scholarly journals Salmonella enterica Serovar Typhimurium Mutants Unable To Convert Malate to Pyruvate and Oxaloacetate Are Avirulent and Immunogenic in BALB/c Mice

2009 ◽  
Vol 77 (4) ◽  
pp. 1397-1405 ◽  
Author(s):  
Regino Mercado-Lubo ◽  
Mary P. Leatham ◽  
Tyrrell Conway ◽  
Paul S. Cohen
Keyword(s):  
Salmonella Enterica ◽  
Type Strain ◽  
Wild Type Strain ◽  
Salmonella Enterica Serovar Typhimurium ◽  
Tca Cycle ◽  
Tricarboxylic Acid ◽  
Oral Infection ◽  
Wild Type ◽  
The Tca Cycle ◽  
Serovar Typhimurium

ABSTRACT Previously, we showed that the Salmonella enterica serovar Typhimurium SR-11 tricarboxylic acid (TCA) cycle must operate as a complete cycle for full virulence after oral infection of BALB/c mice (M. Tchawa Yimga, M. P. Leatham, J. H. Allen, D. C. Laux, T. Conway, and P. S. Cohen, Infect. Immun. 74:1130-1140, 2006). In the same study, we showed that for full virulence, malate must be converted to both oxaloacetate and pyruvate. Moreover, it was recently demonstrated that blocking conversion of succinyl-coenzyme A to succinate attenuates serovar Typhimurium SR-11 but does not make it avirulent; however, blocking conversion of succinate to fumarate renders it completely avirulent and protective against subsequent oral infection with the virulent serovar Typhimurium SR-11 wild-type strain (R. Mercado-Lubo, E. J. Gauger, M. P. Leatham, T. Conway, and P. S. Cohen, Infect. Immun. 76:1128-1134, 2008). Furthermore, the ability to convert succinate to fumarate appeared to be required only after serovar Typhimurium SR-11 became systemic. In the present study, evidence is presented that serovar Typhimurium SR-11 mutants that cannot convert fumarate to malate or that cannot convert malate to both oxaloacetate and pyruvate are also avirulent and protective in BALB/c mice. These results suggest that in BALB/c mice, the malate that is removed from the TCA cycle in serovar Typhimurium SR-11 for conversion to pyruvate must be replenished by succinate or one of its precursors, e.g., arginine or ornithine, which might be available in mouse phagocytes.

scholarly journals A Salmonella enterica Serovar Typhimurium Succinate Dehydrogenase/Fumarate Reductase Double Mutant Is Avirulent and Immunogenic in BALB/c Mice

2007 ◽  
Vol 76 (3) ◽  
pp. 1128-1134 ◽  
Author(s):  
Regino Mercado-Lubo ◽  
Eric J. Gauger ◽  
Mary P. Leatham ◽  
Tyrrell Conway ◽  
Paul S. Cohen
Keyword(s):  
Succinate Dehydrogenase ◽  
Salmonella Enterica ◽  
Double Mutant ◽  
Wild Type Strain ◽  
Salmonella Enterica Serovar Typhimurium ◽  
Tca Cycle ◽  
Fumarate Reductase ◽  
Subsequent Infection ◽  
The Tca Cycle ◽  
Serovar Typhimurium

ABSTRACT Previously we showed that the tricarboxylic acid (TCA) cycle operates as a full cycle during Salmonella enterica serovar Typhimurium SR-11 peroral infection of BALB/c mice (M. Tchawa Yimga et al., Infect. Immun. 74:1130-1140, 2006). The evidence was that a ΔsucCD mutant (succinyl coenzyme A [succinyl-CoA] synthetase), which prevents the conversion of succinyl-CoA to succinate, and a ΔsdhCDA mutant (succinate dehydrogenase), which blocks the conversion of succinate to fumarate, were both attenuated, whereas an SR-11 ΔaspA mutant (aspartase) and an SR-11 ΔfrdABCD mutant (fumarate reductase), deficient in the ability to run the reductive branch of the TCA cycle, were fully virulent. In the present study, evidence is presented that a serovar Typhimurium SR-11 ΔfrdABCD ΔsdhCDA double mutant is avirulent in BALB/c mice and protective against subsequent infection with the virulent serovar Typhimurium SR-11 wild-type strain via the peroral route and is highly attenuated via the intraperitoneal route. These results suggest that fumarate reductase, which normally runs in the reductive pathway in the opposite direction of succinate dehydrogenase, can replace it during infection by running in the same direction as succinate dehydrogenase in order to run a full TCA cycle in an SR-11 ΔsdhCDA mutant. The data also suggest that the conversion of succinate to fumarate plays a key role in serovar Typhimurium virulence. Moreover, the data raise the possibility that S. enterica ΔfrdABCD ΔsdhCDA double mutants and ΔfrdABCD ΔsdhCDA double mutants of other intracellular bacterial pathogens with complete TCA cycles may prove to be effective live vaccine strains for animals and humans.

