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molecular characterization of the viab locus encoding the biosynthetic machinery for vi capsule formation in salmonella typhi.the vi capsular polysaccharide (cps) of salmonella enterica serovar typhi, the cause of human typhoid, is important for infectivity and virulence. the vi biosynthetic machinery is encoded within the viab locus composed of 10 genes involved in regulation of expression (tvia), polymer synthesis (tvib-tvie), and cell surface localization of the cps (vexa-vexe). we cloned the viab locus from s. typhi and transposon insertion mutants of individual viab genes were characterized in escherichia coli dh5 ...201223029132
fruit, a scar-free system for targeted chromosomal mutagenesis, epitope tagging, and promoter replacement in escherichia coli and salmonella enterica.recombineering is a widely-used approach to delete genes, introduce insertions and point mutations, and introduce epitope tags into bacterial chromosomes. many recombineering methods have been described, for a wide range of bacterial species. these methods are often limited by (i) low efficiency, and/or (ii) introduction of "scar" dna into the chromosome. here, we describe a rapid, efficient, pcr-based recombineering method, fruit, that can be used to introduce scar-free point mutations, deletio ...201223028641
ygiw homologous gene from pseudomonas aeruginosa 25w is responsible for tributyltin resistance.a tributyltin (tbt) resistance gene was isolated from the tbt-resistant marine origin bacterium pseudomonas aeruginosa 25w. this gene was identical to pa0320 deposited in the p. aeruginosa pao1 database (http://www.pseudomonas.com). the deduced amino acid sequence of pa0320 appears to be homologous to the ygiw proteins of escherichia coli and salmonella enterica. the deletion mutant of pa0320 showed a reduction of growth rate in the presence of tbt. a susceptibility test to cadmium, mercury, hyd ...201222990488
discovery and biological characterization of geranylated rna in bacteria.a general ms-based screen for unusually hydrophobic cellular small molecule-rna conjugates revealed geranylated rna in escherichia coli, enterobacter aerogenes, pseudomonas aeruginosa and salmonella enterica var. typhimurium. the geranyl group is conjugated to the sulfur atom in two 5-methylaminomethyl-2-thiouridine nucleotides. these geranylated nucleotides occur in the first anticodon position of trna(glu)(uuc), trna(lys)(uuu) and trna(gln)(uug) at a frequency of up to 6.7% (~400 geranylated n ...201222983156
a dual tag system for facilitated detection of surface expressed proteins in escherichia coli.the discovery of the autotransporter family has provided a mechanism for surface expression of proteins in laboratory strains of escherichia coli. we have previously reported the use of the aida-i autotransport system to express the salmonella enterica serovar enteritidis proteins sefa and h:gm. the sefa protein was successfully exposed to the medium, but the orientation of h:gm in the outer membrane could not be determined due to proteolytic cleavage of the n-terminal detection-tag. the goal of ...201222943700
escherichia coli strongly supports the growth of histomonas meleagridis, in a monoxenic culture, without influence on its pathogenicity.based on clonal cultures of histomonas meleagridis, monoxenic cultures have, to our knowledge for the first time, been established in a liquid medium. the faecal flora was exchanged for defined bacterial strains by selective destruction of the initial bacteria with a variety of antibiotics, keeping the flagellate alive. the growth of the protozoan parasite was found to depend on the bacteria, especially on their energy metabolism. escherichia coli was found to strongly support the growth of the ...201222921600
dbdiarrhea: the database of pathogen proteins and vaccine antigens from diarrheal pathogens.diarrhea occurs world-wide and is most commonly caused by gastrointestinal infections which kill around 2.2 million people globally each year, mostly children in developing countries. we describe here dbdiarrhea, which is currently the most comprehensive catalog of proteins implicated in the pathogenesis of diarrhea caused by major bacterial, viral and parasitic species. the current release of the database houses 820 proteins gleaned through an extensive and critical survey of research articles ...201222917656
rates of gyrase supercoiling and transcription elongation control supercoil density in a bacterial chromosome.gyrase catalyzes negative supercoiling of dna in an atp-dependent reaction that helps condense bacterial chromosomes into a compact interwound "nucleoid." the supercoil density (σ) of prokaryotic dna occurs in two forms. diffusible supercoil density (σ(d)) moves freely around the chromosome in 10 kb domains, and constrained supercoil density (σ(c)) results from binding abundant proteins that bend, loop, or unwind dna at many sites. diffusible and constrained supercoils contribute roughly equally ...201222916023
bacteria and protozoa differentially modulate the expression of rab proteins.phagocytic cells represent an important line of innate defense against microorganisms. uptake of microorganisms by these cells involves the formation of a phagosome that matures by fusing with endocytic compartments, resulting in killing of the enclosed microbe. small gtpases of the rab family are key regulators of vesicular trafficking in the endocytic pathway. intracellular pathogens can interfere with the function of these proteins in order to subvert host immune responses. however, it is unk ...201222911692
reduced na+ affinity increases turnover of salmonella enterica serovar typhimurium melb.the melibiose permease of salmonella enterica serovar typhimurium (melb(st)) catalyzes symport of melibiose with na(+), li(+), or h(+). bioinformatics and mutational analyses indicate that a conserved gly117 (helix iv) is a component of the na(+)-binding site. in this study, gly117 was mutated to ser, asn, or cys. all three mutations increase the maximum rate (v(max)) for melibiose transport in escherichia coli dw2 and greatly decrease na(+) affinity, indicating that intracellular release of na( ...201222865849
whole blood-derived microrna signatures in mice exposed to lipopolysaccharides.lipopolysaccharide (lps) is recognized as the most potent microbial mediator presaging the threat of invasion of gram-negative bacteria that implicated in the pathogenesis of sepsis and septic shock. this study was designed to examine the microrna (mirna) expression in whole blood from mice injected with intraperitoneal lps.201222849760
study on antibacterial alginate-stabilized copper nanoparticles by ft-ir and 2d-ir correlation spectroscopy.the objective of this study was to clarify the intermolecular interaction between antibacterial copper nanoparticles (cu nps) and sodium alginate (naalg) by fourier transform infrared spectroscopy (ft-ir) and to process the spectra applying two-dimensional infrared (2d-ir) correlation analysis. to our knowledge, the addition of naalg as a stabilizer of copper nanoparticles has not been previously reported. it is expected that the obtained results will provide valuable additional information on: ...201222848180
