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  • 1
    Online Resource
    Online Resource
    EssE Promotes Staphylococcus aureus ESS-Dependent Protein Secretion To Modify Host Immune Responses during Infection
    American Society for Microbiology ; 2017
    In:  Journal of Bacteriology Vol. 199, No. 1 ( 2017-01)
    Details
    In: Journal of Bacteriology, American Society for Microbiology, Vol. 199, No. 1 ( 2017-01)
    Abstract: Staphylococcus aureus , an invasive pathogen of humans and animals, requires a specialized ESS pathway to secrete proteins (EsxA, EsxB, EsxC, and EsxD) during infection. Expression of ess genes is required for S. aureus establishment of persistent abscess lesions following bloodstream infection; however, the mechanisms whereby effectors of the ESS pathway implement their virulence strategies were heretofore not known. Here, we show that EssE forms a complex with other members of the ESS secretion pathway and its substrates, promoting the secretion of EsxA, EsxB, EsxC, EsxD, and EssD. During bloodstream infection of mice, the S. aureus essE mutant displays defects in host cytokine responses, specifically in the production of interleukin-12 (IL-12) (p40/p70) and the suppression of RANTES (CCL5), activators of T H 1 T cell responses and immune cell chemotaxis, respectively. Thus, essE -mediated secretion of protein effectors via the ESS pathway may enable S. aureus to manipulate host immune responses by modifying the production of cytokines. IMPORTANCE Staphylococcus aureus and other firmicutes evolved a specialized ESS ( E sxA/ESAT-6-like s ecretion s ystem) pathway for the secretion of small subsets of proteins lacking canonical signal peptides. The molecular mechanisms for ESS-dependent secretion and their functional purpose are still unknown. We demonstrate here that S. aureus EssE functions as a membrane assembly platform for elements of the secretion machinery and their substrates. Furthermore, S. aureus EssE-mediated secretion contributes to the production or the suppression of specific cytokines during host infection, thereby modifying immune responses toward this pathogen.
    Type of Medium: Online Resource
    ISSN: 0021-9193 , 1098-5530
    URL: Article
    DOI: 10.1128/JB.00527-16
    Language: English
    Publisher: American Society for Microbiology
    Publication Date: 2017
    detail.hit.zdb_id: 1481988-0
    SSG: 12
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  • 2
    Online Resource
    Online Resource
    Bacillus anthracis SlaQ Promotes S-Layer Protein Assembly
    American Society for Microbiology ; 2015
    In:  Journal of Bacteriology Vol. 197, No. 19 ( 2015-10), p. 3216-3227
    Details
    In: Journal of Bacteriology, American Society for Microbiology, Vol. 197, No. 19 ( 2015-10), p. 3216-3227
    Abstract: Bacillus anthracis vegetative forms assemble an S-layer comprised of two S-layer proteins, Sap and EA1. A hallmark of S-layer proteins are their C-terminal crystallization domains, which assemble into a crystalline lattice once these polypeptides are deposited on the bacterial surface via association between their N-terminal S-layer homology domains and the secondary cell wall polysaccharide. Here we show that slaQ , encoding a small cytoplasmic protein conserved among pathogenic bacilli elaborating S-layers, is required for the efficient secretion and assembly of Sap and EA1. S-layer protein precursors cosediment with SlaQ, and SlaQ appears to facilitate Sap assembly. Purified SlaQ polymerizes and when mixed with purified Sap promotes the in vitro formation of tubular S-layer structures. A model is discussed whereby SlaQ, in conjunction with S-layer secretion factors SecA2 and SlaP, promotes localized secretion and S-layer assembly in B. anthracis . IMPORTANCE S-layer proteins are endowed with the propensity for self-assembly into crystalline arrays. Factors promoting S-layer protein assembly have heretofore not been reported. We identified Bacillus anthracis SlaQ, a small cytoplasmic protein that facilitates S-layer protein assembly in vivo and in vitro .
