scholarly journals The RcsCDB Signaling System and Swarming Motility in Salmonella enterica Serovar Typhimurium: Dual Regulation of Flagellar and SPI-2 Virulence Genes

2007 ◽  
Vol 189 (23) ◽  
pp. 8447-8457 ◽  
Author(s):  
Qingfeng Wang ◽  
Yifang Zhao ◽  
Michael McClelland ◽  
Rasika M. Harshey
Keyword(s):  
Salmonella Enterica ◽  
Target Genes ◽  
Salmonella Enterica Serovar Typhimurium ◽  
Acid Synthesis ◽  
Signaling System ◽  
Swarming Motility ◽  
Colanic Acid ◽  
Serovar Typhimurium ◽  
Type 3 ◽  
Regulatory Properties

ABSTRACT The Rcs phosphorelay is a multicomponent signaling system that positively regulates colanic acid synthesis and negatively regulates motility and virulence. We have exploited a spontaneously isolated mutant, IgaA(T191P), that is nearly maximally activated for the Rcs system to identify a vast set of genes that respond to the stimulation, and we report new regulatory properties of this signaling system in Salmonella enterica serovar Typhimurium. Microarray data show that the Rcs system normally functions as a positive regulator of SPI-2 and other genes important for the growth of Salmonella in macrophages, although when highly activated the system completely represses the SPI-1/SPI-2 virulence, flagellar, and fimbrial biogenesis pathways. The auxiliary protein RcsA, which works with RcsB to positively regulate colanic acid and other target genes, not only stimulates but also antagonizes the positive regulation of many genes in the igaA mutant. We show that RcsB represses motility through the RcsB box in the promoter region of the master operon flhDC and that RcsA is not required for this regulation. Curiously, RcsB selectively stimulates expression of the flagellar type 3 secretion genes fliPQR; an RcsAB box located downstream of fliR influences this regulation. We show that excess colanic acid impairs swimming and inhibits swarming motility, consistent with the inverse regulation of the two pathways by the Rcs system.

Identification of Salmonella enterica Serovar Typhimurium Using Specific PCR Primers Obtained by Comparative Genomics in Salmonella Serovars

2006 ◽  
Vol 69 (7) ◽  
pp. 1653-1661 ◽  
Author(s):  
H. J. KIM ◽  
S. H. PARK ◽  
T. H. LEE ◽  
B. H. NAHM ◽  
Y. H. CHUNG ◽  
...  
Keyword(s):  
Comparative Genomics ◽  
Salmonella Enterica ◽  
Target Genes ◽  
Salmonella Enterica Serovar Typhimurium ◽  
Foodborne Pathogen ◽  
Pcr Primers ◽  
Genomic Sequences ◽  
Local Alignment ◽  
Serovar Typhimurium ◽  
Salmonella Serovars

Salmonella enterica serovar Typhimurium is a major foodborne pathogen throughout the world. Until now, the specific target genes for the detection and identification of serovar Typhimurium have not been developed. To determine the specific probes for serovar Typhimurium, the genes of serovar Typhimurium LT2 that were expected to be unique were selected with the BLAST (Basic Local Alignment Search Tool) program within GenBank. The selected genes were compared with 11 genomic sequences of various Salmonella serovars by BLAST. Of these selected genes, 10 were expected to be specific to serovar Typhimurium and were not related to virulence factor genes of Salmonella pathogenicity island or to genes of the O and H antigens of Salmonella. Primers for the 10 selected genes were constructed, and PCRs were evaluated with various genomic DNAs of Salmonella and non-Salmonella strains for the specific identification of Salmonella serovar Typhimurium. Among all the primer sets for the 10 genes, STM4497 showed the highest degree of specificity to serovar Typhimurium. In this study, a specific primer set for Salmonella serovar Typhimurium was developed on the basis of the comparison of genomic sequences between Salmonella serovars and was validated with PCR. This method of comparative genomics to select target genes or sequences can be applied to the specific detection of microorganisms.

