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 Synthesis of N-Acyl Homoserine Lactone Analogues Reveals Strong Activators of SdiA, the Salmonella enterica Serovar Typhimurium LuxR Homologue

2006 ◽  
Vol 73 (2) ◽  
pp. 535-544 ◽  
Author(s):  
Joost C. A. Janssens ◽  
Kristine Metzger ◽  
Ruth Daniels ◽  
Dave Ptacek ◽  
Tine Verhoeven ◽  
...  
Keyword(s):  
Quorum Sensing ◽  
Salmonella Enterica ◽  
Salmonella Enterica Serovar Typhimurium ◽  
Vibrio Fischeri ◽  
Acyl Chain ◽  
Homoserine Lactone ◽  
Gram Negative Bacteria ◽  
Ligand Interaction ◽  
Homoserine Lactones ◽  
Serovar Typhimurium

ABSTRACT N-Acyl homoserine lactones (AHLs) are molecules that are synthesized and detected by many gram-negative bacteria to monitor the population density, a phenomenon known as quorum sensing. Salmonella enterica serovar Typhimurium is an exceptional species since it does not synthesize its own AHLs, while it does encode a LuxR homologue, SdiA, which enables this bacterium to detect AHLs that are produced by other species. To obtain more information about the specificity of the ligand binding by SdiA, we synthesized and screened a limited library of AHL analogues. We identified two classes of analogues that are strong activators of SdiA: the N-(3-oxo-acyl)-homocysteine thiolactones (3O-AHTLs) and the N-(3-oxo-acyl)-trans-2-aminocyclohexanols. To our knowledge, this is the first report of compounds (the 3O-AHTLs) that are able to activate a LuxR homologue at concentrations that are lower than the concentrations of the most active AHLs. SdiA responds with greatest sensitivity to AHTLs that have a keto modification at the third carbon atom and an acyl chain that is seven or eight carbon atoms long. The N-(3-oxo-acyl)-trans-2-aminocyclohexanols were found to be less sensitive to deactivation by lactonase and alkaline pH than the 3O-AHTLs and the AHLs are. We also examined the activity of our library with LuxR of Vibrio fischeri and identified three new inhibitors of LuxR. Finally, we performed preliminary binding experiments which suggested that SdiA binds its activators reversibly. These results increase our understanding of the specificity of the SdiA-ligand interaction, which could have uses in the development of anti-quorum-sensing-based antimicrobials.

scholarly journals Yersinia enterocolitica Inhibits Salmonella enterica Serovar Typhimurium and Listeria monocytogenes Cellular Uptake

2013 ◽  
Vol 82 (1) ◽  
pp. 174-183 ◽  
Author(s):  
Fabien Habyarimana ◽  
Matthew C. Swearingen ◽  
Glenn M. Young ◽  
Stephanie Seveau ◽  
Brian M. M. Ahmer
Keyword(s):  
Listeria Monocytogenes ◽  
Yersinia Enterocolitica ◽  
Salmonella Enterica ◽  
Effector Proteins ◽  
Cell Uptake ◽  
Secretion Systems ◽  
Content Type ◽  
T3ss Effector ◽  
Luxr Homolog ◽  
Serovar Typhimurium

ABSTRACTYersinia enterocoliticabiovar 1B employs two type three secretion systems (T3SS), Ysa and Ysc, which inject effector proteins into macrophages to prevent phagocytosis. Conversely,Salmonella entericaserovar Typhimurium uses a T3SS encoded bySalmonellapathogenicity island 1 (SPI1) to actively invade cells that are normally nonphagocytic and a second T3SS encoded by SPI2 to survive within macrophages. Given the distinctly different outcomes that occur with regard to host cell uptake ofS. Typhimurium andY. enterocolitica, we investigated how each pathogen influences the internalization outcome of the other.Y. enterocoliticareducesS. Typhimurium invasion of HeLa and Caco-2 cells to a level similar to that observed using anS. Typhimurium SPI1 mutant alone. However,Y. enterocoliticahad no effect onS. Typhimurium uptake by J774.1 or RAW264.7 macrophage-like cells.Y. enterocoliticawas also able to inhibit the invasion of epithelial and macrophage-like cells byListeria monocytogenes.Y. enterocoliticamutants lacking either the Ysa or Ysc T3SS were partially defective, while double mutants were completely defective, in blockingS. Typhimurium uptake by epithelial cells.S. Typhimurium encodes a LuxR homolog, SdiA, which detectsN-acylhomoserine lactones (AHLs) produced byY. enterocoliticaand upregulates the expression of an invasin (Rck) and a putative T3SS effector (SrgE). Two different methods of constitutively activating theS. Typhimurium SdiA regulon failed to reverse the uptake blockade imposed byY. enterocolitica.

