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Wei, Yan, i Charles G. Miller. "Characterization of a Group of Anaerobically Induced, fnr-Dependent Genes of Salmonella typhimurium". Journal of Bacteriology 181, nr 19 (1.10.1999): 6092–97. http://dx.doi.org/10.1128/jb.181.19.6092-6097.1999.
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ABSTRACT We have previously reported the isolation of a group of anaerobically regulated, fnr-dependent lacfusions in Salmonella typhimurium and have grouped theseoxd genes into classes based on map position. In order to identify these genes, we have replaced the original Mud-lacfusion in a member of each oxd class with the much smaller Mud-cam element, cloned the fusion, and determined DNA sequence sufficient to define the oxd gene. Several of the fusions correspond to previously known genes from S. typhimurium or Escherichia coli: oxd-4 = cbiA and oxd-11 = cbiK, oxd-5 = hybB, oxd-7 = dcuB, oxd-8 = moaB, oxd-12 = dmsA, and oxd-14 = napB (aeg-46.5). Two other fusions correspond to previously unknown loci: oxd-2 encodes an acetate/propionate kinase, and oxd-6 encodes a putative ABC transporter present in S. typhimurium but not in E. coli.
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Chittori, Sagar, Dhirendra Kumar Simanshu, Sanchari Banerjee, Ambika Mosale Venkatesh Murthy, Subashini Mathivanan, Handanahal Subbarao Savithri i Mathur Ramabhadrashastry Narasimha Murthy. "Mechanistic features of Salmonella typhimurium propionate kinase (TdcD): Insights from kinetic and crystallographic studies". Biochimica et Biophysica Acta (BBA) - Proteins and Proteomics 1834, nr 10 (październik 2013): 2036–44. http://dx.doi.org/10.1016/j.bbapap.2013.05.020.
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Palacios, Sergio, Vincent J. Starai i Jorge C. Escalante-Semerena. "Propionyl Coenzyme A Is a Common Intermediate in the 1,2-Propanediol and Propionate Catabolic Pathways Needed for Expression of the prpBCDE Operon during Growth of Salmonella enterica on 1,2-Propanediol". Journal of Bacteriology 185, nr 9 (1.05.2003): 2802–10. http://dx.doi.org/10.1128/jb.185.9.2802-2810.2003.
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ABSTRACT The studies reported here identify propionyl coenzyme A (propionyl-CoA) as the common intermediate in the 1,2-propanediol and propionate catabolic pathways of Salmonella enterica serovar Typhimurium LT2. Growth on 1,2-propanediol as a carbon and energy source led to the formation and excretion of propionate, whose activation to propionyl-CoA relied on the activities of the propionate kinase (PduW)/phosphotransacetylase (Pta) enzyme system and the CobB sirtuin-controlled acetyl-CoA and propionyl-CoA (Acs, PrpE) synthetases. The different affinities of these systems for propionate ensure sufficient synthesis of propionyl-CoA to support wild-type growth of S. enterica under low or high concentrations of propionate in the environment. These redundant systems of propionyl-CoA synthesis are needed because the prpE gene encoding the propionyl-CoA synthetase enzyme is part of the prpBCDE operon under the control of the PrpR regulatory protein, which needs 2-methylcitrate as a coactivator. Because the synthesis of 2-methylcitrate by PrpC (i.e., the 2-methylcitrate synthase enzyme) requires propionyl-CoA as a substrate, the level of propionyl-CoA needs to be raised by the Acs or PduW-Pta system before 2-methylcitrate can be synthesized and prpBCDE transcription can be activated.
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Simanshu, Dhirendra K., H. S. Savithri i M. R. N. Murthy. "Crystal structures of Salmonella typhimurium propionate kinase and its complex with Ap4A: Evidence for a novel Ap4A synthetic activity". Proteins: Structure, Function, and Bioinformatics 70, nr 4 (25.09.2007): 1379–88. http://dx.doi.org/10.1002/prot.21626.
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Simanshu, Dhirendra K., H. S. Savithri i M. R. N. Murthy. "Crystal Structures of ADP and AMPPNP-bound Propionate Kinase (TdcD) from Salmonella typhimurium: Comparison with Members of Acetate and Sugar Kinase/Heat Shock Cognate 70/Actin Superfamily". Journal of Molecular Biology 352, nr 4 (wrzesień 2005): 876–92. http://dx.doi.org/10.1016/j.jmb.2005.07.069.
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Horswill, Alexander R., i Jorge C. Escalante-Semerena. "Salmonella typhimurium LT2 Catabolizes Propionate via the 2-Methylcitric Acid Cycle". Journal of Bacteriology 181, nr 18 (15.09.1999): 5615–23. http://dx.doi.org/10.1128/jb.181.18.5615-5623.1999.
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ABSTRACT We previously identified the prpBCDE operon, which encodes catabolic functions required for propionate catabolism inSalmonella typhimurium. Results from13C-labeling experiments have identified the route of propionate breakdown and determined the biochemical role of each Prp enzyme in this pathway. The identification of catabolites accumulating in wild-type and mutant strains was consistent with propionate breakdown through the 2-methylcitric acid cycle. Our experiments demonstrate that the α-carbon of propionate is oxidized to yield pyruvate. The reactions are catalyzed by propionyl coenzyme A (propionyl-CoA) synthetase (PrpE), 2-methylcitrate synthase (PrpC), 2-methylcitrate dehydratase (probably PrpD), 2-methylisocitrate hydratase (probably PrpD), and 2-methylisocitrate lyase (PrpB). In support of this conclusion, the PrpC enzyme was purified to homogeneity and shown to have 2-methylcitrate synthase activity in vitro.1H nuclear magnetic resonance spectroscopy and negative-ion electrospray ionization mass spectrometry identified 2-methylcitrate as the product of the PrpC reaction. Although PrpC could use acetyl-CoA as a substrate to synthesize citrate, kinetic analysis demonstrated that propionyl-CoA is the preferred substrate.
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Liu, Jiaxiu, Wenxiu Zhu, Ningbo Qin, Xiaomeng Ren i Xiaodong Xia. "Propionate and Butyrate Inhibit Biofilm Formation of Salmonella Typhimurium Grown in Laboratory Media and Food Models". Foods 11, nr 21 (3.11.2022): 3493. http://dx.doi.org/10.3390/foods11213493.
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Salmonella is among the most frequently isolated foodborne pathogens, and biofilm formed by Salmonella poses a potential threat to food safety. Short-chain fatty acids (SCFAs), especially propionate and butyrate, have been demonstrated to exhibit a beneficial effect on promoting intestinal health and regulating the host immune system, but their anti-biofilm property has not been well studied. This study aims to investigate the effects of propionate or butyrate on the biofilm formation and certain virulence traits of Salmonella. We investigated the effect of propionate or butyrate on the biofilm formation of Salmonella enterica serovar Typhimurium (S. Typhimurium) SL1344 grown in LB broth or food models (milk or chicken juice) by crystal violet staining methods. Biofilm formation was significantly reduced in LB broth and food models and the reduction was visualized using a scanning electron microscope (SEM). Biofilm metabolic activity was attenuated in the presence of propionate or butyrate. Meanwhile, both SCFAs decreased AI-2 quorum sensing based on reporter strain assay. Butyrate, not propionate, could effectively reduce bacterial motility. Bacterial adhesion to and invasion of Caco-2 cells were also significantly inhibited in the presence of both SCFAs. Finally, two SCFAs downregulated virulence genes related to biofilm formation and invasion through real-time polymerase chain reaction (RT-PCR). These findings demonstrate the potential application of SCFAs in the mitigation of Salmonella biofilm in food systems, but future research mimicking food environments encountered during the food chain is necessitated.
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Fernández-Briera, Almudena, i Amando Garrido-Pertierra. "A degradation pathway of propionate in Salmonella typhimurium LT-2". Biochimie 70, nr 6 (czerwiec 1988): 757–68. http://dx.doi.org/10.1016/0300-9084(88)90105-8.
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HINTON, ARTHUR, MICHAEL E. HUME i JOHN R. DELOACH. "Role of Metabolic Intermediates in the Inhibition of Salmonella typhimurium and Salmonella enteritidis by Veillonella". Journal of Food Protection 56, nr 11 (1.11.1993): 932–37. http://dx.doi.org/10.4315/0362-028x-56.11.932.
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A Veillonella sp. was isolated from the cecal contents of adult chickens. The Veillonella was grown on an agar medium supplemented with 200 mM of lactate, pyruvate, fumarate, or succinate and adjusted to a pH of 6.7, 6.5, 6.3, 6.1, 5.9, or 5.7. No metabolites were added to the control media, but it was adjusted to the same pH levels as the supplemented media. The agar medium on which the Veillonella was grown was overlaid with fresh agar medium. Cultures of Salmonella typhimurium or Salmonella enteritidis were spread on the surface of the agar overlay, and the plates were incubated at 37°C for 14–18 h. Veillonella did not inhibit the growth of either salmonellae on any of the control or pyruvate medium. Veillonella did inhibit the growth of both salmonellae on lactate medium that had been adjusted to pH 6.3, 6.1, or 5.9 and on succinate medium that had been adjusted to pH 5.7. Veillonella also inhibited the growth of S. typhimurium on fumarate medium that had been adjusted to pH 6.7, 6.5, 6.3, 6.1, or 5.9; and it inhibited the growth of S. enteritidis on fumarate medium that had been adjusted to pH 6.7, 6.5, 6.3, or 6.1. Inhibition on lactate agar was correlated with the production of acetate and propionate by Veillonella and residual lactate in the medium; inhibition on fumarate agar was correlated with the production of propionate and lactate by Veillonella; and inhibition on succinate agar was correlated to the production of propionate at low pH levels. The findings indicate that anaerobic bacteria that produce these metabolic intermediates and anaerobic bacteria that can convert the intermediates to volatile fatty acids may be important components of probiotic cultures that can be provided to chicks to reduce colonization by salmonellae.
