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  • 1
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    Bacteria hijack integrin-linked kinase to stabilize focal adhesions and block cell detachment (2009)
    Nature Publishing Group (NPG)
    Details
    Publication Date: 2009-06-03
    Description: The rapid turnover and exfoliation of mucosal epithelial cells provides an innate defence system against bacterial infection. Nevertheless, many pathogenic bacteria, including Shigella, are able to surmount exfoliation and colonize the epithelium efficiently. Here we show that the Shigella flexneri effector OspE (consisting of OspE1 and OspE2 proteins), which is highly conserved among enteropathogenic Escherichia coli, enterohaemorrhagic E. coli, Citrobacter rodentium and Salmonella strains, reinforces host cell adherence to the basement membrane by interacting with integrin-linked kinase (ILK). The number of focal adhesions was augmented along with membrane fraction ILK by ILK-OspE binding. The interaction between ILK and OspE increased cell surface levels of 1 integrin and suppressed phosphorylation of focal adhesion kinase and paxillin, which are required for rapid turnover of focal adhesion in cell motility. Nocodazole-washout-induced focal adhesion disassembly was blocked by expression of OspE. Polarized epithelial cells infected with a Shigella mutant lacking the ospE gene underwent more rapid cell detachment than cells infected with wild-type Shigella. Infection of guinea pig colons with Shigella corroborated the pivotal role of the OspE-ILK interaction in suppressing epithelial detachment, increasing bacterial cell-to-cell spreading, and promoting bacterial colonization. These results indicate that Shigella sustain their infectious foothold by using special tactics to prevent detachment of infected cells.〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Kim, Minsoo -- Ogawa, Michinaga -- Fujita, Yukihiro -- Yoshikawa, Yuko -- Nagai, Takeshi -- Koyama, Tomohiro -- Nagai, Shinya -- Lange, Anika -- Fassler, Reinhard -- Sasakawa, Chihiro -- England -- Nature. 2009 May 28;459(7246):578-82. doi: 10.1038/nature07952.〈br /〉〈span class="detail_caption"〉Author address: 〈/span〉Department of Infectious Disease Control, International Research Center for Infectious Diseases, University of Tokyo, 4-6-1, Shirokanedai, Minato-ku, Tokyo 108-8639, Japan.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/19489119" target="_blank"〉PubMed〈/a〉
    Keywords: Animals ; Antigens, CD29/metabolism ; Bacterial Outer Membrane Proteins/genetics/metabolism ; Cell Adhesion/drug effects/*physiology ; Cell Polarity ; Colon/microbiology ; Epithelial Cells/cytology/microbiology ; Focal Adhesions/drug effects/*physiology ; Guinea Pigs ; HeLa Cells ; Humans ; Mice ; Nocodazole/pharmacology ; Phosphorylation ; Protein Binding ; Protein-Serine-Threonine Kinases/*metabolism ; Shigella flexneri/pathogenicity/*physiology ; Virulence Factors/deficiency/genetics/metabolism
    Print ISSN: 0028-0836
    Electronic ISSN: 1476-4687
    Topics: Biology , Chemistry and Pharmacology , Medicine , Natural Sciences in General , Physics
    Published by Nature Publishing Group (NPG)
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  • 2
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    Innate lymphoid cells regulate intestinal epithelial cell glycosylation (2014)
    American Association for the Advancement of Science (AAAS)
    Details
    Publication Date: 2014-09-13
    Description: Fucosylation of intestinal epithelial cells, catalyzed by fucosyltransferase 2 (Fut2), is a major glycosylation mechanism of host-microbiota symbiosis. Commensal bacteria induce epithelial fucosylation, and epithelial fucose is used as a dietary carbohydrate by many of these bacteria. However, the molecular and cellular mechanisms that regulate the induction of epithelial fucosylation are unknown. Here, we show that type 3 innate lymphoid cells (ILC3) induced intestinal epithelial Fut2 expression and fucosylation in mice. This induction required the cytokines interleukin-22 and lymphotoxin in a commensal bacteria-dependent and -independent manner, respectively. Disruption of intestinal fucosylation led to increased susceptibility to infection by Salmonella typhimurium. Our data reveal a role for ILC3 in shaping the gut microenvironment through the regulation of epithelial glycosylation.