The Small Nucleoid-Binding Proteins H-NS, HU, and Fis Affect
            <i>hilA</i>
            Expression in
            <i>Salmonella enterica</i>
            Serovar Typhimurium

Schechter, Lisa M.; Jain, Shaili; Akbar, Samina; Lee, Catherine A.

doi:10.1128/iai.71.9.5432-5435.2003

Cited by 93 publications

(98 citation statements)

References 25 publications

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“…Some reports have established that low-osmolarity and lowtemperature conditions result in reduced hilA expression (Ono et al, 2005;Schechter et al, 2003), and others have shown that hilA expression is growth phase-dependent, being hilA-induced at the onset of the stationary phase when cells are grown in aerated LB medium (Song et al, 2004).…”

Section: Resultsmentioning

confidence: 99%

“…Their effect seems to be indirect, as they sense osmolarity and bile/short-chain fatty acids, respectively (Altier, 2005;Ellermeier et al, 2005;Lucas & Lee, 2001). Other global regulators that positively modulate hilA expression are Fur (Ellermeier & Slauch, 2008) and the nucleoid-associated proteins Fis, HU (Schechter et al, 2003) and the bacterial IHF (Mangan et al, 2006). IHF binds to many target DNA sequences and plays a role as a transcription factor (Browning et al, 2010).…”

Section: Introductionmentioning

confidence: 99%

“…In turn, HilE expression is sensitive to several inputs, including the two-component systems PhoP/PhoQ and PhoR/PhoB, which either directly or indirectly activate HilE expression, thus leading to SPI1 repression. Negative modulation of hilA is also accomplished by global modulators such as Hha (Fahlen et al, 2001) and H-NS (Olekhnovich & Kadner, 2006;Schechter et al, 2003). Both belong to the superfamily of the nucleoid-associated proteins (Dorman, 2004;Madrid et al, 2007) and have been shown to interact to modulate gene expression (Ellison & Miller, 2006;Madrid et al, 2002;Nieto et al, 1991Nieto et al, , 2002.…”

Section: Introductionmentioning

confidence: 99%

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Integration host factor alleviates H-NS silencing of the Salmonella enterica serovar Typhimurium master regulator of SPI1, hilA

et al. 2011

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Coordination of the expression of Salmonella enterica invasion genes on Salmonella pathogenicity island 1 (SPI1) depends on a complex circuit involving several regulators that converge on expression of the hilA gene, which encodes a transcriptional activator (HilA) that modulates expression of the SPI1 virulence genes. Two of the global regulators that influence hilA expression are the nucleoid-associated proteins Hha and H-NS. They interact and form a complex that modulates gene expression. A chromosomal transcriptional fusion was constructed to assess the effects of these modulators on hilA transcription under several environmental conditions as well as at different stages of growth. The results obtained showed that these proteins play a role in silencing hilA expression at both low temperature and low osmolarity, irrespective of the growth phase. H-NS accounts for the main repressor activity. At high temperature and osmolarity, H-NS-mediated silencing completely ceases when cells enter the stationary phase, and hilA expression is induced. Mutants lacking IHF did not induce hilA in cells entering the stationary phase, and this lack of induction was dependent on the presence of H-NS. Band-shift assays and in vitro transcription data showed that for hilA induction under certain growth conditions, IHF is required to alleviate H-NS-mediated silencing.

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Section: Resultsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Integration host factor alleviates H-NS silencing of the Salmonella enterica serovar Typhimurium master regulator of SPI1, hilA

et al. 2011

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“…H-NS has been shown to repress the transcription of hilA, a number of its activators, and other horizontally acquired SPIs (38,46,48,49,53). We hypothesized that the upregulation of hns in the fur-deficient cells may explain the observed Fur-dependent expression of hilA (Fig.…”