supported lipopolysaccharide bilayers.in this report, the formation of supported lipopolysaccharide bilayers (lps-slbs) is studied with extracted native and glycoengineered lps from escherichia coli ( e. coli ) and salmonella enterica sv typhimurium ( s. typhimurium ) to assemble a platform that allows measurement of lps membrane structure and the detection of membrane tethered saccharide-protein interactions. we present quartz crystal microbalance with dissipation monitoring (qcm-d) and fluorescence recovery after photobleaching (f ...201222830310
thymus maroccanus essential oil, a membranotropic compound active on gram-negative bacteria and resistant isolates.the effects of thymus maroccanus essential oil (eo) on the integrity of the cell membranes and the permeability of the outer membrane (om) and inner membrane (im) of escherichia coli, enterobacter aerogenes and salmonella enterica typhimurium were investigated.201222809088
leuo is a global regulator of gene expression in salmonella enterica serovar typhimurium.we report the first investigation of the binding of the salmonella enterica leuo lysr-type transcription regulator to its genomic targets in vivo. chromatin-immunoprecipitation-on-chip identified 178 leuo binding sites on the chromosome of s. enterica serovar typhimurium strain sl1344. these sites were distributed across both the core and the horizontally acquired genome, and included housekeeping genes and genes known to contribute to virulence. sixty-eight leuo targets were co-bound by the glo ...201222804842
convergent molecular evolution of genomic cores in salmonella enterica and escherichia coli.one of the strongest signals of adaptive molecular evolution of proteins is the occurrence of convergent hot spot mutations: repeated changes in the same amino acid positions. we performed a comparative genome-wide analysis of mutation-driven evolution of core (omnipresent) genes in 17 strains of salmonella enterica subspecies i and 22 strains of escherichia coli. more than 20% of core genes in both salmonella and e. coli accumulated hot spot mutations, with a predominance of identical changes h ...201222797756
a single residue determines the cooperative binding property of a primosomal dna replication protein, prib, to single-stranded dna.prib is a primosomal protein required for re-initiation of replication in bacteria. we characterized and compared the dna-binding properties of prib from salmonella enterica serovar typhimurium lt2 (stprib) and escherichia coli (ecprib). only one residue of ecprib, v6, was different in stprib (replaced by a6). previous structural information revealed that this residue is located on the putative dimer-dimer interface of prib and is not involved in single-stranded dna (ssdna) binding. the cooperat ...201222790931
fima, fimf, and fimh are necessary for assembly of type 1 fimbriae on salmonella enterica serovar typhimurium.salmonella enterica serovar typhimurium is a gram-negative member of the family enterobacteriaceae and is a common cause of bacterial food poisoning in humans. the fimbrial appendages are found on the surface of many enteric bacteria and enable the bacteria to bind to eukaryotic cells. s. typhimurium type 1 fimbriae are characterized by mannose-sensitive hemagglutination and are assembled via the chaperone/usher pathway. s. typhimurium type 1 fimbrial proteins are encoded by the fim gene cluster ...201222778099
infection of zebrafish embryos with intracellular bacterial pathogens.zebrafish (danio rerio) embryos are increasingly used as a model for studying the function of the vertebrate innate immune system in host-pathogen interactions. the major cell types of the innate immune system, macrophages and neutrophils, develop during the first days of embryogenesis prior to the maturation of lymphocytes that are required for adaptive immune responses. the ease of obtaining large numbers of embryos, their accessibility due to external development, the optical transparency of ...201222453760
flagellin from recombinant attenuated salmonella enterica serovar typhimurium reveals a fundamental role in chicken innate immunity.recombinant attenuated salmonella vaccines have been extensively studied, with a focus on eliciting specific immune responses against foreign antigens. however, very little is known about the innate immune responses, particularly the role of flagellin, in the induction of innate immunity triggered by recombinant attenuated salmonella in chickens. in the present report, we describe two salmonella enterica serovar typhimurium vaccine strains, wild-type (wt) or flagellin-deficient (flhd) salmonella ...201222237893
oral vaccination with attenuated salmonella enterica serovar typhimurium expressing cap protein of pcv2 and its immunogenicity in mouse and swine models.attenuated salmonella enterica serovar typhimurium (s. typhimurium) was selected as a transgenic vehicle for the development of oral vaccines against porcine circovirus type 2 (pcv2). the cap-encoding gene of pcv2 was amplified by pcr and cloned into expression vector pya3341. the recombinant plasmid pya3341-cap was transformed into attenuated s. typhimurium x4550. balb/c mice were inoculated orally with various doses of attenuated s. typhimurium x4550/pya3341-cap. the bacterium was safe to mice ...201222326539
early strains of multidrug-resistant salmonella enterica serovar kentucky sequence type 198 from southeast asia harbor salmonella genomic island 1-j variants with a novel insertion sequence.salmonella genomic island 1 (sgi1) is a 43-kb integrative mobilizable element that harbors a great diversity of multidrug resistance gene clusters described in numerous salmonella enterica serovars and also in proteus mirabilis. the majority of sgi1 variants contain an in104-derivative complex class 1 integron inserted between resolvase gene res and open reading frame (orf) s044 in sgi1. recently, the international spread of ciprofloxacin-resistant s. enterica serovar kentucky sequence type 198 ...201222802251
a novel capture compound for the identification and analysis of cyclic di-gmp binding proteins.the second messenger cyclic di-gmp is a near-ubiquitous signaling molecule that globally alters bacterial cell physiology to promote biofilm formation and community behavior. much progress was made in recent years towards the identification and characterization of diguanylate cyclases and phosphodiersterases, enzymes involved in the synthesis and degradation of this signaling compound. in contrast, our knowledge of the nature and mechanistic details of c-di-gmp effector proteins lags behind, pri ...201222652488
optimized culturing and nucleic acid-based methods for the detection of salmonella enterica in poultry environments.the main objective of this trial was to set up a series of assays following quantified inoculation of salmonella samples in 2 initial enrichment methods to ultimately determine the most effective and fastest detection method for recovery of salmonella in a poultry environment matrix. samples were randomly split into 2 different containers containing either buffered peptone water (bpw) + yeast extract, or tetrathionate broth (tt) with added iodine and brilliant green solution 0.1%. a frozen stock ...201223091129
modification of salmonella typhimurium motility by the probiotic yeast strain saccharomyces boulardii.motility is an important component of salmonella enterica serovar typhimurium (st) pathogenesis allowing the bacteria to move into appropriate niches, across the mucus layer and invade the intestinal epithelium. in vitro, flagellum-associated motility is closely related to the invasive properties of st. the probiotic yeast saccharomyces boulardii biocodex (s.b-b) is widely prescribed for the prophylaxis and treatment of diarrheal diseases caused by bacteria or antibiotics. in case of salmonella ...201222442723
