SoxS regulates the expression of the Salmonella enterica serovar Typhimurium ompW gene

OmpW of Salmonella enterica serovar Typhimurium has been described as a minor porin involved in osmoregulation, and is also affected by environmental conditions. Biochemical and genetic evidence from our laboratory indicates that OmpW is involved in efflux of and resistance towards paraquat (PQ), and its expression has been shown to be activated in response to oxidative stress. In this study we have explored ompW expression in response to PQ. Primer extension and transcriptional fusions showed that its expression was induced in the presence of PQ. In silico analyses suggested a putative binding site for the SoxS transcriptional factor at the ompW regulatory region. Electrophoretic mobility shift assays (EMSAs) and footprinting experiments showed that SoxS binds at a region that starts close to −54 and ends at about −197 upstream of the transcription start site. Transcriptional fusions support the relevance of this region in ompW activation. The SoxS site is in the forward orientation and its location suggests that the ompW gene has a class I SoxS-dependent promoter.

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CpxR regulates the colistin susceptibility of Salmonella Typhimurium by a multitarget mechanism

Journal of Antimicrobial Chemotherapy ◽

10.1093/jac/dkaa233 ◽

2020 ◽

Vol 75 (10) ◽

pp. 2780-2786 ◽

Cited By ~ 1

Author(s):

Ya-Jun Zhai ◽

Hua-Run Sun ◽

Xing-Wei Luo ◽

Jian-Hua Liu ◽

Yu-Shan Pan ◽

...

Keyword(s):

Salmonella Typhimurium ◽

Target Genes ◽

Salmonella Enterica Serovar Typhimurium ◽

Efflux Pump ◽

Colistin Resistance ◽

Mobility Shift ◽

Serovar Typhimurium ◽

Electrophoretic Mobility Shift Assays ◽

First Time ◽

Signalling Systems

Abstract Background The two-component signalling systems PmrAB and PhoPQ of Salmonella have been extensively studied with regard to colistin resistance. We previously showed that overexpressed CpxR could significantly increase the colistin susceptibility (16-fold compared with the WT strain) of Salmonella enterica serovar Typhimurium (Salmonella Typhimurium) through PmrAB and PhoPQ. Objectives To identify the potential target genes of CpxR in PmrAB- and PhoPQ-related signalling pathways. Methods His6-CpxR was prokaryotically expressed and purified by Ni-NTA resin affinity chromatography. β-Galactosidase activity assays were conducted to investigate whether CpxR could regulate the promoters of colistin resistance-related genes (CRRGs). Electrophoretic mobility shift assays (EMSAs) were used to further detect His6-CpxR complexes with promoters of CRRGs. Results We demonstrated for the first time (to the best of our knowledge) that CpxR and the AcrAB–TolC efflux pump have reciprocal effects on CRRG transcription. Additionally, CpxR could regulate the colistin susceptibility of Salmonella Typhimurium by binding directly to the promoters of phoPQ, pmrC, pmrH and pmrD at the CpxR box-like sequences or indirectly through other regulators including pmrAB and mgrB. Conclusions CpxR could regulate the colistin susceptibility of Salmonella Typhimurium by a multitarget mechanism.

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Removal of the phage-shock protein PspB causes reduction of virulence in Salmonella enterica serovar Typhimurium independently of NRAMP1

Journal of Medical Microbiology ◽

10.1099/jmm.0.072223-0 ◽

2014 ◽

Vol 63 (6) ◽

pp. 788-795 ◽

Cited By ~ 10

Author(s):

Inke Wallrodt ◽

Lotte Jelsbak ◽

Line E. Thomsen ◽

Lena Brix ◽

Sébastien Lemire ◽

...

Keyword(s):

Salmonella Enterica ◽

Salmonella Enterica Serovar Typhimurium ◽

Single Gene ◽

Systemic Infection ◽

Minor Effect ◽

Membrane Stress ◽

Knock Out ◽

Serovar Typhimurium ◽

A Minor

The phage-shock protein (Psp) system is believed to manage membrane stress in all Enterobacteriaceae and has recently emerged as being important for virulence in several pathogenic species of this phylum. The core of the Psp system consists of the pspA–D operon and the distantly located pspG gene. In Salmonella enterica serovar Typhimurium (S. Typhimurium), it has recently been reported that PspA is essential for systemic infection of mice, but only in NRAMP1+ mice, signifying that attenuation is related to coping with divalent cation starvation in the intracellular environment. In the present study, we investigated the contribution of individual psp genes to virulence of S. Typhimurium. Interestingly, deletion of the whole pspA–D set of genes caused attenuation in both NRAMP1+ and NRAMP1− mice, indicating that one or more of the psp genes contribute to virulence independently of NRAMP1 expression in the host. Investigations of single gene mutants showed that knock out of pspB reduced virulence in both types of mice, while deletion of pspA only caused attenuation in NRAMP1+ mice, and deletion of pspD had a minor effect in NRAMP1− mice, while deletions of either pspC or pspG did not affect virulence. Experiments addressed at elucidating the role of PspB in virulence revealed that PspB is dispensable for uptake to and intracellular replication in cultured macrophages and resistance to complement-induced killing. Furthermore, the Psp system of S. Typhimurium was dispensable during pIV-induced secretin stress. In conclusion, our results demonstrate that removal of PspB reduces virulence in S. Typhimurium independently of host NRAMP1 expression, demonstrating that PspB has roles in intra-host survival distinct from the reported contributions of PspA.

