterium and the host cell. Dendritic cells rapidly underwent apoptosis in response to engulfment of an extrusion, while uptake of an equivalent dose of free Chlamydia had no such effect. Containment within an extrusion also prolonged bacterial survival within dendritic cells and altered the initial innate immune signaling by the dendritic cell.

scholarly journals Evolution and Sequence Diversity of FhuA inSalmonellaandEscherichia

2018 ◽  
Vol 86 (11) ◽  
Author(s):  
Yejun Wang ◽  
Xiongbin Chen ◽  
Yueming Hu ◽  
Guoqiang Zhu ◽  
Aaron P. White ◽  
...  
Keyword(s):  
Gene Mutations ◽  
Comparative Sequence Analysis ◽  
Sequence Diversity ◽  
Bacterial Cells ◽  
Bacterial Survival ◽  
Bacterial Strains ◽  
Content Type ◽  
High Conservation ◽  
High Selection ◽  
Clustering Pattern

ABSTRACTThefhuACDBoperon, present in a number ofEnterobacteriaceae, encodes components essential for the uptake of ferric hydroxamate type siderophores. FhuA acts not only as a transporter for physiologically important chelated ferric iron but also as a receptor for various bacteriophages, toxins, and antibiotics, which are pathogenic to bacterial cells. In this research,fhuAgene distribution and sequence diversity were investigated inEnterobacteriaceae, especiallySalmonellaandEscherichia. Comparative sequence analysis resulted in afhuAphylogenetic tree that did not match the expected phylogeny of species or trees of thefhuCDBgenes. ThefhuAsequences showed a unique mosaic clustering pattern. On the other hand, the gene sequences showed high conservation for strains from the same serovar or serotype. In total, six clusters were identified from FhuA proteins inSalmonellaandEscherichia, among which typical peptide fragment variations could be defined. Six fragmental insertions/deletions and two substitution fragments were discovered, for which the combination of polymorphism patterns could well classify the different clusters. Structural modeling demonstrated that all the six featured insertions/deletions and one substitution fragment are located at the apexes of the long loops present as part of the FhuA external pocket. These frequently mutated regions are likely under high selection pressure, with bacterial strains balancing escape from phage infection or toxin/antibiotics attack viafhuAgene mutations while maintaining the siderophore uptake activity essential for bacterial survival. The unusualfhuAclustering suggests that high-frequency exchange offhuAgenes has occurred between enterobacterial strains after distinctive species were established.

scholarly journals Identification and Functional Characterization of the Novel Edwardsiella tarda Effector EseJ

2015 ◽  
Vol 83 (4) ◽  
pp. 1650-1660 ◽  
Author(s):  
Hai-Xia Xie ◽  
Jin-Fang Lu ◽  
Ying Zhou ◽  
Jia Yi ◽  
Xiu-Jun Yu ◽  
...  
Keyword(s):  
Mutant Strain ◽  
Bacterial Adhesion ◽  
Sequence Similarity ◽  
Functional Characterization ◽  
Lethal Dose ◽  
Edwardsiella Tarda ◽  
Bacterial Cells ◽  
Wild Type ◽  
High Sequence Similarity ◽  
Content Type

Edwardsiella tardais a Gram-negative enteric pathogen that causes hemorrhagic septicemia in fish and gastro- and extraintestinal infections in humans. The type III secretion system (T3SS) ofE. tardahas been identified as a key virulence factor that contributes to pathogenesis in fish. However, little is known about the associated effectors translocated by this T3SS. In this study, by comparing the profile of secreted proteins of the wild-type PPD130/91 and its T3SS ATPase ΔesaNmutant, we identified a new effector by matrix-assisted laser desorption ionization–time of flight (MALDI-TOF) mass spectrometry. This effector consists of 1,359 amino acids, sharing high sequence similarity with Orf29/30 ofE. tardastrain EIB202, and is renamed EseJ. The secretion and translocation of EseJ depend on the T3SS. A ΔeseJmutant strain adheres to epithelioma papillosum of carp (EPC) cells 3 to 5 times more extensively than the wild-type strain does. EseJ inhibits bacterial adhesion to EPC cells from within bacterial cells. Importantly, the ΔeseJmutant strain does not replicate efficiently in EPC cells and fails to replicate in J774A.1 macrophages. In infected J774A.1 macrophages, the ΔeseJmutant elicits higher production of reactive oxygen species than wild-typeE. tarda. The replication defect is consistent with the attenuation of the ΔeseJmutant in the blue gourami fish model: the 50% lethal dose (LD50) of the ΔeseJmutant is 2.34 times greater than that of the wild type, and the ΔeseJmutant is less competitive than the wild type in mixed infection. Thus, EseJ represents a novel effector that contributes to virulence by reducing bacterial adhesion to EPC cells and facilitating intracellular bacterial replication.