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DURANT, JULIET A., DONALD E. CORRIER i STEVEN C. RICKE. "Short-Chain Volatile Fatty Acids Modulate the Expression of the hilA and invF Genes of Salmonella Typhimurium". Journal of Food Protection 63, nr 5 (1.05.2000): 573–78. http://dx.doi.org/10.4315/0362-028x-63.5.573.
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The ability of Salmonella Typhimurium to invade the intestinal mucosal cells is an important step in pathogenesis. This invasion process requires genes encoded on the Salmonella pathogenicity island 1 (SPI1). Two transcriptional activators, HilA and InvF, encoded in SPI1 regulate the expression of invasion genes in response to environmental stimuli such as osmolarity, oxygen tension, and pH. During its pathogenic life cycle, Salmonella Typhimurium is also exposed to short-chain fatty acids (SCFA), especially acetate, propionate, and butyrate, in the intestinal lumen, as well as the SCFA used as food preservatives. The effects of SCFA on the expression of hilA and invF–lacZY transcriptional fusions were examined to determine the potential role of SCFA in the pathogenesis of Salmonella Typhimurium. Growth rates were reduced by increasing SCFA concentrations at pH 6 but not at pH 7. At pH 7, hilA and invF expression was induced by acetate but not by propionate or butyrate, while at pH 6, all SCFA induced hilA and invF expression at 1 h. In general, hilA and invF expression levels when compared to respective control responses were higher at 1 h than at 4 and 8 h in the presence of most SCFA concentrations at pH 6. However, expression levels at 4 and 8 h were either similar or higher than the 1-h responses for the hilA–lacZY fusion strain in the presence of acetate while exposure to 20 mM propionate yielded similar levels of expression at 1, 4, and 8 h. The pH-dependent manner of induction suggests that entry of SCFA into the cell was necessary for induction. We speculate that SCFA may serve as an environmental signal that triggers the expression of invasion genes in the gastrointestinal tract.
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Kwon, Y. M., i S. C. Ricke. "Induction of Acid Resistance of Salmonella typhimurium by Exposure to Short-Chain Fatty Acids". Applied and Environmental Microbiology 64, nr 9 (1.09.1998): 3458–63. http://dx.doi.org/10.1128/aem.64.9.3458-3463.1998.
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ABSTRACT Exposure to short-chain fatty acids (SCFA) is one of the stress conditions Salmonella typhimurium encounters during its life cycle, because SCFA have been widely used as food preservatives and SCFA are also present at high concentrations in the gastrointestinal tracts of host animals. The effects of SCFA on the acid resistance of the organism were examined in an attempt to understand the potential role of SCFA in the pathogenesis of S. typhimurium. The percent survival of S. typhimuriumat pH 3.0 was determined after exposure to SCFA for 1 h at pH 7.0. The percent acid survival, which varied depending on the SCFA species and the concentration used, was 42 after exposure to 100 mM propionate at pH 7.0 under aerobic incubation conditions, while less than 1% could survive without exposure. The SCFA-induced acid resistance was markedly enhanced by anaerobiosis (64%), lowering pH conditions (138% at pH 5.0), or increasing incubation time (165% with 4 h) during exposure to propionic acid. When protein synthesis during exposure to propionate was blocked by chloramphenicol, the percent acid survival was less than 1, indicating that the protein synthesis induced by exposure to propionate is required for the induction of the acid resistance. The percent acid survival determined with the isogenic mutant strains defective in acid tolerance response revealed that AtrB protein is necessary for the full induction of acid resistance by exposure to propionate, while unexpectedly, inactivation of PhoP significantly increased acid resistance over that of the wild type (P < 0.05). The results suggest that the virulence ofS. typhimurium may be enhanced by increasing acid resistance upon exposure to SCFA during its life cycle and further enhanced by anaerobiosis, low pH, and prolonged exposure time.
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Rocco, Christopher J., i Jorge C. Escalante-Semerena. "In Salmonella enterica, 2-Methylcitrate Blocks Gluconeogenesis". Journal of Bacteriology 192, nr 3 (30.11.2009): 771–78. http://dx.doi.org/10.1128/jb.01301-09.
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ABSTRACT Strains of Salmonella enterica serovar Typhimurium LT2 lacking a functional 2-methylcitric acid cycle (2-MCC) display increased sensitivity to propionate. Previous work from our group indicated that this sensitivity to propionate is in part due to the production of 2-methylcitrate (2-MC) by the Krebs cycle enzyme citrate synthase (GltA). Here we report in vivo and in vitro data which show that a target of the 2-MC isomer produced by GltA (2-MCGltA) is fructose-1,6-bisphosphatase (FBPase), a key enzyme in gluconeogenesis. Lack of growth due to inhibition of FBPase by 2-MCGltA was overcome by increasing the level of FBPase or by micromolar amounts of glucose in the medium. We isolated an fbp allele encoding a single amino acid substitution in FBPase (S123F), which allowed a strain lacking a functional 2-MCC to grow in the presence of propionate. We show that the 2-MCGltA and the 2-MC isomer synthesized by the 2-MC synthase (PrpC; 2-MCPrpC) are not equally toxic to the cell, with 2-MCGltA being significantly more toxic than 2-MCPrpC. This difference in 2-MC toxicity is likely due to the fact that as a si-citrate synthase, GltA may produce multiple isomers of 2-MC, which we propose are not substrates for the 2-MC dehydratase (PrpD) enzyme, accumulate inside the cell, and have deleterious effects on FBPase activity. Our findings may help explain human inborn errors in propionate metabolism.
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Nakayama, Shu-ichi, i Haruo Watanabe. "Mechanism of hilA Repression by 1,2-Propanediol Consists of Two Distinct Pathways, One Dependent on and the Other Independent of Catabolic Production of Propionate, in Salmonella enterica Serovar Typhimurium". Journal of Bacteriology 188, nr 8 (15.04.2006): 3121–25. http://dx.doi.org/10.1128/jb.188.8.3121-3125.2006.
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ABSTRACT A glycerol dehydrogenase gene was selected as a multicopy suppressor rescuing the reduced hilA expression in the Salmonella enterica serovar Typhimurium cpxA mutant. A substrate of the enzyme, 1,2-propanediol, repressed hilA expression. The 1,2-propanediol-mediated repression at 150 mM, but not that at 300 mM, was abrogated by blocking the catabolism producing propionate from 1,2-propanediol.
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Ly, Kim Thien, i James E. Casanova. "Abelson Tyrosine Kinase Facilitates Salmonella enterica Serovar Typhimurium Entry into Epithelial Cells". Infection and Immunity 77, nr 1 (20.10.2008): 60–69. http://dx.doi.org/10.1128/iai.00639-08.
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ABSTRACT The intracellular gram-negative bacterial pathogen Salmonella enterica serovar Typhimurium gains entry into nonphagocytic cells by manipulating the assembly of the host actin cytoskeleton. S. enterica serovar Typhimurium entry requires a functional type III secretion system, a conduit through which bacterial effector proteins are directly translocated into the host cytosol. We and others have previously reported the enhancement of tyrosine kinase activities during Salmonella serovar Typhimurium infection; however, neither specific kinases nor their targets have been well characterized. In this study, we investigated the roles of the cellular Abelson tyrosine kinase (c-Abl) and the related protein Arg in the context of serovar Typhimurium infection. We found that bacterial internalization was inhibited by more than 70% in cells lacking both c-Abl and Arg and that treatment of wild-type cells with a pharmaceutical inhibitor of the c-Abl kinase, STI571 (imatinib), reduced serovar Typhimurium invasion efficiency to a similar extent. Bacterial infection led to enhanced phosphorylation of two previously identified c-Abl substrates, the adaptor protein CT10 regulator of kinase (CrkII) and the Abelson-interacting protein Abi1, a component of the WAVE2 complex. Furthermore, overexpression of the nonphosphorylatable form of CrkII resulted in decreased invasion. Taken together, these findings indicate that c-Abl is activated during S. enterica serovar Typhimurium infection and that its phosphorylation of multiple downstream targets is functionally important in bacterial internalization.
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Murthy, Ambika Mosale Venkatesh, Subashini Mathivanan, Sagar Chittori, Handanahal Subbarao Savithri i Mathur Ramabhadrashastry Narasimha Murthy. "Structures of substrate- and nucleotide-bound propionate kinase fromSalmonella typhimurium: substrate specificity and phosphate-transfer mechanism". Acta Crystallographica Section D Biological Crystallography 71, nr 8 (28.07.2015): 1640–48. http://dx.doi.org/10.1107/s1399004715009992.