    Type of Medium: Online Resource
    ISSN: 0021-9193 , 1098-5530
    URL: Article
    DOI: 10.1128/JB.00492-15
    Language: English
    Publisher: American Society for Microbiology
    Publication Date: 2015
    detail.hit.zdb_id: 1481988-0
    SSG: 12
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  • 3
    Online Resource
    Online Resource
    Allelic replacement in Staphylococcus aureus with inducible counter-selection
    Elsevier BV ; 2006
    In:  Plasmid Vol. 55, No. 1 ( 2006-1), p. 58-63
    Details
    In: Plasmid, Elsevier BV, Vol. 55, No. 1 ( 2006-1), p. 58-63
    Type of Medium: Online Resource
    ISSN: 0147-619X
    URL: Article
    DOI: 10.1016/j.plasmid.2005.05.005
    RVK:
    WA 15000
    Language: English
    Publisher: Elsevier BV
    Publication Date: 2006
    detail.hit.zdb_id: 1471554-5
    SSG: 12
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  • 4
    Online Resource
    Online Resource
    hPepT1 transports muramyl dipeptide, activating NF-κB and stimulating IL-8 secretion in human colonic Caco2/bbe cells
    Elsevier BV ; 2004
    In:  Gastroenterology Vol. 127, No. 5 ( 2004-11), p. 1401-1409
    Details
    In: Gastroenterology, Elsevier BV, Vol. 127, No. 5 ( 2004-11), p. 1401-1409
    Type of Medium: Online Resource
    ISSN: 0016-5085
    URL: Article
    DOI: 10.1053/j.gastro.2004.07.024
    RVK:
    XA 44500
    Language: English
    Publisher: Elsevier BV
    Publication Date: 2004
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  • 5
    Online Resource
    Online Resource
    Polymorphisms in the lcrV Gene of Yersinia enterocolitica and Their Effect on Plague Protective Immunity
    American Society for Microbiology ; 2012
    In:  Infection and Immunity Vol. 80, No. 4 ( 2012-04), p. 1572-1582
    Details
    In: Infection and Immunity, American Society for Microbiology, Vol. 80, No. 4 ( 2012-04), p. 1572-1582
    Abstract: Current efforts to develop plague vaccines focus on LcrV, a polypeptide that resides at the tip of type III secretion needles. LcrV-specific antibodies block Yersinia pestis type III injection of Yop effectors into host immune cells, thereby enabling phagocytes to kill the invading pathogen. Earlier work reported that antibodies against Y. pestis LcrV cannot block type III injection by Yersinia enterocolitica strains and suggested that lcrV polymorphisms may provide for escape from LcrV-mediated plague immunity. We show here that polyclonal or monoclonal antibodies raised against Y. pestis KIM D27 LcrV (LcrV D27 ) bind LcrV from Y. enterocolitica O:9 strain W22703 (LcrV W22703 ) or O:8 strain WA-314 (LcrV WA-314 ) but are otherwise unable to block type III injection by Y. enterocolitica strains. Replacing the lcrV gene on the pCD1 virulence plasmid of Y. pestis KIM D27 with either lcrV W22703 or lcrV WA-314 does not affect the ability of plague bacteria to secrete proteins via the type III pathway, to inject Yops into macrophages, or to cause lethal plague infections in mice. LcrV D27 -specific antibodies blocked type III injection by Y. pestis expressing lcrV W22703 or lcrV WA-314 and protected mice against intravenous lethal plague challenge with these strains. Thus, although antibodies raised against LcrV D27 are unable to block the type III injection of Y. enterocolitica strains, expression of lcrV W22703 or lcrV WA-314 in Y. pestis did not allow these strains to escape LcrV-mediated plague protective immunity in the intravenous challenge model.
    Type of Medium: Online Resource
    ISSN: 0019-9567 , 1098-5522
    URL: Article
    DOI: 10.1128/IAI.05637-11
    RVK:
    XA 10000
    Language: English
    Publisher: American Society for Microbiology
    Publication Date: 2012
    detail.hit.zdb_id: 1483247-1
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  • 6
    Online Resource
    Online Resource
    Yersinia pestis caf1 Variants and the Limits of Plague Vaccine Protection
    American Society for Microbiology ; 2008
    In:  Infection and Immunity Vol. 76, No. 5 ( 2008-05), p. 2025-2036
    Details
    In: Infection and Immunity, American Society for Microbiology, Vol. 76, No. 5 ( 2008-05), p. 2025-2036
    Abstract: Yersinia pestis , the highly virulent agent of plague, is a biological weapon. Strategies that prevent plague have been sought for centuries, and immunization with live, attenuated (nonpigmented) strains or subunit vaccines with F1 (Caf1) antigen is considered effective. We show here that immunization with live, attenuated strains generates plague-protective immunity and humoral immune responses against F1 pilus antigen and LcrV. Y. pestis variants lacking caf1 (F1 pili) are not only fully virulent in animal models of bubonic and pneumonic plague but also break through immune responses generated with live, attenuated strains or F1 subunit vaccines. In contrast, immunization with purified LcrV, a protein at the tip of type III needles, generates protective immunity against the wild-type and the fully virulent caf1 mutant strain, in agreement with the notion that LcrV can elicit vaccine protection against both types of virulent plague strains.