β-galactomannan and saccharomyces cerevisiae var. boulardii modulate the immune response against salmonella enterica serovar typhimurium in porcine intestinal epithelial and dendritic cells.salmonella enterica serovar typhimurium is a facultative intracellular pathogen that causes inflammation, necrosis, and diarrhea in pigs, as well as being an important source of food-borne diseases in humans. probiotics and prebiotics are promising alternatives to antibiotics to control and prevent intestinal infections. the present work investigated a recently developed β-galactomannan (βgm) prebiotic compared to the proven probiotic saccharomyces cerevisiae var. boulardii on porcine ileum inte ...201222301691
occurrence and characterization of monophasic salmonella enterica serovar typhimurium (1,4,[5],12:i:-) of non-human origin in poland.the epidemiological role of monophasic salmonella enterica subsp. enterica serovar typhimurium tends to increase, indicating pandemic spread. the aim of the present study was to confirm the occurrence of this serological variant in poland and to report the first cases in belarus and ukraine. genetic similarity of monophasic isolates with salmonella typhimurium already present in these countries was assessed. serotyping, duplex-polymerase chain reaction (pcr) assay, antibiotic resistance and puls ...201223009171
cathelicidin antimicrobial peptide expression is not induced or required for bacterial clearance during salmonella enterica infection of human monocyte-derived macrophages.salmonella enterica serovar typhimurium is able to resist antimicrobial peptide killing by induction of the phop-phoq and pmra-pmrb two-component systems and the lipopolysaccharide (lps) modifications they mediate. murine cathelin-related antimicrobial peptide (cramp) has been reported to inhibit s. typhimurium growth in vitro and in vivo. we hypothesize that infection of human monocyte-derived macrophages (mdms) with salmonella enterica serovar typhi and s. typhimurium will induce human catheli ...201222927052
draft genome sequence of salmonella enterica serovar typhimurium st1660/06, a multidrug-resistant clinical strain isolated from a diarrheic patient.salmonella enterica serovar typhimurium is one of the most prevalent serovars of salmonella that causes human gastroenteritis. here, we report the draft genome sequence of the s. typhimurium multidrug-resistant strain st1660/06. comparative genomic analysis unveiled three strain-specific genomic islands that potentially confer the multidrug resistance and virulence of the strain.201223105062
the late endosomal adaptor p14 is a macrophage host-defense factor against salmonella infection.the outcome of an infection depends on the balance between host resistance and bacterial virulence. here, we show that the late endosomal adaptor p14 (also known as lamtor2) is one of the components for cellular host defense against the intracellular pathogen salmonella enterica serovar typhimurium. during salmonella infection, the complex of p14 and mp1 is required for the accurately timed transport of salmonella through the endolysosomal system. loss of p14 opens a time window that allows salm ...201222427693
evasion of human innate immunity without antagonizing tlr4 by mutant salmonella enterica serovar typhimurium having penta-acylated lipid a.modification of a lipid a moiety in gram-negative bacterial lps to a less acylated form is thought to facilitate bacterial evasion of host innate immunity, thereby enhancing pathogenicity. the contribution of less-acylated lipid a to interactions of whole bacterial cells with host cells (especially in humans) remains unclear. mutant strains of salmonella enterica serovar typhimurium with fewer acylated groups were generated. the major lipid a form in wild-type (wt) and the mutant kcs237 strain i ...201222419537
characterization of dals, an atp-binding cassette transporter for d-alanine, and its role in pathogenesis in salmonella enterica.expansion into new host niches requires bacterial pathogens to adapt to changes in nutrient availability and to evade an arsenal of host defenses. horizontal acquisition of salmonella pathogenicity island (spi)-2 permitted the expansion of salmonella enterica serovar typhimurium into the intracellular environment of host cells by allowing it to deliver bacterial effector proteins across the phagosome membrane. this is facilitated by the ssra-ssrb two-component regulatory system and a type iii se ...201222418438
strand length-dependent antimicrobial activity and membrane-active mechanism of arginine- and valine-rich β-hairpin-like antimicrobial peptides.antimicrobial peptides with amphipathic β-hairpin-like structures have potent antimicrobial properties and low cytotoxicity. the effect of vr or rv motifs on β-hairpin-like antimicrobial peptides has not been investigated. in this study, a series of β-hairpin-like peptides, ac-c(vr)(n)(d)pg (rv)(n)c-nh(2) (n = 1, 2, 3, 4, or 5), were synthesized, and the effect of chain length on antimicrobial activity was evaluated. the antimicrobial activity of the peptides initially increased and then decreas ...201222391533
myd88 signaling promotes both mucosal homeostatic and fibrotic responses during salmonella-induced colitis.salmonella enterica serovar typhimurium is a clinically important gram-negative, enteric bacterial pathogen that activates several toll-like receptors (tlrs). while tlr signaling through the adaptor protein myd88 has been shown to promote inflammation and host defense against the systemic spread of s. typhimurium, curiously, its role in the host response against s. typhimurium within the mammalian gastrointestinal (gi) tract is less clear. we therefore used the recently described salmonella-indu ...201222679002
selective purification of recombinant neuroactive peptides using the flagellar type iii secretion system.the structure, assembly, and function of the bacterial flagellum involves about 60 different proteins, many of which are selectively secreted via a specific type iii secretion system (t3ss) (j. frye et al., j. bacteriol. 188:2233-2243, 2006). the t3ss is reported to secrete proteins at rates of up to 10,000 amino acid residues per second. in this work, we showed that the flagellar t3ss of salmonella enterica serovar typhimurium could be manipulated to export recombinant nonflagellar proteins thr ...201222647788
effect of salmonella enteric serovar typhimurium in pregnant mice: a biochemical and histopathological study.food borne infections caused by salmonella enterica species are increasing globally and pregnancy poses a significant threat in developing countries, where sanitation facilities are inadequate. thus, the present study was designed to delineate the effect of salmonella infection during pregnancy.201227785189
role of mouse peptidoglycan recognition protein pglyrp2 in the innate immune response to salmonella enterica serovar typhimurium infection in vivo.peptidoglycan recognition proteins (pgrps) are a family of innate pattern recognition molecules that bind bacterial peptidoglycan. while the role of pgrps in drosophila innate immunity has been extensively studied, how the four mammalian pgrp proteins (pglyrp1 to pglyrp4) contribute to host defense against bacterial pathogens in vivo remains poorly understood. pglyrp1, pglyrp3, and pglyrp4 are directly bactericidal in vitro, whereas pglyrp2 is an n-acetylmuramyl-l-alanine amidase that cleaves pe ...201222615249
