scholarly journals Leafhopper-Induced Activation of the Jasmonic Acid Response Benefits Salmonella enterica in a Flagellum-Dependent Manner

2018 ◽  
Vol 9 ◽  
Author(s):  
Kimberly N. Cowles ◽  
Russell L. Groves ◽  
Jeri D. Barak
Keyword(s):  
Jasmonic Acid ◽  
Salmonella Enterica ◽  
Dependent Manner ◽  
Jasmonic Acid Response

scholarly journals Regulation of igaA and the Rcs System by the MviA Response Regulator in Salmonella enterica

2009 ◽  
Vol 191 (8) ◽  
pp. 2743-2752 ◽  
Author(s):  
Clara B. García-Calderón ◽  
Josep Casadesús ◽  
Francisco Ramos-Morales
Keyword(s):  
Membrane Protein ◽  
Salmonella Enterica ◽  
Response Regulator ◽  
Regulatory System ◽  
Enteric Bacteria ◽  
Lon Protease ◽  
Dependent Manner ◽  
Independent Manner ◽  
Serovar Typhimurium

ABSTRACT IgaA is a membrane protein that prevents overactivation of the Rcs regulatory system in enteric bacteria. Here we provide evidence that igaA is the first gene in a σ70-dependent operon of Salmonella enterica serovar Typhimurium that also includes yrfG, yrfH, and yrfI. We also show that the Lon protease and the MviA response regulator participate in regulation of the igaA operon. Our results indicate that MviA regulates igaA transcription in an RpoS-dependent manner, but the results also suggest that MviA may regulate RcsB activation in an RpoS- and IgaA-independent manner.

scholarly journals Reducing Mortality in Salmonella enterica Serovar Typhimurium-Infected Mice with a Tripeptidic Serum Fraction

2002 ◽  
Vol 46 (6) ◽  
pp. 1971-1973 ◽  
Author(s):  
Todd A. Parker ◽  
Kenneth O. Willeford ◽  
Suzanne Parker ◽  
Karyl Buddington
Keyword(s):  
Salmonella Enterica ◽  
Salmonella Enterica Serovar Typhimurium ◽  
Dependent Manner ◽  
Serovar Typhimurium ◽  
Dose Dependent

ABSTRACT Salmonellosis-induced mortality in female Swiss Webster mice decreased significantly when tripeptidic immunostimulant (TPI) was administered prophylactically. Prophylactic benefits developed in a dose-dependent manner wherein 15 mg of TPI given 1 day before challenge reduced mortality by 70%.

scholarly journals Novel molecular components involved in callose-mediated Arabidopsis defense against Salmonella enterica and Escherichia coli O157:H7

2020 ◽  
Vol 20 (1) ◽  
Author(s):  
Paula Rodrigues Oblessuc ◽  
Cleverson Carlos Matiolli ◽  
Maeli Melotto
Keyword(s):  
Escherichia Coli ◽  
Pseudomonas Syringae ◽  
Salmonella Enterica ◽  
Plant Pathogens ◽  
Dependent Manner ◽  
Callose Deposition ◽  
E Coli ◽  
Genetic Components ◽  
Ros Burst ◽  
Sa Signaling

Abstract Background Food contamination with Salmonella enterica and enterohemorrhagic Escherichia coli is among the leading causes of foodborne illnesses worldwide and crop plants are associated with > 50% of the disease outbreaks. However, the mechanisms underlying the interaction of these human pathogens with plants remain elusive. In this study, we have explored plant resistance mechanisms against these enterobacteria and the plant pathogen Pseudomonas syringae pv. tomato (Pst) DC3118, as an opportunity to improve food safety. Results We found that S. enterica serovar Typhimurium (STm) transcriptionally modulates stress responses in Arabidopsis leaves, including induction of two hallmark processes of plant defense: ROS burst and cell wall modifications. Analyses of plants with a mutation in the potentially STm-induced gene EXO70H4 revealed that its encoded protein is required for stomatal defense against STm and E. coli O157:H7, but not against Pst DC3118. In the apoplast however, EXO70H4 is required for defense against STm and Pst DC3118, but not against E. coli O157:H7. Moreover, EXO70H4 is required for callose deposition, but had no function in ROS burst, triggered by all three bacteria. The salicylic acid (SA) signaling and biosynthesis proteins NPR1 and ICS1, respectively, were involved in stomatal and apoplastic defense, as well as callose deposition, against human and plant pathogens. Conclusions The results show that EXO70H4 is involved in stomatal and apoplastic defenses in Arabidopsis and suggest that EXO70H4-mediated defense play a distinct role in guard cells and leaf mesophyll cells in a bacteria-dependent manner. Nonetheless, EXO70H4 contributes to callose deposition in response to both human and plant pathogens. NPR1 and ICS1, two proteins involved in the SA signaling pathway, are important to inhibit leaf internalization and apoplastic persistence of enterobacteria and proliferation of phytopathogens. These findings highlight the existence of unique and shared plant genetic components to fight off diverse bacterial pathogens providing specific targets for the prevention of foodborne diseases.