    Type of Medium: Online Resource
    ISSN: 0019-9567 , 1098-5522
    URL: Article
    DOI: 10.1128/IAI.00105-08
    RVK:
    XA 10000
    Language: English
    Publisher: American Society for Microbiology
    Publication Date: 2008
    detail.hit.zdb_id: 1483247-1
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  • 7
    Online Resource
    Online Resource
    Immunogenicity and Protective Immunity against Bubonic Plague and Pneumonic Plague by Immunization of Mice with the Recombinant V10 Antigen, a Variant of LcrV
    American Society for Microbiology ; 2006
    In:  Infection and Immunity Vol. 74, No. 8 ( 2006-08), p. 4910-4914
    Details
    In: Infection and Immunity, American Society for Microbiology, Vol. 74, No. 8 ( 2006-08), p. 4910-4914
    Abstract: In contrast to Yersinia pestis LcrV, the recombinant V10 (rV10) variant (lacking residues 271 to 300) does not suppress the release of proinflammatory cytokines by immune cells. Immunization with rV10 generates robust antibody responses that protect mice against bubonic plague and pneumonic plague, suggesting that rV10 may serve as an improved plague vaccine.
    Type of Medium: Online Resource
    ISSN: 0019-9567 , 1098-5522
    URL: Article
    DOI: 10.1128/IAI.01860-05
    RVK:
    XA 10000
    Language: English
    Publisher: American Society for Microbiology
    Publication Date: 2006
    detail.hit.zdb_id: 1483247-1
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  • 8
    Online Resource
    Online Resource
    Legionella pneumophila Is Directly Sensitive to 2-Deoxyglucose-Phosphate via Its UhpC Transporter but Is Indifferent to Shifts in Host Cell Glycolytic Metabolism
    American Society for Microbiology ; 2018
    In:  Journal of Bacteriology Vol. 200, No. 16 ( 2018-08-15)
    Details
    In: Journal of Bacteriology, American Society for Microbiology, Vol. 200, No. 16 ( 2018-08-15)
    Abstract: Toll-like receptor (TLR) stimulation induces a pronounced shift to increased glycolytic metabolism in mammalian macrophages. We observed that bone marrow-derived macrophages (BMMs) increase glycolysis in response to infection with Legionella pneumophila , but the role of host macrophage glycolysis in terms of intracellular L. pneumophila replication is not currently understood. Treatment with 2-deoxyglucose (2DG) blocks L. pneumophila replication in mammalian macrophages but has no effect on bacteria grown in broth. In addition, we found that 2DG had no effect on bacteria grown in amoebae. We used a serial enrichment strategy to reveal that the effect of 2DG on L. pneumophila in macrophages requires the L. pneumophila hexose-phosphate transporter UhpC. Experiments with UhpC-deficient L. pneumophila revealed that mutant bacteria are also resistant to growth inhibition following treatment with phosphorylated 2DG in broth, suggesting that the inhibitory effect of 2DG on L. pneumophila in mammalian cells requires 2DG phosphorylation. UhpC-deficient L. pneumophila replicates without a growth defect in BMMs and protozoan host cells and also replicates without a growth defect in BMMs treated with 2DG. Our data indicate that neither TLR signaling-dependent increased macrophage glycolysis nor inhibition of macrophage glycolysis has a substantial effect on intracellular L. pneumophila replication. These results are consistent with the view that L. pneumophila can employ diverse metabolic strategies to exploit its host cells. IMPORTANCE We explored the relationship between macrophage glycolysis and replication of an intracellular bacterial pathogen, Legionella pneumophila . Previous studies demonstrated that a glycolysis inhibitor, 2-deoxyglucose (2DG), blocks replication of L. pneumophila during infection of macrophages, leading to speculation that L. pneumophila may exploit macrophage glycolysis. We isolated L. pneumophila mutants resistant to the inhibitory effect of 2DG in macrophages, identifying a L. pneumophila hexose-phosphate transporter, UhpC, that is required for bacterial sensitivity to 2DG during infection. Our results reveal how a bacterial transporter mediates the direct antimicrobial effect of a toxic metabolite. Moreover, our results indicate that neither induction nor impairment of host glycolysis inhibits intracellular replication of L. pneumophila , which is consistent with a view of L. pneumophila as a metabolic generalist.
