scholarly journals Nickel Represses the Synthesis of the Nickel Permease NixA of Helicobacter pylori

2006 ◽  
Vol 188 (4) ◽  
pp. 1245-1250 ◽  
Author(s):  
Lutz Wolfram ◽  
Elvira Haas ◽  
Peter Bauerfeind
Keyword(s):  
Helicobacter Pylori ◽  
Translational Regulation ◽  
Regulatory Protein ◽  
Nickel Concentration ◽  
Uptake System ◽  
Dependent Manner ◽  
Concentration Dependent Manner ◽  
Nickel Uptake ◽  
Protective Reaction ◽  
H Pylori

ABSTRACT Nickel acquisition is necessary for urease activity, a major virulence factor of the human gastric pathogen Helicobacter pylori. NixA was identified as a specific nickel uptake system in this organism. Addition of small amounts of nickel to media strongly stimulates urea hydrolysis. On the other hand, high nickel concentrations are deleterious to cell growth. As a possible protective reaction, nickel uptake seems to be reduced in H. pylori grown in nickel-rich media. These observations led to investigations of regulation of the expression of the nickel permease NixA. We found that increasing the nickel concentration in media reduced the amount of NixA. In order to address the question of whether this phenomenon was subject to transcriptional or translational regulation, we quantified nixA mRNA from H. pylori by real-time PCR. The amount of nixA mRNA was gradually reduced five- to sevenfold in a time- and concentration-dependent manner. Repression could be measured as soon as 5 min after nickel addition, and the maximum repression occurred after 20 to 30 min. The maximum repression was obtained with an external nickel concentration of 100 μM. The observed nickel repression of NixA was dependent on nikR encoding the nickel-responsive regulatory protein NikR. In conclusion, we demonstrated that synthesis of the NixA nickel permease of H. pylori shows nickel-responsive regulation mediated by NikR to maintain the balance between effective nickel acquisition and a toxic overload.

scholarly journals The Nickel-Responsive Regulator NikR Controls Activation and Repression of Gene Transcription in Helicobacter pylori

2005 ◽  
Vol 73 (11) ◽  
pp. 7252-7258 ◽  
Author(s):  
Florian D. Ernst ◽  
Ernst J. Kuipers ◽  
Angela Heijens ◽  
Roya Sarwari ◽  
Jeroen Stoof ◽  
...  
Keyword(s):  
Helicobacter Pylori ◽  
Gene Transcription ◽  
Transcriptional Repression ◽  
Regulatory Protein ◽  
Transcriptional Regulators ◽  
Nickel Uptake ◽  
Regulatory Effects ◽  
H Pylori ◽  
Binding Sequence ◽  
Transcriptional Induction

ABSTRACT 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 NixA-mediated 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 μM NiCl2 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.

scholarly journals Anti-Helicobacter pylori activity of acomplex mixture of Lactobacillus paracasei HP7 including the extract of Perilla frutescens var. acuta and Glycyrrhiza glabra

2020 ◽  
Vol 36 (1) ◽  
Author(s):  
Hyun-A Lee ◽  
Joo-Yun Kim ◽  
Jisoo Kim ◽  
Bora Nam ◽  
Okjin Kim
Keyword(s):  
Helicobacter Pylori ◽  
Complex Mixture ◽  
Perilla Frutescens ◽  
Glycyrrhiza Glabra ◽  
Dependent Manner ◽  
Protective Effects ◽  
Concentration Dependent Manner ◽  
Resistant Strains ◽  
H Pylori ◽  
Drug Resistant Strains