scholarly journals A Plasmid-Encoded FetMP-Fls Iron Uptake System Confers Selective Advantages to Salmonella enterica Serovar Typhimurium in Growth under Iron-Restricted Conditions and for Infection of Mammalian Host Cells

2020 ◽  
Vol 8 (5) ◽  
pp. 630
Author(s):  
Vanesa García ◽  
Ana Herrero-Fresno ◽  
Rosaura Rodicio ◽  
Alfonso Felipe-López ◽  
Ignacio Montero ◽  
...  
Keyword(s):  
Iron Content ◽  
Salmonella Enterica ◽  
Iron Uptake ◽  
Type Strain ◽  
Wild Type Strain ◽  
Salmonella Enterica Serovar Typhimurium ◽  
Iron Acquisition ◽  
Clinical Strain ◽  
Wild Type ◽  
Serovar Typhimurium

The resistance plasmid pUO-StVR2, derived from virulence plasmid pSLT, is widespread in clinical isolates of Salmonella enterica serovar Typhimurium recovered in Spain and other European countries. pUO-StVR2 carries several genes encoding a FetMP-Fls system, which could be involved in iron uptake. We therefore analyzed S. Typhimurium LSP 146/02, a clinical strain selected as representative of the isolates carrying the plasmid, and an otherwise isogenic mutant lacking four genes (fetMP-flsDA) of the fetMP-fls region. Growth curves and determination of the intracellular iron content under iron-restricted conditions demonstrated that deletion of these genes impairs iron acquisition. Thus, under these conditions, the mutant grew significantly worse than the wild-type strain, its iron content was significantly lower, and it was outcompeted by the wild-type strain in competition assays. Importantly, the strain lacking the fetMP-flsDA genes was less invasive in cultured epithelial HeLa cells and replicated poorly upon infection of RAW264.7 macrophages. The genes were introduced into S. Typhimurium ATCC 14028, which lacks the FetMP-Fls system, and this resulted in increased growth under iron limitation as well as an increased ability to multiply inside macrophages. These findings indicate that the FetMP-Fls iron acquisition system exceeds the benefits conferred by the other high-affinity iron uptake systems carried by ATCC 14028 and LSP 146/02. We proposed that effective iron acquisition by this system in conjunction with antimicrobial resistance encoded from the same plasmid have greatly contributed to the epidemic success of S. Typhimurium isolates harboring pUO-StVR2.

scholarly journals Effect of Inactivation of the HtrA-Like Serine Protease DegQ on the Virulence of Salmonella enterica Serovar Typhimurium in Mice

2004 ◽  
Vol 72 (12) ◽  
pp. 7357-7359 ◽  
Author(s):  
Jacinta Farn ◽  
Mark Roberts
Keyword(s):  
Serine Protease ◽  
Salmonella Enterica ◽  
Type Strain ◽  
Wild Type Strain ◽  
Salmonella Enterica Serovar Typhimurium ◽  
Wild Type ◽  
Virulence Determinant ◽  
Serovar Typhimurium

