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  • 1
    Electronic Resource
    Electronic Resource
    Mapping the binding domains on meningococcal Opa proteins for CEACAM1 and CEA receptors (2003)
    Oxford, UK : Blackwell Science Ltd
    Molecular microbiology 50 (2003), S. 0 
    Details
    ISSN: 1365-2958
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology , Medicine
    Notes: The opacity (Opa) proteins of pathogenic Neisseria spp. are adhesins, which play an important role in adhesion and invasion of host cells. Most members of this highly variable family of outer membrane proteins can bind to the human carcinoembryonic antigen-related cell adhesion molecules (CEACAMs). Several studies have identified the Opa-binding region on the CEACAM receptors; however, not much is known about the binding sites on the Opa proteins for the corresponding CEACAM-receptors. The high degree of sequence variation in the surface-exposed loops of Opa proteins raises the question how the binding sites for the CEACAM receptors are conserved. Neisseria meningitidis strain H44/76 possesses four different Opa proteins, of which OpaA and OpaJ bind to CEACAM1, while OpaB and OpaD bind to CEACAM1 and CEA. A sequence motif involved in binding to CEACAM1 was identified by alanine scanning mutagenesis of those amino acid residues conserved within the hypervariable (HV) regions of all four Opa proteins. Hybrid Opa variants with different combinations of HV-1 and HV-2 derived from OpaB and OpaJ showed a reduced binding to CEACAM1 and CEA, indicating that particular combinations of HV-1 and HV-2 are required for the Opa binding capacity. Homologue scanning mutagenesis was used to generate more refined hybrids containing novel combinations of OpaB and OpaJ sequences within HV-1 and HV-2. They could be used to identify residues determining the specificity for CEA binding. The combined results obtained with mutants and hybrids strongly suggest the existence of a conserved binding site for CEACAM receptors by the interaction of HV-1 and HV-2 regions.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1046/j.1365-2958.2003.03749.x
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  • 2
    Electronic Resource
    Electronic Resource
    Identification and characterization of a cross-reactive and a unique B-cell epitope on the hsp60 homologue from Neisseria gonorrhoeae (1992)
    Oxford, UK : Blackwell Publishing Ltd
    FEMS microbiology letters 99 (1992), S. 0 
    Details
    ISSN: 1574-6968
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology
    Notes: Abstract Two monoclonal antibodies (G6 and 7B), generated against a 63-kDa stress protein (GSP63) from Neisseria gonorrhoeae strain VP1, were used to investigate the antigenic heterogeneity of GSP63 among the Neisseriaceae and its antigenic relationship with the Hsp60 heat-shock protein family. Immunoblotting experiments demonstrated antibody reactivity with all pathogenic Neisseria tested and with some of the commensal strains. One of the antibodies (7B) cross-reacted with the 65-kDa M. bovis BCG heat-shock protein and with 14 out of the 21 similarly sized proteins in other bacterial species. The other antibody (G6) specifically recognized neisserial GSP63 homologues. These results demonstrate that GSP63 is a conserved neisserial antigen bearing both a unique neisserial B-cell epitope and a more widely distributed Hsp60 epitope.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1574-6968.1992.tb05536.x
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  • 3
    Electronic Resource
    Electronic Resource
    Stimulation of bacterial adherence by neutrophil defensins varies among bacterial species but not among host cell types (2000)
    Oxford, UK : Blackwell Publishing Ltd
    FEMS immunology and medical microbiology 28 (2000), S. 0 
    Details
    ISSN: 1574-695X
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology , Medicine
    Notes: Adherence of Haemophilus influenzae to bronchial epithelial cells is enhanced by neutrophil defensins, which are released from activated neutrophils during inflammation [Gorter et al. (1998) J. Infect. Dis. 178, 1067–1078]. In this study, we showed that the adherence of H. influenzae to various epithelial, fibroblast-like and endothelial cell types was significantly enhanced by defensins (20 μg ml−1). Defensins stimulated also the adherence of Moraxella catarrhalis, Neisseria meningitidis and nonencapsulated Streptococcus pneumoniae to the NCI-H292 cell line. In contrast, defensins did not affect the adherence of Pseudomonas aeruginosa, encapsulated S. pneumoniae, Escherichia coli and Staphylococcus epidermidis. These results suggest that the defensin-enhanced adherence might support the adherence and possibly persistence of the selected bacterial species using the respiratory tract as port of entry.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1574-695X.2000.tb01463.x
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  • 4