the evaluation of a pcr-based method for identification of salmonella enterica serotypes from environmental samples and various food matrices.the most commonly used method for serotyping salmonella spp. is based on the kaufmann-white scheme, and is composed of serological reactions using antibodies to lps agglutinins. the multiplex pcr used in this investigation was established by kim et al. to serotype the 30 most common clinical salmonella serotypes, as determined by cdc. the pcr assay consists of two five-plex reactions and a single two-plex pcr reaction, based on six genetic loci from salmonella enterica serotype typhimurium and f ...201222608224
stm2209-stm2208 (opvab): a phase variation locus of salmonella enterica involved in control of o-antigen chain length.stm2209 and stm2208 are contiguous loci annotated as putative protein-coding genes in the chromosome of salmonella enterica. lack of homologs in related enterobacteria and low g+c content suggest that s. enterica may have acquired stm2209-stm2208 by horizontal transfer. stm2209 and stm2208 are co-transcribed from a promoter upstream stm2209, and their products are inner (cytoplasmic) membrane proteins. analysis with the bacterial adenylate cyclase two-hybrid system suggests that stm2209 and stm2 ...201222606300
dietary rice bran promotes resistance to salmonella enterica serovar typhimurium colonization in mice.dietary rice bran consists of many bioactive components with disease fighting properties; including the capacity to modulate the gut microbiota. studies point to the important roles of the gut microbiota and the mucosal epithelium in the establishment of protection against enteric pathogens, such as salmonella. the ability of rice bran to reduce the susceptibility of mice to a salmonella infection has not been previously investigated. therefore, we hypothesized that the incorporation of rice bra ...201222583915
salmonella biofilm development depends on the phosphorylation status of rcsb.the rcs phosphorelay pathway is a complex signaling pathway involved in the regulation of many cell surface structures in enteric bacteria. in response to environmental stimuli, the sensor histidine kinase (rcsc) autophosphorylates and then transfers the phosphate through intermediary steps to the response regulator (rcsb), which, once phosphorylated, regulates gene expression. here, we show that salmonella biofilm development depends on the phosphorylation status of rcsb. thus, unphosphorylated ...201222582278
comparative proteomic analysis of salmonella tolerance to the biocide active agent triclosan.concern has been expressed about the overuse of biocides in farm animal production and food industries. biocide application can create selective pressures that lead to increased tolerance to one or more of these compounds and are concomitant with the emergence of cross-resistance to antibiotics. a triclosan sensitive salmonella enterica serovar typhimurium and the isogenic triclosan tolerant mutant were studied at the proteomic level in order to elucidate cellular mechanisms that facilitate bioc ...201222579747
effect of farm type on within-herd salmonella prevalence, serovar distribution, and antimicrobial resistance.salmonella represents a major challenge to the pig industry, as pork presents a risk for human salmonellosis. in this study, we have examined the effect of farm type on the prevalence of fattening pigs shedding salmonella on 12 farms at risk for harboring salmonella. on six open (grow-to-finish) and six closed (farrow-to-finish) farms, the prevalence of pigs shedding salmonella was determined on two occasions approximately 2 months apart. the serovar, phage type, and antimicrobial resistance of ...201222564934
targeted therapy via oral administration of attenuated salmonella expression plasmid-vectored stat3-shrna cures orthotopically transplanted mouse hcc.the development of rna interference-based cancer gene therapies has been delayed due to the lack of effective tumor-targeting delivery systems. attenuated salmonella enterica serovar typhimurium (s. typhimurium) has a natural tropism for solid tumors. we report here the use of attenuated s. typhimurium as a vector to deliver shrna directly into tumor cells. constitutively activated signal transducer and activator of transcription 3 (stat3) is a key transcription factor involved in both hepatocel ...201222555509
srnas and the virulence of salmonella enterica serovar typhimurium.the combination of genomics and high-throughput cdna sequencing technologies has facilitated the identification of many small rnas (srnas) that play a central role in the post-transcriptional gene regulation of salmonella enterica serovar typhimurium. to date, most of the functionally characterized srnas have been involved in the regulation of processes which are not directly linked to virulence. just five srnas have been found to affect the ability of salmonella to replicate within mammalian ce ...201222546935
hypochlorous acid and hydrogen peroxide-induced negative regulation of salmonella enterica serovar typhimurium ompw by the response regulator arca.hydrogen peroxide (h2o2) and hypochlorous acid (hocl) are reactive oxygen species that are part of the oxidative burst encountered by salmonella enterica serovar typhimurium (s. typhimurium) upon internalization by phagocytic cells. in order to survive, bacteria must sense these signals and modulate gene expression. growing evidence indicates that the arcab two component system plays a role in the resistance to reactive oxygen species. we investigated the influx of h2o2 and hocl through ompw and ...201222545862
evidence for lack of acquisition of tolerance in salmonella enterica serovar typhimurium atcc 14028 after exposure to subinhibitory amounts of origanum vulgare l. essential oil and carvacrol.overnight exposure of salmonella enterica serovar typhimurium to sublethal amounts of origanum vulgare essential oil (ov) and carvacrol (car) did not result in direct and cross-bacterial protection. cells subcultured with increasing amounts of ov or car survived up to the mic of either compound, revealing few significant changes in bacterial susceptibility.201222544235
the transcriptional landscape and small rnas of salmonella enterica serovar typhimurium.more than 50 y of research have provided great insight into the physiology, metabolism, and molecular biology of salmonella enterica serovar typhimurium (s. typhimurium), but important gaps in our knowledge remain. it is clear that a precise choreography of gene expression is required for salmonella infection, but basic genetic information such as the global locations of transcription start sites (tsss) has been lacking. we combined three rna-sequencing techniques and two sequencing platforms to ...201222538806
quantifying ligand binding to large protein complexes using electrospray ionization mass spectrometry.an electrospray ionization mass spectrometry (esi-ms) method for quantifying protein-ligand complexes that cannot be directly detected by esi-ms is described. the proxy protein esi-ms method combines direct esi-ms binding measurements with competitive protein-ligand binding. to implement the method, a proxy protein (p(proxy)), which interacts specifically with the ligand of interest with known affinity and can be detected directly by esi-ms, is used to quantitatively monitor the extent of ligand ...201222507285