scholarly journals Enhanced Survival of Rifampin- and Streptomycin-Resistant Escherichia coli Inside Macrophages

2016 ◽  
Vol 60 (7) ◽  
pp. 4324-4332 ◽  
Author(s):  
Paulo Durão ◽  
Daniela Gülereşi ◽  
João Proença ◽  
Isabel Gordo
Keyword(s):  
Gene Expression ◽  
Escherichia Coli ◽  
Multiple Drug Resistance ◽  
Host Cells ◽  
Resistant Bacteria ◽  
Multiple Drug ◽  
Bacterial Survival ◽  
Phagocytic Cells ◽  
Content Type ◽  
Multiple Paths

ABSTRACTThe evolution of multiple-antibiotic-resistant bacteria is an increasing global problem. Even though mutations causing resistance usually incur a fitness cost in the absence of antibiotics, the magnitude of such costs varies across environments and genomic backgrounds. We studied how the combination of mutations that confer resistance to rifampin (Rifr) and streptomycin (Strr) affects the fitness ofEscherichia coliwhen it interacts with cells from the immune system, i.e., macrophages (Mϕs). We found that 13 RifrStrrdoubly resistant genotypes, of the 16 tested, show a survival advantage inside Mϕs, indicating that double resistance can be highly beneficial in this environment. Our results suggest that there are multiple paths to acquire multiple-drug resistance in this context, i.e., if a clone carrying Rifrallele H526 or S531 acquires a second mutation conferring Strr, the resulting double mutant has a high probability of showing increased survival inside Mϕs. On the other hand, we found two cases of sign epistasis between mutations, leading to a significant decrease in bacterial survival. Remarkably, infection of Mϕs with one of these combinations, K88R+H526Y, resulted in an altered pattern of gene expression in the infected Mϕs. This indicates that the fitness effects of resistance may depend on the pattern of gene expression of infected host cells. Notwithstanding the benefits of resistance found inside Mϕs, the RifrStrrmutants have massive fitness costs when the bacteria divide outside Mϕs, indicating that the maintenance of double resistance may depend on the time spent within and outside phagocytic cells.

scholarly journals Small-Molecule Inhibitor of the Shigella flexneri Master Virulence Regulator VirF

2013 ◽  
Vol 81 (11) ◽  
pp. 4220-4231 ◽  
Author(s):  
Veerendra Koppolu ◽  
Ichie Osaka ◽  
Jeff M. Skredenske ◽  
Bria Kettle ◽  
P. Scott Hefty ◽  
...  
Keyword(s):  
Dna Binding ◽  
Small Molecule ◽  
Virulence Genes ◽  
Shigella Flexneri ◽  
Transcription Activation ◽  
Host Cells ◽  
Mrna Levels ◽  
Bacterial Cells ◽  
Content Type ◽  
Arac Family