ABSTRACT DegQ is a serine protease that is highly homologous to HtrA, an important virulence determinant of Salmonella enterica serovar Typhimurium. We examined if DegQ is involved in serovar Typhimurium pathogenesis. A serovar Typhimurium degQ mutant was as virulent as the wild-type strain in mice. However, a serovar Typhimurium htrA degQ mutant survived less well in murine organs, particularly in the liver, than a serovar Typhimurium htrA mutant. DegQ is not essential for serovar Typhimurium pathogenesis but may play a small role during salmonella growth at systemic sites.

scholarly journals The Conserved Cys-X1-X2-Cys Motif Present in the TtcA Protein Is Required for the Thiolation of Cytidine in Position 32 of tRNA from Salmonella enterica serovar Typhimurium

2004 ◽  
Vol 186 (3) ◽  
pp. 750-757 ◽  
Author(s):  
Gunilla Jäger ◽  
Ramune Leipuviene ◽  
Michael G. Pollard ◽  
Qiang Qian ◽  
Glenn R. Björk
Keyword(s):  
Site Selection ◽  
Salmonella Enterica ◽  
Type Strain ◽  
Wild Type Strain ◽  
Salmonella Enterica Serovar Typhimurium ◽  
Mixed Population ◽  
Wild Type ◽  
Serovar Typhimurium ◽  
Trna Species ◽  
A Site

ABSTRACT The modified nucleoside 2-thiocytidine (s2C) has so far been found in tRNA from organisms belonging to the phylogenetic domains Archaea and Bacteria. In the bacteria Escherichia coli and Salmonella enterica serovar Typhimurium, s2C is present in position 32 of only four tRNA species— \batchmode \documentclass[fleqn,10pt,legalpaper]{article} \usepackage{amssymb} \usepackage{amsfonts} \usepackage{amsmath} \pagestyle{empty} \begin{document} \(tRNA_{ICG}^{Arg}\) \end{document} , \batchmode \documentclass[fleqn,10pt,legalpaper]{article} \usepackage{amssymb} \usepackage{amsfonts} \usepackage{amsmath} \pagestyle{empty} \begin{document} \(tRNA_{CCG}^{Arg}\) \end{document} , \batchmode \documentclass[fleqn,10pt,legalpaper]{article} \usepackage{amssymb} \usepackage{amsfonts} \usepackage{amsmath} \pagestyle{empty} \begin{document} \(tRNA_{mnm^{5}UCU}^{Arg}\) \end{document} , and \batchmode \documentclass[fleqn,10pt,legalpaper]{article} \usepackage{amssymb} \usepackage{amsfonts} \usepackage{amsmath} \pagestyle{empty} \begin{document} \(tRNA_{GCU}^{Ser}\) \end{document} . An in-frame deletion of an S. enterica gene (designated ttcA, for “two-thio-cytidine”) was constructed, and such a mutant has no detectable s2C in its tRNA. The TtcA protein family is characterized by the existence of both a PP-loop and a Cys-X1-X2-Cys motif in the central region of the protein but can be divided into two distinct groups based on the presence and location of additional Cys-X1-X2-Cys motifs in terminal regions of the sequence. Mutant analysis showed that both cysteines in this central conserved Cys-X1-X2-Cys motif are required for the formation of s2C. The ΔttcA1 mutant grows at the same rate as the congenic wild-type strain, and no growth disadvantage caused by the lack of s2C was observed in a mixed-population experiment. Lack of s2C32 did not reduce the selection rate at the ribosomal aminoacyl-tRNA site (A-site) for \batchmode \documentclass[fleqn,10pt,legalpaper]{article} \usepackage{amssymb} \usepackage{amsfonts} \usepackage{amsmath} \pagestyle{empty} \begin{document} \(Arg-tRNA_{ICG}^{Arg}\) \end{document} at any of its cognate CGN codons, whereas A-site selection at AGG by \batchmode \documentclass[fleqn,10pt,legalpaper]{article} \usepackage{amssymb} \usepackage{amsfonts} \usepackage{amsmath} \pagestyle{empty} \begin{document} \(Arg-tRNA_{mnm^{5}UCU}^{Arg}\) \end{document} was dependent on the presence of s2C32. The presence of s2C32 in peptidyl- \batchmode \documentclass[fleqn,10pt,legalpaper]{article} \usepackage{amssymb} \usepackage{amsfonts} \usepackage{amsmath} \pagestyle{empty} \begin{document} \(tRNA_{CCU}^{Arg}\) \end{document} or in peptidyl- \batchmode \documentclass[fleqn,10pt,legalpaper]{article} \usepackage{amssymb} \usepackage{amsfonts} \usepackage{amsmath} \pagestyle{empty} \begin{document} \(tRNA_{mnm^{5}UCU}^{Arg}\) \end{document} interfered with decoding in the A-site. The presence of s2C32 in \batchmode \documentclass[fleqn,10pt,legalpaper]{article} \usepackage{amssymb} \usepackage{amsfonts} \usepackage{amsmath} \pagestyle{empty} \begin{document} \(tRNA_{ICG}^{Arg}\) \end{document} decreased the rate of translation of the CGA codon but not that of the CGU codon.

