scholarly journals Expression of ExsA in trans Confers Type III Secretion System-Dependent Cytotoxicity on Noncytotoxic Pseudomonas aeruginosa Cystic Fibrosis Isolates

2001 ◽  
Vol 69 (1) ◽  
pp. 538-542 ◽  
Author(s):  
Denis Dacheux ◽  
Ina Attree ◽  
Bertrand Toussaint
Keyword(s):  
Cystic Fibrosis ◽  
Pseudomonas Aeruginosa ◽  
Transcriptional Activation ◽  
Type Iii Secretion ◽  
Ex Vivo ◽  
Type Iii Secretion System ◽  
Secretion System ◽  
Type Iii ◽  
In Trans

ABSTRACT Twelve Pseudomonas aeruginosa cystic fibrosis isolates that are not able to exert a type III secretion system (TTSS)-dependent cytotoxicity towards phagocytes have been further studied. The strains, although possessing TTSS genes and exsA, which encodes a positive regulator of the TTSS regulon, showed no transcriptional activation of the exsCBA regulatory operon. The expression of exsA in trans restored the in vitro secretion of TTSS proteins and ex vivo cytotoxicity.

scholarly journals Activation of the Pseudomonas aeruginosa Type III Secretion System Requires an Intact Pyruvate Dehydrogenase aceAB Operon

2002 ◽  
Vol 70 (7) ◽  
pp. 3973-3977 ◽  
Author(s):  
Denis Dacheux ◽  
Olivier Epaulard ◽  
Arjan de Groot ◽  
Benoit Guery ◽  
Rozen Leberre ◽  
...  
Keyword(s):  
Pseudomonas Aeruginosa ◽  
Transcriptional Activation ◽  
Pyruvate Dehydrogenase ◽  
Type Iii Secretion ◽  
Type Iii Secretion System ◽  
Secretion System ◽  
Polymorphonuclear Neutrophils ◽  
Type Iii ◽  
New Genes ◽  
Cystic Fibrosis Isolate

ABSTRACT Pseudomonas aeruginosa clinical cystic fibrosis isolate CHA was mutagenized with Tn5Tc to identify new genes involved in type III secretion system (TTSS)-dependent cytotoxicity toward human polymorphonuclear neutrophils. Among 25 mutants affected in TTSS function, 14 contained the insertion at different positions in the aceAB operon encoding the PDH-E1 and -E2 subunits of pyruvate dehydrogenase. In PDH mutants, no transcriptional activation of TTSS genes in response to calcium depletion occurred. Expression in trans of ExsA restored TTSS function and cytotoxicity.

scholarly journals Pseudomonas aeruginosa Type III Secretion System Virulotypes and Their Association with Clinical Features of Cystic Fibrosis Patients

2020 ◽  
Vol Volume 13 ◽  
pp. 3771-3781
Author(s):  
Edilene do Socorro Nascimento Falcão Sarges ◽  
Yan Corrêa Rodrigues ◽  
Ismari Perini Furlaneto ◽  
Marcos Vinicios Hino de Melo ◽  
Giulia Leão da Cunha Brabo ◽  
...  
Keyword(s):  
Cystic Fibrosis ◽  
Pseudomonas Aeruginosa ◽  
Clinical Features ◽  
Type Iii Secretion ◽  
Type Iii Secretion System ◽  
Secretion System ◽  
Type Iii

scholarly journals Pseudomonas aeruginosa Cystic Fibrosis Isolates Induce Rapid, Type III Secretion-Dependent, but ExoU-Independent, Oncosis of Macrophages and Polymorphonuclear Neutrophils

2000 ◽  
Vol 68 (5) ◽  
pp. 2916-2924 ◽  
Author(s):  
Denis Dacheux ◽  
Bertrand Toussaint ◽  
Marceline Richard ◽  
Guy Brochier ◽  
Jacques Croize ◽  
...  
Keyword(s):  
Cystic Fibrosis ◽  
Pseudomonas Aeruginosa ◽  
Dna Fragmentation ◽  
Type Iii Secretion ◽  
Type Iii Secretion System ◽  
Opportunistic Pathogen ◽  
Eukaryotic Cell ◽  
Secretion System ◽  
Polymorphonuclear Neutrophils ◽  
Type Iii