    Type of Medium: Online Resource
    ISSN: 0021-9193 , 1098-5530
    URL: Article
    DOI: 10.1128/JB.00176-18
    Language: English
    Publisher: American Society for Microbiology
    Publication Date: 2018
    detail.hit.zdb_id: 1481988-0
    SSG: 12
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  • 9
    Online Resource
    Online Resource
    Galactosylation of the Secondary Cell Wall Polysaccharide of Bacillus anthracis and Its Contribution to Anthrax Pathogenesis
    American Society for Microbiology ; 2018
    In:  Journal of Bacteriology Vol. 200, No. 5 ( 2018-03)
    Details
    In: Journal of Bacteriology, American Society for Microbiology, Vol. 200, No. 5 ( 2018-03)
    Abstract: Bacillus anthracis , the causative agent of anthrax disease, elaborates a secondary cell wall polysaccharide (SCWP) that is essential for bacterial growth and cell division. B. anthracis SCWP is comprised of trisaccharide repeats with the structure, [→4)-β-ManNAc-(1→4)-β-GlcNAc( O 3-α-Gal)-(1→6)-α-GlcNAc( O 3-α-Gal, O 4-β-Gal)-(1→] 6-12 . The genes whose products promote the galactosylation of B. anthracis SCWP are not yet known. We show here that the expression of galE1 , encoding a UDP-glucose 4-epimerase necessary for the synthesis of UDP-galactose, is required for B. anthracis SCWP galactosylation. The galE1 mutant assembles surface (S) layer and S layer-associated proteins that associate with ketal-pyruvylated SCWP via their S layer homology domains similarly to wild-type B. anthracis , but the mutant displays a defect in γ-phage murein hydrolase binding to SCWP. Furthermore, deletion of galE1 diminishes the capsulation of B. anthracis with poly- d -γ-glutamic acid (PDGA) and causes a reduction in bacterial virulence. These data suggest that SCWP galactosylation is required for the physiologic assembly of the B. anthracis cell wall envelope and for the pathogenesis of anthrax disease. IMPORTANCE Unlike virulent Bacillus anthracis isolates, B. anthracis strain CDC684 synthesizes secondary cell wall polysaccharide (SCWP) trisaccharide repeats without galactosyl modification, exhibits diminished growth in vitro in broth cultures, and is severely attenuated in an animal model of anthrax. To examine whether SCWP galactosylation is a requirement for anthrax disease, we generated variants of B. anthracis strains Sterne 34F2 and Ames lacking UDP-glucose 4-epimerase by mutating the genes galE1 and galE2 . We identified galE1 as necessary for SCWP galactosylation. Deletion of galE1 decreased the poly- d -γ-glutamic acid (PDGA) capsulation of the vegetative form of B. anthracis and increased the bacterial inoculum required to produce lethal disease in mice, indicating that SCWP galactosylation is indeed a determinant of anthrax disease.
    Type of Medium: Online Resource
    ISSN: 0021-9193 , 1098-5530
    URL: Article
    DOI: 10.1128/JB.00562-17
    Language: English
    Publisher: American Society for Microbiology
    Publication Date: 2018
    detail.hit.zdb_id: 1481988-0
    SSG: 12
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  • 10
    Online Resource
    Online Resource
    EssH Peptidoglycan Hydrolase Enables Staphylococcus aureus Type VII Secretion across the Bacterial Cell Wall Envelope
    American Society for Microbiology ; 2018
    In:  Journal of Bacteriology Vol. 200, No. 20 ( 2018-10-15)
    Details
    In: Journal of Bacteriology, American Society for Microbiology, Vol. 200, No. 20 ( 2018-10-15)
    Abstract: The ESAT-6-like secretion system (ESS) of Staphylococcus aureus is assembled in the bacterial membrane from core components that promote the secretion of WXG-like proteins (EsxA, EsxB, EsxC, and EsxD) and the EssD effector. Genes encoding the ESS secretion machinery components, effector, and WXG-like proteins are located in the ess locus. Here, we identify essH , a heretofore uncharacterized gene of the ess locus, whose product is secreted via an N-terminal signal peptide into the extracellular medium of staphylococcal cultures. EssH exhibits two peptidoglycan hydrolase activities, cleaving the pentaglycine cross bridge and the amide bond of N -acetylmuramyl- l -alanine, thereby separating glycan chains and wall peptides with cleaved cross bridges. Unlike other peptidoglycan hydrolases, EssH does not promote the lysis of staphylococci. EssH residues Cys 199 and His 254 , which are conserved in other CHAP domain enzymes, are required for peptidoglycan hydrolase activity and for S. aureus ESS secretion. These data suggest that EssH and its murein hydrolase activity are required for protein secretion by the ESS pathway. IMPORTANCE Gene clusters encoding WXG-like proteins and FtsK/SpoIIIE-like P loop ATPases in Firmicutes encode type 7b secretion systems (T7bSS) for the transport of select protein substrates. The Staphylococcus aureus T7bSS assembles in the bacterial membrane and promotes the secretion of WXG-like proteins and effectors. The mechanisms whereby staphylococci extend the T7SS across the bacterial cell wall envelope are not known. Here, we show that staphylococci secrete EssH to cleave their peptidoglycan, thereby enabling T7bSS transport of proteins across the bacterial cell wall envelope.
    Type of Medium: Online Resource
    ISSN: 0021-9193 , 1098-5530
    URL: Article
    DOI: 10.1128/JB.00268-18
    Language: English
    Publisher: American Society for Microbiology
    Publication Date: 2018
    detail.hit.zdb_id: 1481988-0
    SSG: 12
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