scholarly journals Sensitivity of enrichment-PCR method for Salmonella enterica serovar Typhimurium and Salmonella enterica serovar Enteritidis analysis in chicken carcasses

Food Research ◽  
2021 ◽  
Vol 5 (2) ◽  
pp. 54-61
Author(s):  
H.A. Wulan ◽  
Nurjanah S. ◽  
W.P. Rahayu
Keyword(s):  
Salmonella Enterica ◽  
Pathogenic Bacteria ◽  
Target Genes ◽  
Salmonella Enterica Serovar Typhimurium ◽  
Salmonella Enterica Serovar Enteritidis ◽  
Salmonella Spp ◽  
High Prevalence ◽  
Serovar Typhimurium ◽  
Peptone Water ◽  
Pcr Method

Salmonella spp. is Gram negative-pathogenic bacteria that usually found as a contaminant in chicken carcasses. This study was aimed to increase the sensitivity of PCR enrichment step and apply the enrichment-PCR combination to detect Salmonella in chicken carcasses. In this study were used Salmonella enterica serovar Hadar, Salmonella enterica serovar Typhimurium and Salmonella enterica serovar Enteritidis with the target genes were invA, STM4497, and respectively. A total of 25 g of the chicken carcasses were artificially contaminated by approximately 0.96 and 3.33 MPN/mL for each serovar separately. Samples were incubated in pre-enrichment and enrichment media for 8 hrs prior to the DNA extraction. The pre-enrichment and enrichment media was Buffered Peptone Water and Rappaport-Vassiliadis-soya. The result showed that the target genes of S. enterica ser. Hadar, S. enterica ser. Typhimurium and S. enterica ser. Enteritidis were detected in chicken carcasses, indicated by the presence of DNA band with the size was 429 bp, 311 bp and 135 bp respectively. These result in line with analysis using ISO method and BLAST-comparison analysis of DNA amplicon sequences with GenBank references. Application of this method for Salmonella detection in chicken carcasses sold in the traditional market showed a higher prevalence than the previous result without enrichment. All samples (n = 100) from unsanitary practice sellers were positively contaminated by Salmonella spp. and also high prevalence for S. enterica ser. Typhimurium and S. enterica ser. Enteritidis. It can be concluded that enrichment is an important step to increase the sensitivity detection of PCR method.

scholarly journals Salmonella enterica Serovar Typhimurium Swarming Mutants with Altered Biofilm-Forming Abilities: Surfactin Inhibits Biofilm Formation

2001 ◽  
Vol 183 (20) ◽  
pp. 5848-5854 ◽  
Author(s):  
Joe Robert Mireles ◽  
Adam Toguchi ◽  
Rasika M. Harshey
Keyword(s):  
Polyvinyl Chloride ◽  
Salmonella Enterica ◽  
Biofilm Formation ◽  
Salmonella Enterica Serovar Typhimurium ◽  
Microtiter Plate ◽  
Wild Type ◽  
Swarming Motility ◽  
Microtiter Plate Assay ◽  
Serovar Typhimurium ◽  
Transposon Mutants

ABSTRACT Swarming motility plays an important role in surface colonization by several flagellated bacteria. Swarmer cells are specially adapted to rapidly translocate over agar surfaces by virtue of their more numerous flagella, longer cell length, and encasement of slime. The external slime provides the milieu for motility and likely harbors swarming signals. We recently reported the isolation of swarming-defective transposon mutants of Salmonella enterica serovar Typhimurium, a large majority of which were defective in lipopolysaccharide (LPS) synthesis. Here, we have examined the biofilm-forming abilities of the swarming mutants using a microtiter plate assay. A whole spectrum of efficiencies were observed, with LPS mutants being generally more proficient than wild-type organisms in biofilm formation. Since we have postulated that O-antigen may serve a surfactant function during swarming, we tested the effect of the biosurfactant surfactin on biofilm formation. We report that surfactin inhibits biofilm formation of wild-type S. enterica grown either in polyvinyl chloride microtiter wells or in urethral catheters. Other bio- and chemical surfactants tested had similar effects.

