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  • 1
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    Online Resource
    Corynebacterium pseudodiphtheriticum Exploits Staphylococcus aureus Virulence Components in a Novel Polymicrobial Defense Strategy
    American Society for Microbiology ; 2019
    In:  mBio Vol. 10, No. 1 ( 2019-02-26)
    Details
    In: mBio, American Society for Microbiology, Vol. 10, No. 1 ( 2019-02-26)
    Abstract: Commensal bacteria in the human nasal cavity are known to suppress opportunistic pathogen colonization by competing for limited space and nutrients. It has become increasingly apparent that some commensal bacteria also produce toxic compounds that directly inhibit or kill incoming competitors. Numerous studies suggest that microbial species-specific interactions can affect human nasal colonization by the opportunistic pathogen Staphylococcus aureus . However, the complex and dynamic molecular interactions that mediate these effects on S. aureus nasal colonization are often difficult to study and remain poorly understood. Here, we show that Corynebacterium pseudodiphtheriticum , a common member of the normal nasal microbiota, mediates contact-independent bactericidal activity against S. aureus , including methicillin-resistant S. aureus (MRSA). Bacterial interaction assays revealed that S. aureus isolates that were spontaneously resistant to C. pseudodiphtheriticum killing could be recovered at a low frequency. To better understand the pathways associated with killing and resistance, a S. aureus transposon mutant library was utilized to select for resistant mutant strains. We found that insertional inactivation of agrC , which codes for the sensor kinase of the Agr quorum sensing (Agr QS) system that regulates expression of many virulence factors in S. aureus , conferred resistance to killing. Analysis of the spontaneously resistant S. aureus isolates revealed that each showed decreased expression of the Agr QS components. Targeted analysis of pathways regulated by Agr QS revealed that loss of the phenol-soluble modulins (PSMs), which are effectors of Agr QS, also conferred resistance to bactericidal activity. Transmission electron microscopy analysis revealed that C. pseudodiphtheriticum induced dramatic changes to S. aureus cell surface morphology that likely resulted in cell lysis. Taken together, these data suggest that C. pseudodiphtheriticum -mediated killing of S. aureus requires S. aureus virulence components. While S. aureus can overcome targeted killing, this occurs at the cost of attenuated virulence; loss of Agr QS activity would phenotypically resemble a S. aureus commensal state that would be unlikely to be associated with disease. Commensal competition resulting in dampened virulence of the competitor may represent an exciting and unexplored possibility for development of novel antimicrobial compounds. IMPORTANCE While some individuals are nasally colonized with S. aureus , the underlying factors that determine colonization are not understood. There is increasing evidence that indicates that resident bacteria play a role; some commensal species can eradicate S. aureus from the nasal cavity. Among these, Corynebacterium pseudodiphtheriticum can eliminate S. aureus from the human nose. We sought to understand this phenomenon at a molecular level and found that C. pseudodiphtheriticum produces a factor(s) that specifically kills S. aureus . While resistant S. aureus isolates were recovered at a low frequency, resistance came at the cost of attenuated virulence in these strains. Molecular dissection of the specific strategies used by C. pseudodiphtheriticum to kill S. aureus could lead to the development of novel treatments or therapies. Furthermore, commensal competition that requires virulence components of the competitor may represent an exciting and unexplored possibility for development of novel antimicrobial compounds.
