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  • 1
    ISSN: 1365-2958
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology , Medicine
    Notes: A phospholipase C which cleaves phosphatidylinositol and glycosylphosphatidylinositol (GPI) anchors was identified in Listeria monocytogenes. This 36kDa protein is encoded by the gene plcA, and is homologous to the Bacillus cereus, Bacillus thuringiensis and eukaryotic phosphatidylinositol-specific phospholipases C (PI-PLC). Expression of the plcA gene in Escherichia coli correlates with the appearance of PI-PLC activity in the cells. In Listeria monocytogenes, the activity is secreted to the culture medium. PI-PLC activity was only found in the two pathogenic species of the genus Listeria, namely L. monocytogenes and L. ivanovii. PI-PLC activity was lost and virulence decreased when the plcA gene was disrupted in the chromosome. This suggests that the PI-PLC of L. monocytogenes might be involved in virulence.
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  • 2
    ISSN: 1365-2958
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology , Medicine
    Notes: Listeriotysjn O (LLO), a major virulence factor of the intracellular bacterium Listens monocytogenes, shares with other known ‘thiol-activated toxins’ a conserved undecapeptide, ECTGLAWEWWR, located in the C-terminal region of the protein and containing the unique cysteine of the molecule. Single amino acid substitutions were created in this region to study the role of cysteine and tryptophan residues in the lytic activity of LLO as well as in the virulence of the bacterium. Transformation of a transposon-induced non-haemolytic mutant with plasmids carrying the mutated genes allowed allele exchange and transfer of mutations on to the chromosome by in vivo recombination. The mutant strains secreted a full-length 59 kilodalton LLO. A decrease of 25% in the haemolytic activity in culture supernatants was observed in the case of mutation Cys-484 to Ala and of 80% for mutation Cys-484 to Ser. Mutations Trp-491 and Trp-492 to Ala decreased activity by, respectively, 95% and 99.9%. LLOs produced by the mutants, as the wild type, were active at low pH, inhibited by cholesterol, and able to bind to cell membranes. A close relationship was found between virulence of mutants in the mouse model and haemolytic activity in their culture supematants. These results demonstrate that the thiol group of Cys-484 is not essential for either haemolytic activity in vitro or virulence in vivo. In contrast, Trp-492 appears to be required for both haemolytic activity and virulence. The finding that the nearly non-haemolytic mutant Trp-492-Ala persisted in the spleen for several days after inoculation indicates that mutagenesis of a virulence determinant can attenuate virulence and provides a novel approach to the development of live vaccine strains.
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  • 3
    Electronic Resource
    Electronic Resource
    Oxford, UK : Blackwell Publishing Ltd
    Molecular microbiology 9 (1993), S. 0 
    ISSN: 1365-2958
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology , Medicine
    Type of Medium: Electronic Resource
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  • 4
    ISSN: 1365-2958
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology , Medicine
    Notes: Entry of Listeria monocytogenes into epithelial cells requires expression of inlA, the first gene of an operon comprising two genes: inlA, which encodes internalin, a 800-amino-acid protein, and inlB, which encodes a 630-amino-acid protein. We report here that the inl locus is transcribed on two transcripts in constant relative ratio: a 5 kb transcript spanning inlA and inlB, and a 2.9 kb transcript that covers only inlA. The promoter is located 397 bp from the GTG initiator of inlA and displays in its -35 region a palindrome similar to that found in promoters controlled by the pleiotropic activator prfA. Transcription of the inl locus is, as are several other L. monocytogenes virulence genes, activated by prfA and regulated by temperature—with higher expression at 37°C versus 25°C — and bacterial growth state. It is maximal during exponential growth and correlates with maximal invasivity of the bacteria in the human epithelial cell line Caco-2. It also correlates with maximum amounts of internalin present on the bacterial surface. Internalin is also detected in substantial amounts in culture supernatants. Taken together, these data suggest that surface-bound internalin plays an important role in bacterial entry but do not exclude a role for the released form.
