scholarly journals PduL Is an Evolutionarily Distinct Phosphotransacylase Involved in B12-Dependent 1,2-Propanediol Degradation by Salmonella enterica Serovar Typhimurium LT2

2006 ◽  
Vol 189 (5) ◽  
pp. 1589-1596 ◽  
Author(s):  
Yu Liu ◽  
Nicole A. Leal ◽  
Edith M. Sampson ◽  
Celeste L. V. Johnson ◽  
Gregory D. Havemann ◽  
...  
Keyword(s):  
Salmonella Enterica ◽  
Salmonella Enterica Serovar Typhimurium ◽  
Bacterial Species ◽  
Ectopic Expression ◽  
Dependent Manner ◽  
Enzymatic Assays ◽  
Growth Defects ◽  
Cell Extracts ◽  
Serovar Typhimurium ◽  
Coenzyme B

ABSTRACT Salmonella enterica degrades 1,2-propanediol (1,2-PD) in a coenzyme B12-dependent manner. Previous enzymatic assays of crude cell extracts indicated that a phosphotransacylase (PTAC) was needed for this process, but the enzyme involved was not identified. Here, we show that the pduL gene encodes an evolutionarily distinct PTAC used for 1,2-PD degradation. Growth tests showed that pduL mutants were unable to ferment 1,2-PD and were also impaired for aerobic growth on this compound. Enzyme assays showed that cell extracts from a pduL mutant lacked measurable PTAC activity in a background that also carried a pta mutation (the pta gene was previously shown to encode a PTAC enzyme). Ectopic expression of pduL corrected the growth defects of a pta mutant. PduL fused to eight C-terminal histidine residues (PduL-His8) was purified, and its kinetic constants were determined: the V max was 51.7 ± 7.6 μmol min−1 mg−1, and the Km values for propionyl-PO4 2− and acetyl-PO4 2− were 0.61 and 0.97 mM, respectively. Sequence analyses showed that PduL is unrelated in amino acid sequence to known PTAC enzymes and that PduL homologues are distributed among at least 49 bacterial species but are absent from the Archaea and Eukarya.

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 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 Metabolic Engineering of a Novel Propionate-Independent Pathway for the Production of Poly(3-Hydroxybutyrate-co-3-Hydroxyvalerate) in Recombinant Salmonella enterica Serovar Typhimurium

2002 ◽  
Vol 68 (8) ◽  
pp. 3848-3854 ◽  
Author(s):  
Ilana S. Aldor ◽  
Seon-Won Kim ◽  
Kristala L. Jones Prather ◽  
Jay D. Keasling
Keyword(s):  
Carbon Source ◽  
Salmonella Enterica ◽  
Sole Carbon Source ◽  
Salmonella Enterica Serovar Typhimurium ◽  
Tricarboxylic Acid Cycle ◽  
Expression System ◽  
Tricarboxylic Acid ◽  
Serovar Typhimurium ◽  
Commercial Applications ◽  
Coenzyme B

ABSTRACT A pathway was metabolically engineered to produce poly(3-hydroxybutyrate-co-3-hydroxyvalerate) (PHBV), a biodegradable thermoplastic with proven commercial applications, from a single, unrelated carbon source. An expression system was developed in which a prpC strain of Salmonella enterica serovar Typhimurium, with a mutation in the ability to metabolize propionyl coenzyme A (propionyl-CoA), served as the host for a plasmid harboring the Acinetobacter polyhydroxyalkanoate synthesis operon (phaBCA) and a second plasmid with the Escherichia coli sbm and ygfG genes under an independent promoter. The sbm and ygfG genes encode a novel (2R)-methylmalonyl-CoA mutase and a (2R)-methylmalonyl-CoA decarboxylase, respectively, which convert succinyl-CoA, derived from the tricarboxylic acid cycle, to propionyl-CoA, an essential precursor of 3-hydroxyvalerate (HV). The S. enterica system accumulated PHBV with significant HV incorporation when the organism was grown aerobically with glycerol as the sole carbon source. It was possible to vary the average HV fraction in the copolymer by adjusting the arabinose or cyanocobalamin (precursor of coenzyme B12) concentration in the medium.