Section: Vol 193 2011mentioning

confidence: 99%

Fur Negatively Regulates hns and Is Required for the Expression of HilA and Virulence in Salmonella enterica Serovar Typhimurium

et al. 2011

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Iron is an essential element for the survival of living cells. However, excess iron is toxic, and its uptake is exquisitely regulated by the ferric uptake regulator, Fur. In Salmonella, the Salmonella pathogenicity island 1 (SPI-1) encodes a type three secretion system, which is required for invasion of host epithelial cells in the small intestine. A major activator of SPI-1 is HilA, which is encoded within SPI-1. One known regulator of hilA is Fur. The mechanism of hilA regulation by Fur is unknown. We report here that Fur is required for virulence in Salmonella enterica serovar Typhimurium and that Fur is required for the activation of hilA, as well as of other HilA-dependent genes, invF and sipC. The Fur-dependent regulation of hilA was independent of PhoP, a known repressor of hilA. Instead, the expression of the gene coding for the histone-like protein, hns, was significantly derepressed in the fur mutant. Indeed, the activation of hilA by Fur was dependent on 28 nucleotides located upstream of hns. Moreover, we used chromatin immunoprecipitation to show that Fur bound, in vivo, to the upstream region of hns in a metal-dependent fashion. Finally, deletion of fur in an hns mutant resulted in Fur-independent activation of hilA. In conclusion, Fur activates hilA by repressing the expression of hns.

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“…Thus, most studies have been carried out using bacteria grown under so-called inducing conditions, namely high osmolarity and low oxygen conditions (LB containing 0.3 M NaCl without aeration). Studies of bacteria grown under these conditions have, to date, revealed that hilA expression is regulated by a complex array of regulatory systems including hilC/sirC/sprA (13)(14)(15), hilD (15), sirA/barA (16,17), fis (18,19), csrAB (16,20), envZ/ ompR (21), phoB (7), fadD (7), fliZ (7), hha (22), H-NS (19), and HU (19). Two of these genes, hilC and hilD, encode AraC-like transcriptional activators that activate hilA transcription by binding upstream of the hilA promoter DNA (15,23,24).…”

mentioning

confidence: 99%

ppGpp-dependent Stationary Phase Induction of Genes on Salmonella Pathogenicity Island 1

Song

Kim

et al. 2004

Journal of Biological Chemistry

132

133

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We have examined expression of the genes on Salmonella pathogenicity island 1 (SPI1) during growth under the physiologically well defined standard growth condition of Luria-Bertani medium with aeration. We found that the central regulator hilA and the genes under its control are expressed at the onset of stationary phase. Interestingly, the two-component regulatory genes hilC/ hilD, sirA/barA, and ompR, which are known to modulate expression from the hilA promoter (hilAp) under so-called "inducing conditions" (Luria-Bertani medium containing 0.3 M NaCl without aeration), acted under standard conditions at the stationary phase induction level. The induction of hilAp depended not on RpoS, the stationary phase sigma factor, but on the stringent signal molecule ppGpp. In the ppGpp null mutant background, hilAp showed absolutely no activity. The stationary phase induction of hilAp required spoT but not relA. Consistent with this requirement, hilAp was also induced by carbon source deprivation, which is known to transiently elevate ppGpp mediated by spoT function. The observation that amino acid starvation elicited by the addition of serine hydroxamate did not induce hilAp in a RelA ؉ SpoT ؉ strain suggested that, in addition to ppGpp, some other alteration accompanying entry into the stationary phase might be necessary for induction. It is speculated that during the course of infection Salmonella encounters various stressful environments that are sensed and translated to the intracellular signal, ppGpp, which allows expression of Salmonella virulence genes, including SPI1 genes.

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The Small Nucleoid-Binding Proteins H-NS, HU, and Fis Affect hilA Expression in Salmonella enterica Serovar Typhimurium

Cited by 93 publications

References 25 publications

Integration host factor alleviates H-NS silencing of the Salmonella enterica serovar Typhimurium master regulator of SPI1, hilA

Integration host factor alleviates H-NS silencing of the Salmonella enterica serovar Typhimurium master regulator of SPI1, hilA

Fur Negatively Regulates hns and Is Required for the Expression of HilA and Virulence in Salmonella enterica Serovar Typhimurium

ppGpp-dependent Stationary Phase Induction of Genes on Salmonella Pathogenicity Island 1

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