The toxR gene of Vibrio cholerae encodes a transmembrane, DNA-binding protein that activates transcription the cholera toxin operon and (tcpA) for major subunit pilus colonization factor. We constructed site-directed insertion mutations in by novel method employing chromosomal integration mobilizable suicide plasmid containing portion coding sequence. Mutants these new alleles had an altered outer membrane profile, suggesting two proteins (OmpT OmpU) might be under control toxR....

The transposon TnphoA was used to generate fusions between phoA, the gene for alkaline phosphatase (PhoA), and genes encoding proteins that are secreted by Vibrio cholerae. One of PhoA+ mutants isolated showed a dramatic reduction in its ability colonize intestines suckling mice. This mutant no longer produced 20.5-kDa protein (TcpA) we show is major subunit V. cholerae pilus. Amino-terminal sequence analysis TcpA pilus it shares amino acid homology with pilins several other pathogenic...

Virulent strains of Yersinia enterocolitica cause disease syndromes ranging from mild gastroenteritis to lymphadenitis and septicemia. The ability these bacteria invade intestinal epithelial cells gain access the reticuloendothelial system is thought be an important aspect their virulence. We report here on cloning two Y. chromosomal loci, inv ail, each which confers invasive phenotype Escherichia coli HB101. locus allows a uniformly high level invasion in several tissue culture lines...

Biogenesis of the flagellum, a motive organelle many bacterial species, is best understood for members Enterobacteriaceae. The flagellum heterooligomeric structure that protrudes from surface cell. Its assembly initially involves synthesis dedicated protein export apparatus subsequently transports other flagellar proteins by type III mechanism cytoplasm to outer cell, where oligomerization occurs. In this study, was shown function also as secretion system transport several extracellular in...

We have cloned a positive regulatory gene ( toxR ) from Vibrio cholerae that controls cholera toxin transcription. This was done by first constructing genetic fusion consisting of the lacZ fused to promoter operon ctxAB . used screen V. genomic library for genes could activate ctx in Escherichia coli. method allowed identification gene, , increases expression more than 100-fold. Complementation analysis indicated certain hypotoxinogenic mutants 569B probably mutations gene. Southern blot...

The polysaccharide capsule is an essential virulence factor for Klebsiella pneumoniae in both community-acquired hypervirulent strains as well health care-associated classical that are posing significant challenges due to multidrug resistance. Capsule production known be transcriptionally regulated by a number of proteins, but very little about how these proteins collectively control production. RmpA and RcsB two regulators gene expression, required the hypermucoviscous (HMV) phenotype K....

Although pneumonic plague is the deadliest manifestation of disease caused by bacterium Yersinia pestis, there surprisingly little information on cellular and molecular mechanisms responsible for Y. pestis-triggered pathology in lung. Therefore, to understand progression this unique disease, we characterized an intranasal mouse model primary plague. Mice succumbed a purulent multifocal severe exudative bronchopneumonia that closely resembles observed humans. Analyses revealed strikingly...

Primary pneumonic plague is transmitted easily, progresses rapidly, and causes high mortality, but the mechanisms by which Yersinia pestis overwhelms lungs are largely unknown. We show that plasminogen activator Pla essential for Y. to cause primary less important dissemination during than bubonic plague. Experiments manipulating its temporal expression showed allows replicate rapidly in airways, causing a lethal fulminant pneumonia; if unexpressed, inflammation aborted, lung repair...

The ability to invade the intestinal epithelium of mammals is an essential virulence determinant Yersinia enterocolitica. chromosomally encoded Y. enterocolitica 8081v invasion gene, inv, was disrupted assess its role in pathogenesis. inv mutant (JP273v) approximately 80-fold less invasive than wild type for cultured epithelial cells. When mice were infected intragastrically, up 10(7) fewer JP273v recovered from Peyer's patches early (6-18 hr) after infection compared with type. Analysis...