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Kinases are ubiquitous enzymes that are pivotal to many biochemical processes. There are contrasting views on the phosphoryl-transfer mechanism in propionate kinase, an enzyme that reversibly transfers a phosphoryl group from propionyl phosphate to ADP in the final step of non-oxidative catabolism of L-threonine to propionate. Here, X-ray crystal structures of propionate- and nucleotide-boundSalmonella typhimuriumpropionate kinase are reported at 1.8–2.0 Å resolution. Although the mode of nucleotide binding is comparable to those of other members of the ASKHA superfamily, propionate is bound at a distinct site deeper in the hydrophobic pocket defining the active site. The propionate carboxyl is at a distance of ∼5 Å from the γ-phosphate of the nucleotide, supporting a direct in-line transfer mechanism. The phosphoryl-transfer reaction is likely to occurviaan associative SN2-like transition state that involves a pentagonal bipyramidal structure with the axial positions occupied by the nucleophile of the substrate and the O atom between the β- and the γ-phosphates, respectively. The proximity of the strictly conserved His175 and Arg236 to the carboxyl group of the propionate and the γ-phosphate of ATP suggests their involvement in catalysis. Moreover, ligand binding does not induce global domain movement as reported in some other members of the ASKHA superfamily. Instead, residues Arg86, Asp143 and Pro116-Leu117-His118 that define the active-site pocket move towards the substrate and expel water molecules from the active site. The role of Ala88, previously proposed to be the residue determining substrate specificity, was examined by determining the crystal structures of the propionate-bound Ala88 mutants A88V and A88G. Kinetic analysis and structural data are consistent with a significant role of Ala88 in substrate-specificity determination. The active-site pocket-defining residues Arg86, Asp143 and the Pro116-Leu117-His118 segment are also likely to contribute to substrate specificity.
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Chen, Li-Mei, Shubha Bagrodia, Richard A. Cerione i Jorge E. Galán. "Requirement of p21-activated Kinase (PAK) for Salmonella typhimurium–induced Nuclear Responses". Journal of Experimental Medicine 189, nr 9 (3.05.1999): 1479–88. http://dx.doi.org/10.1084/jem.189.9.1479.
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Salmonella typhimurium has sustained a long-standing association with its host and therefore has evolved sophisticated strategies to multiply and survive within this environment. Central to Salmonella pathogenesis is the function of a dedicated type III secretion system that delivers bacterial effector proteins into the host cell cytoplasm. These effectors stimulate nuclear responses and actin cytoskeleton reorganization leading to the production of proinflammatory cytokines and bacterial internalization. The stimulation of these responses requires the function of Cdc42, a member of the Rho family of small molecular weight GTPases, and SopE, a bacterial effector protein that stimulates guanine nucleotide exchange on Rho GTPases. However, nothing is known about the role of Cdc42 effector proteins in S. typhimurium–induced responses. We showed here that S. typhimurium infection of cultured epithelial cells results in the activation of p21-activated kinase (PAK), a serine/threonine kinase that is an effector of Cdc42-dependent responses. Transient expression of a kinase-defective PAK blocked both S. typhimurium– and SopE-induced c-Jun NH2-terminal kinase (JNK) activation but did not interfere with bacteria-induced actin cytoskeleton rearrangements. Similarly, expression of SH3-binding mutants of PAK did not block actin-mediated S. typhimurium entry into cultured cells. However, expression of an effector loop mutant of Cdc42Hs (Cdc42HsC40) unable to bind PAK and other CRIB (for Cdc42/Rac interacting binding)-containing target proteins resulted in abrogation of both S. typhimurium–induced nuclear and cytoskeletal responses. These results show that PAK kinase activity is required for bacteria-induced nuclear responses but it is not required for cytoskeletal rearrangements, indicating that S. typhimurium stimulates cellular responses through different Cdc42 downstream effector activities. In addition, these results demonstrate that the effector loop of Cdc42 implicated in the binding of PAK and other CRIB-containing target proteins is required for both responses.
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Milillo, S. R., E. Martin, A. Muthaiyan i S. C. Ricke. "Immediate Reduction of Salmonella enterica Serotype Typhimurium Viability via Membrane Destabilization following Exposure to Multiple-Hurdle Treatments with Heated, Acidified Organic Acid Salt Solutions". Applied and Environmental Microbiology 77, nr 11 (8.04.2011): 3765–72. http://dx.doi.org/10.1128/aem.02839-10.
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ABSTRACTThe antimicrobial activity of organic acids in combination with nonchemical treatments was evaluated for inactivation ofSalmonella entericaserotype Typhimurium within 1 min. It was observed that the effectiveness of the multiple-hurdle treatments was temperature (P≤ 0.05) and pH (P≤ 0.05) dependent and corresponded to the degree of organic acid lipophilicity (sodium acetate being least effective and sodium propionate being the most effective). This led to the hypothesis that the loss in viability was due at least in part to cell membrane disruption. Evaluation of osmotic response, potassium ion leakage, and transmission electron micrographs confirmed treatment effects on the cell membrane. Interestingly, all treatments, even those with no effect on viability, such as with sodium acetate, resulted in measurable cellular stress. Microarray experiments explored the specific response ofS. Typhimurium to sodium acetate and sodium propionate, the most similar of the tested treatments in terms of pKaand ionic strength, and found little difference in the changes in gene expression following exposure to either, despite their very different effects on viability. Taken together, the results reported support our hypothesis that treatment with heated, acidified, organic acid salt solutions for 1 min causes loss ofS. Typhimurium viability at least in part by membrane damage and that the degree of effectiveness can be correlated with lipophilicity of the organic acid. Overall, the data presented here indicate that a combined thermal, acidified sodium propionate treatment can provide an effective antimicrobial treatment againstSalmonella.
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Shelton, Catherine D., Woongjae Yoo, Nicolas G. Shealy, Teresa P. Torres, Jacob K. Zieba, M. Wade Calcutt, Nora J. Foegeding i in. "Salmonella enterica serovar Typhimurium uses anaerobic respiration to overcome propionate-mediated colonization resistance". Cell Reports 38, nr 1 (styczeń 2022): 110180. http://dx.doi.org/10.1016/j.celrep.2021.110180.
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Roy, Marie-France, Noémie Riendeau, Christian Bédard, Pierre Hélie, Gundula Min-Oo, Karine Turcotte, Philippe Gros, François Canonne-Hergaux i Danielle Malo. "Pyruvate kinase deficiency confers susceptibility to Salmonella typhimurium infection in mice". Journal of Experimental Medicine 204, nr 12 (12.11.2007): 2949–61. http://dx.doi.org/10.1084/jem.20062606.
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The mouse response to acute Salmonella typhimurium infection is complex, and it is under the influence of several genes, as well as environmental factors. In a previous study, we identified two novel Salmonella susceptibility loci, Ity4 and Ity5, in a (AcB61 × 129S6)F2 cross. The peak logarithm of odds score associated with Ity4 maps to the region of the liver and red blood cell (RBC)–specific pyruvate kinase (Pklr) gene, which was previously shown to be mutated in AcB61. During Plasmodium chabaudi infection, the Pklr mutation protects the mice against this parasite, as indicated by improved survival and lower peak parasitemia. Given that RBC defects have previously been associated with resistance to malaria and susceptibility to Salmonella, we hypothesized that Pklr is the gene underlying Ity4 and that it confers susceptibility to acute S. typhimurium infection in mice. Using a fine mapping approach combined with complementation studies, comparative studies, and functional analysis, we show that Pklr is the gene underlying Ity4 and that it confers susceptibility to acute S. typhimurium infection in mice through its effect on the RBC turnover and iron metabolism.
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Shi, Jing, i James E. Casanova. "Invasion of Host Cells bySalmonella typhimuriumRequires Focal Adhesion Kinase and p130Cas". Molecular Biology of the Cell 17, nr 11 (listopad 2006): 4698–708. http://dx.doi.org/10.1091/mbc.e06-06-0492.
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Salmonella typhimurium colonizes the intestinal epithelium by injecting an array of effector proteins into host cells that induces phagocytic uptake of attached bacteria. However, the host molecules targeted by these effectors remain poorly defined. Here, we demonstrate that S. typhimurium induces formation of focal adhesion-like complexes at sites of bacterial attachment and that both focal adhesion kinase (FAK) and the scaffolding protein p130Cas are required for Salmonella uptake. Entry of Salmonella into FAK−/−cells is dramatically impaired and can be restored to control levels by expression of wild-type FAK. Surprisingly, reconstitution of bacterial internalization requires neither the kinase domain of FAK nor activation of c-Src, but does require a C-terminal PXXP motif through which FAK interacts with Cas. Infection of Cas−/−cells is also impaired, and reconstitution of invasiveness requires the central Cas YXXP repeat domain. The invasion defect in Cas−/−cells can be suppressed by overexpression of FAK, suggesting a functional link between FAK and Cas in the regulation of Salmonella invasion. Together, these findings reveal a novel role for focal adhesion proteins in the invasion of host cells by Salmonella.
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WATERS, SINÉAD M., RICHARD A. MURPHY i RONAN F. G. POWER. "Assessment of the Effects of Nurmi-Type Cultures and a Defined Probiotic Preparation on a Salmonella Typhimurium 29E Challenge In Vivo". Journal of Food Protection 68, nr 6 (1.06.2005): 1222–27. http://dx.doi.org/10.4315/0362-028x-68.6.1222.
