Search results for "Outer membrane protein"
showing 10 items of 52 documents
BBE31 from the Lyme disease agent Borrelia burgdorferi, known to play an important role in successful colonization of the mammalian host, shows the a…
2019
Abstract Lyme disease is a tick-borne infection caused by Borrelia burgdorferi sensu lato complex spirochetes. The spirochete is located in the gut of the tick; as the infected tick starts the blood meal, the spirochete must travel through the hemolymph to the salivary glands, where it can spread to and infect the new host organism. In this study, we determined the crystal structures of the key outer surface protein BBE31 from B. burgdorferi and its orthologous protein BSE31 (BSPA14S_RS05060 gene product) from B. spielmanii. BBE31 is known to be important for the transfer of B. burgdorferi from the gut to the hemolymph in the tick after a tick bite. While BBE31 exerts its function by intera…
Involvement of the Pseudomonas aeruginosa MexAB–OprM efflux pump in the secretion of the metallophore pseudopaline
2020
ABSTRACTThe ability for all organisms to acquire metals from their environment is essential for life. To overcome the metal restriction imposed by the host’s nutritional immunity, bacterial pathogens exploits the use of small high metal affinity molecules called metallophores. Metallophores are first synthetized in the cytoplasm, then secreted into the medium where they sequester the metal. The metal-metallophore complex is then imported into the bacterium following binding to dedicated cell surface receptors. Recently, a new family of metallophores has been discovered in pathogenic bacteria called staphylopine in Staphylococcus aureus and pseudopaline in Pseudomonas aeruginosa. Here, we ar…
Susceptibility of Pseudomonas aeruginosa isolates to ceftazidime is unrelated to the expression of the outer membrane protein OprC.
1997
Previously, it has been postulated that the porin OprC facilitates the diffusion of ceftazidime through the outer membrane of Pseudomonas aeruginosa. To further investigate this claim, the outer membrane protein (OMP) profiles of 22 ceftazidime-susceptible clinical isolates were analyzed. No correlation was found between MIC values and the level of expression of OprC. Further, OprC was either undetectable or expressed in reduced amounts in 12 isolates. In contrast, OprF and OprE were present in all isolates studied. This study suggests that OprC is dispensable for the permeation of ceftazidime through the outer membrane of P. aeruginosa.
The long-term cytoskeletal rearrangement induced by rabbit enteropathogenic Escherichia coli is Esp dependent but intimin independent.
1999
Attaching and effacing rabbit enteropathogenic Escherichia coli (REPEC) of the O103 serogroup adhere diffusely on HeLa cells and trigger a slow progressive cytopathic effect (CPE) characterized by the recruitment of vinculin and the assembly of actin stress fibres. In contrast to REPEC O103, the reference human EPEC strain E2348/69 is unable to trigger the CPE. In this study, we have shown first that the fimbrial adhesin AF/R2, which mediates the diffuse adhesion of REPEC O103, was not sufficient to induce the CPE capability upon E2348/69. Non-polar mutants of REPEC O103 for espA, espB, espD and eae were then constructed. The four mutants were unable to induce attaching and effacing lesions…
Type III Secretion-Dependent Cell Cycle Block Caused in HeLa Cells by Enteropathogenic Escherichia coliO103
2001
ABSTRACT Rabbit enteropathogenic Escherichia coli (EPEC) O103 induces in HeLa cells an irreversible cytopathic effect characterized by the recruitment of focal adhesions, formation of stress fibers, and inhibition of cell proliferation. We have characterized the modalities of the proliferation arrest and investigated its underlying mechanisms. We found that HeLa cells that were exposed to the rabbit EPEC O103 strain E22 progressively accumulated at 4C DNA content and did not enter mitosis. A significant proportion of the cells were able to reinitiate DNA synthesis without division, leading to 8C DNA content. This cell cycle inhibition by E22 was abrogated in mutants lacking EspA, -B, and -D…
Evidence for a new feminizing Wolbachia strain in the isopod Armadillidium vulgare: evolutionary implications.
2004
Wolbachia are intracellular maternally inherited alpha-Proteobacteria infecting a wide range of arthropods. In the common pill bug Armadillidium vulgare, the known Wolbachia strain is responsible for feminization of genetic males. We have investigated Wolbachia diversity in 20 populations of A. vulgare from west and east Europe, north Africa and north America. A new Wolbachia strain (wVulM) was identified through the variability of the wsp gene, distantly related to that previously known (wVulC) in this host species. No individual with multiple infections was detected. Inoculation experiments indicated that the new wVulM bacterial strain also induces feminization in A. vulgare. However, the…
The role of Components of the Outer Membrane of Gram-Negative Bacteria in the Serum-Bactericidal Effect
1982
Abstract Effective killing-capacity of normal human and guinea pig sera depended on Ca ++ , C1q, C2 and C4. Fixation- and transfer-tests revealed that C1 and C1q were bound more tightly to the serum-sensitive R-forms of Salmonella strains than to the serum-resistant S-forms. Since all experiments were done in the absence of antibodies these findings provide evidence that the antibody-independent C1-binding is one of the initial reactions of the serum-mediated killing. This reaction seems to be influenced by the sugar-portion of the lipopolysaccharide (LPs) of the outer membrane: C1-binding to the bacteria occurs with higher affinity the shorter the LPS-molecule. This indicates that other ou…
Isolation of a hemin and hemoglobin binding outer membrane protein of Vibrio vulnificus biotype 2 (serogroup E)
2006
The eel pathogen Vibrio vulnificus biotype 2 (serogroup E) is able to use hemin (Hm) or hemoglobin (Hb) as the sole iron source for growth in vitro and in vivo. The mechanism of heme-iron acquisition in this bacterium requires a direct interaction through binding sites on the bacterial surface (constitutive outer membrane proteins). Using affinity chromatography techniques, a unique protein of around 36.5 kDa was isolated from cell envelopes of E86 strain regardless of the affinity ligand used, hemoglobin or hemin. This protein was purified from both iron-enriched and iron-restricted grown cells. These results support the hypothesis that in this pathogen Hm- and Hb-iron acquisition is media…
Transcriptional regulation of the proton translocating NADH dehydrogenase genes (nuoA-N) of Escherichia coli by electron acceptors, electron donors a…
1995
The promoter region and transcriptional regulation of the nuoA-N gene locus encoding the proton-translocating NADH:quinone oxidoreductase was analysed. A 560 bp intergenic region upstream of the nuo locus was followed by a gene (designated lrhA for LysR homologue A) coding for a gene regulator similar to those of the LysR family. Disruption of lrhA did not affect growth (respiratory or non-respiratory) or expression of nuo significantly. Transcriptional regulation of nuo by electron acceptors, electron donors and the transcriptional regulators ArcA, FNR, NarL and NarP, and by IHF (integration host factor) was studied with protein and operon fusions containing the promoter region up to base …
Utilization of hemin and hemoglobin by Vibrio vulnificus biotype 2
1996
The eel pathogen Vibrio vulnificus biotype 2 is able to use hemoglobin (Hb) and hemin (Hm) to reverse iron limitation. In this stud, the adjuvant effect of both compounds on eel pathogenicity has been evaluated and confirmed. Further, we have studied the heme-iron acquisition mechanism displayed by this bacterium. Whole cells were capable of binding Hb and Hm, independently of (i) iron levels in growth medium and (ii) the presence of polysaccharide capsules on bacterial surface. The Hb- and Hm-binding capacity was retained by the outer membrane protein (OMP) fraction and was abolished after proteolytic digestion of OMP samples. Western blotting (immunoblotting) of denatured OMPs revealed th…