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  • 5
    ISSN: 1365-2958
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology , Medicine
    Notes: Evidence for ptelotropic activation of virulence genes in Listeria monocytogenes is presented. A complementation study of a spontaneous prfA-deletion mutant and analysis of cassette and transposon insertion mutants showed that the gene prfA activates the transcription of four independent genes which code for a phosphatidyl-inositol-specific phospholipase C (gene plcA), listeriolysin O (gene hlyA), a metallo-protease (gene prtA) and a lecithinase (gene prtC). Transcription of prfA is not constitutive. During the growth phase, two peaks of prfA transcript accumulation were observed: the first was during exponential growth, and the second was at the beginning of the stationary phase. In addition, two prf4-specific transcripts of 2.2 kb and 1 kb are detected. Early in exponential growth, prfA is co-transcribed with plcA which lies upstream prfA, giving rise to the 2.2 kb plcA-prfA transcript. In late-exponential growth and at the beginning of the stationary phase, prfA transcripts of 1 kb are predominantly detected. Our results demonstrate that since prfA controls plcA transcription, it also regulates its own synthesis.
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  • 6
    ISSN: 1574-6968
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology
    Notes: Through the analysis of a non-motile mutant of Listeria monocytogenes, we identified and characterized a locus containing the cheR, motA and motB genes. These three genes are homologous to the cheR, and motA/B genes of Bacillus subtilis which in this organism are 954 kb apart. The gene organization in Listeria is also not similar either to that of Escherichia coli in which cheR and motAB are 5.9 kb apart. CheR and motA/B, as previously reported for flaA, the flagellin gene, are thermoregulated with a higher expression at 25°C and low expression at 37°C. In a ΔprfA strain, motA expression was derepressed at 37°C, suggesting that PrfA, the transcriptional activator of virulence genes, downregulates motility genes in Listeria at 37°C.
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  • 7
    Publication Date: 2013-08-03
    Description: Pathogens dramatically affect host cell transcription programs for their own profit during infection, but in most cases, the underlying mechanisms remain elusive. We found that during infection with the bacterium Listeria monocytogenes, the host deacetylase sirtuin 2 (SIRT2) translocates to the nucleus, in a manner dependent on the bacterial factor InlB. SIRT2 associates with the transcription start site of a subset of genes repressed during infection and deacetylates histone H3 on lysine 18 (H3K18). Infecting cells in which SIRT2 activity was blocked or using SIRT2(-/-) mice resulted in a significant impairment of bacterial infection. Thus, SIRT2-mediated H3K18 deacetylation plays a critical role during infection, which reveals an epigenetic mechanism imposed by a pathogenic bacterium to reprogram its host.〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Eskandarian, Haig A -- Impens, Francis -- Nahori, Marie-Anne -- Soubigou, Guillaume -- Coppee, Jean-Yves -- Cossart, Pascale -- Hamon, Melanie A -- New York, N.Y. -- Science. 2013 Aug 2;341(6145):1238858. doi: 10.1126/science.1238858.〈br /〉〈span class="detail_caption"〉Author address: 〈/span〉Unite des Interactions Bacteries-Cellules, Institut Pasteur, Paris, France.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/23908241" target="_blank"〉PubMed〈/a〉
    Keywords: Acetylation ; Animals ; Bacterial Proteins/genetics ; Cell Nucleus/metabolism ; Chromatin/metabolism ; Cytosol/metabolism ; HeLa Cells ; Histones/genetics/*metabolism ; Host-Pathogen Interactions ; Humans ; Listeria monocytogenes/genetics/*pathogenicity ; Listeriosis/*genetics/*metabolism/microbiology ; Lysine/genetics/metabolism ; Membrane Proteins/genetics ; Mice ; Mice, Inbred BALB C ; Mice, Knockout ; Protein Processing, Post-Translational ; Proto-Oncogene Proteins c-met/metabolism ; Sirtuin 2/genetics/*metabolism ; Transcription Initiation Site ; *Transcriptional Activation