three-axis model for atg recruitment in autophagy against salmonella.salmonella enterica serovar typhimurium enter epithelial cells and take up residence there. within epithelial cells, a portion of the bacteria are surrounded by an autophagosome-like double-membrane structure, and they are still residing within the salmonella-containing vacuole (scv). in this paper, we will discuss how the autophagy machinery is recruited in proximity to salmonella. the formation of this double membrane requires atg9l1 and fip200; these proteins are important for autophagy-speci ...201222505927
analysis of hilc/d-dependent invf promoter expression under different culture conditions.in salmonella enterica serovar typhimurium, many of the genes required for intestinal penetration and invasion of host cells are encoded within the salmonella pathogenicity island 1 (spi1). the expression of invf, which is a positive transcriptional activator of spi1, is controlled by hila-dependent (invf-1) and hilc/d-dependent (invf-2) promoters. transcriptional analysis of invf revealed that the invf-2 promoter (p(invf-2)) was not activated when cells were grown in standing culture conditions ...201222480973
association of a protective monoclonal iga with the o antigen of salmonella enterica serovar typhimurium impacts type 3 secretion and outer membrane integrity.invasion of intestinal epithelial cells by salmonella enterica serovar typhimurium is an energetically demanding process, involving the transfer of effector proteins from invading bacteria into host cells via a specialized organelle known as the salmonella pathogenicity island 1 (spi-1) type 3 secretion system (t3ss). by a mechanism that remains poorly understood, entry of s. typhimurium into epithelial cells is inhibited by sal4, a monoclonal, polymeric iga antibody that binds an immunodominant ...201222473607
improving resolution of public health surveillance for human salmonella enterica serovar typhimurium infection: 3 years of prospective multiple-locus variable-number tandem-repeat analysis (mlva).prospective typing of salmonella enterica serovar typhimurium (stm) by multiple-locus variable-number tandem-repeat analysis (mlva) can assist in identifying clusters of stm cases that might otherwise have gone unrecognised, as well as sources of sporadic and outbreak cases. this paper describes the dynamics of human stm infection in a prospective study of stm mlva typing for public health surveillance.201222462487
presence and persistence of salmonella enterica serotype typhimurium in the phyllosphere and rhizosphere of spray-irrigated parsley.salmonella enterica is one of the major food-borne pathogens associated with ready-to-eat fresh foods. although polluted water might be a significant source of contamination in the field, factors that influence the transfer of salmonella from water to the crops are not well understood, especially under conditions of low pathogen levels in water. the aim of this study was to investigate the short- and long-term (1 h to 28 days) persistence of salmonella enterica serotype typhimurium in the phyllo ...201222447598
enhancement of the anti-salmonella immune response in cd154-deficient mice by an attenuated, ifn-γ-expressing, strain of salmonella enterica serovar typhimurium.previously, we demonstrated that cell-cell communications via the cd40-cd154 pathway play a critical role in the induction of type 1 cytokine responses, including il-12 and ifn-γ, which in turn greatly influence the response to salmonella infections. mice genetically deficient in the expression of cd154 exhibited markedly increased susceptibility to infection by an attenuated, double auxotrophic (aroa-arod-) strain, designated brd509, of salmonella enterica serovar typhimurium. in the present st ...201222445817
characterization and differential gene expression between two phenotypic phase variants in salmonella enterica serovar typhimurium.salmonella enterica serovar typhimurium strain 798 has previously been shown to undergo phenotypic phase variation. one of the phenotypes expresses virulence traits such as adhesion, while the other phenotype does not. phenotypic phase variation appears to correlate with the ability of this strain to cause persistent, asymptomatic infections of swine. a new method to detect cells in either phenotypic phase was developed using evans blue-uranine agar plates. using this new assay, rates of phenoty ...201222937065
spontaneous and transient defence against bacteriophage by phase-variable glucosylation of o-antigen in salmonella enterica serovar typhimurium.as natural killers of bacteria, bacteriophages have forced bacteria to develop a variety of defence mechanisms. the alteration of host receptors is one of the most common bacterial defence strategies against phage infection, which completely blocks phage attachment but comes at a potential fitness cost to the bacteria. here, we report the cost-free, transient emergence of phage resistance in salmonella enterica subspecies enterica serovar typhimurium through a phase-variable modification of the ...201222928771
receptor diversity and host interaction of bacteriophages infecting salmonella enterica serovar typhimurium.salmonella enterica subspecies enterica serovar typhimurium is a gram-negative pathogen causing salmonellosis. salmonella typhimurium-targeting bacteriophages have been proposed as an alternative biocontrol agent to antibiotics. to further understand infection and interaction mechanisms between the host strains and the bacteriophages, the receptor diversity of these phages needs to be elucidated.201222927964
type i interferon induces necroptosis in macrophages during infection with salmonella enterica serovar typhimurium.salmonella enterica serovar typhimurium (s. typhimurium) is a virulent pathogen that induces rapid host death. here we observed that host survival after infection with s. typhimurium was enhanced in the absence of type i interferon signaling, with improved survival of mice deficient in the receptor for type i interferons (ifnar1(-/-) mice) that was attributed to macrophages. although there was no impairment in cytokine expression or inflammasome activation in ifnar1(-/-) macrophages, they were h ...201222922364
cationic antimicrobial peptides serve as activation signals for the salmonella typhimurium phopq and pmrab regulons in vitro and in vivo.salmonella enterica serovar typhimurium uses two-component regulatory systems (tcrss) to respond to environmental stimuli. upon infection, the tcrss phop-phoq (phopq) and pmra-pmrb (pmrab) are activated by environmental signals detected in the lumen of the intestine and within host cells. tcrs-mediated gene expression leads to upregulation of genes involved in lipopolysaccharide (lps) modification and cationic antimicrobial peptide (camp) resistance. this research expands on previous studies whi ...201222919691
caspase-11 increases susceptibility to salmonella infection in the absence of caspase-1.inflammasomes are cytosolic multiprotein complexes assembled by intracellular nucleotide-binding oligomerization domain (nod)-like receptors (nlrs) and they initiate innate immune responses to invading pathogens and danger signals by activating caspase-1 (ref. 1). caspase-1 activation leads to the maturation and release of the pro-inflammatory cytokines interleukin (il)-1β and il-18, as well as lytic inflammatory cell death known as pyroptosis. recently, a new non-canonical inflammasome was desc ...201222895188
