scholarly journals A Type IV Secretion System Contributes to Intracellular Survival and Replication of Burkholderia cenocepacia

2008 ◽  
Vol 76 (12) ◽  
pp. 5447-5455 ◽  
Author(s):  
S. Umadevi Sajjan ◽  
Lisa A. Carmody ◽  
Carlos F. Gonzalez ◽  
John J. LiPuma
Keyword(s):  
Epithelial Cells ◽  
Airway Epithelial Cells ◽  
Secretion System ◽  
Type Iv Secretion ◽  
Endocytic Pathway ◽  
Burkholderia Cenocepacia ◽  
Type Iv Secretion System ◽  
Airway Epithelial ◽  
Wild Type ◽  
Type Iv

ABSTRACT Burkholderia cenocepacia is an important respiratory pathogen in persons with cystic fibrosis (CF). Recent studies indicate that B. cenocepacia survives within macrophages and airway epithelial cells in vitro by evading endosome-lysosome fusion. We investigated the role of a plasmid-encoded type IV secretion system in the intracellular survival, replication, and processing of B. cenocepacia. Both a wild-type strain (K56-2) and its type IV secretion system mutant (designated LC101) entered and replicated in CF airway epithelial cells and monocyte-derived macrophages. However, significantly more intracellular K56-2 than LC101 bacteria were found in both cell types at 24 h postinfection. Colocalization of bacteria with markers of the classical endocytic pathway indicated that although both K56-2 and LC101 reside transiently in early endosomes, a greater proportion of the mutant bacteria are targeted to lysosomal degradation. In contrast, wild-type bacteria escape from the classical endocytic pathway and traffic to the endoplasmic reticulum, where they replicate. Our results show that the intracellular processing of B. cenocepacia is similar in both professional and nonprofessional phagocytes and that a functional plasmid-encoded type IV secretion system contributes to the survival and replication of B. cenocepacia in eukaryotic cells.

930 HELICOBACTER PYLORI PROMOTES THE DIFFERENTIATION OF PPAR∂-EXPRESSING EPITHELIAL CELLS FROM LRIG+ STEM CELLS IN A CAG TYPE IV SECRETION SYSTEM-DEPENDENT MANNER

2020 ◽  
Vol 158 (6) ◽  
pp. S-185
Author(s):  
Lydia Wroblewski ◽  
Alberto Delgado ◽  
Maria B. Piazuelo ◽  
Judith Romero-Gallo ◽  
Robert J. Coffey ◽  
...  
Keyword(s):  
Stem Cells ◽  
Helicobacter Pylori ◽  
Epithelial Cells ◽  
Secretion System ◽  
Type Iv Secretion ◽  
Type Iv Secretion System ◽  
Dependent Manner ◽  
Type Iv

scholarly journals Involvement of a Plasmid-Encoded Type IV Secretion System in the Plant Tissue Watersoaking Phenotype of Burkholderia cenocepacia

2004 ◽  
Vol 186 (18) ◽  
pp. 6015-6024 ◽  
Author(s):  
Amanda S. Engledow ◽  
Enrique G. Medrano ◽  
Eshwar Mahenthiralingam ◽  
John J. LiPuma ◽  
Carlos F. Gonzalez
Keyword(s):  
Plant Tissue ◽  
Protein S ◽  
Secretion System ◽  
Type Iv Secretion ◽  
Site Directed Mutagenesis ◽  
Burkholderia Cenocepacia ◽  
Type Iv Secretion System ◽  
Directed Mutagenesis ◽  
Secretion Systems ◽  
Type Iv

ABSTRACT Burkholderia cenocepacia strain K56-2, a representative of the Burkholderia cepacia complex, is part of the epidemic and clinically problematic ET12 lineage. The strain produced plant tissue watersoaking (ptw) on onion tissue, which is a plant disease-associated trait. Using plasposon mutagenesis, mutants in the ptw phenotype were generated. The translated sequence of a disrupted gene (ptwD4) from a ptw-negative mutant showed homology to VirD4-like proteins. Analysis of the region proximal to the transfer gene homolog identified a gene cluster located on the 92-kb resident plasmid that showed homology to type IV secretion systems. The role of ptwD4, ptwC, ptwB4, and ptwB10 in the expression of ptw activity was determined by conducting site-directed mutagenesis. The ptw phenotype was not expressed by K56-2 derivatives with a disruption in ptwD4, ptwB4, or ptwB10 but was observed in a derivative with a disruption in ptwC. Complementation of ptw-negative K56-2 derivatives in trans resulted in complete restoration of the ptw phenotype. In addition, analysis of culture supernatants revealed that the putative ptw effector(s) was a secreted, heat-stable protein(s) that caused plasmolysis of plant protoplasts. A second chromosomally encoded type IV secretion system with complete homology to the VirB-VirD system was identified in K56-2. Site-directed mutagenesis of key secretory genes in the VirB-VirD system did not affect expression of the ptw phenotype. Our findings indicate that in strain K56-2, the plasmid-encoded Ptw type IV secretion system is responsible for the secretion of a plant cytotoxic protein(s).

