scholarly journals CadC Has a Global Translational Effect during Acid Adaptation in Salmonella enterica Serovar Typhimurium

2007 ◽  
Vol 189 (6) ◽  
pp. 2417-2425 ◽  
Author(s):  
Yong Heon Lee ◽  
Bae Hoon Kim ◽  
Ji Hye Kim ◽  
Won Suck Yoon ◽  
Seong Ho Bang ◽  
...  
Keyword(s):  
Salmonella Enterica ◽  
Salmonella Enterica Serovar Typhimurium ◽  
Regulatory System ◽  
Acid Tolerance ◽  
Negative Influence ◽  
Acid Adaptation ◽  
Proteomic Approach ◽  
Serovar Typhimurium ◽  
Tolerance Response ◽  
Porin Proteins

ABSTRACT In Salmonella enterica serovar Typhimurium, the membrane-localized CadC is a transcriptional activator of the cadBA operon, which contributes to the acid tolerance response. Unlike in Escherichia coli, in which transcription of cadC is constitutive, in S. enterica serovar Typhimurium cadC expression is induced by low pH and lysine. Inactivation of cadC suppresses the acid-sensitive phenotype of a cadA mutation, suggesting the existence of other CadC-dependent genes in addition to the cadBA operon. Using a proteomic approach, we identified 8 of the putative CadC-induced proteins and 15 of the putative CadC-repressed proteins. The former include porin proteins OmpC and OmpF. The latter include proteins involved in glycolysis, energy production, and stress tolerance. To better understand the altered levels of OmpC and OmpF, we compared expression of ompR in S. enterica serovar Typhimurium wild-type and cadC mutant strains and determined that CadC exerted a negative influence on ompR transcription. Taken together, our findings strongly suggest that CadC may be a global regulator involved in the OmpR regulatory system during acid adaptation.

scholarly journals The Lactic Acid-Induced Acid Tolerance Response in Salmonella enterica Serovar Typhimurium Induces Sensitivity to Hydrogen Peroxide

2006 ◽  
Vol 72 (8) ◽  
pp. 5623-5625 ◽  
Author(s):  
E. J. Greenacre ◽  
S. Lucchini ◽  
J. C. D. Hinton ◽  
T. F. Brocklehurst
Keyword(s):  
Hydrogen Peroxide ◽  
Lactic Acid ◽  
Salmonella Enterica ◽  
Salmonella Enterica Serovar Typhimurium ◽  
Acid Tolerance ◽  
Down Regulation ◽  
Acid Tolerance Response ◽  
Essential Component ◽  
Serovar Typhimurium ◽  
Tolerance Response

ABSTRACT Transcriptome analyses of Salmonella enterica serovar Typhimurium revealed that 15 genes were significantly up-regulated after 2 h of adaptation with lactic acid. cadB was the most highly up-regulated gene and was shown to be an essential component. Lactic acid-adapted cells exhibited sensitivity to hydrogen peroxide, likely due to down-regulation of the OxyR regulon.

scholarly journals Genetic Analysis of Colistin Resistance in Salmonella enterica Serovar Typhimurium

2009 ◽  
Vol 53 (6) ◽  
pp. 2298-2305 ◽  
Author(s):  
Song Sun ◽  
Aurel Negrea ◽  
Mikael Rhen ◽  
Dan I. Andersson
Keyword(s):  
Mutation Rate ◽  
Salmonella Enterica ◽  
Salmonella Enterica Serovar Typhimurium ◽  
Regulatory System ◽  
Clinical Settings ◽  
Missense Mutations ◽  
Regulator Protein ◽  
Serovar Typhimurium ◽  
Sensor Kinases ◽  
Genes Encoding