ABSTRACTVirF is an AraC family transcriptional activator that is required for the expression of virulence genes associated with invasion and cell-to-cell spread byShigella flexneri, including multiple components of the type three secretion system (T3SS) machinery and effectors. We tested a small-molecule compound, SE-1 (formerly designated OSSL_051168), which we had identified as an effective inhibitor of the AraC family proteins RhaS and RhaR, for its ability to inhibit VirF. Cell-based reporter gene assays withEscherichia coliandShigella, as well asin vitroDNA binding assays with purified VirF, demonstrated that SE-1 inhibited DNA binding and transcription activation (likely by blocking DNA binding) by VirF. Analysis of mRNA levels using real-time quantitative reverse transcription-PCR (qRT-PCR) further demonstrated that SE-1 reduced the expression of the VirF-dependent virulence genesicsA,virB,icsB, andipaBinShigella. We also performed eukaryotic cell invasion assays and found that SE-1 reduced invasion byShigella. The effect of SE-1 on invasion required preincubation ofShigellawith SE-1, in agreement with the hypothesis that SE-1 inhibited the expression of VirF-activated genes required for the formation of the T3SS apparatus and invasion. We found that the same concentrations of SE-1 had no detectable effects on the growth or metabolism of the bacterial cells or the eukaryotic host cells, respectively, indicating that the inhibition of invasion was not due to general toxicity. Overall, SE-1 appears to inhibit transcription activation by VirF, exhibits selectivity toward AraC family proteins, and has the potential to be developed into a novel antibacterial agent.

scholarly journals Pseudomonas aeruginosa ExsA Regulates a Metalloprotease, ImpA, That Inhibits Phagocytosis of Macrophages

2019 ◽  
Vol 87 (12) ◽  
Author(s):  
Zhenyang Tian ◽  
Sen Cheng ◽  
Bin Xia ◽  
Yongxin Jin ◽  
Fang Bai ◽  
...  
Keyword(s):  
Pseudomonas Aeruginosa ◽  
Critical Role ◽  
Surface Protein ◽  
Host Cells ◽  
Bacterial Cells ◽  
Mobility Shift ◽  
Content Type ◽  
Direct Binding ◽  
Mobility Shift Assay ◽  
Opportunistic Pathogenic

ABSTRACT Pseudomonas aeruginosa is an opportunistic pathogenic bacterium whose type III secretion system (T3SS) plays a critical role in acute infections. Translocation of the T3SS effectors into host cells induces cytotoxicity. In addition, the T3SS promotes the intracellular growth of P. aeruginosa during host infections. The T3SS regulon genes are regulated by an AraC-type regulator, ExsA. In this study, we found that an extracellular metalloprotease encoded by impA (PA0572) is under the regulation of ExsA. An ExsA consensus binding sequence was identified upstream of the impA gene, and direct binding of the site by ExsA was demonstrated via an electrophoretic mobility shift assay. We further demonstrate that secreted ImpA cleaves the macrophage surface protein CD44, which inhibits the phagocytosis of the bacterial cells by macrophages. Combined, our results reveal a novel ExsA-regulated virulence factor that cooperatively inhibits the functions of macrophages with the T3SS.

scholarly journals Edwardsiella tarda Eta1, anIn Vivo-Induced Antigen That Is Involved in Host Infection

2012 ◽  
Vol 80 (8) ◽  
pp. 2948-2955 ◽  
Author(s):  
Yun Sun ◽  
Wen-Jiang Zheng ◽  
Yong-Hua Hu ◽  
Bo-Guang Sun ◽  
Li Sun
Keyword(s):  
Early Stage ◽  
Paralichthys Olivaceus ◽  
Cellular Level ◽  
Host Cells ◽  
Edwardsiella Tarda ◽  
Pcr Analysis ◽  
Logarithmic Phase ◽  
Content Type

