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  • 1
    Online Resource
    Online Resource
    Salmonella typhimurium IroN and FepA Proteins Mediate Uptake of Enterobactin but Differ in Their Specificity for Other Siderophores
    American Society for Microbiology ; 1999
    In:  Journal of Bacteriology Vol. 181, No. 11 ( 1999-06), p. 3610-3612
    Details
    In: Journal of Bacteriology, American Society for Microbiology, Vol. 181, No. 11 ( 1999-06), p. 3610-3612
    Abstract: Salmonella typhimurium possesses two outer membrane receptor proteins, IroN and FepA, which have been implicated in the uptake of enterobactin. To determine whether both receptors have identical substrate specificities, fepA and iroN mutants and a double mutant were characterized. While both receptors transported enterobactin, the uptake of corynebactin and myxochelin C was selectively mediated by IroN and FepA, respectively.
    Type of Medium: Online Resource
    ISSN: 0021-9193 , 1098-5530
    URL: Article
    DOI: 10.1128/JB.181.11.3610-3612.1999
    Language: English
    Publisher: American Society for Microbiology
    Publication Date: 1999
    detail.hit.zdb_id: 1481988-0
    SSG: 12
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  • 2
    Online Resource
    Online Resource
    IroN, a Novel Outer Membrane Siderophore Receptor Characteristic of Salmonella enterica
    American Society for Microbiology ; 1998
    In:  Journal of Bacteriology Vol. 180, No. 6 ( 1998-03-15), p. 1446-1453
    Details
    In: Journal of Bacteriology, American Society for Microbiology, Vol. 180, No. 6 ( 1998-03-15), p. 1446-1453
    Abstract: Speciation in enterobacteria involved horizontal gene transfer. Therefore, analysis of genes acquired by horizontal transfer that are present in one species but not its close relatives is expected to give insights into how new bacterial species were formed. In this study we characterize iroN , a gene located downstream of the iroBC operon in the iroA locus of Salmonella enterica serotype Typhi. Like iroBC , the iroN gene is present in all phylogenetic lineages of S. enterica but is absent from closely related species such as Salmonella bongori or Escherichia coli . Comparison of the deduced amino acid sequence of iroN with other proteins suggested that this gene encodes an outer membrane siderophore receptor protein. Mutational analysis in S. enterica and expression in E. coli identified a 78-kDa outer membrane protein as the iroN gene product. When introduced into an E. coli fepA cir fiu aroB mutant on a cosmid, iroN mediated utilization of structurally related catecholate siderophores, including N -(2,3-dihydroxybenzoyl)- l -serine, myxochelin A, benzaldehyde-2,3-dihydroxybenzhydrazone, 2- N ,6- N -bis(2,3-dihydroxybenzoyl)- l -lysine, 2- N ,6- N -bis(2,3-dihydroxybenzoyl)- l -lysine amide, and enterochelin. These results suggest that the iroA locus functions in iron acquisition in S. enterica.
    Type of Medium: Online Resource
    ISSN: 0021-9193 , 1098-5530
    URL: Article
    DOI: 10.1128/JB.180.6.1446-1453.1998
    Language: English
    Publisher: American Society for Microbiology
    Publication Date: 1998
    detail.hit.zdb_id: 1481988-0
    SSG: 12
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  • 3
    Online Resource
    Online Resource
    Molecular Properties of Salmonella enterica Serotype Paratyphi B Distinguish between Its Systemic and Its Enteric Pathovars
    American Society for Microbiology ; 2003
    In:  Journal of Clinical Microbiology Vol. 41, No. 9 ( 2003-09), p. 4270-4278
    Details
    In: Journal of Clinical Microbiology, American Society for Microbiology, Vol. 41, No. 9 ( 2003-09), p. 4270-4278
    Abstract: Salmonella enterica serotype O1,4,5,12:Hb:1,2, designated according to the current Kauffmann-White scheme as S. enterica serotype Paratyphi B, is a very diverse serotype with respect to its clinical and microbiological properties. PCR and blot techniques, which identify the presence, polymorphism, and expression of various effector protein genes, help to distinguish between strains with systemic and enteric outcomes of disease. All serotype Paratyphi B strains from systemic infections have been found to be somewhat genetically related with respect to the pattern of their virulence genes sopB , sopD , sopE1 , avrA , and sptP as well as other molecular properties (multilocus enzyme electrophoresis type, pulsed-field gel electrophoresis [PFGE] type, ribotype, and IS 200 type). They have been classified as members of the systemic pathovar (SPV). All these SPV strains possess a new sopE1 -carrying bacteriophage (designated ΦSopE309) with high SopE1 protein expression but lack the commonly occurring avrA determinant. They exhibit normal SopB protein expression but lack SopD protein production. In contrast, strains from enteric infections classified as belonging to the enteric pathovar possess various combinations of the respective virulence genes, PFGE pattern, and ribotypes. We propose that the PCR technique for testing for the presence of the virulence genes sopE1 and avrA be used as a diagnostic tool for identifying both pathovars of S. enterica serotype Paratyphi B. This will be of great public health importance, since strains of serotype Paratyphi B have recently reemerged worldwide.
