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  • 1
    Electronic Resource
    Electronic Resource
    Enzymatic synthesis of bacteriophage fd viral DNA (1982)
    [s.l.] : Nature Publishing Group
    Nature 296 (1982), S. 828-832 
    Details
    ISSN: 1476-4687
    Source: Nature Archives 1869 - 2009
    Topics: Biology , Chemistry and Pharmacology , Medicine , Natural Sciences in General , Physics
    Notes: [Auszug] An enzyme system with requirements similar to those for replication of phage fd replicative form (RF) DNA in bacteriophage fd-infected cells has been reconstituted with purified fd gene 2 protein, and DNA polymerase III holoenzyme, DNA binding protein I and rep-protein (rep-helicase) of Escherichia ...
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1038/296828a0
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  • 2
    Electronic Resource
    Electronic Resource
    Gene structure and extracellular secretion of Neisseria gonorrhoeae IgA protease (1987)
    [s.l.] : Nature Publishing Group
    Nature 325 (1987), S. 458-462 
    Details
    ISSN: 1476-4687
    Source: Nature Archives 1869 - 2009
    Topics: Biology , Chemistry and Pharmacology , Medicine , Natural Sciences in General , Physics
    Notes: [Auszug] Fig. 1 Sequence of the N. gonorrhoeae MS 11 iga gene. The DNA sequence reveals a single gene of 4,596 bp in association with typical expression signals: a promoter sequence17'19 (positions -43, -35, and -10), a transcription termination signal20 (divergent arrows), and a Shine-Dalgarno (SD) ...
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1038/325458a0
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  • 3
    Electronic Resource
    Electronic Resource
    Helicobacter pylori inhibits phagocytosis by professional phagocytes involving type IV secretion components (2000)
    Oxford, UK : Blackwell Science Ltd
    Molecular microbiology 37 (2000), S. 0 
    Details
    ISSN: 1365-2958
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology , Medicine
    Notes: Gastric infections by Helicobacter pylori are characteristically associated with an intense inflammation and infiltration of mainly polymorphonuclear lymphocytes (PMNs) and monocytes. The inflammatory response by infiltrated immune cells appears to be a primary cause of the damage to surface epithelial layers and may eventually result in gastritis, peptic ulcer, gastric cancer and/or MALT-associated gastric lymphoma. Our analysis of the interaction between H. pylori and PMNs and monocytes revealed that H. pylori inhibits its own uptake by these professional phagocytes. To some degree, this effect resembles antiphagocytosis by Yersinia enterocolitica. Increasing numbers of bacteria associated per cell are more efficient at blocking their own engulfment. In H. pylori, bacterial protein synthesis is necessary to block phagocytic uptake, as shown by the time and concentration dependence of the bacteriostatic protein synthesis inhibitor chloramphenicol. Furthermore, H. pylori appears broadly to inhibit the phagocytic function of monocytes and PMNs, as infection with H. pylori abrogates the phagocytes' ability to engulf latex beads or adherent Neisseria gonorrhoeae cells. This antiphagocytic phenotype depends on distinct virulence (vir) genes, such as virB7 and virB11, encoding core components of a putative type IV secretion apparatus. Our data indicate that H. pylori exhibits an antiphagocytic activity that may play an essential role in the immune escape of this persistent pathogen.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1046/j.1365-2958.2000.02089.x
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  • 4
    Electronic Resource
    Electronic Resource
    From the inside out – processing of the Chlamydial autotransporter PmpD and its role in bacterial adhesion and activation of human host cells (2004)
    Oxford, UK : Blackwell Science Ltd
    Molecular microbiology 51 (2004), S. 0 
    Details
    ISSN: 1365-2958
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology , Medicine
    Notes: Polymorphic membrane protein (Pmp)21 otherwise known as PmpD is the longest of 21 Pmps expressed by Chlamydophila pneumoniae. Recent bioinformatical analyses annotated PmpD as belonging to a family of exported Gram-negative bacterial proteins designated autotransporters. This prediction, however, was never experimentally supported, nor was the function of PmpD known. Here, using 1D and 2D PAGE we demonstrate that PmpD is processed into two parts, N-terminal (N-pmpD), middle (M-pmpD) and presumably third, C-terminal part (C-pmpD). Based on localization  of  the  external  part  on  the  outer  membrane as shown by immunofluorescence, immuno-electron microscopy and immunoblotting combined with trypsinization, we demonstrate that N-pmpD translocates to the surface of bacteria where it non-covalently binds other components of the outer membrane. We propose that N-pmpD functions as an adhesin, as antibodies raised against N-pmpD blocked  chlamydial  infectivity  in  the  epithelial  cells. In addition, recombinant N-pmpD activated human monocytes in vitro by upregulating their metabolic activity and by stimulating IL-8 release in a dose-dependent manner. These results demonstrate that N-PmpD is an autotransporter component of chlamydial outer membrane, important for bacterial invasion and host inflammation.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1046/j.1365-2958.2003.03838.x