    Type of Medium: Online Resource
    ISSN: 2161-2129 , 2150-7511
    URL: Article
    DOI: 10.1128/mBio.02491-18
    Language: English
    Publisher: American Society for Microbiology
    Publication Date: 2019
    detail.hit.zdb_id: 2557172-2
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  • 2
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    Online Resource
    Whole genome sequencing of phage resistant Bacillus anthracismutants reveals an essential role for cell surface anchoring protein CsaB in phage AP50c adsorption
    Springer Science and Business Media LLC ; 2012
    In:  Virology Journal Vol. 9, No. 1 ( 2012-12)
    Details
    In: Virology Journal, Springer Science and Business Media LLC, Vol. 9, No. 1 ( 2012-12)
    Abstract: Spontaneous Bacillus anthracis mutants resistant to infection by phage AP50c (AP50 R ) exhibit a mucoid colony phenotype and secrete an extracellular matrix. Methods Here we utilized a Roche/454-based whole genome sequencing approach to identify mutations that are candidates for conferring AP50c phage resistance, followed by genetic deletion and complementation studies to validate the whole genome sequence data and demonstrate that the implicated gene is necessary for AP50c phage infection. Results Using whole genome sequence data, we mapped the relevant mutations in six AP50 R strains to csaB . Eleven additional spontaneous mutants, isolated in two different genetic backgrounds, were screened by PCR followed by Sanger sequencing of the csaB gene. In each spontaneous mutant, we found either a non-synonymous substitution, a nonsense mutation, or a frame-shift mutation caused by single nucleotide polymorphisms or a 5 base pair insertion in csaB . All together, 5 and 12 of the 17 spontaneous mutations are predicted to yield altered full length and truncated CsaB proteins respectively. As expected from these results, a targeted deletion or frame-shift mutations introduced into csaB in a different genetic background, in a strain not exposed to AP50c, resulted in a phage resistant phenotype. Also, substitution of a highly conserved histidine residue with an alanine residue (H270A) in CsaB resulted in phage resistance, suggesting that a functional CsaB is necessary for phage sensitivity. Conversely, introduction of the wild type allele of csaB in cis into the csaB deletion mutant by homologous recombination or supplying the wild type CsaB protein in trans from a plasmid restored phage sensitivity. The csaB mutants accumulated cell wall material and appeared to have a defective S-layer, whereas these phenotypes were reverted in the complemented strains. Conclusions Taken together, these data suggest an essential role for csaB in AP50c phage infection, most likely in phage adsorption. (The whole genome sequences generated from this study have been submitted to GenBank under SRA project ID: SRA023659.1 and sample IDs: AP50 R1: SRS113675.1, AP50 R2: SRS113676.1, AP50 R3: SRS113728.1, AP50 R4: SRS113733.1, AP50 R6: SRS113734.1, JB220 Parent: SRS150209.1, JB220 Mutant: SRS150211.1).
    Type of Medium: Online Resource
    ISSN: 1743-422X
    URL: Article
    DOI: 10.1186/1743-422X-9-246
    Language: English
    Publisher: Springer Science and Business Media LLC
    Publication Date: 2012
    detail.hit.zdb_id: 2160640-7
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  • 3
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    Separation and Detection of Phosphorylated and Nonphosphorylated BvgA, a Bordetella pertussis Response Regulator, in vivo and in vitro
    Bio-Protocol, LLC ; 2013
    In:  BIO-PROTOCOL Vol. 3, No. 22 ( 2013)
    Details
    In: BIO-PROTOCOL, Bio-Protocol, LLC, Vol. 3, No. 22 ( 2013)
    Type of Medium: Online Resource
    ISSN: 2331-8325
    URL: Article
    DOI: 10.21769/BioProtoc.970
    Language: English
    Publisher: Bio-Protocol, LLC
    Publication Date: 2013
    detail.hit.zdb_id: 2833269-6
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  • 4
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    Online Resource
    Contribution of Regulation by the bvgLocus to Respiratory Infection of Mice by Bordetella pertussis
    American Society for Microbiology ; 1998
    In:  Infection and Immunity Vol. 66, No. 9 ( 1998), p. 4367-4373
    Details
    In: Infection and Immunity, American Society for Microbiology, Vol. 66, No. 9 ( 1998), p. 4367-4373
    Type of Medium: Online Resource
    ISSN: 1098-5522 , 0019-9567
    URL: Article
    DOI: 10.1128/.66.9.4367-4373.1998
    RVK:
    XA 10000
    Language: English
    Publisher: American Society for Microbiology
    Publication Date: 1998