scholarly journals Oral Immunization with an rfaH Mutant Elicits Protection against Salmonellosis in Mice

2004 ◽  
Vol 72 (7) ◽  
pp. 4297-4301 ◽  
Author(s):  
Gábor Nagy ◽  
Ulrich Dobrindt ◽  
Jörg Hacker ◽  
Levente Emödy
Keyword(s):  
Type Strain ◽  
Wild Type Strain ◽  
Lethal Dose ◽  
Fold Increase ◽  
Oral Immunization ◽  
Oral Infection ◽  
Wild Type ◽  
Virulence Attenuation ◽  
Serovar Typhimurium

ABSTRACT Loss of the transcriptional antiterminator RfaH results in virulence attenuation (>104-fold increase in 50% lethal dose) of the archetypal Salmonella enterica serovar Typhimurium strain SL1344 by both orogastric and intraperitoneal routes of infection in BALB/c mice. Oral immunization with the mutant efficiently protects mice against a subsequent oral infection with the wild-type strain. Interestingly, in vitro immunoreactivity is not confined to strain SL1344; rather, it is directed also towards other serovars of S. enterica and even Salmonella bongori strains.

scholarly journals sciS, an icmF Homolog in Salmonella enterica Serovar Typhimurium, Limits Intracellular Replication and Decreases Virulence

2005 ◽  
Vol 73 (7) ◽  
pp. 4338-4345 ◽  
Author(s):  
Duncan A. Parsons ◽  
Fred Heffron
Keyword(s):  
Legionella Pneumophila ◽  
Salmonella Enterica ◽  
Wild Type Strain ◽  
Salmonella Enterica Serovar Typhimurium ◽  
The Body ◽  
Wild Type ◽  
Serovar Typhimurium ◽  
Intracellular Multiplication ◽  
Late Stages ◽  
Made In

ABSTRACT Salmonella enterica serovar Typhimurium utilizes macrophages to disseminate from the intestine to deeper tissues within the body. While S. enterica serovar Typhimurium has been shown to kill its host macrophage, it can persist intracellularly beyond 18 h postinfection. To identify factors involved in late stages of infection, we screened a transposon library made in S. enterica serovar Typhimurium for the ability to persist in J774 macrophages at 24 h postinfection. Through this screen, we identified a gene, sciS, found to be homologous to icmF in Legionella pneumophila. icmF, which is required for intracellular multiplication, is conserved in several gram-negative pathogens, and its homolog appears to have been acquired horizontally in S. enterica serovar Typhimurium. We found that an sciS mutant displayed increased intracellular numbers in J774 macrophages when compared to the wild-type strain at 24 h postinfection. sciS was maximally transcribed at 27 h postinfection and is repressed by SsrB, an activator of genes required for promoting intracellular survival. Finally, we demonstrate that an sciS mutant is hypervirulent in mice when administered intragastrically. Taken together, these data indicate a role for SciS in controlling intracellular bacterial levels at later stages of infection and attenuating virulence in a murine host

scholarly journals Role of Gluconeogenesis and the Tricarboxylic Acid Cycle in the Virulence of Salmonella enterica Serovar Typhimurium in BALB/c Mice

