The tripartite type III secreton of Shigella flexneri inserts IpaB and IpaC into host membranes.
Ariel J. Blocker,Pierre Gounon,Eric Larquet,Kirsten Niebuhr,Véronique Cabiaux,Claude Parsot,Philippe J. Sansonetti +6 more
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The contact hemolytic activity of Shigella flexneri was used to investigate its putative translocator and electron microscopy analysis indicated that secretons were constitutively assembled at 37°C before any host contact.Abstract:
Bacterial type III secretion systems serve to translocate proteins into eukaryotic cells, requiring a secreton and a translocator for proteins to pass the bacterial and host membranes. We used the contact hemolytic activity of Shigella flexneri to investigate its putative translocator. Hemolysis was caused by formation of a 25-A pore within the red blood cell (RBC) membrane. Of the five proteins secreted by Shigella upon activation of its type III secretion system, only the hydrophobic IpaB and IpaC were tightly associated with RBC membranes isolated after hemolysis. Ipa protein secretion and hemolysis were kinetically coupled processes. However, Ipa protein secretion in the immediate vicinity of RBCs was not sufficient to cause hemolysis in the absence of centrifugation. Centrifugation reduced the distance between bacterial and RBC membranes beyond a critical threshold. Electron microscopy analysis indicated that secretons were constitutively assembled at 37°C before any host contact. They were composed of three parts: (a) an external needle, (b) a neck domain, and (c) a large proximal bulb. Secreton morphology did not change upon activation of secretion. In mutants of some genes encoding the secretion machinery the organelle was absent, whereas ipaB and ipaC mutants displayed normal secretons.read more
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Pathogenicity Islands and the Evolution of Microbes
Jörg Hacker,James B. Kaper +1 more
TL;DR: Genomic islands are present in the majority of genomes of pathogenic as well as nonpathogenic bacteria and may encode accessory functions which have been previously spread among bacterial populations and are argued for the generation of pathogenicity islands by horizontal gene transfer.
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The type III secretion injectisome.
TL;DR: The principal structural components of the injectisome, from the base located in the bacterial cytosol to the tip of the needle protruding from the cell surface, have been investigated in detail.
Journal ArticleDOI
Bacterial Adhesion and Entry into Host Cells
Javier Pizarro-Cerdá,Javier Pizarro-Cerdá,Javier Pizarro-Cerdá,Pascale Cossart,Pascale Cossart,Pascale Cossart +5 more
TL;DR: Bacteria use monomeric adhesins/invasins or highly sophisticated macromolecular machines to establish a complex host/pathogen molecular crosstalk that leads to subversion of cellular functions and establishment of disease.
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Assembly and function of type iii secretory systems
Guy R. Cornelis,F. Van Gijsegem +1 more
TL;DR: Type III secretion appears as a fascinating trans-kingdom communication device in plant pathogens where they are involved both in causing disease in susceptible hosts and in eliciting the so-called hypersensitive response in resistant or nonhost plants.
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The type III secretion system of Pseudomonas aeruginosa : infection by injection
TL;DR: This Review summarizes the current knowledge of P. aeruginosa type III secretion, including the secretion and translocation machinery, the regulation of this machinery, and the associated chaperones and effector proteins.
References
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Type III Protein Secretion Systems in Bacterial Pathogens of Animals and Plants
TL;DR: A comparison of the structure, function, regulation, and impact on host cells of the type III secretion systems in the animal pathogens Yersinia spp.
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Spider and web : processing and visualization of images in 3d electron microscopy and related fields
Joachim Frank,Michael Radermacher,Michael Radermacher,Pawel A. Penczek,Jun Zhu,Jun Zhu,Yanhong Li,Mahieddine Ladjadj,Ardean Leith +8 more
TL;DR: Novel features are a suite of operations relating to the determination, modeling, and correction of the contrast transfer function and the availability of the entire documentation in hypertext format.
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Type III Secretion Machines: Bacterial Devices for Protein Delivery into Host Cells
Jorge E. Galán,Alan Collmer +1 more
TL;DR: Several Gram-negative pathogenic bacteria have evolved a complex protein secretion system termed type III to deliver bacterial effector proteins into host cells that then modulate host cellular functions.
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Enteropathogenic E. coli (EPEC) Transfers Its Receptor for Intimate Adherence into Mammalian Cells
Brendan Kenny,Rebekah DeVinney,Markus Stein,Dieter J. Reinscheid,Elizabeth A. Frey,B. Brett Finlay +5 more
TL;DR: It is demonstrated that Hp90 is actually a bacterial protein (Tir), to which this bacterial pathogen inserts its own receptor into mammalian cell surfaces, to which it then adheres to trigger additional host signaling events and actin nucleation.
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Filtration, diffusion, and molecular sieving through porous cellulose membranes.
TL;DR: Experimental results were in close agreement with predictions based on the membrane pore theory of Pappenheimer et al. and Steady-state osmotic pressures of solutions of sucrose and raffinose measured during molecular sieving through cellulose membranes were found to be close to the "ideal" osmosis pressures calculated by van't Hoff's law.