Abstract The effect of standard therapeutic strategies on Helicobacter pylori infection is diminished over time owing to the emergence of drug resistant strains. In this study, we would like to confirm the enhanced effect of L. paracasei HP7, which has been reported to exert antibacterial and gastric mucosal protective effects, in combination with Perilla frutescens var. acuta (P. frutescens)and Glycyrrhiza glabra (G. glabra) extracts. P. frutescens extract and G. glabra extract were found to inhibit the growth of H. pylori in a concentration-dependent manner, and the combination of L. paracasei HP7 and P. frutescens extract and G. glabra extract effectively inhibited H. pylori from attaching to AGS a gastric epithelial cells. Moreover, L. paracasei HP7 complex mixture containing P. frutescens and G. glabra extracts has been shown to inhibit H. pylori virulence genes such as AlpA, CagA, FlaA and UreA. When H. pylori-infected mice were administered a complex mixture of L. paracasei HP7 containing P. frutescens and G. glabra extract, the infection rate of H. pylori was significantly reduced. In addition, the L. paracasei HP7 complex mixture significantly reduced serum IL-8 levels and stomach inflammation in H. pylori infected mice. These results suggest that a complex mixture of L. paracasei HP7 containing P. frutescens and G. glabra extracts may be an alternative to treating diseases caused by H. pylori infection.

scholarly journals NikR Mediates Nickel-Responsive Transcriptional Repression of the Helicobacter pylori Outer Membrane Proteins FecA3 (HP1400) and FrpB4 (HP1512)

2006 ◽  
Vol 74 (12) ◽  
pp. 6821-6828 ◽  
Author(s):  
Florian D. Ernst ◽  
Jeroen Stoof ◽  
Wannie M. Horrevoets ◽  
Ernst J. Kuipers ◽  
Johannes G. Kusters ◽  
...  
Keyword(s):  
Helicobacter Pylori ◽  
Membrane Proteins ◽  
Outer Membrane ◽  
Transcriptional Repression ◽  
Outer Membrane Proteins ◽  
Regulatory Protein ◽  
Start Codon ◽  
Recognition Sequence ◽  
Nickel Uptake ◽  
H Pylori

ABSTRACT The transition metal nickel plays an important role in gastric colonization and persistence of the important human pathogen Helicobacter pylori, as it is the cofactor of the abundantly produced acid resistance factor urease. Nickel uptake through the inner membrane is mediated by the NixA protein, and the expression of NixA is controlled by the NikR regulatory protein. Here we report that NikR also controls the nickel-responsive expression of the FecA3 (HP1400) and FrpB4 (HP1512) outer membrane proteins (OMPs), as well as the nickel-responsive expression of an ExbB-ExbD-TonB system, which may function in energization of outer membrane transport. Transcription and expression of the frpB4 and fecA3 genes were repressed by nickel in wild-type H. pylori 26695, but they were independent of nickel and derepressed in an isogenic nikR mutant. Both the frpB4 and fecA3 genes were transcribed from a promoter directly upstream of their start codon. Regulation by NikR was mediated via nickel-dependent binding to specific operators overlapping either the +1 or −10 sequence in the frpB4 and fecA3 promoters, respectively, and these operators contained sequences resembling the proposed H. pylori NikR recognition sequence (TATWATT-N11-AATWATA). Transcription of the HP1339-1340-1341 operon encoding the ExbB2-ExbD2-TonB2 complex was also regulated by nickel and NikR, but not by Fur and iron. In conclusion, H. pylori NikR controls nickel-responsive expression of the HP1400 (FecA3) and HP1512 (FrpB4) OMPs. We hypothesize that these two NikR-regulated OMPs may participate in the uptake of complexed nickel ions and that this process is energized by the NikR-regulated ExbB2-ExbD2-TonB2 system, another example of the specific adaptation of H. pylori to the gastric lifestyle.

scholarly journals The Helicobacter pylori Autotransporter ImaA (HP0289) Modulates the Immune Response and Contributes to Host Colonization

2012 ◽  
Vol 80 (7) ◽  
pp. 2286-2296 ◽  
Author(s):  
William E. Sause ◽  
Andrea R. Castillo ◽  
Karen M. Ottemann
Keyword(s):  
Immune Response ◽  
Helicobacter Pylori ◽  
Membrane Protein ◽  
Outer Membrane ◽  
Outer Membrane Protein ◽  
Dependent Manner ◽  
Wild Type ◽  
Content Type ◽  
H Pylori ◽  
Murine Infections