2006 ◽  
Vol 74 (2) ◽  
pp. 1130-1140 ◽  
Author(s):  
Merlin Tchawa Yimga ◽  
Mary P. Leatham ◽  
James H. Allen ◽  
David C. Laux ◽  
Tyrrell Conway ◽  
...  
Keyword(s):  
Salmonella Enterica ◽  
Tricarboxylic Acid Cycle ◽  
Carbon Sources ◽  
Tca Cycle ◽  
Tricarboxylic Acid ◽  
Glyoxylate Bypass ◽  
The Tca Cycle ◽  
Mouse Tissues ◽  
Serovar Typhimurium ◽  
Genes Encoding

ABSTRACT In Salmonella enterica serovar Typhimurium, the Cra protein (catabolite repressor/activator) regulates utilization of gluconeogenic carbon sources by activating transcription of genes in the gluconeogenic pathway, the glyoxylate bypass, the tricarboxylic acid (TCA) cycle, and electron transport and repressing genes encoding glycolytic enzymes. A serovar Typhimurium SR-11 Δcra mutant was recently reported to be avirulent in BALB/c mice via the peroral route, suggesting that gluconeogenesis may be required for virulence. In the present study, specific SR-11 genes in the gluconeogenic pathway were deleted (fbp, glpX, ppsA, and pckA), and the mutants were tested for virulence in BALB/c mice. The data show that SR-11 does not require gluconeogenesis to retain full virulence and suggest that as yet unidentified sugars are utilized by SR-11 for growth during infection of BALB/c mice. The data also suggest that the TCA cycle operates as a full cycle, i.e., a sucCD mutant, which prevents the conversion of succinyl coenzyme A to succinate, and an ΔsdhCDA mutant, which blocks the conversion of succinate to fumarate, were both attenuated, whereas both an SR-11 ΔaspA mutant and an SR-11 ΔfrdABC mutant, deficient in the ability to run the reductive branch of the TCA cycle, were fully virulent. Moreover, although it appears that SR-11 replenishes TCA cycle intermediates from substrates present in mouse tissues, fatty acid degradation and the glyoxylate bypass are not required, since an SR-11 ΔfadD mutant and an SR-11 ΔaceA mutant were both fully virulent.

scholarly journals Osmoregulated periplasmic glucans of Salmonella enterica serovar Typhimurium are required for optimal virulence in mice

Microbiology ◽  
2009 ◽  
Vol 155 (1) ◽  
pp. 229-237 ◽  
Author(s):  
Arvind A. Bhagwat ◽  
Won Jun ◽  
Liu Liu ◽  
Porteen Kannan ◽  
Mahesh Dharne ◽  
...  
Keyword(s):  
Salmonella Enterica ◽  
Type Strain ◽  
Wild Type Strain ◽  
Gene Cassette ◽  
Growth Conditions ◽  
Kanamycin Resistance ◽  
Wild Type ◽  
Serovar Typhimurium ◽  
Resistance Gene Cassette ◽  
Reduced Rate

We purified osmoregulated periplasmic glucans (OPGs) from Salmonella enterica serovar Typhimurium and found them to be composed of 100 % glucose with 2-linked glucose as the most abundant residue, with terminal glucose, 2,3-linked and 2,6-linked glucose also present in high quantities. The two structural genes for OPG biosynthesis, opgG and opgH, form a bicistronic operon, and insertion of a kanamycin resistance gene cassette into this operon resulted in a strain devoid of OPGs. The opgGH mutant strain was impaired in motility and growth under low osmolarity conditions. The opgGH mutation also resulted in a 2 log increase in the LD50 in mice compared to the wild-type strain SL1344. Inability to synthesize OPGs had no significant impact on the organism's lipopolysaccharide pattern or its ability to survive antimicrobial peptides-, detergent-, pH- and nutrient-stress conditions. We observed that the opgGH-defective strain respired at a reduced rate under acidic growth conditions (pH 5.0) and had lower ATP levels compared to the wild-type strain. These data indicate that OPGs of S. Typhimurium contribute towards mouse virulence as well as growth and motility under low osmolarity growth conditions.

scholarly journals LuxS-Based Quorum Sensing Does Not Affect the Ability of Salmonella enterica Serovar Typhimurium To Express the SPI-1 Type 3 Secretion System, Induce Membrane Ruffles, or Invade Epithelial Cells