scholarly journals Establishment of Systemic Brucella melitensis Infection through the Digestive Tract Requires Urease, the Type IV Secretion System, and Lipopolysaccharide O Antigen

2009 ◽  
Vol 77 (10) ◽  
pp. 4197-4208 ◽  
Author(s):  
Tatiane A. Paixão ◽  
Christelle M. Roux ◽  
Andreas B. den Hartigh ◽  
Sumathi Sankaran-Walters ◽  
Satya Dandekar ◽  
...  
Keyword(s):  
Digestive Tract ◽  
Cell Model ◽  
Brucella Melitensis ◽  
Secretion System ◽  
Type Iv Secretion ◽  
Human Brucellosis ◽  
Type Iv Secretion System ◽  
Wild Type ◽  
Type Iv ◽  
Mutant Strains

ABSTRACT Human brucellosis is caused mainly by Brucella melitensis, which is often acquired by ingesting contaminated goat or sheep milk and cheese. Bacterial factors required for food-borne infection of humans by B. melitensis are poorly understood. In this study, a mouse model of oral infection was characterized to assess the roles of urease, the VirB type IV secretion system, and lipopolysaccharide for establishing infection through the digestive tract. B. melitensis strain 16M was consistently recovered from the mesenteric lymph node (MLN), spleen, and liver beginning at 3 or 7 day postinfection (dpi). In the gut, persistence of the inoculum was observed up to 21 dpi. No inflammatory lesions were observed in the ileum or colon during infection. Mutant strains lacking the ureABC genes of the ure1 operon, virB2, or pmm encoding phosphomannomutase were constructed and compared to the wild-type strain for infectivity through the digestive tract. Mutants lacking the virB2 and pmm genes were attenuated in the spleen (P < 0.05) and MLN (P < 0.001), respectively. The wild-type and mutant strains had similar levels of resistance to low pH and 5 or 10% bile, suggesting that the reduced colonization of mutants was not the result of reduced resistance to acid pH or bile salts. In an in vitro lymphoepithelial cell (M-cell) model, B. melitensis transited rapidly through polarized enterocyte monolayers containing M-like cells; however, transit through monolayers containing only enterocytes was reduced or absent. These results indicate that B. melitensis is able to spread systemically from the digestive tract after infection, most likely through M cells of the mucosa-associated lymphoid tissue.

Analysis of the type IV secretion system-dependent cell motility of Helicobacter pylori-infected epithelial cells

2004 ◽  
Vol 322 (3) ◽  
pp. 860-866 ◽  
Author(s):  
Laila Al-Ghoul ◽  
Silja Wessler ◽  
Tanja Hundertmark ◽  
Sabine Krüger ◽  
Wolfgang Fischer ◽  
...  
Keyword(s):  
Helicobacter Pylori ◽  
Epithelial Cells ◽  
Cell Motility ◽  
Secretion System ◽  
Type Iv Secretion ◽  
Type Iv Secretion System ◽  
Type Iv ◽  
Dependent Cell

scholarly journals Brucella abortus VirB12 Is Expressed during Infection but Is Not an Essential Component of the Type IV Secretion System

2005 ◽  
Vol 73 (9) ◽  
pp. 6048-6054 ◽  
Author(s):  
Yao-Hui Sun ◽  
Hortensia G. Rolán ◽  
Andreas B. den Hartigh ◽  
David Sondervan ◽  
Renée M. Tsolis
Keyword(s):  
Brucella Abortus ◽  
Secretion System ◽  
Splenic Tissue ◽  
Type Iv Secretion ◽  
Type Iv Secretion System ◽  
Deletion Mutants ◽  
Wild Type ◽  
Intracellular Replication ◽  
Type Iv