ABSTRACTThe human pathogenHelicobacter pyloriemploys a diverse collection of outer membrane proteins to colonize, persist, and drive disease within the acidic gastric environment. In this study, we sought to elucidate the function of the host-induced geneHP0289, which encodes an uncharacterized outer membrane protein. We first generated an isogenicH. pylorimutant that lacksHP0289and found that the mutant has a colonization defect in single-strain infections and is greatly outcompeted in mouse coinfection experiments with wild-typeH. pylori. Furthermore, we used protease assays and biochemical fractionation coupled with an HP0289-targeted peptide antibody to verify that the HP0289 protein resides in the outer membrane. Our previous findings showed that theHP0289promoter is upregulated in the mouse stomach, and here we demonstrate thatHP0289expression is induced under acidic conditions in an ArsRS-dependent manner. Finally, we have shown that theHP0289mutant induces greater expression of the chemokine interleukin-8 (IL-8) and the cytokine tumor necrosis factor alpha (TNF-α) in gastric carcinoma cells (AGS). Similarly, transcription of the IL-8 homolog keratinocyte-derived chemokine (KC) is elevated in murine infections with the HP0289 mutant than in murine infections with wild-typeH. pylori. On the basis of this phenotype, we renamed HP0289 ImaA forimmunomodulatoryautotransporter protein. Our work has revealed that genes inducedin vivoplay an important role inH. pyloripathogenesis. Specifically, the outer membrane protein ImaA modulates a component of the host inflammatory response, and thus may allowH. pylorito fine tune the host immune response based on ImaA expression.

scholarly journals Macrolide resistance in Helicobacter pylori: rapid detection of point mutations and assays of macrolide binding to ribosomes.

1997 ◽  
Vol 41 (12) ◽  
pp. 2724-2728 ◽  
Author(s):  
A Occhialini ◽  
M Urdaci ◽  
F Doucet-Populaire ◽  
C M Bébéar ◽  
H Lamouliatte ◽  
...  
Keyword(s):  
Helicobacter Pylori ◽  
Point Mutations ◽  
Restriction Enzymes ◽  
The United States ◽  
Drug Binding ◽  
Macrolide Resistance ◽  
Rrna Genes ◽  
23S Rrna ◽  
Dependent Manner ◽  
H Pylori

Resistance of Helicobacter pylori to macrolides is a major cause of failure of eradication therapies. Single base substitutions in the H. pylori 23S rRNA genes have been associated with macrolide resistance in the United States. Our goal was to extend this work to European strains, to determine the consequence of this mutation on erythromycin binding to H. pylori ribosomes, and to find a quick method to detect the mutation. Seven pairs of H. pylori strains were used, the parent strain being naturally susceptible to macrolides and the second strain having acquired an in vivo resistance during a treatment regimen that included clarithromycin. The identity of the strains was confirmed by random amplified polymorphic DNA testing with two different primers, indicating that resistance was the result of the selection of variants of the infecting strain. All resistant strains were found to have point mutations at position 2143 (three cases) or 2144 (four cases) but never on the opposite DNA fragment of domain V of the 23S rRNA gene. The mutation was A-->G in all cases except one (A-->C) at position 2143. Using BsaI and BbsI restriction enzymes on the amplified products, we confirmed the mutations of A-->G at positions 2144 and 2143, respectively. Macrolide binding was tested on purified ribosomes isolated from four pairs of strains with [14C]erythromycin. Erythromycin binding increased in a dose-dependent manner for the susceptible strain but not for the resistant one. In conclusion we suggest that the limited disruption of the peptidyltransferase loop conformation, caused by a point mutation, reduces drug binding and consequently confers resistance to macrolides. Finally, the macrolide resistance could be detected without sequencing by performing restriction fragment length polymorphism with appropriate restriction enzymes.

scholarly journals Targeted mobilization of Lrig1+ gastric epithelial stem cell populations by a carcinogenic Helicobacter pylori type IV secretion system

2019 ◽  
Vol 116 (39) ◽  
pp. 19652-19658 ◽  
Author(s):  
Lydia E. Wroblewski ◽  
Eunyoung Choi ◽  
Christine Petersen ◽  
Alberto G. Delgado ◽  
M. Blanca Piazuelo ