Activation of Helicobacter pylori ureA promoter by a hybrid Escherichia coli–H. pylori rpoD gene in E. coli

Shirai, Mutsunori; Fujinaga, Ryutaro; Akada, Junko; Nakazawa, Takahiro

doi:10.1016/s0378-1119(99)00389-3

Cited by 27 publications

(27 citation statements)

References 29 publications

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“…This region in the nixA promoter effectively overlaps with the Ϫ10 and ϩ1 sequence, and this may prevent transcription upon binding of NikR. In contrast, the NikR-binding site in the ureA promoter is located upstream of the canonical 80 promoter motifs (17,36,42), at positions Ϫ56 to Ϫ91, and partially overlaps with the putative palindrome previously suggested as a possible binding sequence for NikR (42). Deletion of the region upstream of residue Ϫ50 in the ureA promoter was previously shown not to affect basal levels of urease expression (17) but prevented nickel-responsive induction of urease expression (42), and this is consistent with the position of the NikR-binding site in the ureA promoter as identified in this study.…”

Section: Discussionmentioning

confidence: 99%

The Nickel-Responsive Regulator NikR Controls Activation and Repression of Gene Transcription inHelicobacter pylori

et al. 2005

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The NikR protein is a nickel-dependent regulatory protein which is a member of the ribbon-helix-helix family of transcriptional regulators. The gastric pathogen Helicobacter pylori expresses a NikR ortholog, which was previously shown to mediate regulation of metal metabolism and urease expression, but the mechanism governing the diverse regulatory effects had not been described until now. In this study it is demonstrated that NikR can regulate H. pylori nickel metabolism by directly controlling transcriptional repression of NixAmediated nickel uptake and transcriptional induction of urease expression. Mutation of the nickel uptake gene nixA in an H. pylori 26695 nikR mutant restored the ability to grow in Brucella media supplemented with 200 M NiCl 2 but did not restore nickel-dependent induction of urease expression. Nickel-dependent binding of NikR to the promoter of the nixA gene resulted in nickel-repressed transcription, whereas nickel-dependent binding of NikR to the promoter of the ureA gene resulted in nickel-induced transcription. Subsequent analysis of NikR binding to the nixA and ureA promoters showed that the regulatory effect was dependent on the location of the NikR-recognized binding sequence. NikR recognized the region from ؊13 to ؉21 of the nixA promoter, encompassing the ؉1 and ؊10 region, and this binding resulted in repression of nixA transcription. In contrast, NikR bound to the region from ؊56 to ؊91 upstream of the ureA promoter, resulting in induction of urease transcription. In conclusion, the NikR protein is able to function both as a repressor and as an activator of gene transcription, depending on the position of the binding site.

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Section: Discussionmentioning

confidence: 99%

The Nickel-Responsive Regulator NikR Controls Activation and Repression of Gene Transcription inHelicobacter pylori

et al. 2005

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“…Little is known about the process of transcriptional regulation in H. pylori, particularly in relation to pathogenesis (5,15,25,28,29,30,31,33 (Fig. 3), we selected nine noncoding intergenic DNA sequences that we considered likely to contain cag gene promoters for analysis using the urease reporter.…”

Section: Discussionmentioning

confidence: 99%

Differential Gene Expression from Two Transcriptional Units in the cag Pathogenicity Island of Helicobacter pylori

et al. 2001

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Infection with Helicobacter pylori strains containing the cag Pathogenicity Island (cag PAI) is strongly correlated with the development of severe gastric disease, including gastric and duodenal ulceration, mucosaassociated lymphoid tissue lymphoma, and gastric carcinoma. Although in vitro studies have demonstrated that the expression of genes within the cag PAI leads to the activation of a strong host inflammatory response, the functions of most cag gene products and how they work in concert to promote an immunological response are unknown. We developed a transcriptional reporter that utilizes urease activity and in which nine putative regulatory sequences from the cag PAI were fused to the H. pylori ureB gene. These fusions were introduced in single copies onto the H. pylori chromosome without disruption of the cag PAI. Our analysis indicated that while each regulatory region confers a reproducible amount of promoter activity under laboratory conditions, they differ widely in levels of expression. Transcription initiating upstream of cag15 and upstream of cag21 is induced when the respective fusion strains are cocultured with an epithelial cell monolayer. Results of mouse colonization experiments with an H. pylori strain carrying the cag15-ureB fusion suggested that this putative regulatory region appears to be induced in vivo, demonstrating the importance of the urease reporter as a significant development toward identifying in vivo-induced gene expression in H. pylori.

