Genomic and proteomic characterization of two strains of Shigella flexneri 2 isolated from infants' stool samples in Argentina.

Background: Shigella specie is a globally important intestinal pathogen disseminated all over the world. In this study we analyzed the genome and the proteomic component of two Shigella flexneri 2a clinical isolates, collected from pediatric patients with gastroenteritis of the Northwest region of Argentina (NWA) in two periods of time, with four years of difference. Our goal was to determine putative changes at molecular levels occurred during these four years, that could explain the presence of this Shigella`s serovar as the prevalent pathogen in the population under study.

Epidemiological study of prevalent pathogens in the Northwest region of Argentina (NWA).

Northwest Argentina (NWA) is a poor economic-geographical region, with the highest rate of diarrhea diseases. At the moment, there are no reports showing the epidemiological status of this region that would allow to establish methods for prevention and control of these infections and to indicate of the prevalent pathogen that produces them. Therefore we carried out an epidemiological study of the gastroenteritis etiological agents and their incidence in the pediatric population.

RcsB-dependent effects on nar operon regulation during the aerobic growth of Salmonella Typhimurium.

The intracellular pathogen Salmonella is an important cause of human foodborne diseases worldwide. Salmonella takes advantage of the phosphorelay regulatory systems to survive in the hostile environment of the host's gastrointestinal tract. It has been reported that the nitrate reductase Z (NR-Z), encoded by the narUZYV operon, is required during Salmonella transition to anaerobic environments and is constitutively produced at low levels, but little is known about the regulatory mechanism involved in the operon gene expression.

The RcsCDB regulatory system plays a crucial role in the protection of Salmonella enterica serovar Typhimurium against oxidative stress.

Dps, the most abundant protein during the stationary growth phase, in Salmonella enterica is required for resistance to reactive oxygen species produced by the host during infection. It has been reported that in Salmonella dps expression is controlled by RpoS and Fur proteins. However, the regulation and function of Dps remain to be resolved.

A novel insight on signal transduction mechanism of RcsCDB system in Salmonella enterica serovar typhimurium.

The RcsCDB system of Salmonella enterica serovar Typhimurium is implicated in the control of capsule and flagella synthesis. The hybrid sensor RcsC, the phosphotransferase RcsD and the RcsB regulator, constitute the main components of the RcsCDB system. The proposed Rcs signaling cascade involves the autophosphorylation of RcsC and the transfer of the phosphate group to RcsB, mediated by RcsD.

The PmrAB system-inducing conditions control both lipid A remodeling and O-antigen length distribution, influencing the Salmonella Typhimurium-host interactions.

The Salmonella enterica serovar Typhimurium lipopolysaccharide consisting of covalently linked lipid A, non-repeating core oligosaccharide, and the O-antigen polysaccharide is the most exposed component of the cell envelope. Previous studies demonstrated that all of these regions act against the host immunity barrier. The aim of this study was to define the role and interaction of PmrAB-dependent gene products required for the lipopolysaccharide component synthesis or modification mainly during the Salmonella infection.

The PmrA/PmrB regulatory system controls the expression of the wzzfepE gene involved in the O-antigen synthesis of Salmonella enterica serovar Typhimurium.

The degree of polymerization of O-antigen from Salmonella enterica serovar Typhimurium is controlled by the products of the wzz(s)(t) and wzz(fepE) genes. In the present study we investigated the role of the PmrA/PmrB regulatory system in wzz(fepE) transcription. We report that the direct binding of the PmrA regulator to a specific promoter site induces the expression of the wzz(fepE) gene.

Transcriptional autoregulation of the RcsCDB phosphorelay system in Salmonella enterica serovar Typhimurium.

The RcsCDB (Rcs) phosphorelay system is involved in the regulation of many envelope genes, such as those responsible for capsule synthesis, flagella production and O-antigen chain length, as well as in other cellular activities of several enteric bacteria. The system is composed of three proteins: the sensor RcsC, the response regulator RcsB, and the phospho-transfer intermediary protein RcsD. Previously, we reported two important aspects of this system: (a) rcsB gene expression is under the control of P(rcsDB) and P(rcsB) promoters, and (b) rcsD gene transcription decreases when the bacteria reach high levels of the RcsB regulator.

Identification of a new promoter for the response regulator rcsB expression in Salmonella enterica serovar Typhimurium.

The RcsCDB (Rcs) phosphorelay system regulates capsule synthesis, flagella production and other cellular activities in several enteric bacteria. This system consists of three proteins: the sensor RcsC, the cognate response regulator RcsB and the histidine-containing phosphotransfer protein RcsD (YojN), which is hypothesized to act as an intermediary in the phosphotransfer from RcsC to RcsB. The rcsC gene is convergently transcribed toward rcsB, which follows rcsD in what appears to be a two-gene operon.