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  • Article  (4)
  • Fortney, Kr  (4)
  • Bacterial Proteins  (4)
  • Bacterial Outer Membrane Proteins
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  • Article  (4)
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  • 1
    Language: English
    In: Infection and immunity, November 2013, Vol.81(11), pp.4160-70
    Description: Expression of the lspB-lspA2 operon encoding a virulence-related two-partner secretion system in Haemophilus ducreyi 35000HP is directly regulated by the CpxRA regulatory system (M. Labandeira-Rey, J. R. Mock, and E. J. Hansen, Infect. Immun. 77:3402-3411, 2009). In the present study, we show that this secretion system is also regulated by the small nucleoid-associated protein Fis. Inactivation of the H. ducreyi fis gene resulted in a reduction in expression of both the H. ducreyi LspB and LspA2 proteins. DNA microarray experiments showed that a H. ducreyi fis deletion mutant exhibited altered expression levels of genes encoding other important H. ducreyi virulence factors, including DsrA and Flp1, suggesting a possible global role for Fis in the control of virulence in this obligate human pathogen. While the H. ducreyi Fis protein has a high degree of sequence and structural similarity to the Fis proteins of other bacteria, its temporal pattern of expression was very different from that of enterobacterial Fis proteins. The use of a lacZ-based transcriptional reporter provided evidence which indicated that the H. ducreyi Fis homolog is a positive regulator of gyrB, a gene that is negatively regulated by Fis in enteric bacteria. Taken together, the Fis protein expression data and the observed regulatory effects of Fis in H. ducreyi suggest that this small DNA binding protein has a regulatory role in H. ducreyi which may differ in substantial ways from that of other Fis proteins.
    Keywords: Gene Expression Regulation, Bacterial ; Operon ; Bacterial Outer Membrane Proteins -- Biosynthesis ; Bacterial Proteins -- Biosynthesis ; Factor For Inversion Stimulation Protein -- Metabolism ; Haemophilus Ducreyi -- Genetics
    ISSN: 00199567
    E-ISSN: 1098-5522
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  • 2
    Language: English
    In: Infection and immunity, September 2010, Vol.78(9), pp.3898-904
    Description: Haemophilus ducreyi must adapt to the environment of the human host to establish and maintain infection in the skin. Bacteria generally utilize stress response systems, such as the CpxRA two-component system, to adapt to hostile environments. CpxRA is the only obvious two-component system contained in the H. ducreyi genome and negatively regulates the lspB-lspA2 operon, which encodes proteins that enable the organism to resist phagocytosis. We constructed an unmarked, in-frame H. ducreyi cpxA deletion mutant, 35000HPDeltacpxA. In human inoculation experiments, 35000HPDeltacpxA formed papules at a rate and size that were significantly less than its parent and was unable to form pustules compared to the parent. CpxA usually has kinase and phosphatase activities for CpxR, and the deletion of CpxA leads to the accumulation of activated CpxR due to the loss of phosphatase activity and the ability of CpxR to accept phosphate groups from other donors. Using a reporter construct, the lspB-lspA2 promoter was downregulated in 35000HPDeltacpxA, confirming that CpxR was activated. Deletion of cpxA downregulated DsrA, the major determinant of serum resistance in the organism, causing the mutant to become serum susceptible. Complementation in trans restored parental phenotypes. 35000HPDeltacpxA is the first H. ducreyi mutant that is impaired in its ability to form both papules and pustules in humans. Since a major function of CpxRA is to control the flow of protein traffic across the periplasm, uncontrolled activation of this system likely causes dysregulated expression of multiple virulence determinants and cripples the ability of the organism to adapt to the host.
    Keywords: Bacterial Proteins -- Physiology ; Haemophilus Ducreyi -- Pathogenicity ; Protein Kinases -- Physiology
    ISSN: 00199567
    E-ISSN: 1098-5522
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  • 3
    Language: English
    In: The Journal of infectious diseases, 15 April 2008, Vol.197(8), pp.1103-9
    Description: Haemophilus ducreyi contains 3 TonB-dependent receptors: the hemoglobin receptor HgbA, which is required for virulence in humans; the heme receptor TdhA; and an uncharacterized conserved hypothetical protein TdX (HD0646). A double tdX/tdhA mutant (FX527) was constructed on the background of a human-passaged variant of strain 35000 (35000HP). Six volunteers were infected with 35000HP at 3 sites on one arm and with FX527 at 3 sites on the other. The pustule formation rate was 55.6% (95% confidence interval [CI], 35.7%-75.4%) at 18 parent-strain sites and 44.4% (95% CI, 15.0%-73.9%) at 18 mutant-strain sites (P = .51). Similar amounts of 35000HP and FX527 were recovered from pustules in semiquantitative culture. Thus, TdX and TdhA are not necessary for virulence, whereas HgbA is both necessary and sufficient for virulence in humans. The data suggest that hemoglobin is the sole source of heme/iron used by H. ducreyi in vivo and has implications for the potential of HgbA as a vaccine.
    Keywords: Bacterial Outer Membrane Proteins -- Biosynthesis ; Bacterial Proteins -- Biosynthesis ; Chancroid -- Microbiology ; Haemophilus Ducreyi -- Pathogenicity ; Membrane Proteins -- Biosynthesis
    ISSN: 0022-1899
    E-ISSN: 15376613
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  • 4
    Language: English
    In: The Journal of Infectious Diseases, 1 March 2000, Vol.181(3), pp.1049-1054
    Description: Haemophilus ducreyi expresses a conserved hemoglobin-binding outer-membrane protein (HgbA). To test the role of HgbA in pathogenesis, we infected 9 adults with isolate 35000 and its isogenic hgbA-inactivated mutant (FX504) on their upper arms in a double-blinded, escalating dose-response study. Papules developed at similar rates at sites inoculated with the mutant or parent. The pustule-formation rate was 55% (95% confidence interval [CI], 30.8%-78.5%) at parent sites and 0 (95% CI, 0-10.5%) at mutant sites (P 〈 .0001). The recovery rate of H. ducreyi from surface cultures was 16% (n = 142) from parent sites and 0 (n = 213) from mutant sites (P 〈 .0001). H. ducreyi was recovered at biopsy from 6 of 7 parent sites and from 0 of 3 mutant sites. The results indicate that hemoglobin may be a critical source of heme or iron for the establishment of H. ducreyi infection in humans.
    Keywords: Physical sciences -- Chemistry -- Chemical compounds -- Haemophilus ducreyi ; Biological sciences -- Biology -- Microbiology -- Haemophilus ducreyi ; Biological sciences -- Biology -- Microbiology -- Haemophilus ducreyi ; Health sciences -- Medical conditions -- Infections -- Haemophilus ducreyi ; Physical sciences -- Chemistry -- Chemical compounds -- Haemophilus ducreyi ; Health sciences -- Medical diagnosis -- Diagnostic methods -- Haemophilus ducreyi ; Health sciences -- Medical sciences -- Pharmacology -- Haemophilus ducreyi ; Health sciences -- Medical sciences -- Immunology -- Haemophilus ducreyi ; Health sciences -- Medical conditions -- Physical trauma -- Haemophilus ducreyi ; Health sciences -- Health and wellness -- Public health -- Haemophilus ducreyi
    ISSN: 00221899
    E-ISSN: 15376613
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