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“…3 and Table 3). These genes were selected because multiple studies have shown them to be acid responsive (8,28) and because their transcriptional start sites are known (1,(28)(29)(30). Acid-responsive expression of both ureA and HP1432 was previously shown to be dependent on the presence of HP0165 (28,29), but a requirement of HP1364 for acid-responsive expression of ureA has not been reported previously.…”

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Requirement of Histidine Kinases HP0165 and HP1364 for Acid Resistance in Helicobacter pylori

Loh¹,

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2006

Infect Immun

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In this study, we investigated a potential requirement of two-component signal transduction systems for acid resistance in Helicobacter pylori. In comparison to a wild-type strain, isogenic strains with null mutations in either HP0165 or HP1364 histidine kinases were impaired in their ability to grow at pH 5.0. The growth of complemented mutant strains was similar to that of the wild-type strain. H. pylori DNA array analyses and transcriptional reporter assays indicated that acid-responsive gene transcription was altered in the HP0165 and HP1364 null mutant strains compared to the parental wild-type strain. These results indicate that intact HP0165 and HP1364 histidine kinases are required for acid resistance in H. pylori.Within the human stomach, Helicobacter pylori encounters a range of acidic pH conditions. The ability of H. pylori to live in this environment is likely to be dependent on regulation of bacterial gene expression in response to pH. Consistent with this view, changes in the pH of the culture medium result in alterations in H. pylori gene expression during growth in vitro (2,4,8,13,23,24,40). Two-component signal transduction systems (TCSTSs), comprised of a sensor histidine kinase and a cognate response regulator, are commonly used by bacteria to detect and respond to environmental signals (reviewed in references 18 and 31). The H. pylori genome is predicted to encode three histidine kinases (3, 33), which have been designated ArsS, AtoS (FlgS, FleS), and CrdS (26,28,38). Other designations include HP0164/HP0165, HP0244, and HP1364 (the respective gene numbers in H. pylori strain 26695) and JHP0151, JHP0229, and JHP1282 (gene numbers in H. pylori strain J99). A genome sequence analysis of H. pylori strain J99 indicated that arsS (JHP0151) is a 1,326-bp open reading frame (ORF) in this strain (3). In contrast, genome sequence analysis of H. pylori strain 26695 indicated the presence of two smaller arsS ORFs, designated HP0165 (519 bp) and HP0164 (762 bp) (33), due to a single nucleotide deletion (at position ϩ497 from the HP0165 translation initiation site). We have sequenced HP0165/HP0164 in our laboratory's copy of H. pylori strain 26695, and it contains a single arsS ORF, similar to that found in strain J99. Consistent with previous studies (8,12,15,28), we use the H. pylori 26695 nomenclature in the current study, and we use the designation HP0165 when describing arsS.H. pylori mutant strains containing deletions of individual histidine kinase genes (HP0165, HP0244, and HP1364) are defective in the capacity to colonize the mouse stomach (27). A recent study (28) reported that the transcription of three genes (HP0119, HP1432, and ureA) was upregulated by acidic pH in a wild-type H. pylori strain but not in an isogenic HP0165 mutant strain. Therefore, it was suggested that the HP0165 histidine kinase may function as an acid sensor (28). Binding of the cognate response regulator (HP0166) to sequences upstream from HP0119 and ureA has been demonstrated experimentally (12,29).Although there is evid...

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Activation of Helicobacter pylori ureA promoter by a hybrid Escherichia coli–H. pylori rpoD gene in E. coli

Cited by 27 publications

References 29 publications

The Nickel-Responsive Regulator NikR Controls Activation and Repression of Gene Transcription inHelicobacter pylori

The Nickel-Responsive Regulator NikR Controls Activation and Repression of Gene Transcription inHelicobacter pylori

Differential Gene Expression from Two Transcriptional Units in the cag Pathogenicity Island of Helicobacter pylori

Requirement of Histidine Kinases HP0165 and HP1364 for Acid Resistance in Helicobacter pylori

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