    Print ISSN: 0036-8075
    Electronic ISSN: 1095-9203
    Topics: Biology , Chemistry and Pharmacology , Computer Science , Medicine , Natural Sciences in General , Physics
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  • 8
    Publication Date: 2016-04-28
    Description: Riboswitches and attenuators are cis-regulatory RNA elements, most of which control bacterial gene expression via metabolite-mediated, premature transcription termination. We developed an unbiased experimental approach for genome-wide discovery of such ribo-regulators in bacteria. We also devised an experimental platform that quantitatively measures the in vivo activity of all such regulators in parallel and enables rapid screening for ribo-regulators that respond to metabolites of choice. Using this approach, we detected numerous antibiotic-responsive ribo-regulators that control antibiotic resistance genes in pathogens and in the human microbiome. Studying one such regulator in Listeria monocytogenes revealed an attenuation mechanism mediated by antibiotic-stalled ribosomes. Our results expose broad roles for conditional termination in regulating antibiotic resistance and provide a tool for discovering riboswitches and attenuators that respond to previously unknown ligands.〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Dar, Daniel -- Shamir, Maya -- Mellin, J R -- Koutero, Mikael -- Stern-Ginossar, Noam -- Cossart, Pascale -- Sorek, Rotem -- New York, N.Y. -- Science. 2016 Apr 8;352(6282):aad9822. doi: 10.1126/science.aad9822.〈br /〉〈span class="detail_caption"〉Author address: 〈/span〉Department of Molecular Genetics, Weizmann Institute of Science, Rehovot 76100, Israel. ; Institut Pasteur, Unite des Interactions Bacteries-Cellules, Paris, F-75015 France. INSERM, U604, Paris, F-75015 France. Institut National de la Recherche Agronomique, USC2020, Paris, F-75015 France. ; Department of Molecular Genetics, Weizmann Institute of Science, Rehovot 76100, Israel. rotem.sorek@weizmann.ac.il.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/27120414" target="_blank"〉PubMed〈/a〉
    Keywords: 3' Untranslated Regions/genetics ; Anti-Bacterial Agents/pharmacology ; Bacillus subtilis/drug effects/genetics ; Drug Resistance, Bacterial/*genetics ; Enterococcus faecalis/drug effects ; Gastrointestinal Microbiome/drug effects/genetics ; *Gene Expression Regulation, Bacterial ; Genome, Bacterial/genetics ; Genome-Wide Association Study/*methods ; High-Throughput Nucleotide Sequencing/*methods ; Humans ; Listeria monocytogenes/drug effects/genetics ; Ribosomes/metabolism ; Riboswitch/*genetics ; Sequence Analysis, RNA/methods ; *Transcription Termination, Genetic
    Print ISSN: 0036-8075
    Electronic ISSN: 1095-9203
    Topics: Biology , Chemistry and Pharmacology , Computer Science , Medicine , Natural Sciences in General , Physics
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  • 9
    Publication Date: 2011-01-22
    Description: Intracellular pathogens such as Listeria monocytogenes subvert cellular functions through the interaction of bacterial effectors with host components. Here we found that a secreted listerial virulence factor, LntA, could target the chromatin repressor BAHD1 in the host cell nucleus to activate interferon (IFN)-stimulated genes (ISGs). IFN-lambda expression was induced in response to infection of epithelial cells with bacteria lacking LntA; however, the BAHD1-chromatin associated complex repressed downstream ISGs. In contrast, in cells infected with lntA-expressing bacteria, LntA prevented BAHD1 recruitment to ISGs and stimulated their expression. Murine listeriosis decreased in BAHD1(+/-) mice or when lntA was constitutively expressed. Thus, the LntA-BAHD1 interplay may modulate IFN-lambda-mediated immune response to control bacterial colonization of the host.〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Lebreton, Alice -- Lakisic, Goran -- Job, Viviana -- Fritsch, Lauriane -- Tham, To Nam -- Camejo, Ana -- Mattei, Pierre-Jean -- Regnault, Beatrice -- Nahori, Marie-Anne -- Cabanes, Didier -- Gautreau, Alexis -- Ait-Si-Ali, Slimane -- Dessen, Andrea -- Cossart, Pascale -- Bierne, Helene -- 233348/European Research Council/International -- New York, N.Y. -- Science. 2011 Mar 11;331(6022):1319-21. doi: 10.1126/science.1200120. Epub 2011 Jan 20.〈br /〉〈span class="detail_caption"〉Author address: 〈/span〉Institut Pasteur, Unite des Interactions Bacteries Cellules, Paris, France.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/21252314" target="_blank"〉PubMed〈/a〉
    Keywords: Amino Acid Sequence ; Animals ; Cell Line ; Cell Line, Tumor ; Cell Nucleus/metabolism ; Chromatin/*metabolism ; Chromosomal Proteins, Non-Histone/*metabolism ; Down-Regulation ; Gene Expression Profiling ; Gene Expression Regulation ; Host-Pathogen Interactions ; Humans ; Interferons/genetics/immunology/*metabolism ; Interleukins/genetics/immunology/*metabolism ; Listeria monocytogenes/genetics/metabolism/*pathogenicity ; Listeriosis/*immunology/microbiology ; Mice ; Mice, Inbred BALB C ; Mice, Inbred C57BL ; Molecular Sequence Data ; Signal Transduction ; Virulence Factors/chemistry/genetics/*metabolism
    Print ISSN: 0036-8075
    Electronic ISSN: 1095-9203
    Topics: Biology , Chemistry and Pharmacology , Computer Science , Medicine , Natural Sciences in General , Physics
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  • 10
    Publication Date: 2014-08-26
    Description: Riboswitches are ligand-binding elements contained within the 5' untranslated regions of bacterial transcripts, which generally regulate expression of downstream open reading frames. Here, we show that in Listeria monocytogenes, a riboswitch that binds vitamin B12 controls expression of a noncoding regulatory RNA, Rli55. Rli55, in turn, controls expression of the eut genes, whose products enable ethanolamine utilization and require B12 as a cofactor. Defects in ethanolamine utilization, or in its regulation by Rli55, significantly attenuate Listeria virulence in mice. Rli55 functions by sequestering the two-component response regulator EutV by means of a EutV-binding site contained within the RNA. Thus, Rli55 is a riboswitch-regulated member of the small group of regulatory RNAs that function by sequestering a protein and reveals a distinctive mechanism of signal integration in bacterial gene regulation.〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Mellin, J R -- Koutero, Mikael -- Dar, Daniel -- Nahori, Marie-Anne -- Sorek, Rotem -- Cossart, Pascale -- Howard Hughes Medical Institute/ -- New York, N.Y. -- Science. 2014 Aug 22;345(6199):940-3. doi: 10.1126/science.1255083.〈br /〉〈span class="detail_caption"〉Author address: 〈/span〉Unite des Interactions Bacteries-Cellules, Institut Pasteur, F-75015 Paris, France. INSERM, U604, Paris, F-75015 France. INRA, USC2020, F-75015 Paris, France. ; Department of Molecular Genetics, Weizmann Institute of Science, Rehovot, Israel. ; Unite des Interactions Bacteries-Cellules, Institut Pasteur, F-75015 Paris, France. INSERM, U604, Paris, F-75015 France. INRA, USC2020, F-75015 Paris, France. pcossart@pasteur.fr.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/25146292" target="_blank"〉PubMed〈/a〉
    Keywords: 5' Untranslated Regions ; Animals ; Ethanolamine/*metabolism ; *Gene Expression Regulation, Bacterial ; Listeria monocytogenes/*genetics/metabolism/virology ; Mice ; Mice, Inbred BALB C ; Operon ; RNA, Untranslated/*metabolism ; Response Elements ; *Riboswitch ; Vitamin B 12/*metabolism
    Print ISSN: 0036-8075
    Electronic ISSN: 1095-9203
    Topics: Biology , Chemistry and Pharmacology , Computer Science , Medicine , Natural Sciences in General , Physics
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