γδ T cell IFNγ production is directly subverted by Yersinia pseudotuberculosis outer protein YopJ in mice and humans.
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ABSTRACT:
SUBMITTER: Chu TH
PROVIDER: S-EPMC8648121 | biostudies-literature |
REPOSITORIES: biostudies-literature
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Project description:SurA is a periplasmic protein folding factor involved in chaperoning and trafficking of outer membrane proteins across the Gram-negative bacterial periplasm. In addition, SurA also possesses peptidyl-prolyl cis/trans isomerase activity. We have previously reported that in enteropathogenic Yersinia pseudotuberculosis, SurA is needed for bacterial virulence and envelope integrity. In this study, we investigated the role of SurA in the assembly of important Yersinia adhesins. Using genetic mutation, biochemical characterization, and an in vitro-based bacterial host cell association assay, we confirmed that surface localization of the invasin adhesin is dependent on SurA. As a surA deletion also has some impact on the levels of individual components of the BAM complex in the Yersinia outer membrane, abolished invasin surface assembly could reflect both a direct loss of SurA-dependent periplasmic targeting and a potentially compromised BAM complex assembly platform in the outer membrane. To various degrees, the assembly of two other adhesins, Ail and the pH 6 antigen fibrillum PsaA, also depends on SurA. Consequently, loss of SurA leads to a dramatic reduction in Yersinia attachment to eukaryotic host cells. Genetic complementation of surA deletion mutants indicated a prominent role for SurA chaperone function in outer membrane protein assembly. Significantly, the N terminus of SurA contributed most of this SurA chaperone function. Despite a dominant chaperoning role, it was also evident that SurA isomerization activity did make a modest contribution to this assembly process.
| S-EPMC3697617 | biostudies-literature
Project description:Pathogenic Yersinia species utilize a type III secretion system to translocate Yop effectors into infected host cells. Yop effectors inhibit innate immune responses in infected macrophages to promote Yersinia pathogenesis. In turn,Yersinia-infected macrophages respond to translocation of Yops by activating caspase-1, but different mechanisms of caspase-1 activation occur, depending on the bacterial genotype and the state of phagocyte activation. In macrophages activated with lipopolysaccharide (LPS) prior to Yersinia pseudotuberculosis infection, caspase-1 is activated by a rapid inflammasome-dependent mechanism that is inhibited by translocated YopM. The possibility that other effectors cooperate with YopM to inhibit caspase-1 activation in LPS-activated macrophages has not been investigated. Toward this aim, epistasis analysis was carried out in which the phenotype of aY. pseudotuberculosis yopM mutant was compared to that of a yopJ yopM, yopE yopM, yopH yopM, yopT yopM, or ypkA yopM mutant. Activation of caspase-1 was measured by cleavage of the enzyme, release of interleukin-1? (IL-1?), and pyroptosis in LPS-activated macrophages infected with wild-type or mutant Y. pseudotuberculosis strains. Results show enhanced activation of caspase-1 after infection with the yopJ yopM mutant relative to infection by any other single or double mutant. Similar results were obtained with the yopJ, yopM, and yopJ yopM mutants ofY ersinia pestis Following intravenous infection of mice, theY. pseudotuberculosis yopJ mutant was as virulent as the wild type, while the yopJ yopM mutant was significantly more attenuated than the yopM mutant. In summary, through epistasis analysis this work uncovered an important role for YopJ in inhibiting caspase-1 in activated macrophages and in promoting Yersinia virulence.
| S-EPMC4807483 | biostudies-literature
Project description:Dissemination of Yersinia pseudotuberculosis within mice after oral inoculation was analyzed. Y. pseudotuberculosis translocated to organs such as the liver and spleen shortly after oral inoculation, but was quickly cleared. In contrast, a second temporally distinct bacterial translocation event resulted in successful hepatosplenic replication of the bacteria. Replicating pools of bacteria could be established in these organs in mouse mutants that lacked Peyer's patches. These animals frequently had sterile mesenteric lymph nodes, a finding consistent with translocation taking place independently of regional lymph node colonization. In further contradiction to accepted models for dissemination of enteropathogens, clonal analysis revealed that bacteria causing disease in the spleen and liver of C57BL/6J mice were derived from populations located outside the intestinal lymph nodes. Replication of bacteria in the intestine before translocation appeared critical for dissemination, as transient selective suppression by streptomycin of bacterial growth in the intestine delayed dissemination of Y. pseudotuberculosis. These results collectively indicate that hepatosplenic colonization appears intimately connected with the ability of Y. pseudotuberculosis to successfully establish replication in the intestinal lumen and does not result from ordered spread leading from the intestine to regional lymph nodes before dissemination.