    Electronic Resource
    Electronic Resource
    Induced Helicobacter pylori vacuolating cytotoxin VacA expression after initial colonisation of human gastric epithelial cells (2003)
    Oxford, UK : Blackwell Publishing Ltd
    FEMS immunology and medical microbiology 39 (2003), S. 0 
    Details
    ISSN: 1574-695X
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology , Medicine
    Notes: To study the effect of initial colonisation on Helicobacter pylori gene expression, altered H. pylori gene transcription during co-culture with human gastric epithelial cells was determined. Therefore, an insertion library of H. pylori with random chromosomal fusions to a promoterless cat gene was grown in the presence of HM02 gastric epithelial cells and varying levels of chloramphenicol. One H. pylori transformant was chloramphenicol-resistant in the presence, but chloramphenicol-susceptible in the absence of gastric epithelial HM02 cells. This transformant had the promoterless cat gene inserted into the HP0887 gene, which encodes the vacuolating cytotoxin VacA, an important virulence factor of H. pylori. Reverse transcriptase polymerase chain reaction on cDNA of this transformant confirmed vacA upregulation near HM02 cells. These results show the applicability of this technique to study H. pylori gene regulation in its natural environment.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1016/S0928-8244(03)00226-8
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  • 5
    Electronic Resource
    Electronic Resource
    Evidence for frequent OspC gene transfer between Borrelia valaisiana sp. nov. and other Lyme disease spirochetes (1999)
    Oxford, UK : Blackwell Publishing Ltd
    FEMS microbiology letters 177 (1999), S. 0 
    Details
    ISSN: 1574-6968
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology
    Notes: Molecular polymorphism of the ospC gene has been reported in Borrelia burgdorferi sensu stricto, Borrelia garinii and Borrelia afzelii, the spirochetes causing human Lyme borreliosis. To assess the genetic relationship between ospC genes from the recently described Borrelia valaisiana sp. nov. and other B. burgdorferi sensu lato species, the ospC genes from eight B. valaisiana isolates were amplified by PCR, cloned and sequenced. The ospC genes of three B. valaisiana isolates were identical, but clearly distinct from ospC genes from other Borrelia species. Four B. valaisiana isolates possessed ospC genes more related to those of B. garinii, and fell into a cluster representing B. garinii species in the phylogenetic tree. One isolate had an ospC gene encoding a protein identical to that of B. afzelii strain. Since five of the eight (62.5%) B. valaisiana isolates contained a gene highly homologous or even identical to ospC genes found among B. garinii and B. afzelii strains, our findings indicate that ospC gene transfer occurs between B. valaisiana and other Lyme disease spirochetes.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1574-6968.1999.tb13745.x
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  • 6
    Electronic Resource
    Electronic Resource
    Human lactoferrin receptor activity in non-encapsulated Haemophilus influenzae (1997)
    Oxford, UK : Blackwell Publishing Ltd
    FEMS microbiology letters 156 (1997), S. 0 
    Details
    ISSN: 1574-6968
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology
    Notes: Since the ability of bacteria to compete with lactoferrin for iron contributes to the pathogenesis of mucosal infections, the presence of lactoferrin receptor activity in non-encapsulated Haemophilus influenzae was investigated. The growth of 18 H. influenzae isolates from the sputum samples of chronic bronchitis patients and of six of seven H. influenzae throat isolates from healthy adults was stimulated by iron saturated human lactoferrin. Apo-lactoferrin did not stimulate the growth of H. influenzae. Human lactoferrin binding to iron limited bacteria was detected for 16 H. influenzae strains from chronic bronchitis patients and for five of seven isolates from healthy adults. We conclude that the majority of H. influenzae isolates tested bind human lactoferrin and that the iron from lactoferrin is used for growth.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1574-6968.1997.tb12723.x
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  • 7
    Electronic Resource
    Electronic Resource
    Representational difference analysis of Neisseria meningitidis identifies sequences that are specific for the hyper-virulent lineage III clone (2000)
    Oxford, UK : Blackwell Publishing Ltd
    FEMS microbiology letters 188 (2000), S. 0 
    Details
    ISSN: 1574-6968
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology