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The effects of treatment with an undefined commercial Nurmi-type culture (NTC), cultured cecal contents, and a dual-strain probiotic, containing Enterococcus faecalis and Pediococcus pentosaceus, on Salmonella Typhimurium colonization were evaluated in a specific-pathogen-free bird model. Two sets of trials were performed, and each study was arranged as a randomized complete block design with three treatments. Treatments consisted of (i) control, (ii) commercial NTC, and (iii) cultured cecal contents in the first set of trials and (i) control, (ii) defined probiotic, and (iii) cultured cecal contents in the second set. On day 1, birds were administered 1.2 × 107 CFU of the appropriate treatment by oral gavage. On day 3, all birds were challenged with 1 × 106 CFU of Salmonella Typhimurium 29E (nalidixic acid resistant). Chicks were asphyxiated with argon gas on day 10, and ceca were aseptically removed. Salmonella Typhimurium counts (CFU per milliliter of cecal contents) were determined on brilliant green agar containing 30 mg of nalidixic acid per liter, and CFU counts were log transformed prior to analysis. Cecal pH and volatile fatty acid concentrations were also determined. Data were analyzed by one-way analysis of variance, and means were compared by Tukey's pairwise analysis. Commercial NTC and cultured cecal contents treatments resulted in a significant decrease (P ≤ 0.05) in Salmonella Typhimurium 29E colonization, with the NTC offering a higher level of protection. In the second set of trials, the defined probiotic tended to reduce colonization by Salmonella Typhimurium (P = 0.07), while chicks treated with cultured cecal contents displayed a significant decrease (P = 0.03) when compared to the negative control. No significant change was observed in cecal pH or in acetate and propionate concentrations; however, a significant increase in butyrate concentrations in both the cultured cecal contents and defined probiotic treatment groups was observed when compared to the control birds. These observations suggest that defined cultures are less effective Salmonella control agents than are preparations generated from the complete cecal microflora.
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Moreira, Cristiano G., David Weinshenker i Vanessa Sperandio. "QseC Mediates Salmonella enterica Serovar Typhimurium Virulence In Vitro and In Vivo". Infection and Immunity 78, nr 3 (22.12.2009): 914–26. http://dx.doi.org/10.1128/iai.01038-09.
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ABSTRACT The autoinducer-3 (AI-3)/epinephrine (Epi)/norepinephrine (NE) interkingdom signaling system mediates chemical communication between bacteria and their mammalian hosts. The three signals are sensed by the QseC histidine kinase (HK) sensor. Salmonella enterica serovar Typhimurium is a pathogen that uses HKs to sense its environment and regulate virulence. Salmonella serovar Typhimurium invades epithelial cells and survives within macrophages. Invasion of epithelial cells is mediated by the type III secretion system (T3SS) encoded in Salmonella pathogenicity island 1 (SPI-1), while macrophage survival and systemic disease are mediated by the T3SS encoded in SPI-2. Here we show that QseC plays an important role in Salmonella serovar Typhimurium pathogenicity. A qseC mutant was impaired in flagellar motility, in invasion of epithelial cells, and in survival within macrophages and was attenuated for systemic infection in 129x1/SvJ mice. QseC acts globally, regulating expression of genes within SPI-1 and SPI-2 in vitro and in vivo (during infection of mice). Additionally, dopamine β-hydroxylase knockout (Dbh − / −) mice that do not produce Epi or NE showed different susceptibility to Salmonella serovar Typhimurium infection than wild-type mice. These data suggest that the AI-3/Epi/NE signaling system is a key factor during Salmonella serovar Typhimurium pathogenesis in vitro and in vivo. Elucidation of the role of this interkingdom signaling system in Salmonella serovar Typhimurium should contribute to a better understanding of the complex interplay between the pathogen and the host during infection.
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Palacios, Sergio, i Jorge C. Escalante-Semerena. "2-Methylcitrate-dependent activation of the propionate catabolic operon (prpBCDE) of Salmonella enterica by the PrpR protein". Microbiology 150, nr 11 (1.11.2004): 3877–87. http://dx.doi.org/10.1099/mic.0.27299-0.
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The function of the PrpR protein of Salmonella enterica serovar Typhimurium LT2 was studied in vitro and in vivo. The PrpR protein is a sensor of 2-methylcitrate (2-MC), an intermediate of the 2-methylcitric acid cycle used by this bacterium to convert propionate to pyruvate. PrpR was unresponsive to citrate (a close structural analogue of 2-MC) and to propionate, suggesting that 2-MC, not propionate, is the metabolite that signals the presence of propionate in the environment to S. enterica. prpR alleles encoding mutant proteins with various levels of 2-MC-independent activity were isolated. All lesions causing constitutive PrpR activity were mapped to the N-terminal domain of the protein. Removal of the entire sensing domain resulted in a protein (PrpRc) with the highest 2-MC-independent activity. Residue A162 is critical to 2-MC sensing, since the mutant PrpR protein PrpRA162T was as active as the PrpRc protein in the absence of 2-MC. DNA footprinting studies identified the site in the region between prpR and the prpBCDE operon to which the PrpR protein binds. Analysis of the binding-site sequence revealed two sites with dyad symmetry. Results from DNase I footprinting assays suggested that the PrpR protein may have higher affinity for the site proximal to the PprpBCDE promoter.
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JUNG, YONG SOO, ROBIN C. ANDERSON, THOMAS S. EDRINGTON, KENNETH J. GENOVESE, J. ALLEN BYRD, TODD R. CALLAWAY i DAVID J. NISBET. "Experimental Use of 2-Nitropropanol for Reduction of Salmonella Typhimurium in the Ceca of Broiler Chicks†‡". Journal of Food Protection 67, nr 9 (1.09.2004): 1945–47. http://dx.doi.org/10.4315/0362-028x-67.9.1945.
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The effect of 2-nitropropanol (2NPOH) administration on Salmonella enterica serovar Typhimurium in experimentally infected chicks was determined. Chicks orally challenged with 106 CFU/ml of a novobiocin- and naladixic acid–resistant Salmonella Typhimurium at 6 days of age were divided into three groups receiving 0 (control), 6.5, and 13 mg 2NPOH per bird (experiment 1) or four groups receiving 0 (control), 13, 65, and 130 mg 2NPOH per bird (experiment 2). Treatments were administered orally 1 day post–Salmonella challenge. Cecal contents collected at necropsy 24 and 48 h after treatment were subjected to bacterial and volatile fatty acid (VFA) analysis. In experiment 1, concentrations (mean ± SD log CFU per g) of Salmonella were reduced (P < 0.05) in the group administered 13 mg 2NPOH per bird at both the 24- and 48-h samplings compared with the controls (2.58 ± 2.10 versus 4.64 ± 1.79 and 2.88 ± 2.78 versus 5.03 ± 2.42 at 24 and 48 h, respectively). In experiment 2, mean ± SD populations of Salmonella were reduced (P < 0.05) in all groups receiving 2NPOH compared with untreated controls (3.65 ± 2.01, 3.39 ± 2.42, and 3.47 ± 1.55 at 13, 65, and 130 mg, respectively, versus 6.09 ± 1.02). Propionate concentrations were reduced (P < 0.05) by the 13-mg 2NPOH per bird treatment. Total VFA concentrations from the group treated with 13 mg 2NPOH per bird were lower (P < 0.05) by 48, but not 24, hours posttreatment than those from the group treated with 6.5 mg 2NPOH per bird. These results demonstrate the inhibitory activity of 2NPOH against Salmonella Typhimurium in vivo.
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Mynott, Tracey L., Ben Crossett i S. Radhika Prathalingam. "Proteolytic Inhibition of Salmonella enterica Serovar Typhimurium-Induced Activation of the Mitogen-Activated Protein Kinases ERK and JNK in Cultured Human Intestinal Cells". Infection and Immunity 70, nr 1 (styczeń 2002): 86–95. http://dx.doi.org/10.1128/iai.70.1.86-95.2002.
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ABSTRACT Bromelain, a mixture of cysteine proteases from pineapple stems, blocks signaling by the mitogen-activated protein (MAP) kinases extracellular regulated kinase 1 (ERK-1) and ERK-2, inhibits inflammation, and protects against enterotoxigenic Escherichia coli infection. In this study, we examined the effect of bromelain on Salmonella enterica serovar Typhimurium infection, since an important feature of its pathogenesis is its ability to induce activation of ERK-1 and ERK-2, which leads to internalization of bacteria and induction of inflammatory responses. Our results show that bromelain dose dependently blocks serovar Typhimurium-induced ERK-1, ERK-2, and c-Jun NH2-terminal kinase (JNK) activation in Caco-2 cells. Bromelain also blocked signaling induced by carbachol and anisomycin, pharmacological MAP kinase agonists. Despite bromelain inhibition of serovar Typhimurium-induced MAP kinase signaling, it did not prevent subsequent invasion of the Caco-2 cells by serovar Typhimurium or alter serovar Typhimurium -induced decreases in resistance across Caco-2 monolayers. Surprisingly, bromelain also did not block serovar Typhimurium-induced interleukin-8 (IL-8) secretion but synergized with serovar Typhimurium to enhance IL-8 production. We also found that serovar Typhimurium does not induce ERK phosphorylation in Caco-2 cells in the absence of serum but that serovar Typhimurium-induced invasion and decreases in monolayer resistance are unaffected. Collectively, these data indicate that serovar Typhimurium-induced invasion of Caco-2 cells, changes in the resistance of epithelial cell monolayers, and IL-8 production can occur independently of the ERK and JNK signaling pathways. Data also confirm that bromelain is a novel inhibitor of MAP kinase signaling pathways and suggest a novel role for proteases as inhibitors of signal transduction pathways in intestinal epithelial cells.