2009 ◽  
Vol 191 (23) ◽  
pp. 7253-7259 ◽  
Author(s):  
Charlotte A. Perrett ◽  
Michail H. Karavolos ◽  
Suzanne Humphrey ◽  
Pietro Mastroeni ◽  
Isabel Martinez-Argudo ◽  
...  
Keyword(s):  
Epithelial Cells ◽  
Quorum Sensing ◽  
Salmonella Enterica ◽  
Type Strain ◽  
Wild Type Strain ◽  
Wild Type ◽  
Protein Fusion ◽  
Serovar Typhimurium ◽  
In The Wild ◽  
Type 3

ABSTRACT Bacterial species can communicate by producing and sensing small autoinducer molecules by a process known as quorum sensing. Salmonella enterica produces autoinducer 2 (AI-2) via the luxS synthase gene, which is used by some bacterial pathogens to coordinate virulence gene expression with population density. We investigated whether the luxS gene might affect the ability of Salmonella enterica serovar Typhimurium to invade epithelial cells. No differences were found between the wild-type strain of S. Typhimurium, SL1344, and its isogenic luxS mutant with respect to the number and morphology of the membrane ruffles induced or their ability to invade epithelial cells. The dynamics of the ruffling process were also similar in the wild-type strain (SL1344) and the luxS mutant. Furthermore, comparing the Salmonella pathogenicity island 1 (SPI-1) type 3 secretion profiles of wild-type SL1344 and the luxS mutant by Western blotting and measuring the expression of a single-copy green fluorescent protein fusion to the prgH (an essential SPI-1 gene) promoter indicated that SPI-1 expression and activity are similar in the wild-type SL1344 and luxS mutant. Genetic deletion of luxS did not alter the virulence of S. Typhimurium in the mouse model, and therefore, it appears that luxS does not play a significant role in regulating invasion of Salmonella in vitro or in vivo.

scholarly journals Invasion Genes Are Not Required for Salmonella enterica Serovar Typhimurium To Breach the Intestinal Epithelium: Evidence That Salmonella Pathogenicity Island 1 Has Alternative Functions during Infection

2000 ◽  
Vol 68 (9) ◽  
pp. 5050-5055 ◽  
Author(s):  
Rose Ann Murray ◽  
Catherine A. Lee
Keyword(s):  
Intestinal Epithelium ◽  
Salmonella Enterica ◽  
Type Strain ◽  
Wild Type Strain ◽  
Bacterial Colonization ◽  
Intestinal Barrier ◽  
Pathogenicity Island ◽  
Bacterial Invasion ◽  
Wild Type ◽  
Serovar Typhimurium

ABSTRACT Salmonella enterica serovar Typhimurium invasion genes are necessary for bacterial invasion of intestinal epithelial cells and are thought to allow salmonellae to enter and cross the intestinal epithelium during infection. Many invasion genes are encoded on Salmonella pathogenicity island 1 (SPI1), and their expression is activated by HilA, a transcription factor also encoded on SPI1. We have studied the role ofSalmonella invasion genes during infection of mice following intragastric inoculation. We have found that strains containing a mutation in hilA orinvG were recovered from the intestinal contents, intestinal tissues, and systemic tissues at a lower frequency than their parental wild-type strain. In contrast, a strain in which SPI1 is deleted was recovered from infected mice at a frequency similar to that of its parental wild-type strain. The ΔSPI1 phenotype indicates that S. enterica does not require invasion genes to cross the intestinal epithelium and infect systemic tissues. This result has forced us to reconsider the long-held belief that invasion genes directly mediate bacterial infection of the intestinal mucosa and traversion of the intestinal barrier during infection. Instead, our results suggest that hilA is required for bacterial colonization of the host intestine. The seemingly contradictory phenotype of the ΔSPI1 mutant suggests that deletion of another gene(s) encoded on SPI1 suppresses thehilA mutant defect. We propose a model for S. enterica pathogenesis in which hilA and invasion genes are required for salmonellae to overcome a host clearance response elicited by another SPI1 gene product(s).

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