A secreted anti-activator, OspD1, and its chaperone, Spa15, are involved in the control of transcription by the type III secretion apparatus activity in Shigella flexneri.

Bacteria of Shigella spp. are responsible for shigellosis in humans and use a type III secretion (TTS) system to enter epithelial cells and trigger apoptosis in macrophages. Transit of translocator and effector proteins through the TTS apparatus is activated upon contact of bacteria with host cells.

Two msbB genes encoding maximal acylation of lipid A are required for invasive Shigella flexneri to mediate inflammatory rupture and destruction of the intestinal epithelium.

Shigella flexneri is a Gram-negative pathogen that invades and causes inflammatory destruction of the human colonic epithelium, thus leading to bloody diarrhea and dysentery. A type III secretion system that delivers effector proteins into target eukaryotic cells is largely responsible for cell and tissue invasion. However, the respective role of this invasive phenotype and of lipid A, the endotoxin of the Shigella LPS, in eliciting the inflammatory cascade that leads to rupture and destruction of the epithelial barrier, was unknown.

The virulence plasmid pWR100 and the repertoire of proteins secreted by the type III secretion apparatus of Shigella flexneri.

Bacteria of Shigella spp. are the causative agents of shigellosis. The virulence traits of these pathogens include their ability to enter into epithelial cells and induce apoptosis in macrophages.

SopA, the outer membrane protease responsible for polar localization of IcsA in Shigella flexneri.

The spreading ability of Shigella flexneri, a facultative intracellular Gram-negative bacterium, within the host-cell cytoplasm is the result of directional assembly and accumulation of actin filaments at one pole of the bacterium. IcsA/VirG, the 120 kDa outer membrane protein that is required for intracellular motility, is located at the pole of the bacterium where actin polymerization occurs. Bacteria growing in laboratory media and within infected cells release a certain proportion of the surface-exposed IcsA after proteolytic cleavage.

Lack of cleavage of IcsA in Shigella flexneri causes aberrant movement and allows demonstration of a cross-reactive eukaryotic protein.

Once in the cytoplasm of mammalian cells, Shigella flexneri expresses a motile phenotype caused by polar directional assembly of actin. This process depends on accumulation of IcsA (VirG), a 120-kDa protein with ATPase activity, at the pole of the bacterium opposite to that at which ongoing septation occurs. IcsA is also secreted into the bacterial supernatant as a 95-kDa species, after cleavage at an SSRRASS sequence which, when mutagenized, blocks processing.