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Jepson, Mark A., Hélène B. Schlecht i Carla B. Collares-Buzato. "Localization of Dysfunctional Tight Junctions inSalmonella enterica Serovar Typhimurium-Infected Epithelial Layers". Infection and Immunity 68, nr 12 (1.12.2000): 7202–8. http://dx.doi.org/10.1128/iai.68.12.7202-7208.2000.
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ABSTRACT Infection of polarized MDCK epithelial layers by Salmonella enterica serovar Typhimurium is accompanied by increased tight junction permeability and by contraction of perijunctional actinomyosin. We localized dysfunctional tight junctions in serovar Typhimurium-infected MDCK layers by imaging apical-basolateral intramembrane diffusion of fluorescent lipid and found that loss of the apical-basolateral diffusion barrier (tight junction fence function) was most marked in areas of prominent perijunctional contraction. The protein kinase inhibitor staurosporine prevented perijunctional contraction but did not reverse the effects of serovar Typhimurium on tight junction barrier function. Hence, perijunctional contraction is not required for Salmonella-induced tight junction dysfunction and this epithelial response to infection may be multifactorial.
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Munitic, Ivana, Maria Letizia Giardino-Torchia i Jonathan Ashwell. "Optineurin is dispensable for LPS- and Salmonella typhimurium-induced autophagy (INM3P.412)". Journal of Immunology 194, nr 1_Supplement (1.05.2015): 127.17. http://dx.doi.org/10.4049/jimmunol.194.supp.127.17.
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Abstract In vitro studies demonstrated that optineurin, a ubiquitin (Ub)-binding protein, becomes an autophagy cargo receptor upon being phosphorylated on Ser177 by TANK binding kinase 1 (TBK1) in response to cytosolic Salmonella typhimurium. Phosphorylated optineurin then regulates autophagy by delivering ubiquinated bacteria to autophagosomal membranes via light chain 3 (LC3), hence restricting their growth. To test the in vivo relevance of these findings, we used a mouse model with C-terminal optineurin truncation, which lacks the Ub-binding region (Optn470T). No difference was found between WT and Optn470T macrophages in LC3 lipidation during LPS-induced autophagy. Similarly, p62+LC3+ aggresome-like structures generated upon LPS or Salmonella typhimurium stimulation in Optn470T macrophages colocalized with lysosomal marker LAMP1 to the same extent as in WT cells, demonstrating no perturbation in autophagosome fusion to lysosomes. Importantly, upon in vivo infection with Salmonella typhimurium, no difference was found in bacterial replication in WT and Optn470T mice. These results argue against the role of optineurin in Salmonella typhimurium infection in vivo.
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Kim, Hugh, Colin D. White, Zhigang Li i David B. Sacks. "Salmonella enterica serotype Typhimurium usurps the scaffold protein IQGAP1 to manipulate Rac1 and MAPK signalling". Biochemical Journal 440, nr 3 (28.11.2011): 309–18. http://dx.doi.org/10.1042/bj20110419.
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Salmonella enterica serotype Typhimurium invades eukaryotic cells by re-arranging the host-cell cytoskeleton. However, the precise mechanisms by which Salmonella induces cytoskeletal changes remain undefined. IQGAP1 (IQ motif-containing GTPase-activating protein 1) is a scaffold protein that binds multiple proteins including actin, the Rho GTPases Rac1 and Cdc42 (cell division cycle 42), and components of the MAPK (mitogen-activated protein kinase) pathway. We have shown previously that optimal invasion of Salmonella into HeLa cells requires IQGAP1. In the present paper, we use IQGAP1-null MEFs (mouse embryonic fibroblasts) and selected well-characterized IQGAP1 mutant constructs to dissect the molecular determinants of Salmonella invasion. Knockout of IQGAP1 expression reduced Salmonella invasion into MEFs by 75%. Reconstituting IQGAP1-null MEFs with wild-type IQGAP1 completely rescued invasion. By contrast, reconstituting IQGAP1-null cells with mutant IQGAP1 constructs that specifically lack binding to either Cdc42 and Rac1 (termed IQGAP1ΔMK24), actin, MEK [MAPK/ERK (extracellular-signal-regulated kinase) kinase] or ERK only partially restored Salmonella entry. Cell-permeant inhibitors of Rac1 activation or MAPK signalling reduced Salmonella invasion into control cells by 50%, but had no effect on bacterial entry into IQGAP1-null MEFs. Importantly, the ability of IQGAP1ΔMK24 to promote Salmonella invasion into IQGAP1-null cells was abrogated by chemical inhibition of MAPK signalling. Collectively, these results imply that the scaffolding function of IQGAP1, which integrates Rac1 and MAPK signalling, is usurped by Salmonella to invade fibroblasts and suggest that IQGAP1 may be a potential therapeutic target for Salmonella pathogenesis.
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Garcia-Olalla, C., i A. Garrido-Pertierra. "Purification and kinetic properties of pyruvate kinase isoenzymes of Salmonella typhimurium". Biochemical Journal 241, nr 2 (15.01.1987): 573–81. http://dx.doi.org/10.1042/bj2410573.
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Two forms of pyruvate kinase (ATP: pyruvate 2-O-phosphotransferase, EC 2.7.1.40) present in Salmonella typhimurium were purified to homogeneity from the same cultures by (NH4)2SO4 fractionation and gel filtration, anion-exchange and affinity chromatography. Mr values, subunit structure, amino acid composition and activity and stability conditions were determined for the two forms. Kinetic and regulatory properties of the two purified isoenzymes were studied.
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Tafazoli, Farideh, Karl-Eric Magnusson i Limin Zheng. "Disruption of Epithelial Barrier Integrity by Salmonella enterica Serovar Typhimurium Requires Geranylgeranylated Proteins". Infection and Immunity 71, nr 2 (luty 2003): 872–81. http://dx.doi.org/10.1128/iai.71.2.872-881.2003.
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ABSTRACT Epithelial cells that line the human intestinal mucosa constitute the initial sites of host invasion by bacterial pathogens. A number of bacteria, such as Salmonella and Yersinia spp., have been shown to disrupt the integrity of the epithelial barrier, although little is known about the mechanisms underlying that effect. We found that polarized MDCK-1 epithelial cells infected with invasive Salmonella enterica serovar Typhimurium SL1344 exhibited marked changes in F-actin organization, an increase in the paracellular flux of dextran, and a rapid decrease in transepithelial electrical resistance (TER). In contrast, infection with an isogenic noninvasive mutant (hilA) increased the TER in these cells. Pretreating MDCK-1 cells with the inhibitors for tyrosine kinase (genistein) or phosphatidylinositol 3-kinase (wortmannin) did not affect invasion and subsequent perturbation of the epithelial barrier by serovar Typhimurium. Instead, the geranylgeranyltransferase 1 inhibitor GGTI-298, but not the farnesyltransferase inhibitor FTI-277, clearly reversed the capacity of serovar Typhimurium to disrupt the epithelial barrier. The substrates for GGTI-298 include Rho family GTPases, as indicated by inhibiting prenylation of Rac1 and Cdc42. Infection with wild-type serovar Typhimurium increased the level of activated Rac1 and Cdc42 and caused these proteins to accumulate apically in MDCK-1 cells. This Salmonella-induced accumulation of Rac1 and Cdc42 and alteration of the junction-associated proteins ZO-1, occludin, and E-cadherin in MDCK-1 cells were markedly inhibited by GGTI-298. These results suggest that activation of geranylgeranylated proteins, including Rac1 and Cdc42, is critical for disruption of barrier integrity by serovar Typhimurium in polarized MDCK-1 cells.
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Silva, Milton, Cecilia Song, William J. Nadeau, Jeffrey B. Matthews i Beth A. McCormick. "Salmonella typhimuriumSipA-induced neutrophil transepithelial migration: involvement of a PKC-α-dependent signal transduction pathway". American Journal of Physiology-Gastrointestinal and Liver Physiology 286, nr 6 (czerwiec 2004): G1024—G1031. http://dx.doi.org/10.1152/ajpgi.00299.2003.
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Salmonella typhimurium elicits an intense proinflammatory response characterized by movement of polymorphonuclear neutrophils (PMN) across the epithelial barrier to the intestinal lumen. We previously showed that S. typhimurium, via the type III secretion system effector protein SipA, initiates an ADP-ribosylation factor-6- and phospholipase D-dependent lipid-signaling cascade that directs activation of protein kinase C (PKC) and subsequent transepithelial movement of PMN. Here we sought to determine the specific PKC isoforms that are induced by the S. typhimurium effector SipA in model intestinal epithelia and to link the functional consequences of these isoforms in the promotion of PMN transepithelial migration. In vitro kinase PKC activation assays performed on polarized monolayers of T84 cells revealed that S. typhimurium and recombinant SipA induced activation of PKC-α, -δ, and -ε. To elucidate which of these isoforms play a key role in mediating epithelial cell responses that lead to the observed PMN transepithelial migration, we used a variety of PKC inhibitors with different isoform selectivity profiles. Inhibitors selective for PKC-α (Gö-6976 and 2,2′,3,3′,4,4′-hexahydroxyl-1,1′-biphenyl-6,6′-dimethanoldimethyl ether) markedly reduced S. typhimurium- and recombinant SipA-induced PMN transepithelial migration, whereas inhibitors to PKC-δ (rottlerin) or PKC-ε (V1-2) failed to exhibit a significant decrease in transepithelial movement of PMN. These results were confirmed biochemically and by immunofluorescence coupled to confocal microscopy. Our results are the first to show that the S. typhimurium effector protein SipA can activate multiple PKC isoforms, but only PKC-α is involved in the signal transduction cascade leading to PMN transepithelial migration.