    detail.hit.zdb_id: 1483247-1
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  • 5
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    A Novel Bvg-Repressed Promoter Causes vrg -Like Transcription of fim3 but Does Not Result in the Production of Serotype 3 Fimbriae in Bvg − Mode Bordetella pertussis
    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: In Bordetella pertussis , two serologically distinct fimbriae, FIM2 and FIM3, undergo on/off phase variation independently of each other via variation in the lengths of C stretches in the promoters for their major subunit genes, fim2 and fim3 . These two promoters are also part of the BvgAS virulence regulon and therefore, if in an on configuration, are activated by phosporylated BvgA (BvgA~P) under normal growth conditions (Bvg + mode) but not in the Bvg − mode, inducible by growth in medium containing MgSO 4 or other compounds, termed modulators. In the B. pertussis Tohama I strain (FIM2 + FIM3 − ), the fim3 promoter is in the off state. However, a high level of transcription of the fim3 gene is observed in the Bvg − mode. In this study, we provide an explanation for this anomalous behavior by defining a Bvg-repressed promoter (BRP), located approximately 400 bp upstream of the P fim3 transcriptional start. Although transcription of the fim3 gene in the Bvg − mode resulted in Fim3 translation, as measured by LacZ translational fusions, no accumulation of Fim3 protein was detectable. We propose that Fim3 protein resulting from translation of mRNA driven by BRP in the Bvg − mode is unstable due to a lack of the fimbrial assembly apparatus encoded by the fimBC genes, located within the fha operon, and therefore is not expressed in the Bvg − mode. IMPORTANCE In Bordetella pertussis , the promoter P fim3 -15C for the major fimbrial subunit gene fim3 is activated by the two-component system BvgAS in the Bvg + mode but not in the Bvg − mode. However, many transcriptional profiling studies have shown that fim3 is transcribed in the Bvg − mode even when P fim3 is in a nonpermissive state (P fim3 -13C), suggesting the presence of a reciprocally regulated element upstream of P fim3 . Here, we provide evidence that BRP is the cause of this anomalous behavior of fim3 . Although BRP effects vrg -like transcription of fim3 in the Bvg − mode, it does not lead to stable production of FIM3 fimbriae, because expression of the chaperone and usher proteins FimB and FimC occurs only in the Bvg + mode.
    Type of Medium: Online Resource
    ISSN: 0021-9193 , 1098-5530
    URL: Article
    DOI: 10.1128/JB.00175-18
    Language: English
    Publisher: American Society for Microbiology
    Publication Date: 2018
    detail.hit.zdb_id: 1481988-0
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  • 6
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    Online Resource
    Analysis of BvgA Activation of the Pertactin Gene Promoter in Bordetella pertussis
    American Society for Microbiology ; 1999
    In:  Journal of Bacteriology Vol. 181, No. 17 ( 1999-09), p. 5234-5241
    Details
    In: Journal of Bacteriology, American Society for Microbiology, Vol. 181, No. 17 ( 1999-09), p. 5234-5241
    Abstract: Bordetella pertussis , the causative agent of whooping cough, regulates expression of its virulence factors via a two-component signal transduction system encoded by the bvg regulatory locus. It has been shown by activation kinetics that several of the virulence factors are differentially regulated. fha is transcribed at 10 min following an inducing signal, while ptx is not transcribed until 2 to 4 h after the inducing signal. We present data indicating that prn is transcribed at 1 h, an intermediate time compared to those of fha and ptx . We have identified cis -acting sequences necessary for expression of prn in B. pertussis by using prn-lac fusions containing alterations in the sequence upstream of the prn open reading frame. In vitro transcription and DNase I footprinting analyses provided evidence to support our hypothesis that BvgA binds to this sequence upstream of prn to activate transcription from the promoter. Our genetic data indicate that the region critical for prn activation extends upstream to position −84. However, these data do not support the location of the prn transcription start site as previously published. We used a number of methods, including prn-lac fusions, reverse transcriptase PCR, and 5′ rapid amplification of cDNA ends, to localize and identify the bvg -dependent 5′ end of the prn transcript to the cytosine at −125 with respect to the published start site.