biofilm formation, cell surface hydrophobicity, and fatty acids analysis of starved salmonella enterica serovar typhimurium in seawater.salmonella is an international foodborne pathogen widely disseminated in seawater that regularly causes large outbreaks of food poisoning. in this study, we have investigated the effect of starvation on the ability of salmonella enterica serovar typhimurium cells to adhere to polystyrene microplate and hep2 cells in seawater microcosms after incubation for 3 years. cell surface hydrophobicity was evaluated. effect of stress on fatty acids composition was also established. our results showed that ...201222891961
non-genetic diversity shapes infectious capacity and host resistance.the spontaneous generation of distinct phenotypes within a clonal population of cells allows for both bet-hedging at the population level and the division of labor among subpopulations. this is emerging as an important theme in bacterial pathogenesis, because bacterial pathogens exhibit phenotypic heterogeneity with respect to characteristics that impact virulence. the phenomenon of persister cells and models of salmonella enterica serovar typhimurium (s. typhimurium) pathogenesis illustrate the ...201222889945
low-shear modeled microgravity enhances salmonella enterica resistance to hydrogen peroxide through a mechanism involving katg and katn.studies carried out in recent years have established that growth under conditions of reduced gravity enhances salmonella enterica serovar typhimurium virulence. to analyze the possibility that this microgravity-induced increase in pathogenicity could involve alterations in the ability of salmonella to withstand oxidative stress, we have compared the resistance to hydrogen peroxide of various salmonella enterica strains grown under conditions of low shear modeled microgravity (lsmmg) or normal gr ...201222888375
evolution of a multiple antibiotic resistance region in inchi1 plasmids: reshaping resistance regions in situ.to determine the structure of the resistance region in an inchi1 plasmid conferring resistance to multiple antibiotics, including gentamicin, recovered from a salmonella enterica serovar typhimurium isolate from a horse.201222888274
genome scanning for conditionally essential genes in salmonella enterica serotype typhimurium.as more whole-genome sequences become available, there is an increasing demand for high-throughput methods that link genes to phenotypes, facilitating discovery of new gene functions. in this study, we describe a new version of the tn-seq method involving a modified ez:tn5 transposon for genome-wide and quantitative mapping of all insertions in a complex mutant library utilizing massively parallel illumina sequencing. this tn-seq method was applied to a genome-saturating salmonella enterica sero ...201222367088
a third mode of surface-associated growth: immobilization of salmonella enterica serovar typhimurium modulates the rpos-directed transcriptional programme.although the growth of bacteria has been studied for more than a century, it is only in recent decades that surface-associated growth has received attention. in addition to the well-characterized biofilm and swarming lifestyles, bacteria can also develop as micro-colonies supported by structured environments in both food products and the gi tract. this immobilized mode of growth has not been widely studied. to develop our understanding of the effects of immobilization upon a food-borne bacterial ...201222356617
laboratory-based surveillance of non-typhoidal salmonella infections in guangdong province, china.salmonella is one of the most common foodborne pathogens in humans. laboratory-based surveillance for non-typhoidal salmonella infection was conducted in guangdong province, china to improve understanding about the disease burden and detection of dispersed outbreaks. salmonella isolated from patients with diarrhea were sent from 16 sentinel hospitals to local public health laboratories for confirmation, serotyping, antimicrobial susceptibility testing, and pulsed-field gel electrophoresis (pfge) ...201222356574
peroral ciprofloxacin therapy impairs the generation of a protective immune response in a mouse model for salmonella enterica serovar typhimurium diarrhea, while parenteral ceftriaxone therapy does not.nontyphoidal salmonella (nts) species cause self-limiting diarrhea and sometimes severe disease. antibiotic treatment is considered only in severe cases and immune-compromised patients. the beneficial effects of antibiotic therapy and the consequences for adaptive immune responses are not well understood. we used a mouse model for salmonella diarrhea to assess the effects of per os treatment with ciprofloxacin (15 mg/kg of body weight intragastrically 2 times/day, 5 days) or parenteral ceftriaxo ...201222354292
igg keeps virulent salmonella from evading dendritic cell uptake.dendritic cells (dcs) are phagocytic professional antigen-presenting cells that can prime naive t cells and initiate anti-bacterial immunity. however, several pathogenic bacteria have developed virulence mechanisms to impair dc function. for instance, salmonella enterica serovar typhimurium can prevent dcs from activating antigen-specific t cells. in addition, it has been described that the salmonella pathogenicity island 1 (spi-1), which promotes phagocytosis of bacteria in non-phagocytic cells ...201222352313
hfq and hfq-dependent small rnas are major contributors to multicellular development in salmonella enterica serovar typhimurium.the rna chaperone hfq and its associated small rnas (srnas) regulate a variety of phenotypes in bacteria. in this work, we show that hfq is a master regulator of biofilm formation in salmonella enterica serovar typhimurium. hfq and two hfq-dependent srnas (arcz and sdsr) are required for rdar morphotype expression in s. typhimurium. hfq controls rdar biofilm formation through the major biofilm regulator csgd. while csgd mrna steady-state levels are altered in a sdsr mutant, arcz seems to work ma ...201222336758
development of carbapenem resistance during therapy for non-typhoid salmonella infection.multidrug-resistant salmonella infection is a global problem, and carbapenems may represent the last therapeutic choice. we report a case of infection caused by ceftriaxone-resistant and ciprofloxacin-resistant salmonella enterica serotype typhimurium. a bla(cmy-2) -containing tn6092, located on a self-transferable inci1 plasmid, was found in all isolates derived from the patient. during ertapenem treatment, the strain developed carbapenem resistance. apart from the ompd deficiency found in all ...201222329543
dksa-dependent resistance of salmonella enterica serovar typhimurium against the antimicrobial activity of inducible nitric oxide synthase.in coordination with the ppgpp alarmone, the rna polymerase regulatory protein dksa controls the stringent response of eubacteria, negatively regulating transcription of translational machinery and directly activating amino acid promoters and de novo amino acid biosynthesis. given the effects of nitric oxide (no) on amino acid biosynthetic pathways and the intimate relationship of dksa with amino acid synthesis and transport, we tested whether dksa contributes to the resistance of salmonella to ...201222311927
the evaluation of clusters of hospital infections due to multidrug-resistant salmonella enterica serovar typhimurium in the neonatal unit: a two-year experience.seven clusters of hospital infection due to salmonella enterica serovar typhimurium were documented in the neonatology clinic of a children's hospital between april 2002 and march 2004. eighty-one neonates were infected. three cases were asymptomatic, 73 cases had gastroenteritis as the only clinical condition, and 5 cases had bacteremia associated with gastroenteritis. all isolates from stool and blood samples (n=86) were identified as salmonella enterica serovar typhimurium. extended-spectrum ...201222272451