Yersinia enterocolitica is a heterogeneous group of organisms with more than 50 serotypes and several biotypes. Only few these cause gastrointestinal disease in otherwise healthy hosts; are the pathogenic serotypes. Although Y. requires high-molecular-weight plasmid to disease, chromosome-encoded determinants required for full expression virulence. The ability spp. invade eucaryotic cells thought be virulence factor, because nonpathogenic noninvasive animals tissue culture cell models....

We describe the cloning of toxS gene from Vibrio cholerae E1 Tor strain E7946. This lies downstream toxR gene, which encodes transcriptional activator for cholera toxin (ctx) operon in V. cholerae. show that ToxS acts conjunction with ToxR to activate expression ctx Escherichia coli. The classical 569B, is attenuated virulance but synthesizes high levels vitro, carries a deletion 1.2 kilobase pairs DNA, removes toxS. present evidence an toxR.

Klebsiella pneumoniae is a Gram-negative enterobacterium that has historically been, and currently remains, significant cause of human disease. It frequent urinary tract infections pneumonia, subsequent systemic can have mortality rates as high 60%. Despite its clinical significance, few virulence factors K. been identified or characterized. In this study we present mouse model acute respiratory infection using an intranasal inoculation method, examine the progression both pulmonary...

Iron acquisition systems are essential for the in vivo growth of bacterial pathogens. Despite epidemiological importance Klebsiella pneumoniae, few experiments have examined siderophores pathogenesis this species. A previously reported signature-tagged mutagenesis screen identified an attenuated strain that featured insertional disruption ybtQ, which encodes a transporter siderophore yersiniabactin. We used finding as starting point to evaluate physiology and K. pneumoniae. Isogenic strains...

In a ferromagnet, an applied electric field E invariably produces anomalous Hall current J H that flows perpendicular to the plane defined by and M (the magnetization). For decades, question of whether is dissipationless (independent scattering rate) has been debated without experimental resolution. ferromagnetic spinel CuCr 2 Se 4– x Br , resistivity ρ (at low temperature) may be increased several decades varying (Br) degrading M. We show /E (normalized per carrier, at 5 kelvin) remains...

Pathogenic Yersinia species are associated with both localized and systemic infections in mammalian hosts. In this study, signature-tagged transposon mutagenesis was used to identify enterocolitica genes required for survival a mouse model of infection. Approximately 2000 insertion mutants were screened attenuation. This led the identification 55 defective animal host, as judged by their ability compete wild-type strain mixed infections. A total 28 had insertions virulence plasmid,...

The ability to enter (invade) eucaryotic cells is a property common many pathogenic bacteria. Yersinia enterocolitica facultative intracellular pathogen whose primary site of multiplication the reticuloendothelial system. In an effort understand how Y. crosses intestinal epithelial cell layer, we previously reported cloning two loci from that individually conferred invasive phenotype normally noninvasive Escherichia coli HB101. One these loci, ail, encoded by region DNA less than 650 base...

Nasal colonization by both gram-positive and gram-negative pathogens induces expression of the innate immune protein lipocalin 2 (Lcn2). Lcn2 binds sequesters iron-scavenging siderophore enterobactin (Ent), preventing bacterial iron acquisition. In addition, bound to Ent release IL-8 from cultured respiratory cells. As a countermeasure, Enterobacteriaceae family such as Klebsiella pneumoniae produce additional siderophores yersiniabactin (Ybt) contain iroA locus encoding an glycosylase that...

The pathogenic species of Yersinia contain the transcriptional regulator RovA. In pseudotuberculosis and enterocolitica , RovA regulates expression invasion factor invasin ( inv ), which mediates translocation across intestinal epithelium. A Y . rov mutant has a significant decrease in virulence by LD 50 analysis an altered rate dissemination compared with either wild type or mutant, suggesting that multiple factors. Here, we show involvement pestis naturally lacks functional gene. Δrov is...