scholarly journals PhoP-Responsive Expression of the Salmonella enterica Serovar Typhimurium slyA Gene

2003 ◽  
Vol 185 (12) ◽  
pp. 3508-3514 ◽  
Author(s):  
Valia A. Norte ◽  
Melanie R. Stapleton ◽  
Jeffrey Green
Keyword(s):  
Transcription Factors ◽  
Salmonella Enterica ◽  
Promoter Region ◽  
External Signal ◽  
Dependent Manner ◽  
Factors Analysis ◽  
Upstream Promoter ◽  
Serovar Typhimurium ◽  
Transcription Regulators ◽  
Upstream Promoter Region

ABSTRACT The SlyA protein of Salmonella enterica serovar Typhimurium is a member of the MarR family of transcription regulators and is required for virulence and survival in professional macrophages. Isolated SlyA protein was able to bind a specific DNA target without posttranslational modification. This suggested that SlyA might not be activated by directly sensing an external signal but rather that the intracellular concentration of SlyA is enhanced in appropriate environments through the action of other transcription factors. Analysis of slyA transcription reveals the presence of a promoter region located upstream of the previously recognized SlyA repressed promoter. The newly identified upstream promoter region did not respond to SlyA but was activated by Mg(II) starvation in a PhoP-dependent manner. We present here evidence for a direct link between two transcription factors (PhoP and SlyA) crucial for Salmonella virulence.

scholarly journals Modulation of Virulence by Two Acidified Nitrite-Responsive Loci of Salmonella enterica Serovar Typhimurium

2003 ◽  
Vol 71 (6) ◽  
pp. 3196-3205 ◽  
Author(s):  
Charles C. Kim ◽  
Denise Monack ◽  
Stanley Falkow
Keyword(s):  
Salmonella Enterica ◽  
Fluorescent Protein ◽  
Dependent Manner ◽  
Wild Type ◽  
Independent Manner ◽  
Inducible Promoters ◽  
Serovar Typhimurium ◽  
Bacterial Genes ◽  
Green Fluorescent

ABSTRACT Two acidified nitrite-inducible genes of Salmonella enterica serovar Typhimurium were identified with a green fluorescent protein-based promoter-trap screen. The nitrite-inducible promoters were located upstream of loci that we designated nipAB and nipC, which correspond to hcp-hcr (hybrid cluster protein) of Escherichia coli and norA of Alcaligenes eutrophus, respectively. Maximal induction of the promoters by nitrite was dependent on pH. The nipAB promoter was regulated by oxygen in an Fnr-dependent manner. The nipC promoter was also regulated by oxygen but in an Fnr-independent manner. The promoters were upregulated in activated RAW264.7 macrophage-like cells, which produce NO via the inducible nitric oxide synthase (iNOS), and the induction was inhibited by aminoguanidine, an inhibitor of iNOS. Although the nipAB and nipC mutants displayed no defects under a variety of in vitro conditions or in tissue culture infections, they exhibited lower oral 50% lethal doses (LD50s) than did the wild type in C57BL/6J mouse infections. The lower LD50s reflected an unexpected increased ability of small inoculating doses of the mutant bacteria to cause lethal infection 2 to 3 weeks after challenge, compared to a similar challenge dose of wild-type bacteria. We conclude that these genes are regulated by physiological nitrogen oxides and that the absence of these bacterial genes in some way diminishes the ability of mice to clear a low dose infection.

scholarly journals Jasmonic Acid Impairs Arabidopsis Seedling Salt Stress Tolerance Through MYC2-Mediated Repression of CAT2 Expression

2021 ◽  
Vol 12 ◽  
Author(s):  
Ru-Feng Song ◽  
Ting-Ting Li ◽  
Wen-Cheng Liu
Keyword(s):  
Salt Stress ◽  
Jasmonic Acid ◽  
Stress Tolerance ◽  
High Salinity ◽  
Vital Role ◽  
Plant Response ◽  
Wild Type Plant ◽  
Dependent Manner ◽  
Salt Stress Tolerance ◽  
Arabidopsis Seedling