| S-EPMC2118325 | biostudies-other
Project description:Prostaglandin E2 (PGE2) is an essential immunomodulatory lipid released by cells in response to infection with many bacteria, yet its function in macrophage-mediated bacterial clearance is poorly understood. Yersinia overall inhibits the inflammatory circuit, but its effect on PGE2 production is unknown. We hypothesized that one of the Yersinia effector proteins is responsible for the inhibition of PGE2 biosynthesis. We identified that yopB-deficient Y. enterocolitica and Y. pseudotuberculosis deficient in the secretion of virulence proteins via a type 3 secretion system (T3SS) failed to inhibit PGE2 biosynthesis in macrophages. Consistently, COX-2-mediated PGE2 biosynthesis is upregulated in cells treated with heat-killed or T3SS-deficient Y. pseudotuberculosis but diminished in the presence of a MAPK/ERK inhibitor. Mutants expressing catalytically inactive YopJ induce similar levels of PGE2 as heat-killed or ΔyopB Y. pseudotuberculosis, reversed by YopJ complementation. Shotgun proteomics discovered host pathways regulated in a YopJ-mediated manner, including pathways regulating PGE2 synthesis and oxidative phosphorylation. Consequently, this study identified that YopJ-mediated inhibition of MAPK signal transduction serves as a mechanism targeting PGE2, an alternative means of inflammasome inhibition by Yersinia. Finally, we showed that EP4 signaling supports macrophage function in clearing intracellular bacteria. In summary, our unique contribution was to determine a bacterial virulence factor that targets COX-2 transcription, thereby enhancing the intracellular survival of yersiniae. Future studies should investigate whether PGE2 or its stable synthetic derivatives could serve as a potential therapeutic molecule to improve the outcomes of specific bacterial infections. Since other pathogens encode YopJ homologs, this mechanism is expected to be present in other infections. IMPORTANCE PGE2 is a critical immunomodulatory lipid, but its role in bacterial infection and pathogen clearance is poorly understood. We previously demonstrated that PGE2 leads to macrophage polarization toward the M1 phenotype and stimulates inflammasome activation in infected macrophages. Finally, we also discovered that PGE2 improved the clearance of Y. enterocolitica. The fact that Y. enterocolitica hampers PGE2 secretion in a type 3 secretion system (T3SS)-dependent manner and because PGE2 appears to assist macrophage in the clearance of this bacterium indicates that targeting of the eicosanoid pathway by Yersinia might be an adaption used to counteract host defenses. Our study identified a mechanism used by Yersinia that obstructs PGE2 biosynthesis in human macrophages. We showed that Y. pseudotuberculosis interferes with PGE2 biosynthesis by using one of its T3SS effectors, YopJ. Specifically, YopJ targets the host COX-2 enzyme responsible for PGE2 biosynthesis, which happens in a MAPK/ER-dependent manner. Moreover, in a shotgun proteomics study, we also discovered other pathways that catalytically active YopJ targets in the infected macrophages. YopJ was revealed to play a role in limiting host LPS responses, including repression of EGR1 and JUN proteins, which control transcriptional activation of proinflammatory cytokine production such as interleukin-1β. Since YopJ has homologs in other bacterial species, there are likely other pathogens that target and inhibit PGE2 biosynthesis. In summary, our study's unique contribution was to determine a bacterial virulence factor that targets COX-2 transcription. Future studies should investigate whether PGE2 or its stable synthetic derivatives could serve as a potential therapeutic target.
| S-EPMC8552654 | biostudies-literature
Project description:BackgroundRovA is a global transcriptional regulator of gene expression in pathogenic Yersinia. RovA levels are kept in check by a sophisticated layering of distinct transcriptional and post-transcriptional regulatory mechanisms. In the enteropathogen Y. pseudotuberculosis, we have previously reported that the extracytoplasmic stress sensing CpxA-CpxR two-component regulatory system modulates rovA expression.Methodology/principal findingsIn this study, we characterized CpxR phosphorylation (CpxR?P) in vitro, and determined that phosphorylation was necessary for CpxR to efficiently bind to the PCR-amplified upstream regulatory region of rovA. The precise CpxR?P binding site was mapped by a nuclease protection assay and directed mutagenesis confirmed that in vivo binding to the rovA promoter inhibits transcription. Reduced RovA production was most pronounced following CpxR?P accumulation in the Yersinia cytoplasm during chronic Cpx pathway activation and by the indiscriminate phosphodonor action of acetyl phosphate.Conclusions/significanceCpx pathway activation restricts levels of the RovA global regulator. The regulatory influence of CpxR?P must therefore extend well beyond periplasmic quality control in the Yersinia envelope, to include genes involved in environmental survival and pathogenicity.
