The non-motile phenotype of Salmonella hha ydgT mutants is mediated through PefI-SrgD

Wallar, Lauren E.; Bysice, Andrew M.; Coombes, Brian K.

doi:10.1186/1471-2180-11-141

Cited by 9 publications

(11 citation statements)

References 38 publications

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“…We also show that the PpefB promoter, but not the PpefA promoter, is silenced by Hha-YdgT and StpA, the paralog of H-NS, but these nucleoproteins affect pef operon transcription less than H-NS. The use of a double ΔhhaΔydgT mutant was necessary to obtain this phenotype, which is consistent with the already described redundancy of these proteins [25,36,47]. Concerning StpA, our results are the first demonstration of StpA gene silencing after bacterial growth in late stationary phase, i.e.…”

Section: Discussionsupporting

confidence: 90%

H-NS is the major repressor of Salmonella Typhimurium Pef fimbriae expression

et al. 2019

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Fimbriae play an important role in adhesion and are therefore essential for the interaction of bacteria with the environments they encounter. Most of them are expressed in vivo but not in vitro, thus making difficult the full characterization of these fimbriae. Here, we characterized the silencing of plasmid-encoded fimbriae (Pef) expression, encoded by the pef operon, in the worldwide pathogen Salmonella Typhimurium. We demonstrated that the nucleoid-associated proteins H-NS and Hha, and their respective paralogs StpA and YdgT, negatively regulate at pH 5.1 and pH 7.1 the transcription of the pef operon. Two promoters, PpefB and PpefA, direct the transcription of this operon. All the nucleoid-associated proteins silence the PpefB promoter and H-NS also targets the PpefA promoter. While Hha and YdgT are mainly considered as acting primarily through H-NS to modulate gene transcription, our results strongly suggest that Hha and YdgT silence pef transcription at acidic pH either by interacting with StpA or independently of H-NS and StpA. We also confirmed the previously described post-transcriptional repression of Pef fimbriae by CsrA titration via the fim mRNA and CsrB and CsrC sRNA. Finally, among all these regulators, H-NS clearly appeared as the major repressor of Pef expression. These results open new avenues of research to better characterize the regulation of these bacterial adhesive proteins and to clarify their role in the virulence of pathogens.

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Section: Discussionsupporting

confidence: 90%

H-NS is the major repressor of Salmonella Typhimurium Pef fimbriae expression

et al. 2019

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“…However, one of these three regulators, PefI, has already a known function as a negative regulator of the pef operon (Nicholson and Low, 2000). A putative role of SrgD as a transcriptional regulator of flagellar gene expression has also been suggested (Wozniak et al, 2009;Wallar et al, 2011) unlike the putative transcriptional regulator SrgC which has currently no described role.…”

Section: Discussionmentioning

confidence: 99%

“…According to the work of Wallar et al . () and Wozniak et al . (), SrgD could be involved in regulation of flagellar gene expression and motility.…”

Section: Introductionmentioning

confidence: 86%

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Direct regulation of the pefI‐srgC operon encoding the Rck invasin by the quorum‐sensing regulator SdiA in Salmonella Typhimurium

Abed

Grépinet

Canepa

et al. 2014

Molecular Microbiology

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SummaryOne important step for the pathogenesis of Salmonella is its ability to penetrate host cells. Recently, a new entry system involving the outer membrane protein Rck has been characterized. Previous studies have shown that the pefI-srgC locus, which contains rck, was regulated by the temperature and SdiA, the transcriptional regulator of quorum sensing in Salmonella. To decipher the regulation of rck by SdiA, we first confirmed the operon organization of the pefI-srgC locus. Using plasmid-based transcriptional fusions, we showed that only the predicted distal promoter upstream of pefI, PefIP2, displays an SdiA-and acylhomoserine lactones-dependent activity while the predicted proximal PefIP1 promoter exhibits a very low activity independent on SdiA in our culture conditions. A direct and specific interaction of SdiA with this PefIP2 region was identified using electrophoretic mobility shift assays and surface plasmon resonance studies. We also observed that Rck expression is negatively regulated by the nucleoid-associated H-NS protein at both 25°C and 37°C. This work is the first demonstration of a direct regulation of genes by SdiA in Salmonella and will help further studies designed to identify environmental conditions required for Rck expression and consequently contribute to better characterize the role of this invasin in vivo.

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“…Also localized on the rck operon, srgD encodes a putative transcriptional regulator. Recently, it has been shown that SrgD acts in cooperation with PefI to induce a synergistic negative regulation of flagellar genes expression (Wozniak et al, 2009;Wallar et al, 2011). The remaining genes on the rck operon have unknown functions and encode a putative outer membrane protein, SrgB, and a putative transcriptional regulator, SrgC.…”

Section: Rck Regulationmentioning

confidence: 99%