    Type of Medium: Online Resource
    ISSN: 0021-9193 , 1098-5530
    URL: Article
    DOI: 10.1128/JB.181.17.5234-5241.1999
    Language: English
    Publisher: American Society for Microbiology
    Publication Date: 1999
    detail.hit.zdb_id: 1481988-0
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  • 7
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    Online Resource
    Four Superoxide Dismutases Contribute to Bacillus anthracis Virulence and Provide Spores with Redundant Protection from Oxidative Stress
    American Society for Microbiology ; 2009
    In:  Infection and Immunity Vol. 77, No. 1 ( 2009-01), p. 274-285
    Details
    In: Infection and Immunity, American Society for Microbiology, Vol. 77, No. 1 ( 2009-01), p. 274-285
    Abstract: The Bacillus anthracis genome encodes four superoxide dismutases (SODs), enzymes capable of detoxifying oxygen radicals. That two of these SODs, SOD15 and SODA1, are present in the outermost layers of the B. anthracis spore is indicated by previous proteomic analyses of the exosporium. Given the requirement that spores must survive interactions with reactive oxygen species generated by cells such as macrophages during infection, we hypothesized that SOD15 and SODA1 protect the spore from oxidative stress and contribute to the pathogenicity of B. anthracis . To test these theories, we constructed a double-knockout (Δ sod15 Δ sodA1 ) mutant of B. anthracis Sterne strain 34F2 and assessed its lethality in an A/J mouse intranasal infection model. The 50% lethal dose of the Δ sod15 Δ sodA1 strain was similar to that of the wild type (34F2), but surprisingly, measurable whole-spore SOD activity was greater than that in 34F2. A quadruple-knockout strain (Δ sod15 Δ sodA1 Δ sodC Δ sodA2 ) was then generated, and as anticipated, spore-associated SOD activity was diminished. Moreover, the quadruple-knockout strain, compared to the wild type, was attenuated more than 40-fold upon intranasal challenge of mice. Spore resistance to exogenously generated oxidative stress and to macrophage-mediated killing correlated with virulence in A/J mice. Allelic exchange that restored sod15 and sodA1 to their wild-type state restored wild-type characteristics. We conclude that SOD molecules within the spore afford B. anthracis protection against oxidative stress and enhance the pathogenicity of B. anthracis in the lung. We also surmise that the presence of four SOD alleles within the genome provides functional redundancy for this key enzyme.
    Type of Medium: Online Resource
    ISSN: 0019-9567 , 1098-5522
    URL: Article
    DOI: 10.1128/IAI.00515-08
    RVK:
    XA 10000
    Language: English
    Publisher: American Society for Microbiology
    Publication Date: 2009
    detail.hit.zdb_id: 1483247-1
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  • 8
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    Pertactin Is Required for Bordetella Species To Resist Neutrophil-Mediated Clearance
    American Society for Microbiology ; 2010
    In:  Infection and Immunity Vol. 78, No. 7 ( 2010-07), p. 2901-2909
    Details
    In: Infection and Immunity, American Society for Microbiology, Vol. 78, No. 7 ( 2010-07), p. 2901-2909
    Abstract: Pertactin (PRN) is an autotransporter protein produced by all members of the Bordetella bronchiseptica cluster, which includes B. pertussis , B. parapertussis , and B. bronchiseptica . It is a primary component of acellular pertussis vaccines, and anti-PRN antibody titers correlate with protection. In vitro studies have suggested that PRN functions as an adhesin and that an RGD motif located in the center of the passenger domain is important for this function. Two regions of PRN that contain sequence repeats (region 1 [R1] and R2) show polymorphisms among strains and have been implicated in vaccine-driven evolution. We investigated the role of PRN in pathogenesis using B. bronchiseptica and natural-host animal models. A Δ prn mutant did not differ from wild-type B. bronchiseptica in its ability to adhere to epithelial and macrophage-like cells in vitro or to establish respiratory infection in rats but was cleared much faster than wild-type bacteria in a mouse lung inflammation model. Unlike wild-type B. bronchiseptica , the Δ prn mutant was unable to cause a lethal infection in SCID-Bg mice, but, like wild-type bacteria, it was lethal for neutropenic mice. These results suggest that PRN plays a critical role in allowing Bordetella to resist neutrophil-mediated clearance. Mutants producing PRN proteins in which the RGD motif was replaced with RGE or in which R1 and R2 were deleted were indistinguishable from wild-type bacteria in all assays, suggesting that these sequences do not contribute to PRN function.