proteomic pleiotropy of opggh, an operon necessary for efficient growth of salmonella enterica serovar typhimurium under low-osmotic conditions.salmonella enterica, a bacterial, food-borne pathogen of humans, can contaminate raw fruits and vegetables. unfortunately for consumers, the bacteria can survive in water used to wash away contaminating bacteria. the ability to survive the low-osmotic conditions of the wash water is attributed to the opggh operon that leads to the production of osmotically regulated periplasmic glucans. mutants lacking opggh grow slowly under low-osmotic conditions, but there are also unexpected traits such as a ...201222264073
death receptor 3 is essential for generating optimal protective cd4⁺ t-cell immunity against salmonella.the tnf receptor superfamily member death receptor 3 (dr3) exacerbates th2- and th17-cell-mediated inflammatory and autoimmune conditions, yet no role in host defence has been reported. here, we examined the role of dr3 during infection with salmonella enterica serovar typhimurium. infection resulted in protracted expression of the dr3 ligand tl1a but not the related tnf superfamily proteins ox40l or cd30l. tl1a expression was localized to splenic f4/80(+) macrophages where s. enterica typhimuri ...201222259035
foodborne outbreak and nonmotile salmonella enterica variant, france.we report a food-related outbreak of salmonellosis in humans caused by a nonmotile variant of salmonella enterica serotype typhimurium in france in 2009. this nonmotile variant had been circulating in laying hens but was not considered as typhimurium and consequently escaped european poultry flock regulations.201222257550
molecular identification in monophasic and nonmotile variants of salmonella enterica serovar typhimurium.variant strains of salmonella enterica serovar typhimurium, lacking one or both flagellar phases have been widely reported. the monophasic s.1,4,[5],12:i:- variant has emerged worldwide in the past few years and has become one of the most frequently encountered in many countries. in contrast, monophasic s.1,4,[5],12:-:1,2 and nonmotile s.1,4,[5],12:-:- strains are rarely described. this study investigated seven molecular markers to identify and delineate monophasic s.1,4,[5],12:i:- (n = 90), s.1 ...201223233427
an altered immune response, but not individual cationic antimicrobial peptides, is associated with the oral attenuation of ara4n-deficient salmonella enterica serovar typhimurium in mice.salmonella enterica serovar typhimurium (s. typhimurium) uses two-component regulatory systems (tcrs) to respond to stimuli in the local microenvironment. upon infection, the salmonella tcrss phop-phoq (phopq) and pmra-pmrb (pmrab) are activated by environmental signals in the intestinal lumen and within host cells. tcrs-mediated gene expression results in lipopolysaccharide (lps) modification and cationic antimicrobial peptide resistance. the pmra-regulated pmrhfijklm operon mediates 4-amino-4- ...201223166721
flagella overexpression attenuates salmonella pathogenesis.flagella are cell surface appendages involved in a number of bacterial behaviors, such as motility, biofilm formation, and chemotaxis. despite these important functions, flagella can pose a liability to a bacterium when serving as potent immunogens resulting in the stimulation of the innate and adaptive immune systems. previous work showing appendage overexpression, referred to as attenuating gene expression (age), was found to enfeeble wild-type salmonella. thus, this approach was adapted to di ...201223056473
genetic manipulation of pathogenicity loci in non-typhimurium salmonella.the traditional genetic tools used in salmonella enterica serovar typhimurium rely heavily on a high-transducing mutant of bacteriophage p22. p22 recognizes its hosts by the structure of their o-antigens, which vary among serovars of salmonella; therefore, it cannot be used in most non-typhimurium salmonella, including the majority of those causing food-borne illnesses in both humans and livestock. bacteriophage p1 infects a variety of enteric bacteria, including gale mutants of serovar typhimur ...201223041268
on-cell mas nmr: physiological clues from living cells.while structural information on biomolecules is mainly obtained from purified in vitro samples, nmr can also be applied in the context of entire cells or organisms. the present study describes maturation processes in living salmonella enterica serovar typhimurium, a prevalent cause for human gastroenteritis. in our physiological study, we follow the composition of the o-antigen on the outer bacterial membrane with high-resolution mas nmr spectroscopy. we detect and characterize an evolution of t ...201223030432
very long o-antigen chains enhance fitness during salmonella-induced colitis by increasing bile resistance.intestinal inflammation changes the luminal habitat for microbes through mechanisms that have not been fully resolved. we noticed that the fepe regulator of very long o-antigen chain assembly in the enteric pathogen salmonella enterica serotype typhimurium (s. typhimurium) conferred a luminal fitness advantage in the mouse colitis model. however, a fepe mutant was not defective for survival in tissue, resistance to complement or resistance to polymyxin b. we performed metabolite profiling to ide ...201223028318
microbial amyloids induce interleukin 17a (il-17a) and il-22 responses via toll-like receptor 2 activation in the intestinal mucosa.the toll-like receptor 2 (tlr2)/tlr1 receptor complex responds to amyloid fibrils, a common component of biofilm material produced by members of the phyla firmicutes, bacteroidetes, and proteobacteria. to determine whether this tlr2/tlr1 ligand stimulates inflammatory responses when bacteria enter intestinal tissue, we investigated whether expression of curli amyloid fibrils by the invasive enteric pathogen salmonella enterica serotype typhimurium contributes to t helper 1 and t helper 17 respon ...201223027540
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 ...201223019341
expression of stm4467-encoded arginine deiminase controlled by the stm4463 regulator contributes to salmonella enterica serovar typhimurium virulence.arginine deiminase (adi), carbamate kinase (ck), and ornithine transcarbamoylase (otc) constitute the adi system. in addition to metabolic functions, the adi system has been implicated in the virulence of certain pathogens. the pathogenic intracellular bacterium salmonella enterica serovar typhimurium possesses the stm4467, stm4466, and stm4465 genes, which are predicted to encode adi, ck, and otc, respectively. here we report that the stm4467 gene encodes an adi and that adi activity plays a ro ...201223006851
targeting essential genes in salmonella enterica serovar typhimurium with antisense peptide nucleic acid.we investigated the capability of antisense peptide nucleic acids (pnas) conjugated to the (kff)(3)k cell-penetrating peptide to target possible essential genes (liga, rpoa, rpod, enga, tsf, and kdta) in salmonella enterica serovar typhimurium and inhibit bacterial growth in vitro and in cell culture. all targeted pna-based gene inhibition has shown great potency in gene expression inhibition in a sequence-specific and dose-dependent manner at micromolar concentrations. among tested pnas, the an ...201223006748