| S-EPMC3158067 | biostudies-literature
Project description:Neutrophils are essential components of immunity and are rapidly recruited to infected or injured tissue. Upon their activation, neutrophils release granules to the cell's exterior, through a process called degranulation. These granules contain proteins with antimicrobial properties that help combat infection. The enteropathogenic bacterium Yersinia pseudotuberculosis successfully persists as an extracellular bacterium during infection by virtue of its translocation of virulence effectors (Yersinia outer proteins [Yops]) that act in the cytosol of host immune cells to subvert phagocytosis and proinflammatory responses. Here, we investigated the effect of Y. pseudotuberculosis on neutrophil degranulation upon cell contact. We found that virulent Y. pseudotuberculosis was able to prevent secondary granule release. The blocking effect was general, as the release of primary and tertiary granules was also reduced. Degranulation of secondary granules was also blocked in primed neutrophils, suggesting that this mechanism could be an important element of immune evasion. Further, wild-type bacteria conferred a transient block on neutrophils that prevented their degranulation upon contact with plasmid-cured, avirulent Y. pseudotuberculosis and Escherichia coli Detailed analyses showed that the block was strictly dependent on the cooperative actions of the two antiphagocytic effectors, YopE and YopH, suggesting that the neutrophil target structures constituting signaling molecules needed to initiate both phagocytosis and general degranulation. Thus, via these virulence effectors, Yersinia can impair several mechanisms of the neutrophil's antimicrobial arsenal, which underscores the power of its virulence effector machinery.
| S-EPMC5116715 | biostudies-literature
Project description:Two cases of community-acquired septicemia caused by serotype-O1 Yersinia pseudotuberculosis were diagnosed in middle-aged, HIV-positive, immunodeficient patients during an 8-month period. Bacterial isolates were genetically indistinguishable, but no epidemiologic link between the 2 patients was established. HIV-related immunosuppression should be regarded as a risk factor for Y. pseudotuberculosis septicemia.
| S-EPMC3371805 | biostudies-literature
Project description:SignificanceYersinia pestis, the etiologic agent of plague, has been responsible for high mortality in several epidemics throughout human history. This plague bacillus has been used as a biological weapon during human history and is currently one of the deadliest biological threats. Currently, no licensed plague vaccines are available in the Western world. Since an array of immunogens are enclosed in outer membrane vesicles (OMVs), immune responses elicited by OMVs against a diverse range of antigens may reduce the likelihood of antigen circumvention. Therefore, self-adjuvanting OMVs from a remodeled Yersinia pseudotuberculosis strain as a type of plague vaccine could diversify prophylactic choices and solve current vaccine limitations.
| S-EPMC8931243 | biostudies-literature
Project description:MAPK signaling cascades are evolutionally conserved. The bacterial effector, YopJ, uses the unique activity of Ser/Thr acetylation to inhibit the activation of the MAPK kinase (MKK) and prevent activation by phosphorylation. YopJ is also able to block yeast MAPK signaling pathways using this mechanism. Based on these observations, we performed a genetic screen to isolate mutants in the yeast MKK, Pbs2, that suppress YopJ inhibition. One suppressor contains a mutation in a conserved tyrosine residue and bypasses YopJ inhibition by increasing the basal activity of Pbs2. Mutations on the hydrophobic face of the conserved G alpha-helix in the kinase domain prevent both binding and acetylation by YopJ. Corresponding mutants in human MKKs showed that they are conserved not only structurally, but also functionally. These studies reveal a conserved binding site found on the superfamily of MAPK kinases while providing insight into the molecular interactions required for YopJ inhibition.
| S-EPMC2147050 | biostudies-literature
Project description:Lipopolysaccharide (LPS), localized in the outer leaflet of the outer membrane, serves as the major surface component of the Gram-negative bacterial cell envelope responsible for the activation of the host's innate immune system. Variations of the LPS structure utilized by Gram-negative bacteria promote survival by providing resistance to components of the innate immune system and preventing recognition by TLR4. This review summarizes studies of the biosynthesis of Yersinia pseudotuberculosis complex LPSs, and the roles of their structural components in molecular mechanisms of yersiniae pathogenesis and immunogenesis.
| S-EPMC8533242 | biostudies-literature