ABSTRACT Pseudomonas aeruginosa, an opportunistic pathogen responsible most notably for severe infections in cystic fibrosis (CF) patients, utilizes the type III secretion system for eukaryotic cell intoxication. The CF clinical isolate CHA shows toxicity towards human polymorphonuclear neutrophils (PMNs) which is dependent on the type III secretion system but independent of the cytotoxin ExoU. In the present study, the cytotoxicity of this strain toward human and murine macrophages was demonstrated. In low-multiplicity infections (multiplicity of infection, 10), approximately 40% of the cells die within 60 min. Analysis of CHA-infected cells by transmission electron microscopy, DNA fragmentation assay, and Hoechst staining revealed the hallmarks of oncosis: cellular and nuclear swelling, disintegration of the plasma membrane, and absence of DNA fragmentation. A panel of 29P. aeruginosa CF isolates was screened for type III system genotype, protein secretion profile, and cytotoxicity toward PMNs and macrophages. This study showed that six CF isolates were able to induce rapid ExoU-independent oncosis on phagocyte cells.

scholarly journals Cell Death of Human Polymorphonuclear Neutrophils Induced by a Pseudomonas aeruginosa Cystic Fibrosis Isolate Requires a Functional Type III Secretion System

1999 ◽  
Vol 67 (11) ◽  
pp. 6164-6167 ◽  
Author(s):  
D. Dacheux ◽  
I. Attree ◽  
C. Schneider ◽  
B. Toussaint
Keyword(s):  
Cystic Fibrosis ◽  
Pseudomonas Aeruginosa ◽  
Type Iii Secretion ◽  
Type Iii Secretion System ◽  
Secretion System ◽  
Polymorphonuclear Neutrophils ◽  
Bactericidal Action ◽  
Cellular Death ◽  
Type Iii ◽  
Cystic Fibrosis Isolate

ABSTRACT With a coincubation model incorporating Pseudomonas aeruginosa and human polymorphonuclear neutrophils (PMNs), a cystic fibrosis (CF) P. aeruginosa isolate has been shown to resist the bactericidal action of PMNs and to induce their cellular death. An isogenic mutant of this CF isolate in which the type III secretion system was rendered nonfunctional was unable to induce cellular death of PMNs.

scholarly journals Role of the Type III Secreted Exoenzymes S, T, and Y in Systemic Spread of Pseudomonas aeruginosa PAO1 In Vivo

2005 ◽  
Vol 73 (3) ◽  
pp. 1706-1713 ◽  
Author(s):  
Russell E. Vance ◽  
Arne Rietsch ◽  
John J. Mekalanos
Keyword(s):  
Pseudomonas Aeruginosa ◽  
Cell Line ◽  
Type Iii Secretion ◽  
Type Iii Secretion System ◽  
Secretion System ◽  
Host Cells ◽  
Macrophage Cell ◽  
Type Iii

ABSTRACT Pseudomonas aeruginosa uses a dedicated type III secretion system to deliver toxins directly into the cytoplasm of host cells. While progress has been made in elucidating the function of type III-secreted toxins in vitro, the in vivo functions of the type III-secreted exoenzymes are less well understood, particularly for the sequenced strain PAO1. Therefore, we have systematically deleted the genes for the three known type III effector molecules (exoS, exoT, and exoY) in P. aeruginosa PAO1 and assayed the effect of the deletions, both singly and in combination, on cytotoxicity in vitro and in vivo. We found that the type III secretion system acts differently on different cell types, causing an exoST-dependent rounding of a lung epithelial-like cell line in contrast to causing an exoSTY-independent but translocase (popB)-dependent lysis of a macrophage cell line. We utilized an in vivo competitive infection model to test each of our mutants, examining replication in the lung and spread to secondary sites such as the blood and spleen. Type III mutants inoculated intranasally exhibited only a minor defect in replication and survival in the lung, but popB and exoSTY triple mutants were profoundly defective in their ability to spread systemically. Intravenous injection of the mutants indicated that the type III secretion machinery is required for survival in the blood. Furthermore, our findings suggest that the effector-independent popB-dependent cytotoxicity that we and others have observed in vitro in macrophage cell lines may not be of great importance in vivo.

scholarly journals Functional Domains of ExsA, the Transcriptional Activator of the Pseudomonas aeruginosa Type III Secretion System

2009 ◽  
Vol 191 (12) ◽  
pp. 3811-3821 ◽  
Author(s):  
Evan D. Brutinel ◽  
Christopher A. Vakulskas ◽  
Timothy L. Yahr
Keyword(s):  
Pseudomonas Aeruginosa ◽  
Amino Acid ◽  
Type Iii Secretion ◽  
Type Iii Secretion System ◽  
Secretion System ◽  
Binding Studies ◽  
Type Iii ◽  
Amino Terminal ◽  
Terminal Domain