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  • 5
    Electronic Resource
    Electronic Resource
    Mutagenesis of the Neisseria gonorrhoeae porin reduces invasion in epithelial cells and enhances phagocyte responsiveness (1999)
    Oxford BSL : Blackwell Science Ltd
    Molecular microbiology 31 (1999), S. 0 
    Details
    ISSN: 1365-2958
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology , Medicine
    Notes: Porin (PorB), the major outer membrane protein of Neisseria gonorrhoeae, has been implicated in pathogenesis previously. However, the fact that porin deletion mutants are not viable has complicated investigations. Here, we describe a method of manipulating the porin gene site-specifically. N. gonorrhoeae MS11, which harbours the porB1B (P.1B) porin allele, was used to generate mutants carrying deletions in the surface loops 1 and 5. An 11-amino-acid deletion in loop 1 impaired Opa50-dependent invasion into human Chang epithelial cells, whereas loop 5 deletion exhibited no apparent phenotype. In a second approach, the complete gonococcal porB1B was replaced by the porBNla gene of Neisseria lactamica. Such mutants were unable to induce efficient uptake by epithelial cells but induced an enhanced respiratory response in HL60 phagocytic cells. The increased respiratory burst was accompanied by an enhanced phagocytic uptake of the mutant compared with the wild-type strain. Our data extend previous evidence for multiple central functions of PorB in the infection process.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1046/j.1365-2958.1999.01230.x
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  • 6
    Electronic Resource
    Electronic Resource
    Potential role of two Helicobacter pylori relaxases in DNA transfer? (1998)
    Oxford BSL : Blackwell Science Ltd
    Molecular microbiology 30 (1998), S. 0 
    Details
    ISSN: 1365-2958
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology , Medicine
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1046/j.1365-2958.1998.01086.x
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  • 7
    Electronic Resource
    Electronic Resource
    Differential Opa specificities for CD66 receptors influence tissue interactions and cellular response to Neisseria gonorrhoeae (1997)
    Oxford, UK : Blackwell Science Ltd
    Molecular microbiology 26 (1997), S. 0 
    Details
    ISSN: 1365-2958
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology , Medicine
    Notes: The ability of all 11 variable opacity (Opa) proteins encoded by Neisseria gonorrhoeae MS11 to interact directly with the five CD66 antigens was determined. Transfected HeLa cell lines expressing individual CD66 antigens were infected with recombinant N. gonorrhoeae and Escherichia coli strains expressing defined Opas. Based upon the ability of these bacteria to bind and invade and to isolate specifically CD66 antigens from detergent-soluble extracts of the corresponding cell lines, distinct specificity groups of Opa interaction with CD66 were seen. Defining these specificity groups allowed us to assign a specific function for CD66a in the Opa-mediated interaction of gonococci with two different target cell types, which are both known to co-express multiple CD66 antigens. The competence of individual Opas to interact with CD66a was strictly correlated with their ability to induce an oxidative response by polymorphonuclear neutrophils. The same Opa specificity was observed for the level of gonococcal binding to primary endothelial cells after stimulation with TNFα, which was shown to increase the expression of CD66a rather than CD66e. As CD66e alone is expressed on other target tissues of gonococcal pathogenicity, Opa variation probably contributes to the cell tropism displayed by gonococci.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1046/j.1365-2958.1997.6342006.x
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  • 8
    Electronic Resource
    Electronic Resource
    PilC of Neisseria meningitidis is involved in class II pilus formation and restores pilus assembly, natural transformation competence and adherence to epithelial cells in PilC-deficient gonococci (1997)
    Oxford BSL : Blackwell Science Ltd
    Molecular microbiology 23 (1997), S. 0 
    Details
    ISSN: 1365-2958
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology , Medicine
