H-NS Nucleoid Protein Controls Virulence Features of Klebsiella pneumoniae by Regulating the Expression of Type 3 Pili and the Capsule Polysaccharide

Ares, Miguel A.; Fernández-Vázquez, José Luís; Rosales-Reyes, Roberto; Jarillo-Quijada, Ma Dolores; Bargen, Kristine von; Torres, Javier; González-y-Merchand, Jorge A.; Alcántar‐Curiel, María Dolores; Cruz, Miguel A. De la

doi:10.3389/fcimb.2016.00013

Cited by 69 publications

(93 citation statements)

References 92 publications

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“…Quality of RNA was assessed using a NanoDrop (ND-1000; Thermo Scientific) and a bleach 2% agarose gel as previously described (Aranda et al, 2012). qRT-PCR was performed as previously reported (Ares et al, 2016). Specific primers were designed with the Primer3Plus software 2 and are listed in Table 2 .…”

Section: Methodsmentioning

confidence: 99%

Gene Expression Profiling of Transcription Factors of Helicobacter pylori under Different Environmental Conditions

et al. 2017

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Helicobacter pylori is a Gram-negative bacterium that colonizes the human gastric mucosa and causes peptic ulcers and gastric carcinoma. H. pylori strain 26695 has a small genome (1.67 Mb), which codes for few known transcriptional regulators that control bacterial metabolism and virulence. We analyzed by qRT-PCR the expression of 16 transcriptional regulators in H. pylori 26695, including the three sigma factors under different environmental conditions. When bacteria were exposed to acidic pH, urea, nickel, or iron, the sigma factors were differentially expressed with a particularly strong induction of fliA. The regulatory genes hrcA, hup, and crdR were highly induced in the presence of urea, nickel, and iron. In terms of biofilm formation fliA, flgR, hp1021, fur, nikR, and crdR were induced in sessile bacteria. Transcriptional expression levels of rpoD, flgR, hspR, hp1043, and cheY were increased in contact with AGS epithelial cells. Kanamycin, chloramphenicol, and tetracycline increased or decreased expression of regulatory genes, showing that these antibiotics affect the transcription of H. pylori. Our data indicate that environmental cues which may be present in the human stomach modulate H. pylori transcription.

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Section: Methodsmentioning

confidence: 99%

Gene Expression Profiling of Transcription Factors of Helicobacter pylori under Different Environmental Conditions

et al. 2017

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“…Purification of RNA, and qRT-PCR were performed as previously reported (Ares et al, 2016). Briefly, DNA was removed with TURBO DNA-free (Ambion, Inc.) and the quality of RNA was assessed using a NanoDrop (ND-1000; Thermo Scientific) and a bleach agarose gel 2% as previously described (Aranda et al, 2012).…”

Section: Methodsmentioning

confidence: 99%

“…Adhesion to abiotic surface (polystyrene) was analyzed using 96-well plates as previously described (Ares et al, 2016). H. pylori 26695 was grown for 2 days on blood agar culture plates containing 10% defibrinated sheep blood at 37°C under microaerophilic conditions, and a bacterial suspension was prepared in Brucella broth supplemented with 10% decomplemented FBS and adjusted to an optical density of 0.1 at 600 nm.…”

Section: Methodsmentioning

confidence: 99%

Transcriptional Profiling of Type II Toxin–Antitoxin Genes of Helicobacter pylori under Different Environmental Conditions: Identification of HP0967–HP0968 System