High salinity causes ionic, osmotic, and oxidative stresses to plants, and the antioxidant enzyme Catalase2 (CAT2) plays a vital role in this process, while how CAT2 expression is regulated during plant response to high salinity remains elusive. Here, we report that phytohormone jasmonic acid (JA) impairs plant salt stress tolerance by repressing CAT2 expression in an MYC2-dependent manner. Exogenous JA application decreased plant salt stress tolerance while the jar1 mutant with reduced bioactive JA-Ile accumulation showed enhanced salt stress tolerance. JA enhanced salt-induced hydrogen peroxide (H2O2) accumulation, while treatment with H2O2-scavenger glutathione compromised such effects of JA on plant H2O2 accumulation and salt stress tolerance. In addition, JA repressed CAT2 expression in salt-stressed wild-type plant but not in myc2, a mutant of the master transcriptional factor MYC2 in JA signaling, therefore, the myc2 mutant exhibited increased salt stress tolerance. Further study showed that mutation of CAT2 largely reverted lower reactive oxygen species (ROS) accumulation, higher CAT activity, and enhanced salt stress tolerance of the myc2 mutant in myc2 cat2-1 double mutant, revealing that CAT2 functions downstream JA-MYC2 module in plant response to high salinity. Together, our study reveals that JA impairs Arabidopsis seedling salt stress tolerance through MYC2-mediated repression of CAT2 expression.

scholarly journals The Microbial Lipopeptide Paenibacterin Disrupts Desiccation Resistance in Salmonella enterica Serovars Tennessee and Eimsbuettel

2019 ◽  
Vol 85 (14) ◽  
Author(s):  
Ahmed G. Abdelhamid ◽  
Ahmed E. Yousef
Keyword(s):  
Salmonella Enterica ◽  
Health Hazard ◽  
Active Agent ◽  
Resistance Mechanisms ◽  
Food Preservation ◽  
Control Measures ◽  
Dependent Manner ◽  
Desiccation Resistance ◽  
Concentration Dependent Manner ◽  
Content Type

ABSTRACT Salmonella enterica is increasingly linked to disease outbreaks associated with consumption of low-water-activity (low-aw) foods. Persistence of the pathogen in these foods was attributed to its ability to implement desiccation resistance mechanisms. Published knowledge about methods that disrupt desiccation resistance in S. enterica is lacking. We hypothesize that strong membrane-active compounds disrupt the desiccation resistance that S. enterica may acquire in low-aw foods or environments. The newly discovered antimicrobial lipopeptide paenibacterin was the membrane-active agent investigated in this study. Strains of S. enterica serovars Tennessee and Eimsbuettel, with a history of association with low-moisture foods, were investigated. The viability of these strains did not decrease significantly during dehydration and subsequent storage in the dehydrated state. Considering that the paenibacterin MIC against S. enterica strains was 8 μg/ml, concentrations of 4 to 16 μg/ml paenibacterin were tested. Within this range, desiccation-adapted S. Eimsbuettel was much more tolerant to the antimicrobial agent than the desiccation-adapted S. Tennessee. Pretreatment with 8 μg/ml paenibacterin increased inactivation of S. enterica during desiccation. The use of paenibacterin at 16 μg/ml or higher concentrations resulted in leakage of intracellular potassium ions from desiccation-adapted cells. Paenibacterin significantly decreased the biosynthesis of the intracellular osmoprotectant solute, trehalose, in a concentration-dependent manner. Treatment with 64 μg/ml paenibacterin increased the permeability of the cytoplasmic membranes of desiccation-adapted cells. Transcription of the desiccation-related genes proV, STM1494, kdpA, and otsB in response to paenibacterin treatment was investigated using reverse transcription-quantitative PCR. Transcription of some of these genes was downregulated in a concentration- and strain-dependent manner. IMPORTANCE Salmonella enterica adapts effectively and persists for a long time in low-aw foods or environments through resistance mechanisms to desiccation stress. Desiccation-resistant cells compromise food safety and constitute a serious health hazard. Strategies to combat desiccation resistance in S. enterica are needed to sensitize the pathogen to lethal processes used in food preservation. The study proved that the membrane-active lipopeptide paenibacterin disrupts the resistance in desiccation-adapted S. enterica, as measured by phenotypic, biochemical, and genetic analyses. This study highlighted the role of the lipopeptide paenibacterin in disrupting mechanisms employed by S. enterica to resist desiccation. This knowledge may lead to the design of novel control measures to improve the safety of low-aw foods.

scholarly journals Targeting Essential Genes in Salmonella enterica Serovar Typhimurium with Antisense Peptide Nucleic Acid

2012 ◽  
Vol 56 (12) ◽  
pp. 6407-6409 ◽  
Author(s):  
Muhammad A. Soofi ◽  
Mohamed N. Seleem
Keyword(s):  
Salmonella Enterica ◽  
Salmonella Enterica Serovar Typhimurium ◽  
Essential Genes ◽  
Dependent Manner ◽  
Content Type ◽  
Serovar Typhimurium ◽  
Gene Inhibition ◽  
Dose Dependent ◽  
Antisense Peptide ◽  
Great Potency