    Notes: Type 4 pili produced by the pathogenic Neisseria species constitute primary determinants for the adherence to host tissues. In addition to the major pilin subunit (PilE), neisserial pili contain the variable PilC proteins represented by two variant gene copies in most pathogenic Neisseria isolates. Based upon structural differences in the conserved regions of PilE, two pilus classes can be distinguished in Neisseria meningitidis. For class I pili found in both Neisseria gonorrhoeae and N. meningitidis, PilC proteins have been implicated in pilus assembly, natural transformation competence and adherence to epithelial cells. In this study, we used primers specific for the pilC2 gene of N. gonorrhoeae strain MS11 to amplify, by the polymerase chain reaction, and clone a homologous pilC gene from N. meningitidis strain A1493 which produces class II pili. This gene was sequenced and the deduced amino acid sequence showed 75.4% and 73.8% identity with the gonococcal PilC1 and PilC2, respectively. These values match the identity value of 74.1% calculated for the two N. gonorrhoeae MS11 PilC proteins, indicating a horizontal relationship between the N. gonorrhoeae and N. meningitidispilC genes. We provide evidence that PilC functions in meningococcal class II pilus assembly and adherence. Furthermore, expression of the cloned N. meningitidis pilC gene in a gonococcal pilC1,2 mutant restores pilus assembly, adherence to ME-180 epithelial cells, and transformation competence to the wild-type level. Thus, PilC proteins exhibit indistinguishable functions in the context of class I and class II pili.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1046/j.1365-2958.1997.2631630.x
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  • 9
    Electronic Resource
    Electronic Resource
    Pilus biogenesis and epithelial cell adherence of Neisseria gonorrhoeae pilC double knock-out mutants (1995)
    Osney Mead, Oxford OX2 0EL, UK : Blackwell Scientific Publications
    Molecular microbiology 17 (1995), S. 0 
    Details
    ISSN: 1365-2958
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology , Medicine
    Notes: The phase-variable PilC proteins of pathogenic Neisseria species have recently been implicated in both assembly and cellular adherence functions of the type 4 pili of these pathogens. We describe here the cloning of full-length pilC1 and pilC2 genes and the complete sequencing of the pilC2 gene of Neisseria gonorrhoeae MS11. Sequential inactivation of both genes by gene replacement in piliated (P+) variants of N. gonorrhoeae MS11 led initially to a non-piliated (P−) phenotype; however, spontaneous P+ variants could be derived from some pilC1,2 double mutants which produced morphologically intact pili. Purified pili from pilC1,2 mutants revealed no detectable PilC protein. Instead, a novel protein about 70 kDa in size appeared in the pili preparations of P+ mutants; this protein exhibited no immunological cross-reactivity with PilC1 or PilC2. We propose that this novel factor replaces the function of PilC in pilus biogenesis. Using isogenic N. gonorrhoeae strains which produce identical PilE (pilin) proteins we demonstrate that pili associated with the 70 kDa protein do not confer gonococcal adherence to human epithelial cells, in contrast to pili assembled in the presence of PilC1 or PilC2.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1365-2958.1995.mmi_17061057.x
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  • 10
    Electronic Resource
    Electronic Resource
    Opa binding to cellular CD66 receptors mediates the transcellular traversal of Neisseria gonorrhoeae across polarized T84 epithelial cell monolayers (1998)
    Oxford BSL : Blackwell Science Ltd
    Molecular microbiology 30 (1998), S. 0 
    Details
    ISSN: 1365-2958
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology , Medicine
    Notes: We have analysed the capacity of the 11 phase-variable, opacity-associated (Opa) proteins encoded by Neisseria gonorrhoeae MS11 to mediate traversal across polarized monolayers of the human colonic carcinoma T84 cell line. Gonococci expressing either the heparan sulphate proteoglycan (HSPG) binding Opa protein (Opa50) or no Opa protein (Opa−) did not interact with the apical pole of T84 monolayers, whereas the 10 variant Opa proteins previously shown to bind CD66 receptors were found to mediate efficient gonococcal adherence and transepithelial traversal. Consistent with this, T84 cells were shown by reverse transcriptase–polymerase chain reaction (RT–PCR) and immunoblotting to co-express CD66a (BGP), CD66c (NCA) and CD66e (CEA). The recruitment of CD66 receptors by Opa-expressing gonococci indicates their involvement in mediating adherence to the surface of T84 cells, and these bacterial interactions could be inhibited completely using polyclonal antibodies cross-reacting with all of the CD66 proteins co-expressed on T84 cells. Consistent results were obtained when Opa proteins were expressed in Escherichia coli, suggesting that the Opa–CD66 interaction is sufficient to mediate bacterial traversal. Transcytosis of Opa-expressing N. gonorrhoeae or E. coli did not disrupt the barrier function of infected monolayers, as indicated by a sustained transepithelial electrical resistance (TEER) throughout the course of infection, and confocal laser scanning and electron microscopy both suggest a transcellular rather than a paracellular route of traversal across the monolayers. Parallels between the results seen here and previous work done with organ cultures confirm that T84 monolayers provide a valid model for studying neisserial interactions with the mucosal surface, and suggest that CD66 receptors contribute to this process in vivo.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1046/j.1365-2958.1998.01102.x
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