et al. 2016

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Helicobacter pylori is a Gram-negative bacterium that colonizes the human gastric mucosa and is responsible for causing peptic ulcers and gastric carcinoma. The expression of virulence factors allows the persistence of H. pylori in the stomach, which results in a chronic, sometimes uncontrolled inflammatory response. Type II toxin–antitoxin (TA) systems have emerged as important virulence factors in many pathogenic bacteria. Three type II TA systems have previously been identified in the genome of H. pylori 26695: HP0315–HP0316, HP0892–HP0893, and HP0894–HP0895. Here we characterized a heretofore undescribed type II TA system in H. pylori, HP0967–HP0968, which is encoded by the bicistronic operon hp0968–hp0967 and belongs to the Vap family. The predicted HP0967 protein is a toxin with ribonuclease activity whereas HP0968 is an antitoxin that binds to its own regulatory region. We found that all type II TA systems were expressed in H. pylori during early stationary growth phase, and differentially expressed in the presence of urea, nickel, and iron, although, the hp0968–hp0967 pair was the most affected under these environmental conditions. Transcription of hp0968–hp0967 was strongly induced in a mature H. pylori biofilm and when the bacteria interacted with AGS epithelial cells. Kanamycin and chloramphenicol considerably boosted transcription levels of all the four type II TA systems. The hp0968–hp0967 TA system was the most frequent among 317 H. pylori strains isolated from all over the world. This study is the first report on the transcription of type II TA genes in H. pylori under different environmental conditions. Our data show that the HP0967 and HP0968 proteins constitute a bona fide type II TA system in H. pylori, whose expression is regulated by environmental cues, which are relevant in the context of infection of the human gastric mucosa.

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“…H‐NS acts as a thermoregulator of virulence factors in several pathogenic bacteria (Falconi et al ., ; Umanski et al ., ; Ares et al ., ). We analyzed the regulatory effect of H‐NS and CRP on lngA expression at 37 and 25°C.…”

Section: Resultsmentioning

confidence: 97%

“…Our data showed that H‐NS, but not CRP, was involved in the thermoregulation of lngA , making sure that there is higher repression of Longus at lower temperatures found outside of the host (Fig. B), such as has been described in other pathogens (Falconi et al ., ; Umanski et al ., ; Ares et al ., ). Thus, it appears that CRP and H‐NS have been incorporated into the complex virulence gene regulatory networks of many bacteria to respond to nutritional and environmental stimuli, activating or repressing the expression of virulence genes (Fig.…”

Section: Discussionmentioning

confidence: 97%

The expression of Longus type 4 pilus of enterotoxigenic Escherichia coli is regulated by LngR and LngS and by H‐NS, CpxR and CRP global regulators

Cruz

Ruiz-Tagle

Ares

et al. 2017

Environmental Microbiology

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Enterotoxigenic Escherichia coli produces a long type 4 pilus called Longus. The regulatory elements and the environmental signals controlling the expression of Longus-encoding genes are unknown. We identified two genes lngR and lngS in the Longus operon, whose predicted products share homology with transcriptional regulators. Isogenic lngR and lngS mutants were considerably affected in transcription of lngA pilin gene. The expression of lngA, lngR and lngS genes was optimally expressed at 37°C at pH 7.5. The presence of glucose and sodium chloride had a positive effect on Longus expression. The presence of divalent ions, particularly calcium, appears to be an important stimulus for Longus production. In addition, we studied H-NS, CpxR and CRP global regulators, on Longus expression. The response regulator CpxR appears to function as a positive regulator of lng genes as the cpxR mutant showed reduced levels of lngRSA expression. In contrast, H-NS and CRP function as negative regulators since expression of lngA was up-regulated in isogenic hns and crp mutants. H-NS and CRP were required for salt- and glucose-mediated regulation of Longus. Our data suggest the existence of a complex regulatory network controlling Longus expression, involving both local and global regulators in response to different environmental signals.

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H-NS Nucleoid Protein Controls Virulence Features of Klebsiella pneumoniae by Regulating the Expression of Type 3 Pili and the Capsule Polysaccharide

Cited by 69 publications

References 92 publications

Gene Expression Profiling of Transcription Factors of Helicobacter pylori under Different Environmental Conditions

Gene Expression Profiling of Transcription Factors of Helicobacter pylori under Different Environmental Conditions

Transcriptional Profiling of Type II Toxin–Antitoxin Genes of Helicobacter pylori under Different Environmental Conditions: Identification of HP0967–HP0968 System

The expression of Longus type 4 pilus of enterotoxigenic Escherichia coli is regulated by LngR and LngS and by H‐NS, CpxR and CRP global regulators

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