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Role of Periplasmic Peptidylprolyl Isomerases in Salmonella enterica Serovar Typhimurium Virulence

Infection and Immunity ◽

10.1128/iai.71.9.5386-5388.2003 ◽

2003 ◽

Vol 71 (9) ◽

pp. 5386-5388 ◽

Cited By ~ 27

Author(s):

Sue Humphreys ◽

Gary Rowley ◽

Andrew Stevenson ◽

William J. Kenyon ◽

Michael P. Spector ◽

...

Keyword(s):

Sigma Factor ◽

Salmonella Enterica ◽

Salmonella Enterica Serovar Typhimurium ◽

Minor Effect ◽

Alternative Sigma Factor ◽

Macrophage Cell ◽

Serovar Typhimurium ◽

A Minor ◽

Peptidylprolyl Isomerase

ABSTRACT FkpA is a peptidylprolyl isomerase whose expression is regulated by the alternative sigma factor, sigma factor E (σE). In contrast to the results of a previous report, inactivation of fkpA was found to have only a minor effect on the ability of Salmonella enterica serovar Typhimurium to invade and survive within epithelial and macrophage cell lines and cause infection in mice. However, an effect of the fkpA mutation on serovar Typhimurium virulence was seen if the mutation was combined with mutations in surA or htrA, two other σE-regulated genes, which encode proteins involved in protein folding and/or degradation in the periplasm.

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The Transcript from the σ28-Dependent Promoter Is Translationally Inert in the Expression of the σ28-Encoding GenefliAin thefliAZOperon of Salmonella enterica Serovar Typhimurium

Journal of Bacteriology ◽

10.1128/jb.05909-11 ◽

2011 ◽

Vol 193 (22) ◽

pp. 6132-6141 ◽

Cited By ~ 9

Author(s):

Yasushi Tanabe ◽

Takeo Wada ◽

Katsuhiko Ono ◽

Tatsuhiko Abo ◽

Kazuhiro Kutsukake

Keyword(s):

Rna Polymerase ◽

Salmonella Enterica ◽

Salmonella Enterica Serovar Typhimurium ◽

Regulatory Region ◽

Content Type ◽

Ribosome Binding ◽

Serovar Typhimurium ◽

Shine Dalgarno Sequence

There are three classes of promoters for flagellar operons inSalmonella. Class 2 promoters are transcribed by σ70RNA polymerase in the presence of an essential activator, FlhD4C2, and activated by an auxiliary regulator, FliZ. Class 3 promoters are transcribed by σ28RNA polymerase and repressed by an anti-σ28factor, FlgM. σ28(FliA) and FliZ are encoded by thefliAandfliZgenes, respectively, which together constitute an operon transcribed in this order. This operon is transcribed from both class 2 and class 3 promoters, suggesting that it should be activated by its own product, σ28, even in the absence of FlhD4C2. However, σ28-dependent transcription occursin vivoonly in the presence of FlhD4C2, indicating that transcription from the class 2 promoter is a prerequisite to that from the class 3 promoter. In this study, we examined the effects of variously modified versions of thefliAregulatory region on transcription and translation of thefliAgene. We showed that FliA is not significantly translated from the class 3 transcript. In contrast, the 5′-terminal AU-rich sequence found in the class 2 transcript confers efficientfliAtranslation. Replacement of the Shine-Dalgarno sequence of thefliAgene with a better one improvedfliAtranslation from the class 3 transcript. These results suggest that the 5′-terminal AU-rich sequence of the class 2 transcript may assist ribosome binding. FliZ was shown to be expressed from both the class 2 and class 3 transcripts.

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H-NS Silencing of the Salmonella Pathogenicity Island 6-Encoded Type VI Secretion System Limits Salmonella enterica Serovar Typhimurium Interbacterial Killing

Infection and Immunity ◽

10.1128/iai.00198-15 ◽

2015 ◽

Vol 83 (7) ◽

pp. 2738-2750 ◽

Cited By ~ 33

Author(s):

Yannick R. Brunet ◽

Ahmad Khodr ◽

Laureen Logger ◽

Laurent Aussel ◽

Tâm Mignot ◽

...

Keyword(s):

Salmonella Enterica ◽

Secretion System ◽

Bacterial Toxin ◽

Type Vi Secretion System ◽

Secretion Systems ◽

Mobility Shift ◽

Content Type ◽

Type Vi Secretion ◽

Serovar Typhimurium ◽

Electrophoretic Mobility Shift Assays

The secretion of bacterial toxin proteins is achieved by dedicated machineries called secretion systems. The type VI secretion system (T6SS) is a widespread versatile machine used for the delivery of protein toxins to both prokaryotic and eukaryotic cells. InSalmonella entericaserovar Typhimurium, the expression of the T6SS genes is activated during macrophage or mouse infection. Here, we show that the T6SS gene cluster is silenced by the histone-like nucleoid structuring H-NS protein using a combination of reporter fusions, electrophoretic mobility shift assays, DNase footprinting, and fluorescence microscopy. We further demonstrate that derepression of theS. Typhimurium T6SS genes induces T6SS-dependent intoxication of competing bacteria. Our results suggest that relieving T6SS H-NS silencing may be used as a sense-and-kill mechanism that will helpS. Typhimurium to homogenize and synchronize the microbial population to gain efficiency during infection.

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