    Type of Medium: Online Resource
    ISSN: 0095-1137 , 1098-660X
    URL: Article
    DOI: 10.1128/JCM.41.9.4270-4278.2003
    RVK:
    XA 10000
    Language: English
    Publisher: American Society for Microbiology
    Publication Date: 2003
    detail.hit.zdb_id: 1498353-9
    SSG: 12
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  • 4
    Online Resource
    Online Resource
    Multiple Viral microRNAs Regulate Interferon Release and Signaling Early during Infection with Epstein-Barr Virus
    American Society for Microbiology ; 2021
    In:  mBio Vol. 12, No. 2 ( 2021-04-27)
    Details
    In: mBio, American Society for Microbiology, Vol. 12, No. 2 ( 2021-04-27)
    Abstract: Epstein-Barr virus (EBV), a human herpesvirus, encodes 44 microRNAs (miRNAs), which regulate many genes with various functions in EBV-infected cells. Multiple target genes of the EBV miRNAs have been identified, some of which play important roles in adaptive antiviral immune responses. Using EBV mutant derivatives, we identified additional roles of viral miRNAs in governing versatile type I interferon (IFN) responses upon infection of human primary mature B cells. We also found that Epstein-Barr virus-encoded small RNAs (EBERs) and LF2, viral genes with previously reported functions in inducing or regulating IFN-I pathways, had negligible or even contrary effects on secreted IFN-α in our model. Data mining and Ago PAR-CLIP experiments uncovered more than a dozen previously uncharacterized, direct cellular targets of EBV miRNA associated with type I IFN pathways. We also identified indirect targets of EBV miRNAs in B cells, such as TRL7 and TLR9, in the prelatent phase of infection. The presence of epigenetically naive, non-CpG methylated viral DNA was essential to induce IFN-α secretion during EBV infection in a TLR9-dependent manner. In a newly established fusion assay, we verified that EBV virions enter a subset of plasmacytoid dendritic cells (pDCs) and determined that these infected pDCs are the primary producers of IFN-α in EBV-infected peripheral blood mononuclear cells. Our findings document that many EBV-encoded miRNAs regulate type I IFN response in newly EBV infected primary human B cells in the prelatent phase of infection and dampen the acute release of IFN-α in pDCs upon their encounter with EBV. IMPORTANCE Acute antiviral functions of all nucleated cells rely on type I interferon (IFN-I) pathways triggered upon viral infection. Host responses encompass the sensing of incoming viruses, the activation of specific transcription factors that induce the transcription of IFN-I genes, the secretion of different IFN-I types and their recognition by the heterodimeric IFN-α/β receptor, the subsequent activation of JAK/STAT signaling pathways, and, finally, the transcription of many IFN-stimulated genes (ISGs). In sum, these cellular functions establish a so-called antiviral state in infected and neighboring cells. To counteract these cellular defense mechanisms, viruses have evolved diverse strategies and encode gene products that target antiviral responses. Among such immune-evasive factors are viral microRNAs (miRNAs) that can interfere with host gene expression. We discovered that multiple miRNAs of Epstein-Barr virus (EBV) control over a dozen cellular genes that contribute to the antiviral states of immune cells, specifically B cells and plasmacytoid dendritic cells (pDCs). We identified the viral DNA genome as the activator of IFN-α and question the role of abundant EBV EBERs, that, contrary to previous reports, do not have an apparent inducing function in the IFN-I pathway early after infection.
    Type of Medium: Online Resource
    ISSN: 2150-7511
    URL: Article
    DOI: 10.1128/mBio.03440-20
    Language: English
    Publisher: American Society for Microbiology
    Publication Date: 2021
    detail.hit.zdb_id: 2557172-2
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  • 5
    Online Resource
    Online Resource
    Ralstonia eutropha H16 Flagellation Changes According to Nutrient Supply and State of Poly(3-Hydroxybutyrate) Accumulation
    American Society for Microbiology ; 2008
    In:  Applied and Environmental Microbiology Vol. 74, No. 14 ( 2008-07-15), p. 4477-4490
    Details
    In: Applied and Environmental Microbiology, American Society for Microbiology, Vol. 74, No. 14 ( 2008-07-15), p. 4477-4490
    Abstract: Two-dimensional polyacrylamide gel electrophoresis (2D PAGE), in combination with matrix-assisted laser desorption ionization-time of flight analysis, and the recently revealed genome sequence of Ralstonia eutropha H16 were employed to detect and identify proteins that are differentially expressed during different phases of poly(3-hydroxybutyric acid) (PHB) metabolism. For this, a modified protein extraction protocol applicable to PHB-harboring cells was developed to enable 2D PAGE-based proteome analysis of such cells. Subsequently, samples from (i) the exponential growth phase, (ii) the stationary growth phase permissive for PHB biosynthesis, and (iii) a phase permissive for PHB mobilization were analyzed. Among several proteins exhibiting quantitative changes during the time course of a cultivation experiment, flagellin, which is the main protein of bacterial flagella, was identified. Initial investigations that report on changes of flagellation for R. eutropha were done, but 2D PAGE and electron microscopic examinations of cells revealed clear evidence that R. eutropha exhibited further significant changes in flagellation depending on the life cycle, nutritional supply, and, in particular, PHB metabolism. The results of our study suggest that R. eutropha is strongly flagellated in the exponential growth phase and loses a certain number of flagella in transition to the stationary phase. In the stationary phase under conditions permissive for PHB biosynthesis, flagellation of cells admittedly stagnated. However, under conditions permissive for intracellular PHB mobilization after a nitrogen source was added to cells that are carbon deprived but with full PHB accumulation, flagella are lost. This might be due to a degradation of flagella; at least, the cells stopped flagellin synthesis while normal degradation continued. In contrast, under nutrient limitation or the loss of phasins, cells retained their flagella.
    Type of Medium: Online Resource
    ISSN: 0099-2240 , 1098-5336
    URL: Article
    DOI: 10.1128/AEM.00440-08
    RVK:
    WA 15000
    Language: English
    Publisher: American Society for Microbiology
    Publication Date: 2008
    detail.hit.zdb_id: 223011-2
    detail.hit.zdb_id: 1478346-0
    SSG: 12
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