ABSTRACT Colistin is a cyclic cationic peptide that kills gram-negative bacteria by interacting with and disrupting the outer membrane. We isolated 44 independent mutants in Salmonella enterica serovar Typhimurium with reduced susceptibility to colistin and identified 27 different missense mutations located in the pmrA and pmrB genes (encoding the regulator and sensor of a two-component regulatory system) that conferred increased resistance. By comparison of the two homologous sensor kinases, PmrB and EnvZ, the 22 missense mutations identified in pmrB were shown to be located in four different structural domains of the protein. All five pmrA mutations were located in the phosphate receiver domain of the regulator protein. The mutants appeared at a mutation rate of 0.6 × 10−6 per cell per generation. The MICs of colistin for the mutants increased 2- to 35-fold, and the extent of killing was reduced several orders of magnitude compared to the susceptible strain. The growth rates of the mutants were slightly reduced in both rich medium and M9-glycerol minimal medium, whereas growth in mice appeared unaffected by the pmrA and pmrB mutations. The low fitness costs and the high mutation rate suggest that mutants with reduced susceptibility to colistin could emerge in clinical settings.

Influence of RpoS, cAMP-receptor protein, and ppGpp on expression of the opgGH operon and osmoregulated periplasmic glucan content of Salmonella enterica serovar Typhimurium

2009 ◽  
Vol 55 (11) ◽  
pp. 1284-1293 ◽  
Author(s):  
Cristina S. Costa ◽  
Ramón A. Pizarro ◽  
Dora N. Antón
Keyword(s):  
Salmonella Enterica ◽  
Salmonella Enterica Serovar Typhimurium ◽  
Regulatory System ◽  
Receptor Protein ◽  
Transcriptional Level ◽  
Camp Receptor Protein ◽  
High Osmolarity ◽  
Serovar Typhimurium ◽  
Camp Receptor ◽  
Periplasmic Glucan

A transcriptional fusion (opgG1::MudJ) to the opgGH operon of Salmonella enterica serovar Typhimurium (S. Typhimurium) LT2, isolated by resistance to mecillinam, was used to study the influence of global regulators RpoS, ppGpp, and cAMP/cAMP-receptor protein (CRP) on expression of the opgGH operon and osmoregulated periplasmic glucan (OPG) content. Neither high growth medium osmolarity nor absence of ppGpp or CRP had important effects on opgG1::MudJ expression in exponential cultures. However, under the same conditions, OPG content was strongly decreased by high osmolarity or cAMP/CRP defectiveness, and reduced to a half by lack of ppGpp. In stationary cultures, high osmolarity as well as CRP loss caused significant descents in opgG1::MudJ expression that were compensated by inactivation of RpoS σ factor. No effect of RpoS inactivation on OPG content was observed. It is concluded that opgGH expression in S. Typhimurium is only slightly affected by high osmolarity, but is inversely modulated by RpoS level. On the other hand, osmolarity and the cAMP/CRP global regulatory system appear to control OPG content, either directly or indirectly, mainly at the post-transcriptional level.

scholarly journals Alteration of the Rugose Phenotype in waaG and ddhC Mutants of Salmonella enterica Serovar Typhimurium DT104 Is Associated with Inverse Production of Curli and Cellulose

2006 ◽  
Vol 72 (7) ◽  
pp. 5002-5012 ◽  
Author(s):  
Yuda Anriany ◽  
Surashri N. Sahu ◽  
Kimberly R. Wessels ◽  
Lindsay M. McCann ◽  
Sam W. Joseph
Keyword(s):  
Salmonella Enterica ◽  
Biofilm Formation ◽  
Salmonella Enterica Serovar Typhimurium ◽  
Regulatory System ◽  
Cell Aggregation ◽  
Scanning Electron Micrographs ◽  
Serovar Typhimurium ◽  
Potential Component ◽  
Matrix Production ◽  
Opposing Effects