ABSTRACT The Brucella abortus virB operon, consisting of 11 genes, virB1 to virB11, and two putative genes, orf12 (virB12) and orf13, encodes a type IV secretion system (T4SS) that is required for intracellular replication and persistent infection in the mouse model. This study was undertaken to determine whether orf12 (virB12) encodes an essential part of the T4SS apparatus. The virB12 gene was found to encode a 17-kDa protein, which was detected in vitro in B. abortus grown to stationary phase. Mice infected with B. abortus 2308 produced an antibody response to the protein encoded by virB12, showing that this gene is expressed during infection. Expression of virB12 was not required for survival in J774 macrophages. VirB12 was also dispensable for the persistence of B. abortus, B. melitensis, and B. suis in mice up to 4 weeks after infection, since deletion mutants lacking virB12 were recovered from splenic tissue at wild-type levels. These results show that VirB12 is not essential for the persistence of the human-pathogenic Brucella spp. in the mouse and macrophage models of infection.

scholarly journals Legionella pneumophila Catalase-Peroxidases Are Required for Proper Trafficking and Growth in Primary Macrophages

2003 ◽  
Vol 71 (8) ◽  
pp. 4526-4535 ◽  
Author(s):  
Purnima Bandyopadhyay ◽  
Brenda Byrne ◽  
Yolande Chan ◽  
Michele S. Swanson ◽  
Howard M. Steinman
Keyword(s):  
Legionella Pneumophila ◽  
Type Strain ◽  
Wild Type Strain ◽  
Acanthamoeba Castellanii ◽  
Secretion System ◽  
Type Iv Secretion ◽  
Type Iv Secretion System ◽  
Wild Type ◽  
Type Iv ◽  
Virulence Traits

ABSTRACT Legionella pneumophila, a parasite of aquatic amoebae and pathogen of pulmonary macrophages, replicates intracellularly, utilizing a type IV secretion system to subvert the trafficking of Legionella-containing phagosomes. Defense against host-derived reactive oxygen species has been proposed as critical for intracellular replication. Virulence traits of null mutants in katA and katB, encoding the two Legionella catalase-peroxidases, were analyzed to evaluate the hypothesis that L. pneumophila must decompose hydrogen peroxide to establish a replication niche in macrophages. Phagosomes containing katA or katB mutant Legionella colocalize with LAMP-1, a late endosomal-lysosomal marker, at twice the frequency of those of wild-type strain JR32 and show a decreased frequency of bacterial replication, in similarity to phenotypes of mutants with mutations in dotA and dotB, encoding components of the Type IV secretion system. Quantitative similarity of the katA/B phenotypes indicates that each contributes to virulence traits largely independently of intracellular compartmentalization (KatA in the periplasm and KatB in the cytosol). These data support a model in which KatA and KatB maintain a critically low level of H2O2 compatible with proper phagosome trafficking mediated by the type IV secretion apparatus. During these studies, we observed that dotA and dotB mutations in wild-type strain Lp02 had no effect on intracellular multiplication in the amoeba Acanthamoeba castellanii, indicating that certain dotA/B functions in Lp02 are dispensable in that experimental model. We also observed that wild-type JR32, unlike Lp02, shows minimal contact-dependent cytotoxicity, suggesting that cytotoxicity of JR32 is not a prerequisite for formation of replication-competent Legionella phagosomes in macrophages.

scholarly journals Genes Required for Assembly of Pili Associated with the Helicobacter pylori cag Type IV Secretion System

2014 ◽  
Vol 82 (8) ◽  
pp. 3457-3470 ◽  
Author(s):  
Elizabeth M. Johnson ◽  
Jennifer A. Gaddy ◽  
Bradley J. Voss ◽  
Ewa E. Hennig ◽  
Timothy L. Cover
Keyword(s):  
Helicobacter Pylori ◽  
Epithelial Cells ◽  
Secretion System ◽  
Type Iv Secretion ◽  
Type Iv Secretion System ◽  
Gastric Epithelial Cells ◽  
Content Type ◽  
Type Iv ◽  
Pilus Biogenesis ◽  
H Pylori

ABSTRACTHelicobacter pyloricauses numerous alterations in gastric epithelial cells through processes that are dependent on activity of thecagtype IV secretion system (T4SS). Filamentous structures termed “pili” have been visualized at the interface betweenH. pyloriand gastric epithelial cells, and previous studies suggested that pilus formation is dependent on the presence of thecagpathogenicity island (PAI). Thus far, there has been relatively little effort to identify specific genes that are required for pilus formation, and the role of pili in T4SS function is unclear. In this study, we selected 7 genes in thecagPAI that are known to be required for T4SS function and investigated whether these genes were required for pilus formation.cagT,cagX,cagV,cagM, andcag3mutants were defective in both T4SS function and pilus formation; complemented mutants regained T4SS function and the capacity for pilus formation.cagYandcagCmutants were defective in T4SS function but retained the capacity for pilus formation. These results define a set ofcagPAI genes that are required for both pilus biogenesis and T4SS function and reveal that these processes can be uncoupled in specific mutant strains.