prevalence of salmonella enterica serovar 4,[5],12:i:- in england and wales, 2010.difficulties in accurately identifying serovar 4,[5],12:i:- as monophasic variants of salmonella enterica serovar typhimurium mean there is confusion in the reporting of serovars typhimurium and 4,[5],12:i:-. to gain insight into the prevalence and diversity of these monophasic variants in england and wales, screening for fljb, hin and the serovar 4,[5],12:i:- dt193-associated genomic island was conducted on 609 s. enterica isolates designated as definitive phage type (dt) 193, and 142 isolates ...201222995432
persistence of salmonella enterica during dehydration and subsequent cold storage.despite the fact that salmonella enterica serotype typhimurium sl 1344 has served as a model pathogen in many studies, information regarding its desiccation response is still scarce. in this study, we investigated environmental conditions that affect salmonella survival following dehydration and subsequent cold storage, using a 96-well polystyrene plate model. the sl 1344 strain exhibited high survival compared with other typhimurium isolates and s. enterica serotypes. further characterization o ...201222986208
membrane topology of salmonella invasion protein sipb confers osmotolerance.salmonella enterica serovar typhimurium is a major cause of human gastrointestinal illness worldwide. this pathogen can persist in a wide range of environments, making it of great concern to public health. here, we report that the salmonella pathogenicity island (spi)-1 effector protein sipb exhibits a membrane topology that confers bacterial osmotolerance. disruption of the sipb gene or the invg gene (spi-1 component) significantly reduced the osmotolerance of s. typhimurium lt2. biochemical as ...201222975346
m cell differentiation: distinct lineage or phenotypic transition? salmonella provides answers.whether m cells arise from a distinct lineage or result from phenotypic transition is a matter of debate. in this issue of cell host & microbe, tahoun et al. (2012) provide evidence that sopb, a virulence factor of salmonella enterica serovar typhimurium, can induce phenotypic transition of lymphoid follicle-associated enterocytes into m cells.201223159049
neutrophil elastase alters the murine gut microbiota resulting in enhanced salmonella colonization.the intestinal microbiota has been found to play a central role in the colonization of salmonella enterica serovar typhimurium in the gastrointestinal tract. in this study, we present a novel process through which salmonella benefit from inflammatory induced changes in the microbiota in order to facilitate disease. we show that salmonella infection in mice causes recruitment of neutrophils to the gut lumen, resulting in significant changes in the composition of the intestinal microbiota. this oc ...201223155475
systemic flagellin immunization stimulates mucosal cd103+ dendritic cells and drives foxp3+ regulatory t cell and iga responses in the mesenteric lymph node.mucosal immunity is poorly activated after systemic immunization with protein ags. nevertheless, induction of mucosal immunity in such a manner would be an attractive and simple way to overcome the intrinsic difficulties in delivering ag to such sites. flagellin from salmonella enterica serovar typhimurium (flic) can impact markedly on host immunity, in part via its recognition by tlr5. in this study, we show that systemic immunization with soluble flic (sflic) drives distinct immune responses c ...201223152564
tissue dyslipidemia in salmonella-infected rats treated with amoxillin and pefloxacin.this study investigated the effects of salmonella infection and its chemotherapy on lipid metabolism in tissues of rats infected orally with salmonella typhimurium and treated intraperitoneally with pefloxacin and amoxillin.201223137290
complete genome sequence of bacteriophage ssu5 specific for salmonella enterica serovar typhimurium rough strains.salmonella enterica serovar typhimurium rough strain-specific phage ssu5 was isolated, and its whole genome was sequenced. the 103,229-bp-long double-stranded dna genome of ssu5 encodes 130 open reading frames with one trna for asparagine. genomic analysis revealed that ssu5 might be the phylogenetic origin of cryptic plasmid phcm2 harbored by salmonella typhi ct18.201222966187
regulation of rama by ramr in salmonella enterica serovar typhimurium: isolation of a ramr superrepressor.rama is a transcription factor involved in regulating multidrug resistance in salmonella enterica serovar typhimurium sl1344. green fluorescent protein (gfp) reporter fusions were exploited to investigate the regulation of rama expression by ramr. we show that ramr represses the rama promoter by binding to a palindromic sequence and describe a superrepressor ramr mutant that binds to the rama promoter sequence more efficiently, thus exhibiting a rama inactivated phenotype.201222948865
global transcriptional analysis of dehydrated salmonella enterica serovar typhimurium.despite the scientific and industrial importance of desiccation tolerance in salmonella, knowledge regarding its genetic basis is still scarce. in the present study, we performed a transcriptomic analysis of dehydrated and water-suspended salmonella enterica serovar typhimurium using microarrays. dehydration induced expression of 90 genes and downregulated that of 7 genes. ribosomal structural genes represented the most abundant functional group with a relatively higher transcription during dehy ...201222941081
phosphorylation of nlrc4 is critical for inflammasome activation.nlrc4 is a cytosolic member of the nod-like receptor family that is expressed in innate immune cells. it senses indirectly bacterial flagellin and type iii secretion systems, and responds by assembling an inflammasome complex that promotes caspase-1 activation and pyroptosis. here we use knock-in mice expressing nlrc4 with a carboxy-terminal 3×flag tag to identify phosphorylation of nlrc4 on a single, evolutionarily conserved residue, ser 533, following infection of macrophages with salmonella e ...201222885697
grapefruit juice and its constituents augment the effect of low ph on inhibition of survival and adherence to intestinal epithelial cells of salmonella enterica serovar typhimurium pt193.the present study examined the survival of salmonella typhimurium and its adherence to intestinal epithelial cells following inoculation into grapefruit juice and apple cider. both liquids significantly inactivated s. typhimurium (0.8-2.2 log reduction compared to the control); surviving salmonella in grapefruit juice was 1.0-1.4 log lower than in apple cider at 24h incubation. grapefruit juice contains the antimicrobial substances naringin (nar) and naringenin (nge); however, the effect of grap ...201222867848
tandem attenuators control expression of the salmonella mgtcbr virulence operon.the mgtcbr operon from salmonella enterica serovar typhimurium specifies the virulence protein mgtc, the mg(2+) transporter mgtb and the regulatory peptide mgtr. the mgtcbr transcript includes a long leader region harbouring two short open reading frames (orfs). translation of these orfs is anticipated to impact the formation of particular stem-loop structures and control transcription of the coding region by an attenuation-like mechanism. we previously reported that orf mgtm enables salmonella ...201222857388
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