An early step in the pathogenesis of Salmonella enterica serovar Typhimurium infection is bacterial penetration of the intestinal epithelium. Penetration requires the expression of invasion genes found in Salmonella pathogenicity island 1 (SPI1). These genes are controlled in a complex manner by regulators in SPI1, including HilA and InvF, and those outside SPI1, such as two-component regulator...

Salmonella enterica encodes a type III protein secretion system within a pathogenicity island (SPI-1) that is located at centisome 63 of its chromosome. This system is required for the ability of these bacteria to stimulate cellular responses that are essential for their pathogenicity. Expression of components and substrates of this system is subject to complex regulatory mechanisms. These mech...

Salmonella enterica serovar Typhimurium harbors five pathogenicity islands (SPI) required for infection in vertebrate hosts. Although the role of SPI1 in promoting epithelial invasion and proinflammatory cell death has been amply documented, SPI4 has only more recently been implicated in Salmonella virulence. SPI4 is a 24-kb pathogenicity island containing six open reading frames, siiA to siiF....

Salmonella enterica serovar Typhimurium causes human gastroenteritis and a systemic typhoid-like infection in mice. Infection is initiated by entry of the bacteria into intestinal epithelial cells and is mediated by a type III secretion system that is encoded by genes in Salmonella pathogenicity island 1. The expression of invasion genes is tightly regulated by environmental conditions such as ...

Sequences between -332 and -39 upstream of the hilA promoter are required for repression of hilA. An unidentified repressor is thought to bind these upstream repressing sequences (URS) to inhibit hilA expression. Two AraC-like transcriptional regulators encoded on Salmonella pathogenicity island 1 (SPI1), HilC and HilD, bind to the URS to counteract the repression of hilA. The URS is required f...

Pathogens express virulence genes in response to the combination of environmental conditions present in the host environment. The crop is the first gastrointestinal environment encountered in birds. However, feed withdrawal alters the crop environment resulting in an increased pH, and decreased concentrations of lactate, glucose and amino acids compared with unmoulted birds. Salmonella enteriti...

The expression of genes encoding proteins secreted by the SPI1 (Salmonella pathogenicity island) type III secretion apparatus is known to require the transcriptional activators SirA and HilA. However, neither SirA nor HilA is believed to directly activate the promoters of these genes. invF, the first gene of the inv-spa gene cluster, is predicted to encode an AraC-type transcriptional activator...

hilA gene promoter, component of the Salmonella Pathogenicity Island 1, has been found in Salmonella serovar Typhimurium, being important for the regulation of type III secretion apparatus genes. We detected hilA gene sequences in Salmonella serovars Typhi, Enteritidis, Choleraesuis, Paratyphi A and B, and Pullorum, by polymerase chain reaction (PCR) and hybridization techniques. The primers to...

UML state machines are a widely used language for modeling software behavior. They are considered to be simple and intuitively comprehensible, and are hence one of the most popular languages for modeling reactive components. However, this seeming ease to use vanishes rapidly as soon as the complexity of the system to model increases. In fact, even state machines modeling “almost trivial” behavi...

Expression of invasion genes in Salmonella pathogenicity island 1 (SPI-1) is mainly driven by the transcriptional activator HilA. Transcription of hilA is subject to complex control and is stimulated by the SPI-1-encoded HilC and HilD proteins. The C-terminal domain of RpoA contributes to hilA activation by HilC/D under certain inducing conditions.