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Aiastui, Ana, M. Graciela Pucciarelli i Francisco García-del Portillo. "Salmonella enterica Serovar Typhimurium Invades Fibroblasts by Multiple Routes Differing from the Entry into Epithelial Cells". Infection and Immunity 78, nr 6 (5.04.2010): 2700–2713. http://dx.doi.org/10.1128/iai.01389-09.
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ABSTRACT Fibroblasts are ubiquitous cells essential to tissue homeostasis. Despite their nonphagocytic nature, fibroblasts restrain replication of intracellular bacterial pathogens such as Salmonella enterica serovar Typhimurium. The extent to which the entry route of the pathogen determines this intracellular response is unknown. Here, we analyzed S. Typhimurium invasion in fibroblasts obtained from diverse origins, including primary cultures and stable nontransformed cell lines derived from normal tissues. Features distinct to the invasion of epithelial cells were found in all fibroblasts tested. In some fibroblasts, bacteria lacking the type III secretion system encoded in the Salmonella pathogenicity island 1 displayed significant invasion rates and induced the formation of lamellipodia and filopodia at the fibroblast-bacteria contact site. Other bacterial invasion traits observed in fibroblasts were the requirement of phosphatidylinositol 3-kinase, mitogen-activated protein kinase MEK1, and both actin filaments and microtubules. RNA interference studies showed that different Rho family GTPases are targeted by S. Typhimurium to enter into distinct fibroblasts. Rac1 and Cdc42 knockdown affected invasion of normal rat kidney fibroblasts, whereas none of the GTPases tested (Rac1, Cdc42, RhoA, or RhoG) was essential for invasion of immortalized human foreskin fibroblasts. Collectively, these data reveal a marked diversity in the modes used by S. Typhimurium to enter into fibroblasts.
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Du, Lin, Yolanda Wong Ying Yip, Him Kwan Ng, Bo Man Ho, Jing-Na He, Sun On Chan, Chi Pui Pang i Wai Kit Chu. "Ruxolitinib Alleviates Uveitis Caused by Salmonella typhimurium Endotoxin". Microorganisms 9, nr 7 (11.07.2021): 1481. http://dx.doi.org/10.3390/microorganisms9071481.
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Uveitis is characterized by inflammatory lesions of intraocular structures. It is one of the important manifestations in patients with Reiter’s syndrome, an inflammatory arthritis, which is caused by enteric infection with bacteria, including Salmonella typhimurium. Corticosteroids remain the most frequently used therapies against uveitis associating with inflammatory arthritis. However, the long-term administration of steroids results in many side effects, and some uveitis patients do not respond to steroid treatment. Non-steroidal treatments are needed for uveitis patients. Our previous study found that Janus kinase (JAK) 1/2 inhibitor, ruxolitinib could suppress the expression of proinflammatory mediators in the ciliary body and iris. However, the impacts of ruxolitinib on ophthalmic features in uveitic eyes are still unknown. In this study, Salmonella typhimurium endotoxin-induced uveitis (EIU) was induced in Sprague Dawley rats by the injection of lipopolysaccharide (LPS). Compared with LPS-induced rats treated with water, ruxolitinib significantly attenuated the clinical manifestations, infiltrating cells and protein exudation in the aqueous humor, and retina–choroid thickening. Amplitudes of b-wave in both scotopic and photopic electroretinogram (ERG), and the amplitude of a-wave in scotopic ERG in EIU animals were alleviated by ruxolitinib. Collectively, we propose ruxolitinib could attenuate endotoxin-induced uveitis and rescue visual functions in rats by inhibiting the JAK2-STAT3 pathway.
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Hos, Nina Judith, Raja Ganesan, Saray Gutiérrez, Deniz Hos, Jennifer Klimek, Zeinab Abdullah, Martin Krönke i Nirmal Robinson. "Type I interferon enhances necroptosis of Salmonella Typhimurium–infected macrophages by impairing antioxidative stress responses". Journal of Cell Biology 216, nr 12 (20.10.2017): 4107–21. http://dx.doi.org/10.1083/jcb.201701107.
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Salmonella enterica serovar Typhimurium exploits the host’s type I interferon (IFN-I) response to induce receptor-interacting protein (RIP) kinase–mediated necroptosis in macrophages. However, the events that drive necroptosis execution downstream of IFN-I and RIP signaling remain elusive. In this study, we demonstrate that S. Typhimurium infection causes IFN-I–mediated up-regulation of the mitochondrial phosphatase Pgam5 through RIP3. Pgam5 subsequently interacts with Nrf2, which sequesters Nrf2 in the cytosol, thereby repressing the transcription of Nrf2-dependent antioxidative genes. The impaired ability to respond to S. Typhimurium–induced oxidative stress results in reactive oxygen species–mediated mitochondrial damage, energy depletion, transient induction of autophagy, and autophagic degradation of p62. Reduced p62 levels impair interaction of p62 with Keap1, which further decreases Nrf2 function and antioxidative responses to S. Typhimurium infection, eventually leading to cell death. Collectively, we identify impaired Nrf2-dependent redox homeostasis as an important mechanism that promotes cell death downstream of IFN-I and RIP3 signaling in S. Typhimurium–infected macrophages.
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Bertelsen, Lone S., Günther Paesold, Sandra L. Marcus, Brett B. Finlay, Lars Eckmann i Kim E. Barrett. "Modulation of chloride secretory responses and barrier function of intestinal epithelial cells by theSalmonellaeffector protein SigD". American Journal of Physiology-Cell Physiology 287, nr 4 (październik 2004): C939—C948. http://dx.doi.org/10.1152/ajpcell.00413.2003.
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The Salmonella effector protein SigD is an inositol phosphate phosphatase that inhibits phosphatidylinositol 3-kinase-dependent signaling. Because epidermal growth factor (EGF) inhibits chloride secretion via phosphatidylinositol 3-kinase, we explored whether Salmonella infection might modify the inhibitory effect of EGF. As expected, EGF inhibited chloride secretion induced by carbachol in T84epithelial cells. Infection with wild-type (WT) but not sigD−mutant S. typhimurium SL1344 decreased CCh-stimulated chloride secretion. Moreover, WT but not sigD−Salmonella reduced the inhibitory effect of EGF on carbachol-stimulated chloride secretion. Complementation of sigD restored the ability of mutant Salmonella to reverse the inhibitory effect of EGF. EGF-induced EGF receptor phosphorylation was similar in cells infected with either WT or mutant Salmonella, and neither WT nor sigD−Salmonella altered recruitment of the p85 subunit of phosphatidylinositol 3-kinase to EGF receptor, implying that SigD acts downstream of these signaling events. Furthermore, transepithelial resistance fell more rapidly in cells infected with WT vs. sigD−Salmonella, indicating an early role for SigD in reducing barrier function, perhaps via activation of protein kinase C. We conclude that the Salmonella bacterial effector protein SigD may play critical roles in the pathogenesis of disease caused by this microorganism.
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Sanowar, Sarah, i Hervé Le Moual. "Functional reconstitution of the Salmonella typhimurium PhoQ histidine kinase sensor in proteoliposomes". Biochemical Journal 390, nr 3 (5.09.2005): 769–76. http://dx.doi.org/10.1042/bj20050060.
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Two-component signal-transduction systems are widespread in bacteria. They are usually composed of a transmembrane histidine kinase sensor and a cytoplasmic response regulator. The PhoP/PhoQ two-component system of Salmonella typhimurium contributes to virulence by co-ordinating the adaptation to low concentrations of environmental Mg2+. Limiting concentrations of extracellular Mg2+ activate the PhoP/PhoQ phosphorylation cascade modulating the transcription of PhoP-regulated genes. In contrast, high concentrations of extracellular Mg2+ stimulate the dephosphorylation of the response regulator PhoP by the PhoQ kinase sensor. In the present study, we report the purification and functional reconstitution of PhoQHis, a PhoQ variant with a C-terminal His tag, into Escherichia coli liposomes. The functionality of PhoQHis was essentially similar to that of PhoQ as shown in vivo and in vitro. Purified PhoQHis was inserted into liposomes in a unidirectional orientation, with the sensory domain facing the lumen and the catalytic domain facing the extraluminal environment. Reconstituted PhoQHis exhibited all the catalytic activities that have been described for histidine kinase sensors. Reconstituted PhoQHis was capable of autokinase activity when incubated in the presence of Mg2+-ATP. The phosphoryl group could be transferred from reconstituted PhoQHis to PhoP. Reconstituted PhoQHis catalysed the dephosphorylation of phospho-PhoP and this activity was stimulated by the addition of extraluminal ADP.
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Garrido, Victoria, Lourdes Migura-García, Inés Gaitán, Ainhoa Arrieta-Gisasola, Ilargi Martínez-Ballesteros, Lorenzo Fraile i María Jesús Grilló. "Prevalence of Salmonella in Free-Range Pigs: Risk Factors and Intestinal Microbiota Composition". Foods 10, nr 6 (18.06.2021): 1410. http://dx.doi.org/10.3390/foods10061410.