scholarly journals RamA, a Member of the AraC/XylS Family, Influences Both Virulence and Efflux in Salmonella enterica Serovar Typhimurium

2010 ◽  
Vol 192 (6) ◽  
pp. 1607-1616 ◽  
Author(s):  
Andrew M. Bailey ◽  
Al Ivens ◽  
Rob Kingsley ◽  
Jennifer L. Cottell ◽  
John Wain ◽  
...  
Keyword(s):  
Salmonella Enterica ◽  
Target Genes ◽  
Salmonella Enterica Serovar Typhimurium ◽  
Consensus Sequence ◽  
Altered Expression ◽  
Expression Of Genes ◽  
Mouse Macrophages ◽  
Serovar Typhimurium ◽  
Genes Encoding ◽  
High Level

ABSTRACT The transcriptomes of Salmonella enterica serovar Typhimurium SL1344 lacking a functional ramA or ramR or with plasmid-mediated high-level overexpression of ramA were compared to those of the wild-type parental strain. Inactivation of ramA led to increased expression of 14 SPI-1 genes and decreased expression of three SPI-2 genes, and it altered expression of ribosomal biosynthetic genes and several amino acid biosynthetic pathways. Furthermore, disruption of ramA led to decreased survival within RAW 264.7 mouse macrophages and attenuation within the BALB/c ByJ mouse model. Highly overexpressed ramA led to increased expression of genes encoding multidrug resistance (MDR) efflux pumps, including acrAB, acrEF, and tolC. Decreased expression of 34 Salmonella pathogenicity island (SPI) 1 and 2 genes, decreased SipC production, decreased adhesion to and survival within macrophages, and decreased colonization of Caenorhabditis elegans were also seen. Disruption of ramR led to the increased expression of ramA, acrAB, and tolC, but not to the same level as when ramA was overexpressed on a plasmid. Inactivation of ramR had a more limited effect on pathogenicity gene expression. In silico analysis of a suggested RamA-binding consensus sequence identified target genes, including ramR, acrA, tolC, sipABC, and ssrA. This study demonstrates that the regulation of a mechanism of MDR and expression of virulence genes show considerable overlap, and we postulate that such a mechanism is dependent on transcriptional activator concentration and promoter sensitivity. However, we have no evidence to support the hypothesis that increased MDR via RamA regulation of AcrAB-TolC gives rise to a hypervirulent strain.

scholarly journals Delineation of the Salmonella enterica Serovar Typhimurium HilA Regulon through Genome-Wide Location and Transcript Analysis

2007 ◽  
Vol 189 (13) ◽  
pp. 4587-4596 ◽  
Author(s):  
Inge M. V. Thijs ◽  
Sigrid C. J. De Keersmaecker ◽  
Abeer Fadda ◽  
Kristof Engelen ◽  
Hui Zhao ◽  
...  
Keyword(s):  
Salmonella Enterica ◽  
Target Genes ◽  
Salmonella Enterica Serovar Typhimurium ◽  
Pathogenicity Island ◽  
Secretion System ◽  
Effector Proteins ◽  
Transcript Analysis ◽  
Genome Wide ◽  
Serovar Typhimurium ◽  
Genes Encoding

ABSTRACT The Salmonella enterica serovar Typhimurium HilA protein is the key regulator for the invasion of epithelial cells. By a combination of genome-wide location and transcript analysis, the HilA-dependent regulon has been delineated. Under invasion-inducing conditions, HilA binds to most of the known target genes and a number of new target genes. The sopB, sopE, and sopA genes, encoding effector proteins secreted by the type III secretion system on Salmonella pathogenicity island 1 (SPI-1), were identified as being both bound by HilA and differentially regulated in an HilA mutant. This suggests a cooperative role for HilA and InvF in the regulation of SPI-1-secreted effectors. Also, siiA, the first gene of SPI-4, is both bound by HilA and differentially regulated in an HilA mutant, thus linking this pathogenicity island to the invasion key regulator. Finally, the interactions of HilA with the SPI-2 secretion system gene ssaH and the flagellar gene flhD imply a repressor function for HilA under invasion-inducing conditions.