ABSTRACTWe investigated the capability of antisense peptide nucleic acids (PNAs) conjugated to the (KFF)3K cell-penetrating peptide to target possible essential genes (ligA,rpoA,rpoD,engA,tsf, andkdtA) inSalmonella entericaserovar Typhimurium and inhibit bacterial growthin 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 anti-rpoAand -rpoDPNAs showed the greatest potency.

scholarly journals Flagellin Is Required for Host Cell Invasion and Normal Salmonella Pathogenicity Island 1 Expression by Salmonella enterica Serovar Paratyphi A

2015 ◽  
Vol 83 (9) ◽  
pp. 3355-3368 ◽  
Author(s):  
Dana Elhadad ◽  
Prerak Desai ◽  
Galia Rahav ◽  
Michael McClelland ◽  
Ohad Gal-Mor
Keyword(s):  
Host Cell ◽  
Cell Invasion ◽  
Salmonella Enterica ◽  
Pathogenicity Island ◽  
Dependent Manner ◽  
Content Type ◽  
Type Three Secretion System ◽  
Serovar Typhimurium ◽  
System 1 ◽  
Type Three Secretion

Salmonella entericaserovar Paratyphi A is a human-specific serovar that, together withSalmonella entericaserovar Typhi andSalmonella entericaserovar Sendai, causes enteric fever. Unlike the nontyphoidalSalmonella entericaserovar Typhimurium, the genomes ofS. Typhi andS. Paratyphi A are characterized by inactivation of multiple genes, including in the flagellum-chemotaxis pathway. Here, we explored the motility phenotype ofS. Paratyphi A and the role of flagellin in key virulence-associated phenotypes. Motility studies established that the human-adapted typhoidalS. Typhi,S. Paratyphi A, andS. Sendai are all noticeably less motile thanS. Typhimurium, and comparative transcriptome sequencing (RNA-Seq) showed that inS. Paratyphi A, the entire motility-chemotaxis regulon is expressed at significantly lowers levels than inS. Typhimurium. Nevertheless,S. Paratyphi A, likeS. Typhimurium, requires a functional flagellum for epithelial cell invasion and macrophage uptake, probably in a motility-independent mechanism. In contrast, flagella were found to be dispensable for host cell adhesion. Moreover, we demonstrate that inS. Paratyphi A, but not inS. Typhimurium, the lack of flagellin results in increased transcription of the flagellar and theSalmonellapathogenicity island 1 (SPI-1) regulons in a FliZ-dependent manner and in oversecretion of SPI-1 effectors via type three secretion system 1. Collectively, these results suggest a novel regulatory linkage between flagellin and SPI-1 inS. Paratyphi A that does not occur inS. Typhimurium and demonstrate curious distinctions in motility and the expression of the flagellum-chemotaxis regulon between these clinically relevant pathogens.

scholarly journals A Salmonella enterica Serovar Typhimurium hemA Mutant Is Highly Susceptible to Oxidative DNA Damage

2002 ◽  
Vol 184 (14) ◽  
pp. 3774-3784 ◽  
Author(s):  
Maya Elgrably-Weiss ◽  
Sunny Park ◽  
Eliana Schlosser-Silverman ◽  
Ilan Rosenshine ◽  
James Imlay ◽  
...  
Keyword(s):  
Hydrogen Peroxide ◽  
Dna Damage ◽  
Salmonella Enterica ◽  
Fenton Reaction ◽  
Oxidative Dna Damage ◽  
Salmonella Enterica Serovar Typhimurium ◽  
Mrna Levels ◽  
Dependent Manner ◽  
Intracellular Iron ◽  
Serovar Typhimurium

ABSTRACT The first committed step in the biosynthesis of heme, an important cofactor of two catalases and a number of cytochromes, is catalyzed by the hemA gene product. Salmonella enterica serovar Typhimurium hemA26::Tn10d (hemA26) was identified in a genetic screen of insertion mutants that were sensitive to hydrogen peroxide. Here we show that the hemA26 mutant respires at half the rate of wild-type cells and is highly susceptible to the effects of oxygen species. Exposure of the hemA26 strain to hydrogen peroxide results in extensive DNA damage and cell death. The chelation of intracellular free iron fully abrogates the sensitivity of this mutant, indicating that the DNA damage results from the iron-catalyzed formation of hydroxyl radicals. The inactivation of heme synthesis does not change the amount of intracellular iron, but by diminishing the rate of respiration, it apparently increases the amount of reducing equivalents available to drive the Fenton reaction. We also report that hydrogen peroxide has opposite effects on the expression of hemA and hemH, the first and last genes of heme biosynthesis pathway, respectively. hemA mRNA levels decrease, while the transcription of hemH is induced by hydrogen peroxide, in an oxyR-dependent manner. The oxyR-dependent induction is suppressed under conditions that accelerate the Fenton reaction by a mechanism that is not yet understood.

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