    Type of Medium: Online Resource
    ISSN: 0019-9567 , 1098-5522
    URL: Article
    DOI: 10.1128/IAI.00188-10
    RVK:
    XA 10000
    Language: English
    Publisher: American Society for Microbiology
    Publication Date: 2010
    detail.hit.zdb_id: 1483247-1
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  • 9
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    O Antigen Protects Bordetella parapertussis from Complement
    American Society for Microbiology ; 2008
    In:  Infection and Immunity Vol. 76, No. 4 ( 2008-04), p. 1774-1780
    Details
    In: Infection and Immunity, American Society for Microbiology, Vol. 76, No. 4 ( 2008-04), p. 1774-1780
    Abstract: Bordetella pertussis , a causative agent of whooping cough, expresses BrkA, which confers serum resistance, but the closely related human pathogen that also causes whooping cough, Bordetella parapertussis , does not. Interestingly, B. parapertussis , but not B. pertussis , produces an O antigen, a factor shown in other models to confer serum resistance. Using a murine model of infection, we determined that O antigen contributes to the ability of B. parapertussis to colonize the respiratory tract during the first week of infection, but not thereafter. Interestingly, an O antigen-deficient strain of B. parapertussis was not defective in colonizing mice lacking the complement cascade. O antigen prevented both complement component C3 deposition on the surface and complement-mediated killing of B. parapertussis . In addition, O antigen was required for B. parapertussis to systemically spread in complement-sufficient mice, but not complement-deficient mice. These data indicate that O antigen enables B. parapertussis to efficiently colonize the lower respiratory tract by protecting against complement-mediated control and clearance.
    Type of Medium: Online Resource
    ISSN: 0019-9567 , 1098-5522
    URL: Article
    DOI: 10.1128/IAI.01629-07
    RVK:
    XA 10000
    Language: English
    Publisher: American Society for Microbiology
    Publication Date: 2008
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  • 10
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    Genetic Evidence for the Involvement of the S-Layer Protein Gene sap and the Sporulation Genes spo0A , spo0B , and spo0F in Phage AP50c Infection of Bacillus anthracis
    American Society for Microbiology ; 2014
    In:  Journal of Bacteriology Vol. 196, No. 6 ( 2014-03-15), p. 1143-1154
    Details
    In: Journal of Bacteriology, American Society for Microbiology, Vol. 196, No. 6 ( 2014-03-15), p. 1143-1154
    Abstract: In order to better characterize the Bacillus anthracis typing phage AP50c, we designed a genetic screen to identify its bacterial receptor. Insertions of the transposon mariner or targeted deletions of the structural gene for the S-layer protein Sap and the sporulation genes spo0A , spo0B , and spo0F in B. anthracis Sterne resulted in phage resistance with concomitant defects in phage adsorption and infectivity. Electron microscopy of bacteria incubated with AP50c revealed phage particles associated with the surface of bacilli of the Sterne strain but not with the surfaces of Δ sap , Δ spo0A , Δ spo0B , or Δ spo0F mutants. The amount of Sap in the S layer of each of the spo0 mutant strains was substantially reduced compared to that of the parent strain, and incubation of AP50c with purified recombinant Sap led to a substantial reduction in phage activity. Phylogenetic analysis based on whole-genome sequences of B. cereus sensu lato strains revealed several closely related B. cereus and B. thuringiensis strains that carry sap genes with very high similarities to the sap gene of B. anthracis . Complementation of the Δ sap mutant in trans with the wild-type B. anthracis sap or the sap gene from either of two different B. cereus strains that are sensitive to AP50c infection restored phage sensitivity, and electron microscopy confirmed attachment of phage particles to the surface of each of the complemented strains. Based on these data, we postulate that Sap is involved in AP50c infectivity, most likely acting as the phage receptor, and that the spo0 genes may regulate synthesis of Sap and/or formation of the S layer.
    Type of Medium: Online Resource
    ISSN: 0021-9193 , 1098-5530
    URL: Article
    DOI: 10.1128/JB.00739-13
    Language: English
    Publisher: American Society for Microbiology
    Publication Date: 2014
    detail.hit.zdb_id: 1481988-0
    SSG: 12
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