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.

scholarly journals The Ferritin-Like Dps Protein Is Required for Salmonella enterica Serovar Typhimurium Oxidative Stress Resistance and Virulence

2004 ◽  
Vol 72 (2) ◽  
pp. 1155-1158 ◽  
Author(s):  
Thomas A. Halsey ◽  
Andrés Vazquez-Torres ◽  
Daniel J. Gravdahl ◽  
Ferric C. Fang ◽  
Stephen J. Libby
Keyword(s):  
Oxidative Stress ◽  
Salmonella Enterica ◽  
Salmonella Enterica Serovar Typhimurium ◽  
Bacterial Species ◽  
Phagocytic Cells ◽  
Evolutionarily Conserved ◽  
Serovar Typhimurium ◽  
Environmental Bacteria ◽  
Dps Protein

ABSTRACT Resistance to phagocyte-derived reactive oxygen species is essential for Salmonella enterica serovar Typhimurium pathogenesis. Salmonella can enhance its resistance to oxidants through the induction of specific genetic pathways controlled by SoxRS, OxyR, σS, σE, SlyA, and RecA. These regulons can be found in a wide variety of pathogenic and environmental bacteria, suggesting that evolutionarily conserved mechanisms defend against oxidative stress both endogenously generated by aerobic respiration and exogenously produced by host phagocytic cells. Dps, a ferritin-like protein found in many eubacterial and archaebacterial species, appears to protect cells from oxidative stress by sequestering iron and limiting Fenton-catalyzed oxyradical formation. In Escherichia coli and some other bacterial species, Dps has been shown to accumulate during stationary phase in a σS-dependent fashion, bind nonspecifically to DNA, and form a crystalline structure that compacts and protects chromatin from oxidative damage. In the present study, we provide evidence that Dps protects Salmonella from iron-dependent killing by hydrogen peroxide, promotes Salmonella survival in murine macrophages, and enhances Salmonella virulence. Reduced numbers of dps mutant bacteria in the livers and spleens of infected mice are consistent with a role of Dps in protecting Salmonella from oxidative stress encountered during infection.

scholarly journals Salmonella enterica Serovar Typhimurium Periplasmic Superoxide Dismutases SodCI and SodCII Are Required for Protection against the Phagocyte Oxidative Burst

2002 ◽  
Vol 70 (9) ◽  
pp. 5312-5315 ◽  
Author(s):  
Laura M. Sly ◽  
Donald G. Guiney ◽  
Neil E. Reiner
Keyword(s):  
Vitamin D ◽  
Oxidative Burst ◽  
Salmonella Enterica ◽  
Salmonella Enterica Serovar Typhimurium ◽  
Antimicrobial Effect ◽  
Dependent Manner ◽  
Serovar Typhimurium ◽  
Phagocyte Oxidase

ABSTRACT Vitamin D3 (1,25-dihydroxycholecalciferol) induced the phagocyte oxidative burst and intracellular killing of Salmonella enterica serovar Typhimurium in a phosphatidylinositol 3-kinase-dependent manner. The antimicrobial effect was more pronounced for Salmonella SodCI and SodCII mutants, confirming the role of the phagocyte oxidase in the vitamin D3 effect. The results for an in vitro system with human THP-1 cells correlate with in vivo virulence data for mice and show that both the SodCI and SodCII enzymes are required to protect against the oxidative burst.

scholarly journals Salmonella enterica Serovar Typhimurium Can Detect Acyl Homoserine Lactone Production by Yersinia enterocolitica in Mice