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Extensive pig systems are gaining importance as quality production systems and as the standard for sustainable rural development and animal welfare. However, the effects of natural foods on Salmonella epidemiology remain unknown. Herein, we assessed the presence of Salmonella and the composition of the gut microbiota in pigs from both Salmonella-free and high Salmonella prevalence farms. In addition, risk factors associated with the presence of Salmonella were investigated. The pathogen was found in 32.2% of animals and 83.3% of farms, showing large differences in prevalence between farms. Most isolates were serovars Typhimurium monophasic (79.3%) and Bovismorbificans (10.3%), and exhibited a multi-drug resistance profile (58.6%). Risk factor analysis identified feed composition, type/variety of vegetation available, and silos’ cleaning/disinfection as the main factors associated with Salmonella prevalence. Clear differences in the intestinal microbiota were found between Salmonella-positive and Salmonella-negative populations, showing the former with increasing Proteobacteria and decreasing Bacteroides populations. Butyrate and propionate producers including Clostridium, Turicibacter, Bacteroidaceae_uc, and Lactobacillus were more abundant in the Salmonella-negative group, whereas acetate producers like Sporobacter, Escherichia or Enterobacter were more abundant in the Salmonella-positive group. Overall, our results suggest that the presence of Salmonella in free-range pigs is directly related to the natural vegetation accessible, determining the composition of the intestinal microbiota.
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García-Quintanilla, Meritxell, Francisco Ramos-Morales i Josep Casadesús. "Conjugal Transfer of the Salmonella enterica Virulence Plasmid in the Mouse Intestine". Journal of Bacteriology 190, nr 6 (4.01.2008): 1922–27. http://dx.doi.org/10.1128/jb.01626-07.
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ABSTRACT BALB/c mice were infected with two Salmonella enterica serovar Typhimurium strains, one of which lacked the virulence plasmid. Transconjugants were found at high frequencies in the mouse feces and at low frequencies in the liver and the spleen, suggesting that mating occurred in the gut. Laboratory conditions that mimic those of the small intestine (microaerophilic growth in the presence of 0.3 M NaCl) increased the frequency of virulence plasmid transfer. Sodium deoxycholate, which is found at high concentrations in the duodenum, and sodium propionate, which is abundant in the large intestine, reduced the conjugation frequency. Feces inhibited conjugation. Altogether, these observations suggested that transfer of the virulence plasmid occurred in the distal portion of the small intestine. Conjugation trials in ileal loops provided direct evidence that conjugal transfer of the Salmonella virulence plasmid occurs in the ileum in mice.
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Li, Pengcheng, Qinghua Yu, Xiaolan Ye, Zhisheng Wang i Qian Yang. "Lactobacillus S-layer protein inhibition of Salmonella-induced reorganization of the cytoskeleton and activation of MAPK signalling pathways in Caco-2 cells". Microbiology 157, nr 9 (1.09.2011): 2639–46. http://dx.doi.org/10.1099/mic.0.049148-0.
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Surface layer (S-layer) proteins are crystalline arrays of proteinaceous subunits that are present as the outermost component of the cell wall in several Lactobacillus species. The S-layer proteins have been shown to play a role in the antimicrobial activity of certain lactobacilli. However, it is not fully understood how the S-layer proteins exert this biological function. The aim of this study was to test the hypothesis that Lactobacillus acidophilus S-layer proteins antagonize Salmonella Typhimurium (S. Typhimurium) infection by protecting against F-actin cytoskeleton rearrangements and the activation of mitogen-activated protein kinase (MAPK) signalling pathways. Monolayer transepithelial electrical resistance (TER) was measured after S. Typhimurium infection in Caco-2 cultured human intestinal cells with L. acidophilus S-layer proteins. F-actin rearrangement and MAPK activation were also assessed by immunofluorescence staining or Western blotting. The results showed that when S. Typhimurium was co-incubated with S-layer proteins, the S. Typhimurium-induced Caco-2 cell F-actin rearrangement was reduced, and the S. Typhimurium-induced TER decrease and interleukin 8 (IL-8) secretion were attenuated. Additionally, L. acidophilus S-layer proteins could inhibit S. Typhimurium-induced phosphorylation of extracellular signal-regulated kinases 1 and 2 (ERK1/2), c-Jun amino-terminal kinase (JNK) and p38. This study indicates that L. acidophilus S-layer proteins are able to inhibit S. Typhimurium infection through blocking S. Typhimurium-induced F-actin rearrangements and S. Typhimurium-induced ERK1/2, JNK and p38 activation in Caco-2 cells. These data provide a rationale for the use of lactobacillus S-layer proteins as therapeutic and preventative agents, at least in infectious diarrhoea.
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Paulini, Stephanie, Florian D. Fabiani, Anna S. Weiss, Ana Laura Moldoveanu, Sophie Helaine, Bärbel Stecher i Kirsten Jung. "The Biological Significance of Pyruvate Sensing and Uptake in Salmonella enterica Serovar Typhimurium". Microorganisms 10, nr 9 (30.08.2022): 1751. http://dx.doi.org/10.3390/microorganisms10091751.
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Pyruvate (CH3COCOOH) is the simplest of the alpha-keto acids and is at the interface of several metabolic pathways both in prokaryotes and eukaryotes. In an amino acid-rich environment, fast-growing bacteria excrete pyruvate instead of completely metabolizing it. The role of pyruvate uptake in pathological conditions is still unclear. In this study, we identified two pyruvate-specific transporters, BtsT and CstA, in Salmonella enterica serovar Typhimurium (S. Typhimurium). Expression of btsT is induced by the histidine kinase/response regulator system BtsS/BtsR upon sensing extracellular pyruvate, whereas expression of cstA is maximal in the stationary phase. Both pyruvate transporters were found to be important for the uptake of this compound, but also for chemotaxis to pyruvate, survival under oxidative and nitrosative stress, and persistence of S. Typhimurium in response to gentamicin. Compared with the wild-type cells, the ΔbtsTΔcstA mutant has disadvantages in antibiotic persistence in macrophages, as well as in colonization and systemic infection in gnotobiotic mice. These data demonstrate the surprising complexity of the two pyruvate uptake systems in S. Typhimurium.
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Hobbie, S., L. M. Chen, R. J. Davis i J. E. Galán. "Involvement of mitogen-activated protein kinase pathways in the nuclear responses and cytokine production induced by Salmonella typhimurium in cultured intestinal epithelial cells." Journal of Immunology 159, nr 11 (1.12.1997): 5550–59. http://dx.doi.org/10.4049/jimmunol.159.11.5550.
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Abstract Central to the pathogenesis of Salmonella typhimurium is its ability to engage the host cell in a two-way biochemical interaction. As a consequence of this interaction, a dedicated protein secretion system, termed type III, is activated in these bacteria and directs the translocation of signaling proteins into the host cell. Secretion of these proteins stimulates host cell signal transduction pathways that lead to a variety of cellular responses. An important feature of S. typhimurium pathogenesis is the induction of a profound inflammatory response in the intestinal epithelium. In this report, we show that S. typhimurium induces host cell signal transduction pathways that lead to the activation of the transcription factors NF-kappaB and AP-1, resulting in the production of proinflammatory cytokines such as IL-8. We also show that S. typhimurium infection of cultured intestinal epithelial cells results in the activation of the mitogen-activated protein (MAP) kinases ERK, JNK, and p38. Induction of these signaling pathways and the synthesis of IL-8 was strictly dependent on the function of the invasion-associated type III protein secretion system encoded by S. typhimurium. Pretreatment of cells with the highly specific p38 MAP kinase inhibitor SB 203580 prevented S. typhimurium-induced IL-8 production. These results indicate that the inflammatory response induced by S. typhimurium may be due to the specific stimulation of MAP kinase signaling pathways leading to nuclear responses.
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Price-Carter, Marian, Thomas G. Fazzio, Ester Ibañez Vallbona i John R. Roth. "Polyphosphate Kinase Protects Salmonella enterica from Weak Organic Acid Stress". Journal of Bacteriology 187, nr 9 (1.05.2005): 3088–99. http://dx.doi.org/10.1128/jb.187.9.3088-3099.2005.
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ABSTRACT Mutants of Salmonella enterica lacking polyphosphate kinase (ppk) grow poorly in the presence of the weak organic acids acetate, propionate, and benzoate. This sensitivity is corrected by methionine and seems to result from destabilization of MetA (homoserine transsuccinylase), the first enzyme in methionine biosynthesis. The MetA protein is known to be sensitive to thermal inactivation, and ppk mutants are more sensitive to heat-induced methionine auxotrophy. Peroxide increases the sensitivity of ppk mutants to both heat and acid and may oxidatively damage (carbonylate) destabilized MetA. While acid appears to impair methionine biosynthesis, it leads to derepression of MetA and may inhibit growth by causing toxic accumulation of denatured protein. This is supported by the observation that the overexpression of MetA in ppk mutants causes acid sensitivity that is not corrected by methionine. We propose that polyphosphate acts as a chemical chaperone that helps refold MetA and/or may stimulate proteolysis of toxic denatured protein. The instability of MetA protein may provide a metabolic fuse that blocks growth under conditions that denature proteins; the sensitivity of this fuse is modulated by polyphosphate.
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Kwon, Y. M., i S. C. Ricke. "Salmonella typhimurium poultry isolate growth response to propionic acid and sodium propionate under aerobic and anaerobic conditions". International Biodeterioration & Biodegradation 43, nr 4 (czerwiec 1999): 161–65. http://dx.doi.org/10.1016/s0964-8305(99)00045-1.