〈br /〉〈br /〉〈a href="https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4774895/" target="_blank"〉〈img src="https://static.pubmed.gov/portal/portal3rc.fcgi/4089621/img/3977009" border="0"〉〈/a〉   〈a href="https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4774895/" target="_blank"〉This paper as free author manuscript - peer-reviewed and accepted for publication〈/a〉〈br /〉〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Goto, Yoshiyuki -- Obata, Takashi -- Kunisawa, Jun -- Sato, Shintaro -- Ivanov, Ivaylo I -- Lamichhane, Aayam -- Takeyama, Natsumi -- Kamioka, Mariko -- Sakamoto, Mitsuo -- Matsuki, Takahiro -- Setoyama, Hiromi -- Imaoka, Akemi -- Uematsu, Satoshi -- Akira, Shizuo -- Domino, Steven E -- Kulig, Paulina -- Becher, Burkhard -- Renauld, Jean-Christophe -- Sasakawa, Chihiro -- Umesaki, Yoshinori -- Benno, Yoshimi -- Kiyono, Hiroshi -- 1R01DK098378/DK/NIDDK NIH HHS/ -- R01 DK098378/DK/NIDDK NIH HHS/ -- New York, N.Y. -- Science. 2014 Sep 12;345(6202):1254009. doi: 10.1126/science.1254009. Epub 2014 Aug 21.〈br /〉〈span class="detail_caption"〉Author address: 〈/span〉Division of Mucosal Immunology, Department of Microbiology and Immunology, The Institute of Medical Science, The University of Tokyo, Tokyo 108-8639, Japan. Core Research for Evolutional Science and Technology, Japan Science and Technology Agency, Saitama 332-0012, Japan. Microbe Division/Japan Collection of Microorganisms, RIKEN BioResource Center, Tsukuba 305-0074, Japan. ; Division of Mucosal Immunology, Department of Microbiology and Immunology, The Institute of Medical Science, The University of Tokyo, Tokyo 108-8639, Japan. Microbe Division/Japan Collection of Microorganisms, RIKEN BioResource Center, Tsukuba 305-0074, Japan. ; Division of Mucosal Immunology, Department of Microbiology and Immunology, The Institute of Medical Science, The University of Tokyo, Tokyo 108-8639, Japan. Laboratory of Vaccine Materials, National Institute of Biomedical Innovation, Osaka 567-0085, Japan. Division of Mucosal Immunology, International Research and Development Center for Mucosal Vaccines, The Institute of Medical Science, The University of Tokyo, Tokyo 108-8639, Japan. ; Division of Mucosal Immunology, Department of Microbiology and Immunology, The Institute of Medical Science, The University of Tokyo, Tokyo 108-8639, Japan. Core Research for Evolutional Science and Technology, Japan Science and Technology Agency, Saitama 332-0012, Japan. ; Department of Microbiology and Immunology, Columbia University Medical Center, New York, NY 10032, USA. ; Division of Mucosal Immunology, Department of Microbiology and Immunology, The Institute of Medical Science, The University of Tokyo, Tokyo 108-8639, Japan. ; Division of Mucosal Immunology, Department of Microbiology and Immunology, The Institute of Medical Science, The University of Tokyo, Tokyo 108-8639, Japan. Nippon Institute for Biological Science, Tokyo 198-0024, Japan. ; Microbe Division/Japan Collection of Microorganisms, RIKEN BioResource Center, Tsukuba 305-0074, Japan. ; Yakult Central Institute, Tokyo 186-8650, Japan. ; Division of Innate Immune Regulation, International Research and Development Center for Mucosal Vaccines, The Institute of Medical Science, The University of Tokyo, Tokyo 108-8639, Japan. Department of Mucosal Immunology, School of Medicine, Chiba University, 1-8-1 Inohana, Chuou-ku, Chiba, 260-8670, Japan. ; Laboratory of Host Defense, WPI Immunology Frontier Research Center, Osaka University, Osaka 565-0871, Japan. ; Department of Obstetrics and Gynecology, Cellular and Molecular Biology Program, University of Michigan Medical Center, Ann Arbor, MI 48109-5617, USA. ; Institute of Experimental Immunology, University of Zurich, Winterthurerstrasse 190, Zurich CH-8057, Switzerland. ; Ludwig Institute for Cancer Research and Universite Catholique de Louvain, Brussels B-1200, Belgium. ; Nippon Institute for Biological Science, Tokyo 198-0024, Japan. Division of Bacterial Infection, The Institute of Medical Science, The University of Tokyo, Tokyo 108-8639, Japan. Medical Mycology Research Center, Chiba University, Chiba 260-8673, Japan. ; Benno Laboratory, Innovation Center, RIKEN, Wako, Saitama 351-0198, Japan. ; Division of Mucosal Immunology, Department of Microbiology and Immunology, The Institute of Medical Science, The University of Tokyo, Tokyo 108-8639, Japan. Core Research for Evolutional Science and Technology, Japan Science and Technology Agency, Saitama 332-0012, Japan. Division of Mucosal Immunology, International Research and Development Center for Mucosal Vaccines, The Institute of Medical Science, The University of Tokyo, Tokyo 108-8639, Japan.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/25214634" target="_blank"〉PubMed〈/a〉
    Keywords: Animals ; Base Sequence ; Disease Models, Animal ; Fucose/*metabolism ; Fucosyltransferases/genetics/metabolism ; Germ-Free Life ; Glycosylation ; Goblet Cells/enzymology/immunology/microbiology ; Ileum/enzymology/immunology/microbiology ; *Immunity, Innate ; Interleukins/immunology ; Intestinal Mucosa/enzymology/*immunology/microbiology ; Lymphocytes/*immunology ; Mice ; Mice, Inbred BALB C ; Mice, Inbred C57BL ; Mice, Mutant Strains ; Microbiota/*immunology ; Molecular Sequence Data ; Paneth Cells/enzymology/immunology/microbiology ; Salmonella Infections/*immunology/microbiology ; *Salmonella typhimurium
    Print ISSN: 0036-8075
    Electronic ISSN: 1095-9203
    Topics: Biology , Chemistry and Pharmacology , Computer Science , Medicine , Natural Sciences in General , Physics
    Published by American Association for the Advancement of Science (AAAS)
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  • 3
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    Escape of intracellular Shigella from autophagy (2004)
    American Association for the Advancement of Science (AAAS)
    Details
    Publication Date: 2004-12-04
    Description: The degradation of undesirable cellular components or organelles, including invading microbes, by autophagy is crucial for cell survival. Here, Shigella, an invasive bacteria, was found to be able to escape autophagy by secreting IcsB by means of the type III secretion system. Mutant bacteria lacking IcsB were trapped by autophagy during multiplication within the host cells. IcsB did not directly inhibit autophagy. Rather, Shigella VirG, a protein required for intracellular actin-based motility, induced autophagy by binding to the autophagy protein, Atg5. In nonmutant Shigella, this binding is competitively inhibited by IcsB binding to VirG.〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Ogawa, Michinaga -- Yoshimori, Tamotsu -- Suzuki, Toshihiko -- Sagara, Hiroshi -- Mizushima, Noboru -- Sasakawa, Chihiro -- New York, N.Y. -- Science. 2005 Feb 4;307(5710):727-31. Epub 2004 Dec 2.〈br /〉〈span class="detail_caption"〉Author address: 〈/span〉Department of Microbiology and Immunology, Institute of Medical Science, University of Tokyo, 4-6-1, Shirokanedai, Minato-ku, Tokyo 108-8639, Japan.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/15576571" target="_blank"〉PubMed〈/a〉
    Keywords: Animals ; *Autophagy ; Bacterial Proteins/genetics/*metabolism ; Cell Line ; DNA-Binding Proteins/*metabolism ; Humans ; Mice ; Mice, Knockout ; Microscopy, Electron ; Microtubule-Associated Proteins/metabolism ; Phagosomes/metabolism/*microbiology/ultrastructure ; Protein Binding ; Recombinant Fusion Proteins/metabolism ; Shigella flexneri/genetics/growth & development/metabolism/*pathogenicity ; Transcription Factors/*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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  • 4
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    The Shigella flexneri effector OspI deamidates UBC13 to dampen the inflammatory response (2012)
    Nature Publishing Group (NPG)
    Details
    Publication Date: 2012-03-13
    Description: Many bacterial pathogens can enter various host cells and then survive intracellularly, transiently evade humoral immunity, and further disseminate to other cells and tissues. When bacteria enter host cells and replicate intracellularly, the host cells sense the invading bacteria as damage-associated molecular patterns (DAMPs) and pathogen-associated molecular patterns (PAMPs) by way of various pattern recognition receptors. As a result, the host cells induce alarm signals that activate the innate immune system. Therefore, bacteria must modulate host inflammatory signalling and dampen these alarm signals. How pathogens do this after invading epithelial cells remains unclear, however. Here we show that OspI, a Shigella flexneri effector encoded by ORF169b on the large plasmid and delivered by the type IotaIotaIota secretion system, dampens acute inflammatory responses during bacterial invasion by suppressing the tumour-necrosis factor (TNF)-receptor-associated factor 6 (TRAF6)-mediated signalling pathway. OspI is a glutamine deamidase that selectively deamidates the glutamine residue at position 100 in UBC13 to a glutamic acid residue. Consequently, the E2 ubiquitin-conjugating activity required for TRAF6 activation is inhibited, allowing S. flexneri OspI to modulate the diacylglycerol-CBM (CARD-BCL10-MALT1) complex-TRAF6-nuclear-factor-kappaB signalling pathway. We determined the 2.0 A crystal structure of OspI, which contains a putative cysteine-histidine-aspartic acid catalytic triad. A mutational analysis showed this catalytic triad to be essential for the deamidation of UBC13. Our results suggest that S. flexneri inhibits acute inflammatory responses in the initial stage of infection by targeting the UBC13-TRAF6 complex.〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Sanada, Takahito -- Kim, Minsoo -- Mimuro, Hitomi -- Suzuki, Masato -- Ogawa, Michinaga -- Oyama, Akiho -- Ashida, Hiroshi -- Kobayashi, Taira -- Koyama, Tomohiro -- Nagai, Shinya -- Shibata, Yuri -- Gohda, Jin -- Inoue, Jun-ichiro -- Mizushima, Tsunehiro -- Sasakawa, Chihiro -- England -- Nature. 2012 Mar 11;483(7391):623-6. doi: 10.1038/nature10894.〈br /〉〈span class="detail_caption"〉Author address: 〈/span〉Department of Infectious Disease Control, International Research Center for Infectious Diseases, University of Tokyo, Minato-ku, Tokyo 108-8639, Japan.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/22407319" target="_blank"〉PubMed〈/a〉
    Keywords: *Adaptor Proteins, Signal Transducing/metabolism ; Amidohydrolases/*chemistry/genetics/*metabolism ; Amino Acid Sequence ; Animals ; Aspartic Acid/metabolism ; Biocatalysis ; Caspases/metabolism ; Catalytic Domain/genetics ; Crystallography, X-Ray ; Cysteine/metabolism ; DNA Mutational Analysis ; Diglycerides/antagonists & inhibitors/metabolism ; Dysentery, Bacillary/microbiology ; Glutamic Acid/metabolism ; Glutamine/metabolism ; HEK293 Cells ; HeLa Cells ; Histidine/metabolism ; Humans ; Immunity, Innate ; Inflammation/enzymology/*immunology/*metabolism ; Mice ; Models, Molecular ; Molecular Sequence Data ; NF-kappa B/metabolism ; Neoplasm Proteins/metabolism ; Shigella flexneri/*enzymology/genetics/*immunology/pathogenicity ; TNF Receptor-Associated Factor 6/deficiency/genetics/metabolism ; Ubiquitin-Conjugating Enzymes/chemistry/genetics/*metabolism ; Virulence Factors/metabolism
    Print ISSN: 0028-0836
    Electronic ISSN: 1476-4687
    Topics: Biology , Chemistry and Pharmacology , Medicine , Natural Sciences in General , Physics
    Published by Nature Publishing Group (NPG)
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  • 5
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    Microtubule-severing activity of Shigella is pivotal for intercellular spreading (2006)
    American Association for the Advancement of Science (AAAS)
    Details
    Publication Date: 2006-11-11
    Description: Some pathogenic bacteria actually invade the cytoplasm of their target host cells. Invasive bacteria acquire the propulsive force to move by recruiting actin and inducing its polymerization. Here we show that Shigella movement within the cytoplasm was severely hindered by microtubules and that the bacteria destroyed surrounding microtubules by secreting VirA by means of the type III secretion system. Degradation of microtubules by VirA was dependent on its alpha-tubulin-specific cysteine protease-like activity. virA mutants did not move within the host cytoplasm and failed to move into adjacent cells.〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Yoshida, Sei -- Handa, Yutaka -- Suzuki, Toshihiko -- Ogawa, Michinaga -- Suzuki, Masato -- Tamai, Asuka -- Abe, Akio -- Katayama, Eisaku -- Sasakawa, Chihiro -- New York, N.Y. -- Science. 2006 Nov 10;314(5801):985-9.〈br /〉〈span class="detail_caption"〉Author address: 〈/span〉Department of Microbiology and Immunology, International Research Center for Infectious Diseases, Institute of Medical Science, University of Tokyo, 4-6-1, Shirokanedai, Minato-ku, Tokyo 108-8639, Japan.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/17095701" target="_blank"〉PubMed〈/a〉
    Keywords: Actins/metabolism ; Animals ; COS Cells ; Cercopithecus aethiops ; Cysteine Endopeptidases/*metabolism ; Cytoplasm/*microbiology ; Dysentery, Bacillary/microbiology ; Mice ; Mice, Inbred C57BL ; Microscopy, Fluorescence ; Microtubules/drug effects/*metabolism/ultrastructure ; Movement ; Mutation ; Nocodazole/pharmacology ; Shigella flexneri/enzymology/genetics/*pathogenicity/*physiology ; Tubulin/*metabolism ; Virulence Factors/*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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  • 6
    Electronic Resource
    Electronic Resource
    The absence of a surface protease, OmpT, determines the intercellular spreading ability of Shigella: the relationship between the ompT and kcpA loci (1993)
    Oxford, UK : Blackwell Publishing Ltd
    Molecular microbiology 9 (1993), S. 0 
    Details