    Notes: Neisseria meningitidis may cause meningitis and septicemia. Since the early 1980s, an increased incidence of meningococcal disease has been caused by the lineage III clone in many countries in Europe and in New Zealand. We hypothesized that lineage III meningococci have specific DNA sequences, providing an opportunity to facilitate epidemiological studies by detecting lineage III isolates rapidly. Applying representational difference analysis on one lineage III tester strain and two non-lineage III driver strains, we identified three lineage III-specific sequences, probably part of a single locus encoding a restriction modification system. A PCR based on one of these sequences identified lineage III meningococcal isolates with a sensitivity of 100% and a specificity of 93%, which is superior to the serological identification of lineage III isolates.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1574-6968.2000.tb09179.x
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  • 8
    Electronic Resource
    Electronic Resource
    Analysis of a VMP-like sequence (vls) locus in Borrelia garinii and Vls homologues among four Borrelia burgdorferi sensu lato species (2001)
    Oxford, UK : Blackwell Publishing Ltd
    FEMS microbiology letters 199 (2001), S. 0 
    Details
    ISSN: 1574-6968
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology
    Notes: The VMP-like sequence (vls) locus that consists of one expressed vlsE gene and 15 silent vls cassettes has been described in Borrelia burgdorferi sensu stricto B31. In the present study, the vls locus from a Borrelia garinii isolate A87SA was analyzed. DNA fragments that contained three complete and five partial vls cassettes were cloned and sequenced. Pulsed-field gel electrophoresis (PFGE) analysis and Southern hybridization of the PFGE blot indicated that the vls locus of B. garinii A87SA, consisting of at least eight vls cassettes, was located on a 21-kb linear plasmid. The size of the three complete vls cassettes varied from 573 to 612 bp. They had 93.8–94.3% identity at the nucleotide level and 84.9–87.3% amino acid identity. The amino acid sequences of the three vls cassettes of B. garinii A87SA exhibited 45.9–50.8% identity to the VlsE sequence of B. burgdorferi B31, and 30.0–33.8% identity to the VMP17 sequence of B. hermsii HS1. Homologues of the vls locus of B. garinii were detected by dot blot hybridization among 24 of the 30 (80.0%) isolates representing four B. burgdorferi sensu lato species distributed widely in Europe. Our findings indicate that B. garinii might possess a similar vls structure to that described in B. burgdorferi sensu stricto. The highly conserved nature of the vls locus among various B. burgdorferi sensu lato species suggests that it may be important in the physiology and pathogenesis of Lyme disease spirochetes.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1574-6968.2001.tb10648.x
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  • 9
    Electronic Resource
    Electronic Resource
    Operator sequences for the regulatory proteins of restriction modification systems (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
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1046/j.1365-2958.1999.01253.x
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  • 10
    Electronic Resource
    Electronic Resource
    Neisseria meningitidis producing the Opc adhesin binds epithelial cell proteoglycan receptors (1998)
    Oxford BSL : Blackwell Science Ltd, UK
    Molecular microbiology 27 (1998), S. 0 
    Details
    ISSN: 1365-2958
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology , Medicine
    Notes: Neisseria meningitidis possesses a repertoire of surface adhesins that promote bacterial adherence to and entry into mammalian cells. Here, we have identified heparan sulphate proteoglycans as epithelial cell receptors for the meningococcal Opc invasin. Binding studies with radiolabelled heparin and heparin affinity chromatography demonstrated that Opc is a heparin binding protein. Subsequent binding experiments with purified 35SO4-labelled epithelial cell proteoglycan receptors and infection assays with epithelial cells that had been treated with heparitinase to remove glycosaminoglycans confirmed that Opc-expressing meningococci exploit host cell-surface proteoglycans to gain access to the epithelial cell interior. Unexpectedly, Opa28-producing meningococci lacking Opc also bound proteoglycans. These bacteria also bound CEA receptors in contrast to the Opc-expressing phenotype, suggesting that Opa28 may possess domains with specificity for different receptors. Opa/Opc-negative meningococci did not bind either proteoglycan or CEA receptors. Using a set of genetically defined mutants with different lipopolysaccharide (LPS) and capsular phenotype, we were able to demonstrate that surface sialic acids interfere with the Opc–proteoglycan receptor interaction. This effect may provide the molecular basis for the reported modulatory effect of capsule and LPS on meningococcal adherence to and entry into various cell types.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1046/j.1365-2958.1998.00763.x
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