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Uchiya, Kei-ichi, i Toshiaki Nikai. "Salmonella enterica Serovar Typhimurium Infection Induces Cyclooxygenase 2 Expression in Macrophages: Involvement of Salmonella Pathogenicity Island 2". Infection and Immunity 72, nr 12 (grudzień 2004): 6860–69. http://dx.doi.org/10.1128/iai.72.12.6860-6869.2004.
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ABSTRACT Salmonella pathogenicity island 2 (SPI-2) is required for intramacrophage survival and systemic infection in mice. We have recently reported that Salmonella enterica causes activation of the protein kinase A (PKA) signaling pathway in a manner dependent on SPI-2, resulting in the upregulation of interleukin-10 expression in macrophages (K. Uchiya et al., Infect. Immun. 72:1964-1973, 2004). We show in the present study the involvement of SPI-2 in a signal transduction pathway that induces the expression of cyclooxygenase 2 (COX-2), an inducible enzyme involved in the synthesis of prostanoids. High levels of prostaglandin E2 (PGE2) and prostacyclin (PGI2), which are known to activate the PKA signaling pathway via their receptors, were induced in J774 macrophages infected with wild-type Salmonella compared to a strain carrying a mutation in the spiC gene, located within SPI-2. The increased production of both prostanoids was dependent on COX-2. COX-2 expression was dose dependently blocked by treatment with a specific inhibitor of the extracellular signal-regulated kinase 1/2 (ERK1/2) signaling pathway, and the phosphorylation level of ERK1/2 was higher in macrophages infected with wild-type Salmonella compared to the spiC mutant. Taken together, these results indicate that Salmonella causes an SPI-2-dependent ERK1/2 activation that leads to increased COX-2 expression, resulting in the upregulation of PGE2 and PGI2 production in macrophages. A COX-2 inhibitor inhibited not only Salmonella-induced activation of the PKA signaling pathway but also growth of wild-type Salmonella within macrophages, suggesting that Salmonella utilizes the COX-2 pathway to survive within macrophages and that the mechanism involves activation of the PKA signaling pathway.
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Liu, Weiwei, Xia’nan Liu, Yu Li, Junjie Zhao, Zhenshan Liu, Zhuqin Hu, Ying Wang i in. "LRRK2 promotes the activation of NLRC4 inflammasome during Salmonella Typhimurium infection". Journal of Experimental Medicine 214, nr 10 (18.08.2017): 3051–66. http://dx.doi.org/10.1084/jem.20170014.
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Although genetic polymorphisms in the LRRK2 gene are associated with a variety of diseases, the physiological function of LRRK2 remains poorly understood. In this study, we report a crucial role for LRRK2 in the activation of the NLRC4 inflammasome during host defense against Salmonella enteric serovar Typhimurium infection. LRRK2 deficiency reduced caspase-1 activation and IL-1β secretion in response to NLRC4 inflammasome activators in macrophages. Lrrk2−/− mice exhibited impaired clearance of pathogens after acute S. Typhimurium infection. Mechanistically, LRRK2 formed a complex with NLRC4 in the macrophages, and the formation of the LRRK2–NLRC4 complex led to the phosphorylation of NLRC4 at Ser533. Importantly, the kinase activity of LRRK2 is required for optimal NLRC4 inflammasome activation. Collectively, our study reveals an important role for LRRK2 in the host defense by promoting NLRC4 inflammasome activation.
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Byrne, Kristen A., Julian M. Trachsel, Zahra F. Bond, Jamison R. Slate, Brian J. Kerr, Bradley L. Bearson, Shawn M. Bearson i Crystal L. Loving. "Dietary β-glucan reduced Salmonella shedding, shifted intestinal microbiome, and altered intestinal integrity". Journal of Immunology 204, nr 1_Supplement (1.05.2020): 92.15. http://dx.doi.org/10.4049/jimmunol.204.supp.92.15.
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Abstract β-glucan is a prebiotic dietary fiber with immune and microbiota modulating properties. Dietary β-glucan can shift intestinal microbial populations and concentrations of short chain fatty acids (notably, butyrate and propionate), which may alter local populations of regulatory T-cells. Additionally, epigenetic reprograming of monocytes by β-glucan impacts subsequent monocyte responses to heterologous agonists, a form of innate training. Here, β-glucan from Saccharomyces cerevisiae was evaluated as a non-antibiotic dietary additive to limit shedding of the foodborne pathogen, Salmonella enterica server Typhimurium, via changes to the intestinal microbiota, intestinal integrity, and/or the local and peripheral immune system in pigs. Overall Salmonella shedding and cecal mucosa burden was significantly reduced in pigs fed dietary β-glucan compared to Salmonella challenged pigs on control diet. Shifts in microbial communities were associated with reduced Salmonella burden, as pigs fed β-glucan exhibited enhanced cecal epithelial barrier function, altered fecal bacterial communities, and increased short chain fatty acid concentrations. However, no significant differences in regulatory T cell population nor ex vivo monocyte responses were found between groups. Collectively, the non-antibiotic dietary additive β-glucan altered microbial communities and host epithelial cell function in conjunction with reduced Salmonella shedding in pigs.
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Fox, D. K., i S. Roseman. "Isolation and characterization of homogeneous acetate kinase from Salmonella typhimurium and Escherichia coli." Journal of Biological Chemistry 261, nr 29 (październik 1986): 13487–97. http://dx.doi.org/10.1016/s0021-9258(18)67045-0.
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Wang, Sutian, Shoulong Deng, Yang Cao, Rui Zhang, Zhixian Wang, Xiaojing Jiang, Jiahao Wang i in. "Overexpression of Toll-Like Receptor 4 Contributes to Phagocytosis of Salmonella Enterica Serovar Typhimurium via Phosphoinositide 3-Kinase Signaling in Sheep". Cellular Physiology and Biochemistry 49, nr 2 (2018): 662–77. http://dx.doi.org/10.1159/000493032.
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Background/Aims: Phagocytosis of bacteria by monocytes/macrophages can trigger the immune response and the clearance of bacteria. This innate immune response involves Toll-like receptor 4 (TLR4). However, much remains unknown about the mechanism of TLR4-regulated phagocytosis of Salmonella enterica serovar Typhimurium (S. typhimurium) within sheep monocytes/macrophages. Here, we aimed to address these knowledge gaps by infecting transgenic sheep overexpressing TLR4 with S. typhimurium and examining the phagocytic mechanisms involved. Methods: Transgenic sheep were generated by microinjection of the constructed plasmids into fertilized eggs. Monocytes/macrophages isolated from sheep blood were stimulated with LPS and S. typhimurium. Phagocytosis-related factor expression, phagocytic ability, and adhesion were then determined. TLR4/phosphatidylinositide 3-kinase (PI3K) signaling was inhibited to investigate if this pathway is involved in changes in bacterial internalization in sheep. Results: We found that TLR4 overexpression effectively activated the PI3K signaling pathway and upregulated the expression of scavenger receptors. Additionally, actin polymerization and adhesive capacity were both enhanced in TLR4-overexpressing sheep monocytes/macrophages. TLR4 inhibition decreased S. typhimurium phagocytosis by reducing the actin polymerization and adhesive capacity of cells. Furthermore, inhibition of PI3K markedly impaired TLR4-dependent phagocytosis by restraining actin polymerization and scavenger receptor expression and reduced the adhesive capacity of the monocytes/macrophages. Conclusion: Our findings indicate that overexpression of TLR4 enhances phagocytosis through PI3K signaling and the subsequent activation of actin polymerization and scavenger receptors in sheep monocytes/macrophages infected with S. typhimurium.
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Sly, Laura M., Donald G. Guiney i Neil E. Reiner. "Salmonella enterica Serovar Typhimurium Periplasmic Superoxide Dismutases SodCI and SodCII Are Required for Protection against the Phagocyte Oxidative Burst". Infection and Immunity 70, nr 9 (wrzesień 2002): 5312–15. http://dx.doi.org/10.1128/iai.70.9.5312-5315.2002.
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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.
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Choi, Younho, Jeongjoon Choi, Eduardo A. Groisman, Dong-Hyun Kang, Dongwoo Shin i Sangryeol Ryu. "Expression ofSTM4467-Encoded Arginine Deiminase Controlled by theSTM4463Regulator Contributes to Salmonella enterica Serovar Typhimurium Virulence". Infection and Immunity 80, nr 12 (24.09.2012): 4291–97. http://dx.doi.org/10.1128/iai.00880-12.
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ABSTRACTArginine 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 bacteriumSalmonella entericaserovar Typhimurium possesses theSTM4467,STM4466, andSTM4465genes, which are predicted to encode ADI, CK, and OTC, respectively. Here we report that theSTM4467gene encodes an ADI and that ADI activity plays a role in the successful infection of a mammalian host byS. Typhimurium. AnSTM4467deletion mutant was defective for replication inside murine macrophages and was attenuated for virulence in mice. We determined that a regulatory protein encoded by theSTM4463gene functions as an activator forSTM4467expression. The expression of the ADI pathway genes was enhanced inside macrophages in a process that required STM4463. Lack of STM4463 impaired the ability ofS. Typhimurium to replicate within macrophages. A mutant defective inSTM4467-encoded ADI displayed normal production of nitric oxide by macrophages.