    ISSN: 1365-2958
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology , Medicine
    Notes: A large plasmid-encoded protein, VirG, on the bacterial surface is essential for the spreading of Shigella by eliciting polar deposition of filamentous actin In the cytoplasm of epithelial cells. VirG expression from the large plasmid is diminished greatly when it is introduced into Escherichia coli K-12 from Shigella. In an attempt to identify factors affecting VirG expression, we found that the absence of the ompT gene, encoding outer membrane protease OmpT, restored full production of VirG protein to E. coli K-12. Conversely, upon introduction of the ompT gene of E. coii K-12 into Shigella, spreading ability was completely abolished, probably because of the proteolytic degradation of VirG protein by OmpT. Analysis of the DNA sequence of the ompT region indicated that the absence of the ompT gene occurred in Shigella and enteroinvasive E. coli strains, and that the absent DNA segment corresponded to a remnant lambdoid phage structure found in E. coli K-12, which encompasses a 21 kb DNA segment spanning from argU through to the ompT genes. Since ompT is located near purE in E. coli K-12 and a virulence locus for provoking keratocon-junctivitis in the eyes of guinea-pigs, named kcpA is located near purE in S. fiexnerl, and the two loci are involved in VirG expression, the KcpA∼ mutants of S. flexneri 2a constructed were examined for correlation between acquisition of ompT and VirG degradation. Our data suggest that the previous recognition of a kcpA locus in S. flexneri is the result of transfer of the ompr gene from E. coli K-12, giving rise to a KcpA phenotype. These results indicate that the lack of OmpT protease confers upon Shigella the ability to spread into adjacent epithelial cells.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1365-2958.1993.tb01707.x
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  • 7
    Electronic Resource
    Electronic Resource
    Identification and characterization of virK, a virulence-associated large plasmid gene essential for intercellular spreading of Shigella flexneri (1992)
    Oxford, UK : Blackwell Publishing Ltd
    Molecular microbiology 6 (1992), S. 0 
    Details
    ISSN: 1365-2958
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology , Medicine
    Notes: Seven virulence loci have been identified by Tn5 insertion mutagenesis on the large 230 kb plasmid (pMYSH6000) of Shigella flexneri 2a. In this study, we used Tn10 insertion mutagenesis and identified a novel virulence locus on pMYSH6000 responsible for bacterial spread. Characterization of the invading bacteria of the Tn10 insertion mutants in the epithelial cells revealed that the bacteria were capable of at least some intracellular spreading but not intercellular spreading. Immunoblot analysis of lysates of the Tn10 insertion mutants with a VirG-specific antipeptide antibody revealed diminished levels of the 116 kDa VirG protein. The virG mRNA in the mutants, however, was expressed at the same level as that in the wild type. The DNA region required for the virulence phenotype was localized to a 1.6 kb DNA sequence in the Sal I-K fragment on the plasmid, and thus the locus was designated virK. Expression of virK in Escherichia coli using a T7 RNA polymerase-dependent promoter system yielded a 36 kDa protein. The nucleotide sequence of 1642 bp encoding VirK function was determined, and an open reading frame encoding 316 amino acid residues was shown to encode the VirK protein. The virK region was highly conserved among the large virulence plasmids of shigellae and enteroinvasive Escherichia coli. These results suggest that VirK function is an essential virulence determinant for shigellae Involved in the expression of virG gene product at post-transcriptional level.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1365-2958.1992.tb01413.x
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  • 8
    Electronic Resource
    Electronic Resource
    Construction of a physical map of the chromosome of Shigella flexneri 2a and the direct assignment of nine virulence-associated loci identified by Tn5 insertions (1991)
    Oxford, UK : Blackwell Publishing Ltd
    Molecular microbiology 5 (1991), S. 0 
    Details
    ISSN: 1365-2958
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology , Medicine