ABSTRACTEdwardsiella tarda, a Gram-negative bacterium, is a severe fish pathogen that can also infect humans. In this study, we identified, viain vivo-induced antigen technology, anE. tardaantigen, Eta1, and analyzed its function in a Japanese flounder (Paralichthys olivaceus) model. Eta1 is composed of 226 residues and shares homology with putative bacterial adhesins. Quantitative real-time reverse transcriptase (RT)-PCR analysis indicated that when culturedin vitro,eta1expression was growth phase dependent and reached maximum at mid-logarithmic phase. During infection of flounder lymphocytes,eta1expression was drastically increased at the early stage of infection. Compared to the wild type, theeta1-defective mutant, TXeta1, was unaffected in growth but exhibited attenuated overall virulence, reduced tissue dissemination and colonization capacity, and impaired ability to invade flounder lymphocytes and to block the immune response of host cells. The lost virulence of TXeta1 was restored when a functionaleta1gene was reintroduced into the strain. Western blot and immunodetection analyses showed that Eta1 is localized to the outer membrane and exposed on the surface ofE. tardaand that recombinant Eta1 (rEta1) was able to interact with flounder lymphocytes. Consistent with these observations, antibody blocking of Eta1 inhibitedE. tardainfection at the cellular level. Furthermore, when used as a subunit vaccine, rEta1 induced strong protective immunity in flounder against lethalE. tardachallenge. Taken together, these results indicate that Eta1 is anin vivo-induced antigen that mediates pathogen-host interaction and, as a result, is required for optimal bacterial infection.

scholarly journals A Matter of Timing: Contrasting Effects of Hydrogen Sulfide on Oxidative Stress Response in Shewanella oneidensis

2015 ◽  
Vol 197 (22) ◽  
pp. 3563-3572 ◽  
Author(s):  
Genfu Wu ◽  
Fen Wan ◽  
Huihui Fu ◽  
Ning Li ◽  
Haichun Gao
Keyword(s):  
Oxidative Stress ◽  
Hydrogen Sulfide ◽  
Shewanella Oneidensis ◽  
Inhibitory Effect ◽  
Time Dependent ◽  
Bacterial Cells ◽  
Bacterial Survival ◽  
Intracellular Iron ◽  
Content Type ◽  
Stress Responding

ABSTRACTHydrogen sulfide (H2S), well known for its toxic properties, has recently become a research focus in bacteria, in part because it has been found to prevent oxidative stress caused by treatment with some antibiotics. H2S has the ability to scavenge reactive oxygen species (ROS), thus preventing oxidative stress, but it is also toxic, leading to conflicting reports of its effects in different organisms. Here, withShewanella oneidensisas a model, we report that the effects of H2S on the response to oxidative stress are time dependent. When added simultaneously with H2O2, H2S promoted H2O2toxicity by inactivating catalase, KatB, a heme-containing enzyme involved in H2O2degradation. Such an inhibitory effect may apply to other heme-containing proteins, such as cytochromecbb3oxidase. When H2O2was supplied 20 min or later after the addition of H2S, the oxidative-stress-responding regulator OxyR was activated, resulting in increased resistance to H2O2. The activation of OxyR was likely triggered by the influx of iron, a response to lowered intracellular iron due to the iron-sequestering property of H2S. Given thatShewanellabacteria thrive in redox-stratified environments that have abundant sulfur and iron species, our results imply that H2S is more important for bacterial survival in such environmental niches than previously believed.IMPORTANCEPrevious studies have demonstrated that H2S is either detrimental or beneficial to bacterial cells. While it can act as a growth-inhibiting molecule by damaging DNA and denaturing proteins, it helps cells to combat oxidative stress. Here we report that H2S indeed has these contrasting biological functions and that its effects are time dependent. Immediately after H2S treatment, there is growth inhibition due to damage of heme-containing proteins, at least to catalase and cytochromecoxidase. In contrast, when added a certain time later, H2S confers an enhanced ability to combat oxidative stress by activating the H2O2-responding regulator OxyR. Our data reconcile conflicting observations about the functions of H2S.

scholarly journals The Mechanism behind Bacterial Lipoprotein Release: Phenol-Soluble Modulins Mediate Toll-Like Receptor 2 Activation via Extracellular Vesicle Release from Staphylococcus aureus

mBio ◽  
2018 ◽  
Vol 9 (6) ◽  
Author(s):  
Katja Schlatterer ◽  
Christian Beck ◽  
Dennis Hanzelmann ◽  
Marco Lebtig ◽  
Birgit Fehrenbacher ◽  
...  
Keyword(s):  
Staphylococcus Aureus ◽  
Cytoplasmic Membrane ◽  
Cell Envelope ◽  
Membrane Vesicles ◽  
Extracellular Vesicle ◽  
Host Cells ◽  
Bacterial Cells ◽  
Toll Like Receptor ◽  
Vesicle Release ◽  
Content Type