ABSTRACT The rugose (also known as wrinkled or rdar) phenotype in Salmonella enterica serovar Typhimurium DT104 Rv has been associated with cell aggregation and the ability, at low temperature under low-osmolarity conditions, to form pellicles and biofilms. Two Tn5 insertion mutations in genes that are involved in lipopolysaccharide (LPS) synthesis, ddhC (A1-8) and waaG (A1-9), of Rv resulted in diminished expression of colony rugosity. Scanning electron micrographs revealed that the ddhC mutant showed reduced amounts of extracellular matrix, while there was relatively more, profuse matrix production in the waaG mutant, compared to Rv. Both mutants appeared to produce decreased levels of curli, as judged by Western blot assays probed with anti-AgfA (curli) antibodies but, surprisingly, were observed to have increased amounts of cellulose relative to Rv. Comparison with a non-curli-producing mutant suggested that the alteration in curli production may have engendered the increased presence of cellulose. While both mutants had impaired biofilm formation when grown in rich medium with low osmolarity, they constitutively formed larger amounts of biofilms when the growth medium was supplemented with either glucose or a combination of glucose and NaCl. These observations indicated that LPS alterations may have opposing effects on biofilm formation in these mutants, depending upon either the presence or the absence of these osmolytes. The phenotypes of the waaG mutant were further confirmed in a constructed, nonpolar deletion mutant of S. enterica serovar Typhimurium LT2, where restoration to the wild-type phenotypes was accomplished by complementation. These results highlight the importance of an integral LPS, at both the O-antigen and core polysaccharide levels, in the modulation of curli protein and cellulose production, as well as in biofilm formation, thereby adding another potential component to the complex regulatory system which governs multicellular behaviors in S. enterica serovar Typhimurium.

scholarly journals Salmonella enterica Serovar Typhimurium and Listeria monocytogenes Acid Tolerance Response Induced by Organic Acids at 20°C: Optimization and Modeling

2003 ◽  
Vol 69 (7) ◽  
pp. 3945-3951 ◽  
Author(s):  
E. J. Greenacre ◽  
T. F. Brocklehurst ◽  
C. R. Waspe ◽  
D. R. Wilson ◽  
P. D. G. Wilson
Keyword(s):  
Acetic Acid ◽  
Lactic Acid ◽  
Listeria Monocytogenes ◽  
Salmonella Enterica ◽  
Acid Tolerance ◽  
Acid Tolerance Response ◽  
Serovar Typhimurium ◽  
Tolerance Response ◽  
Acid Inactivation ◽  
Log Linear

ABSTRACT An acid tolerance response (ATR) has been demonstrated in Listeria monocytogenes and Salmonella enterica serovar Typhimurium in response to low pH poised (i.e., adapted) with acetic or lactic acids at 20°C and modeled by using dynamic differential equations. The ATR was not immediate or prolonged, and optimization occurred after exposure of L. monocytogenes for 3 h at pH 5.5 poised with acetic acid and for 2 h at pH 5.5 poised with lactic acid and after exposure of S. enterica serovar Typhimurium for 2 h at pH 5.5 poised with acetic acid and for 3 h at pH 5.5 poised with lactic acid. An objective mechanistic analysis of the acid inactivation data yielded estimates of the duration of the shoulder (t s ), the log-linear decline (k max), and the magnitude of a critical component (C). The magnitude of k max gave the best agreement with estimates of conditions for optimum ATR induction made from the raw data.

scholarly journals Global Transcriptome and Mutagenic Analyses of the Acid Tolerance Response of Salmonella enterica Serovar Typhimurium

2015 ◽  
Vol 81 (23) ◽  
pp. 8054-8065 ◽  
Author(s):  
Daniel Ryan ◽  
Niladri Bhusan Pati ◽  
Urmesh K. Ojha ◽  
Chandrashekhar Padhi ◽  
Shilpa Ray ◽  
...  
Keyword(s):  
Salmonella Enterica ◽  
Molecular Mechanisms ◽  
Acid Stress ◽  
Acid Tolerance ◽  
Differentially Expressed ◽  
Acid Tolerance Response ◽  
Content Type ◽  
Serovar Typhimurium ◽  
Tolerance Response