2009 ◽  
Vol 192 (1) ◽  
pp. 29-37 ◽  
Author(s):  
Jessica L. Dyszel ◽  
Jenee N. Smith ◽  
Darren E. Lucas ◽  
Jitesh A. Soares ◽  
Matthew C. Swearingen ◽  
...  
Keyword(s):  
Yersinia Enterocolitica ◽  
Salmonella Enterica ◽  
Salmonella Enterica Serovar Typhimurium ◽  
Bacterial Species ◽  
Homoserine Lactone ◽  
Homoserine Lactones ◽  
Fitness Advantage ◽  
Acyl Homoserine Lactones ◽  
Luxr Homolog ◽  
Serovar Typhimurium

ABSTRACT LuxR-type transcription factors detect acyl homoserine lactones (AHLs) and are typically used by bacteria to determine the population density of their own species. Escherichia coli and Salmonella enterica serovar Typhimurium cannot synthesize AHLs but can detect the AHLs produced by other bacterial species using the LuxR homolog, SdiA. Previously we determined that S. Typhimurium did not detect AHLs during transit through the gastrointestinal tract of a guinea pig, a rabbit, a cow, 5 mice, 6 pigs, or 12 chickens. However, SdiA was activated during transit through turtles colonized by Aeromonas hydrophila, leading to the hypothesis that SdiA is used for detecting the AHL production of other pathogens. In this report, we determined that SdiA is activated during the transit of S. Typhimurium through mice infected with the AHL-producing pathogen Yersinia enterocolitica. SdiA is not activated during transit through mice infected with a yenI mutant of Y. enterocolitica that cannot synthesize AHLs. However, activation of SdiA did not confer a fitness advantage in Yersinia-infected mice. We hypothesized that this is due to infrequent or short interactions between S. Typhimurium and Y. enterocolitica or that the SdiA regulon members do not function in mice. To test these hypotheses, we constructed an S. Typhimurium strain that synthesizes AHLs to mimic a constant interaction with Y. enterocolitica. In this background, sdiA + S. Typhimurium rapidly outcompetes the sdiA mutant in mice. All known members of the sdiA regulon are required for this phenotype. Thus, all members of the sdiA regulon are functional in mice.

scholarly journals Contribution of the SirA regulon to biofilm formation in Salmonella enterica serovar Typhimurium

Microbiology ◽  
2006 ◽  
Vol 152 (11) ◽  
pp. 3411-3424 ◽  
Author(s):  
Max Teplitski ◽  
Ali Al-Agely ◽  
Brian M. M. Ahmer
Keyword(s):  
Salmonella Enterica ◽  
Biofilm Formation ◽  
Salmonella Enterica Serovar Typhimurium ◽  
Bacterial Species ◽  
Virulence Gene ◽  
Two Component System ◽  
Serovar Typhimurium ◽  
Regulatory Rnas

Orthologues of the Salmonella enterica serovar Typhimurium (S. typhimurium) BarA/SirA two-component system are important for biofilm formation and virulence in many γ-Proteobacteria. In S. typhimurium, SirA activates the csrB and csrC carbon storage regulatory RNAs and the virulence gene regulators hilA and hilC. The regulatory RNAs antagonize the activity of the CsrA protein, allowing translation of those same virulence genes, and inhibiting the translation of flagellar genes. In this report, it was determined that SirA and the Csr system also control the fim operon that encodes type 1 fimbriae. sirA orthologues in other bacterial species, and the fim operon of S. typhimurium, are known to play a role in biofilm formation; therefore, all members of the S. typhimurium sirA regulon were tested for in vitro biofilm production. A sirA mutant, a csrB csrC double mutant, and a fimI mutant, were all defective in biofilm formation. Conversely, inactivation of flhDC increased biofilm formation. Therefore, SirA activates csrB, csrC and the fim operon to promote biofilm formation. In turn, csrB and csrC promote the translation of the fim operon, while at the same time inhibiting the translation of flagella, which are inhibitory to biofilm formation.

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