ABSTRACT The innate immune system uses Toll-like receptor (TLR) 2 to detect conserved bacterial lipoproteins of invading pathogens. The lipid anchor attaches lipoproteins to the cytoplasmic membrane and prevents their release from the bacterial cell envelope. How bacteria release lipoproteins and how these molecules reach TLR2 remain unknown. Staphylococcus aureus has been described to liberate membrane vesicles. The composition, mode of release, and relevance for microbe-host interaction of such membrane vesicles have remained ambiguous. We recently reported that S. aureus can release lipoproteins only when surfactant-like small peptides, the phenol-soluble modulins (PSMs), are expressed. Here we demonstrate that PSM peptides promote the release of membrane vesicles from the cytoplasmic membrane of S. aureus via an increase in membrane fluidity, and we provide evidence that the bacterial turgor is the driving force for vesicle budding under hypotonic osmotic conditions. Intriguingly, the majority of lipoproteins are released by S. aureus as components of membrane vesicles, and this process depends on surfactant-like molecules such as PSMs. Vesicle disruption at high detergent concentrations promotes the capacity of lipoproteins to activate TLR2. These results reveal that vesicle release by bacterium-derived surfactants is required for TLR2-mediated inflammation. IMPORTANCE Our study highlights the roles of surfactant-like molecules in bacterial inflammation with important implications for the prevention and therapy of inflammatory disorders. It describes a potential pathway for the transfer of hydrophobic bacterial lipoproteins, the major TLR2 agonists, from the cytoplasmic membrane of Gram-positive bacteria to the TLR2 receptor at the surface of host cells. Moreover, our study reveals a molecular mechanism that explains how cytoplasmic and membrane-embedded bacterial proteins can be released by bacterial cells without using any of the typical protein secretion routes, thereby contributing to our understanding of the processes used by bacteria to communicate with host organisms and the environment.

scholarly journals Type III Secretion System Translocon Component EseB Forms Filaments on and Mediates Autoaggregation of and Biofilm Formation by Edwardsiella tarda

2015 ◽  
Vol 81 (17) ◽  
pp. 6078-6087 ◽  
Author(s):  
Zhi Peng Gao ◽  
Pin Nie ◽  
Jin Fang Lu ◽  
Lu Yi Liu ◽  
Tiao Yi Xiao ◽  
...  
Keyword(s):  
Type Iii Secretion ◽  
Biofilm Formation ◽  
Type Iii Secretion System ◽  
Secretion System ◽  
Effector Proteins ◽  
Host Cells ◽  
Edwardsiella Tarda ◽  
Dependent Manner ◽  
Content Type ◽  
Type Iii

ABSTRACTThe type III secretion system (T3SS) ofEdwardsiella tardaplays an important role in infection by translocating effector proteins into host cells. EseB, a component required for effector translocation, is reported to mediate autoaggregation ofE. tarda. In this study, we demonstrate that EseB forms filamentous appendages on the surface ofE. tardaand is required for biofilm formation byE. tardain Dulbecco's modified Eagle's medium (DMEM). Biofilm formation byE. tardain DMEM does not require FlhB, an essential component for assembling flagella. Dynamic analysis of EseB filament formation, autoaggregation, and biofilm formation shows that the formation of EseB filaments occurs prior to autoaggregation and biofilm formation. The addition of an EseB antibody toE. tardacultures before bacterial autoaggregation prevents autoaggregation and biofilm formation in a dose-dependent manner, whereas the addition of the EseB antibody toE. tardacultures in which biofilm is already formed does not destroy the biofilm. Therefore, EseB filament-mediated bacterial cell-cell interaction is a prerequisite for autoaggregation and biofilm formation.

Sign in / Sign up

Export Citation Format

Share Document