    Notes: To establish the molecular basis of the chromosomal virulence genes of Shigella flexneri 2a (YSH6000), a Notl restriction map of the chromosome was constructed by exploiting Notl-linking clones, partial Notl digestion and DNA probes from various genes of Escherichia coli K-12. The map revealed at least three local differences in the placements of genes between YSH6000 and E. coli K-12. Using the additional Notl sites introduced by Tn5 insertion, nine virulence loci Identified previously by random Tn5 insertions were physically mapped on the chromosome. To demonstrate the versatility of the Notl map in direct assignment of the virulence loci tagged by Tn5 to a known genetic region in E. coli K-12, the major class of avirulent mutants defective in the core structure of lipopolysaccharide (LPS) was examined for the sites of Tn5 insertions. The two Notl segments created by the Tn5 insertion in the Notl fragment were analysed by Southern blotting with two DNA probes for the 5′ and 3’flanking regions of the rfa region, and shown to hybridize separately with each of them, confirming the sites of Tn5 in the rfa locus. This approach will facilitate direct comparison of genetically mapped Tn5 insertion mutations of S. flexneri with genes physically determined in E. coli K-12.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1365-2958.1991.tb02147.x
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  • 9
    Electronic Resource
    Electronic Resource
    Functional organization and nucleotide sequence of virulence Region-2 on the large virulence plasmid in Shigella flexneri 2a (1989)
    Oxford, UK : Blackwell Publishing Ltd
    Molecular microbiology 3 (1989), S. 0 
    Details
    ISSN: 1365-2958
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology , Medicine
    Notes: The 7kb virulence Region-2 of the large (virulence) plasmid in Shigella flexneri 2a encodes several proteins required for invasion of intestinal epithelial cells. Insertion and deletion mutagenesis, DNA subcloning and SDS-polyacrylamide gel electro-phoresis of proteins synthesized in minicells demonstrated five genes in this region. They encode 24, 18, 62 (lpaB), 41 (lpaC) and 37 (lpaD)-kiloDalton (kD) proteins. Complementation of Tn5-induced mutations in Region-2 with the above plasmid constructs indicated that Region-2 consists of two operons and that the three lpa proteins are essential for the virulence phenotype. The transcriptional organization determined by Northern blotting, S1 nuclease protection and the effect of Tn5 insertions on expression of the lpa proteins revealed that Region-2 has three promoters that transcribe RNAs of 4.0, 4.5 and 7.5kb. The 4.0 kb RNA was the transcript for the operon encoding the 24, 18 kD, lpaB and C proteins and the 4.5 kb RNA for the ipsD gene. In addition, the full-length RNA of 7.5 kb which covers Region-2 supplemented full expression of the lpa proteins. The 7663 nucleotides of Region-2 were determined to confirm the five open reading frames encoding 23655, 17755, 62168, 41077 and 36660 Dalton proteins, respectively, and their regulatory sequences.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1365-2958.1989.tb00269.x
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  • 10
    Electronic Resource
    Electronic Resource
    A dual transcriptional activation system for the 230 kb plasmid genes coding for virulence-associated antigens of Shigella flexneri (1989)
    Oxford, UK : Blackwell Publishing Ltd
    Molecular microbiology 3 (1989), S. 0 
    Details
    ISSN: 1365-2958
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology , Medicine
    Notes: The expression of plasmid-encoded, invasion-related antigens lpa b, c and d of Shigella flexneri was found to be positively regulated at transcriptional level by a 33kD protein produced by the previously defined, virulence-associated Region 1 on the SalI fragment B of the 230 kb invasion plasmid. The gene (designated virB) was identified and its nucleotide sequence determined. No Ipa b or c was produced in the absence of an intact virB gene although lower levels of d were produced. The previously reported regulatory activity of the virF gene some 30 kb distance away was shown to act exclusively through virB. In contrast, the activation of the virG gene necessary for intercellular spread occurred directly by virF without the requirement for virB. This study thus ascribes a critical function to a previously recognized, but functionally undefined, virulence locus on the large invasion plasmid of S. flexneri. The virF gene appears to have a central role in activation of the 230kb plasmid-encoded virulence genes.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1365-2958.1989.tb00210.x
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