ABSTRACTSalmonella entericaserovar Typhimurium (S. Typhimurium) is one of the leading causative agents of food-borne bacterial gastroenteritis. Swift invasion through the intestinal tract and successful establishment in systemic organs are associated with the adaptability ofS. Typhimurium to different stress environments. Low-pH stress serves as one of the first lines of defense in mammalian hosts, whichS. Typhimurium must efficiently overcome to establish an infection. Therefore, a better understanding of the molecular mechanisms underlying the adaptability ofS. Typhimurium to acid stress is highly relevant. In this study, we have performed a transcriptome analysis ofS. Typhimurium under the acid tolerance response (ATR) and found a large number of genes (∼47%) to be differentially expressed (more than 1.5-fold or less than −1.5-fold;P< 0.01). Functional annotation revealed differentially expressed genes to be associated with regulation, metabolism, transport and binding, pathogenesis, and motility. Additionally, our knockout analysis of a subset of differentially regulated genes facilitated the identification of proteins that contribute toS. Typhimurium ATR and virulence. Mutants lacking genes encoding the K+binding and transport protein KdpA, hypothetical protein YciG, the flagellar hook cap protein FlgD, and the nitrate reductase subunit NarZ were significantly deficient in their ATRs and displayed variedin vitrovirulence characteristics. This study offers greater insight into the transcriptome changes ofS. Typhimurium under the ATR and provides a framework for further research on the subject.

Tolerance to Stress and Ability of Acid-Adapted and Non–Acid-Adapted Salmonella enterica Serovar Typhimurium DT104 To Invade and Survive in Mammalian Cells In Vitro†

2003 ◽  
Vol 66 (7) ◽  
pp. 1115-1125 ◽  
Author(s):  
PINA M. FRATAMICO
Keyword(s):  
Acetic Acid ◽  
Cell Lines ◽  
Salmonella Enterica ◽  
Mammalian Cells ◽  
Salmonella Enterica Serovar Typhimurium ◽  
Intestinal Cell ◽  
Acid Adaptation ◽  
Apple Cider ◽  
Serovar Typhimurium

The ability of acid-adapted (AA) and non–acid-adapted (NA) Salmonella enterica serovar Typhimurium definitive type 104 (DT104) strains to invade and multiply in mammalian cells in vitro and to survive stress conditions was examined. DT104 and non-DT104 strains were grown in tryptic soy broth without glucose (NA) or in tryptic soy broth containing 1% glucose (AA) for 18 h at 37°C. The invasiveness of DT104 strains in J774A.1 macrophage and Int407 intestinal cell lines was not more extensive than that of non-DT104 strains. In most cases, AA bacteria were less invasive than NA bacteria in both cell lines. Confocal microscopy showed that both DT104 and non-DT104 strains replicated in the two cell lines. In related studies, the survival levels of three strains of AA and NA DT104 and a non-DT104 (LT2) strain in 150 and 15 mM H2O2, 170 and 43 mM acetic acid, 2.6 M NaCl, 2.6 M NaCl containing 170 mM acetic acid, synthetic gastric fluid (SGF) at pH 2 and pH 3, and apple cider were compared. For all four strains, acid adaptation did not result in increased survival in apple cider. After 15 days of storage at 4°C, reductions ranged from 1.96 to 4.1 log10 CFU/ml for AA bacteria and from 0.48 to 1.34 log10 CFU/ml for NA bacteria from a starting level of ca. 7.00 log10 CFU/ml of cider. Neither AA nor NA DT104 strains were more resistant to NaCl, acetic acid, H2O2, or SGF solutions than non-DT104 strain LT2. The level of AA bacteria was not appreciably reduced after exposure to SGF; however, the level of NA bacteria decreased to nondetectable levels in SGF at pH 2 within 3 h of exposure. These results indicate that the DT104 strains examined were not more invasive, nor did they display increased survival in mammalian cells or increased resistance to food environment stresses compared with non-DT104 strains. However, acid adaptation resulted in increased resistance to a low-pH gastric environment for all strains tested. These data indicate that DT104 strains are likely not more virulent or resistant to stresses relevant to foods than are non-DT104 Salmonella and that procedures used to inactivate or inhibit the growth of Salmonella in foods are likely adequate for DT104 strains.

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