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 The Acyl Homoserine Lactone Receptor, SdiA, of Escherichia coli and Salmonella enterica Serovar Typhimurium Does Not Respond to Indole

2012 ◽  
Vol 78 (15) ◽  
pp. 5424-5431 ◽  
Author(s):  
Anice Sabag-Daigle ◽  
Jitesh A. Soares ◽  
Jenée N. Smith ◽  
Mohamed E. Elmasry ◽  
Brian M. M. Ahmer
Keyword(s):  
Escherichia Coli ◽  
Salmonella Enterica ◽  
Biofilm Formation ◽  
Salmonella Enterica Serovar Typhimurium ◽  
Homoserine Lactone ◽  
Acyl Homoserine Lactone ◽  
Content Type ◽  
E Coli ◽  
Serovar Typhimurium ◽  
High Concentrations

ABSTRACTIn this study, we tested the hypothesis that the SdiA proteins ofEscherichia coliandSalmonella entericaserovar Typhimurium respond to indole. While indole was found to have effects on gene expression and biofilm formation, these effects were notsdiAdependent. However, high concentrations of indole did inhibitN-acyl-l-homoserine lactone (AHL) sensing by SdiA. We conclude that SdiA does not respond to indole but indole can inhibit SdiA activity inE. coliandSalmonella.

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 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.

scholarly journals pfs-Dependent Regulation of Autoinducer 2 Production in Salmonella enterica Serovar Typhimurium

2002 ◽  
Vol 184 (13) ◽  
pp. 3450-3456 ◽  
Author(s):  
Anne L. Beeston ◽  
Michael G. Surette
Keyword(s):  
Gene Product ◽  
Salmonella Enterica ◽  
Salmonella Enterica Serovar Typhimurium ◽  
Regulation Of Gene Expression ◽  
Carbon Sources ◽  
Homoserine Lactone ◽  
Bacterial Cells ◽  
Autoinducer 2 ◽  
Serovar Typhimurium ◽  
Signal Synthesis

ABSTRACT Bacterial intercellular communication provides a mechanism for signal-dependent regulation of gene expression to promote coordinated population behavior. Salmonella enterica serovar Typhimurium produces a non-homoserine lactone autoinducer in exponential phase as detected by a Vibrio harveyi reporter assay for autoinducer 2 (AI-2) (M. G. Surette and B. L. Bassler, Proc. Natl. Acad. Sci. USA 95:7046-7050, 1998). The luxS gene product mediates the production of AI-2 (M. G. Surette, M. B. Miller, and B. L. Bassler, Proc. Natl. Acad. Sci. USA 96:1639-1644, 1999). Environmental cues such as rapid growth, the presence of preferred carbon sources, low pH, and/or high osmolarity were found to influence the production of AI-2 (M. G. Surette and B. L. Bassler, Mol. Microbiol. 31:585-595, 1999). In addition to LuxS, the pfs gene product (Pfs) is required for AI-2 production, as well as S-adenosylhomocysteine (SAH) (S. Schauder, K. Shokat, M. G. Surette, and B. L. Bassler, Mol. Microbiol. 41:463-476, 2001). In bacterial cells, Pfs exhibits both 5′-methylthioadenosine (MTA) and SAH nucleosidase functions. Pfs is involved in methionine metabolism, regulating intracellular MTA and SAH levels (elevated levels of MTA and SAH are potent inhibitors of polyamine synthetases and S-adenosylmethionine dependent methyltransferase reactions, respectively). To further investigate regulation of AI-2 production in Salmonella, we constructed pfs and luxS promoter fusions to a luxCDABE reporter in a low-copy-number vector, allowing an examination of transcription of the genes in the pathway for signal synthesis. Here we report that luxS expression is constitutive but that the transcription of pfs is tightly correlated to AI-2 production in Salmonella serovar Typhimurium 14028. Neither luxS nor pfs expression appears to be regulated by AI-2. These results suggest that AI-2 production is regulated at the level of LuxS substrate availability and not at the level of luxS expression. Our results indicate that AI-2-dependent signaling is a reflection of metabolic state of the cell and not cell density.

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