scholarly journals Cholesterol Depletion Reduces Helicobacter pylori CagA Translocation and CagA-Induced Responses in AGS Cells

2008 ◽  
Vol 76 (7) ◽  
pp. 3293-3303 ◽  
Author(s):  
Chih-Ho Lai ◽  
Yun-Chieh Chang ◽  
Shin-Yi Du ◽  
Hung-Jung Wang ◽  
Chun-Hsien Kuo ◽  
...  
Keyword(s):  
Helicobacter Pylori ◽  
Epithelial Cells ◽  
Secretion System ◽  
Membrane Dynamics ◽  
Type Iv Secretion ◽  
Type Iv Secretion System ◽  
Cholesterol Depletion ◽  
Dependent Manner ◽  
Ags Cells ◽  
Type Iv

ABSTRACT Infection with Helicobacter pylori cagA-positive strains is associated with gastritis, ulcerations, and gastric cancer. CagA is translocated into infected epithelial cells by a type IV secretion system and can be tyrosine phosphorylated, inducing signal transduction and motogenic responses in epithelial cells. Cellular cholesterol, a vital component of the membrane, contributes to membrane dynamics and functions and is important in VacA intoxication and phagocyte evasion during H. pylori infection. In this investigation, we showed that cholesterol extraction by methyl-β-cyclodextrin reduced the level of CagA translocation and phosphorylation. Confocal microscope visualization revealed that a significant portion of translocated CagA was colocalized with the raft marker GM1 and c-Src during infection. Moreover, GM1 was rapidly recruited into sites of bacterial attachment by live-cell imaging analysis. CagA and VacA were cofractionated with detergent-resistant membranes (DRMs), suggesting that the distribution of CagA and VacA is associated with rafts in infected cells. Upon cholesterol depletion, the distribution shifted to non-DRMs. Accordingly, the CagA-induced hummingbird phenotype and interleukin-8 induction were blocked by cholesterol depletion. Raft-disrupting agents did not influence bacterial adherence but did significantly reduce internalization activity in AGS cells. Together, these results suggest that delivery of CagA into epithelial cells by the bacterial type IV secretion system is mediated in a cholesterol-dependent manner.

scholarly journals Inactivation of the Type IV Secretion System Reduces the Th1 Polarization of the Immune Response to Brucella abortus Infection

2008 ◽  
Vol 76 (7) ◽  
pp. 3207-3213 ◽  
Author(s):  
Hortensia García Rolán ◽  
Renée M. Tsolis
Keyword(s):  
Immune Response ◽  
T Cells ◽  
Brucella Abortus ◽  
Secretion System ◽  
Type Iv Secretion ◽  
Type Iv Secretion System ◽  
Wild Type ◽  
Type Iv ◽  
Ifn Γ ◽  
Th1 Polarization

ABSTRACT The Brucella abortus type IV secretion system (T4SS), encoded by the virB operon, is essential for establishing persistent infection in the murine reticuloendothelial system. To gain insight into the in vivo interactions mediated by the T4SS, we compared host responses elicited by B. abortus with those of an isogenic mutant in the virB operon. Mice infected with the B. abortus virB mutant elicited smaller increases in serum levels of immunoglobulin G2a, gamma interferon (IFN-γ), and interleukin-12p40 than did mice infected with wild-type B. abortus. Despite equal bacterial loads in the spleen, at 3 to 4 days postinfection, levels of IFN-γ were higher in mice infected with wild-type B. abortus than in mice infected with the virB mutant, as shown by real-time PCR, intracellular cytokine staining, and cytokine levels. IFN-γ-producing CD4+ T cells were more abundant in spleens of mice infected with wild-type B. abortus than in virB mutant-infected mice. Similar numbers of IFN-γ-secreting CD8+ T cells were observed in the spleens of mice infected with B. abortus 2308 or a virB mutant. These results suggest that early differences in cytokine responses contribute to a stronger Th1 polarization of the immune response in mice infected with wild-type B. abortus than in mice infected with the virB mutant.

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