ABSTRACT The opportunistic pathogen Pseudomonas aeruginosa utilizes a type III secretion system (T3SS) to evade phagocytosis and damage eukaryotic cells. Transcription of the T3SS regulon is controlled by ExsA, a member of the AraC/XylS family of transcriptional regulators. These family members generally consist of an ∼100-amino acid carboxy-terminal domain (CTD) with two helix-turn-helix DNA binding motifs and an ∼200-amino acid amino-terminal domain (NTD) with known functions including oligomerization and ligand binding. In the present study, we show that the CTD of ExsA binds to ExsA-dependent promoters in vitro and activates transcription from ExsA-dependent promoters both in vitro and in vivo. Despite possessing these activities, the CTD lacks the cooperative binding properties observed for full-length ExsA at the P exsC promoter. In addition, the CTD is unaffected by the negative regulatory activity of ExsD, an inhibitor of ExsA activity. Binding studies confirm that ExsD interacts directly with the NTD of ExsA. Our data are consistent with a model in which a single ExsA molecule first binds to a high-affinity site on the P exsC promoter. Protein-protein interactions mediated by the NTD then recruit an additional ExsA molecule to a second site on the promoter to form a complex capable of stimulating wild-type levels of transcription. These findings provide important insight into the mechanisms of transcriptional activation by ExsA and inhibition of ExsA activity by ExsD.

scholarly journals A Salmonella Virulence Factor Activates the NOD1/NOD2 Signaling Pathway

mBio ◽  
2011 ◽  
Vol 2 (6) ◽  
Author(s):  
A. Marijke Keestra ◽  
Maria G. Winter ◽  
Daisy Klein-Douwel ◽  
Mariana N. Xavier ◽  
Sebastian E. Winter ◽  
...  
Keyword(s):  
Signaling Pathway ◽  
Type Iii Secretion ◽  
Salmonella Enterica ◽  
Intestinal Inflammation ◽  
Inflammatory Responses ◽  
Type Iii Secretion System ◽  
Secretion System ◽  
Content Type ◽  
Type Iii

ABSTRACTThe invasion-associated type III secretion system (T3SS-1) ofSalmonella entericaserotype Typhimurium (S. Typhimurium) activates the transcription factor NF-κB in tissue culture cells and induces inflammatory responses in animal models through unknown mechanisms. Here we show that bacterial delivery or ectopic expression of SipA, a T3SS-1-translocated protein, led to the activation of the NOD1/NOD2 signaling pathway and consequent RIP2-mediated induction of NF-κB-dependent inflammatory responses. SipA-mediated activation of NOD1/NOD2 signaling was independent of bacterial invasionin vitrobut required an intact T3SS-1. In the mouse colitis model, SipA triggered mucosal inflammation in wild-type mice but not in NOD1/NOD2-deficient mice. These findings implicate SipA-driven activation of the NOD1/NOD2 signaling pathway as a mechanism by which the T3SS-1 induces inflammatory responsesin vitroandin vivo.IMPORTANCESalmonella entericaserotype Typhimurium (S. Typhimurium) deploys a type III secretion system (T3SS-1) to induce intestinal inflammation and benefits from the ensuing host response, which enhances growth of the pathogen in the intestinal lumen. However, the mechanisms by which the T3SS-1 triggers inflammatory responses have not been resolved. Here we show that the T3SS-1 effector protein SipA induces NF-κB activation and intestinal inflammation by activating the NOD1/NOD2 signaling pathway. These data suggest that the T3SS-1 escalates innate responses through a SipA-mediated activation of pattern recognition receptors in the host cell cytosol.

scholarly journals An in vivo inducible gene of Pseudomonas aeruginosa encodes an anti-ExsA to suppress the type III secretion system

2004 ◽  
Vol 54 (2) ◽  
pp. 307-320 ◽  
Author(s):  
Un-Hwan Ha ◽  
Jaewha Kim ◽  
Hassan Badrane ◽  
Jinghua Jia ◽  
Henry V. Baker ◽  
...  
Keyword(s):  
Pseudomonas Aeruginosa ◽  
Type Iii Secretion ◽  
Type Iii Secretion System ◽  
Secretion System ◽  
Type Iii ◽  
Inducible Gene
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