Salmonella
Research ArticleHilD, HilC, and RtsA Form Homodimers and Heterodimers To Regulate Expression of the Salmonella Pathogenicity Island I Type III Secretion SystemThe SPI1 type three secretion system is a key virulence factor required for Salmonella to both cause gastroenteritis and initiate serious systemic disease. The system responds to numerous environmental signals in the intestine, integrating this information via a complex regulatory network. Here, we show that the primary regulatory proteins in the network function as both homodimers and heterodimers, providing information...
Research Article | SpotlightUnder Elevated c-di-GMP in Escherichia coli, YcgR Alters Flagellar Motor Bias and Speed Sequentially, with Additional Negative Control of the Flagellar Regulon via the Adaptor Protein RssBFlagellum-driven motility has been studied in E. coli and Salmonella for nearly half a century. Over 60 genes control flagellar assembly and function. The expression of these genes is regulated at multiple levels in response to a variety of environmental signals. Cues that elevate c-di-GMP levels, however, inhibit motility by direct binding of the effector...
Research ArticleThe Small RNA PinT Contributes to PhoP-Mediated Regulation of the Salmonella Pathogenicity Island 1 Type III Secretion System in Salmonella enterica Serovar TyphimuriumSalmonella is one of the most important food-borne pathogens, infecting over one million people in the United States every year. These bacteria use a needle-like device to interact with intestinal epithelial cells, leading to invasion of the cells and induction of inflammatory diarrhea. A complex regulatory network controls expression of the invasion system in response to numerous environmental signals. Here we explore the...
Special Issue Meeting PresentationHuman Bile-Mediated Regulation of Salmonella Curli FimbriaeTyphoid fever is caused by Salmonella enterica serovar Typhi, and 3% to 5% of patients become chronic gallbladder (GB) carriers (also known as “Typhoid Marys”). We have previously demonstrated a role for Salmonella biofilm formation on gallstones as a primary mechanism of carriage. In this study, we found that the important biofilm extracellular matrix...
Special Issue Meeting PresentationCytotoxic Curli Intermediates Form during Salmonella Biofilm DevelopmentAmyloid proteins are the major proteinaceous components of biofilms, which are associated with up to 65% of human bacterial infections. Amyloids produced by human cells are also associated with diseases such as Alzheimer’s. The amyloid monomeric subunits self-associate to form oligomers, protofibrils, and finally mature fibrils. Amyloid β oligomers are more cytotoxic to cells than the mature amyloid fibrils. Here we detected oligomeric...
Research ArticleYshB Promotes Intracellular Replication and Is Required for Salmonella VirulenceSalmonella gastroenteritis is one of the most common causes of foodborne disease, possibly affecting millions of people globally each year. Here we characterize the role of a novel small protein, YshB, in mediating Salmonella intracellular survival. This elucidation adds to the body of knowledge regarding how this bacterium achieves intracellular survival.
Research ArticlePhoP-Mediated Repression of the SPI1 Type 3 Secretion System in Salmonella enterica Serovar TyphimuriumSalmonella is one of the most common foodborne pathogens, causing an estimated 1.2 million illnesses per year in the United States. A key step in infection is the activation of the bacterial invasion machinery, which induces uptake of the bacterium into epithelial cells and leads to induction of inflammatory diarrhea. Upon entering the vacuolar compartments of host cells, Salmonella senses an environmental transition...
Meeting PresentationPathoadaptive Alteration of Salmonella Biofilm Formation in Response to the Gallbladder EnvironmentChronic carriers are the main reservoirs for the spread of typhoid fever in regions of endemicity. Salmonella Typhi forms biofilms on gallstones in order to persist. A strain with enhanced biofilm-forming ability was recovered after a nine-month chronic-carriage mouse study. After sequencing this strain and recreating some of the mutations, we could not duplicate the phenotype. The isolate did show a difference in flagella, a...
Research ArticleSlyA and HilD Counteract H-NS-Mediated Repression on the ssrAB Virulence Operon of Salmonella enterica Serovar Typhimurium and Thus Promote Its Activation by OmpRThe global regulator H-NS represses the expression of acquired genes and thus avoids possible detrimental effects on bacterial fitness. Regulatory mechanisms are adapted to induce expression of the acquired genes in particular niches to obtain a benefit from the information encoded in the foreign DNA, as for pathogenesis. Here, we show two mechanisms that were integrated for the expression of virulence genes in...
Research ArticleEffect of the MotA(M206I) Mutation on Torque Generation and Stator Assembly in the Salmonella H+-Driven Flagellar MotorThe bacterial flagellar motor is a rotary nanomachine driven by the electrochemical transmembrane potential (ion motive force). About 10 stators (MotA/MotB complexes) are docked around a rotor, and the stator recruitment depends on the load, ion motive force, and coupling ion flux. The MotA(M206I) mutation slows motor rotation and decreases the number of docked stators in Salmonella. We show that lowering the external pH...