scholarly journals Characterization of Novel Factors Involved in Swimming and Swarming Motility in Salmonella enterica Serovar Typhimurium

PLoS ONE ◽  
2015 ◽  
Vol 10 (8) ◽  
pp. e0135351 ◽  
Author(s):  
Julia Andrea Deditius ◽  
Sebastian Felgner ◽  
Imke Spöring ◽  
Caroline Kühne ◽  
Michael Frahm ◽  
...  
Keyword(s):  
Salmonella Enterica ◽  
Salmonella Enterica Serovar Typhimurium ◽  
Swarming Motility ◽  
Serovar Typhimurium

scholarly journals Uncovering a Large Set of Genes That Affect Surface Motility in Salmonella enterica Serovar Typhimurium

2006 ◽  
Vol 188 (22) ◽  
pp. 7981-7984 ◽  
Author(s):  
Qingfeng Wang ◽  
Susana Mariconda ◽  
Asaka Suzuki ◽  
Michael McClelland ◽  
Rasika M. Harshey
Keyword(s):  
Salmonella Enterica ◽  
Salmonella Enterica Serovar Typhimurium ◽  
Expression Patterns ◽  
Gene Expression Patterns ◽  
Large Set ◽  
Flagellar Gene ◽  
Swarming Motility ◽  
Microarray Experiments ◽  
Serovar Typhimurium ◽  
Surface Motility

ABSTRACT We describe a large set of genes affecting motility in Salmonella enterica serovar Typhimurium. Identified in microarray experiments as displaying flagellar gene expression patterns or controlled by known flagellar regulators, we show that null mutations in these genes primarily affect swarming motility. Three genes function in chemotaxis.

scholarly journals Role of Salmonella enterica Serovar Typhimurium Two-Component System PreA/PreB in Modulating PmrA-Regulated Gene Transcription

2006 ◽  
Vol 188 (1) ◽  
pp. 141-149 ◽  
Author(s):  
Massimo Merighi ◽  
Amanda Carroll-Portillo ◽  
Alecia N. Septer ◽  
Aditi Bhatiya ◽  
John S. Gunn
Keyword(s):  
Salmonella Enterica ◽  
Target Genes ◽  
Salmonella Enterica Serovar Typhimurium ◽  
Response Regulator ◽  
Polymyxin B ◽  
Response Regulators ◽  
Two Component System ◽  
Component System ◽  
Two Component ◽  
Serovar Typhimurium

ABSTRACT The PmrA/PmrB two-component system encoded by the pmrCAB operon regulates the modification of Salmonella enterica serovar Typhimurium lipopolysaccharide leading to polymyxin B resistance. PmrA and PhoP are the only known activators of pmrCAB. A transposon mutagenesis screen for additional regulators of a pmrC::MudJ fusion led to the identification of a two-component system, termed PreA/PreB (pmrCAB regulators A and B), that controls the transcription of the pmrCAB operon in response to unknown signals. The initial observations indicated that insertions in, or a deletion of, the preB sensor, but not the preA response regulator, caused upregulation of pmrCAB. Interestingly, the expression of pmrCAB was not upregulated in a preAB mutant grown in LB broth, implicating PreA in the increased expression of pmrCAB in the preB strain. This was confirmed by overexpression of preA + in preAB or preB backgrounds, which resulted in significant upregulation or further upregulation of pmrCAB. No such effect was observed in any tested preB + backgrounds. Additionally, an ectopic construct expressing a preA[D51A] allele also failed to upregulate pmrC in any of the pre backgrounds tested, which implies that there is a need for phosphorylation in the activation of the target genes. The observed upregulation of pmrCAB occurred independently of the response regulators PmrA and PhoP. Although a preB mutation led to increased transcription of pmrCAB, this did not result in a measurable effect on polymyxin B resistance. Our genetic data support a model of regulation whereby, in response to unknown signals, the PreB sensor activates PreA, which in turn indirectly upregulates pmrCAB transcription.

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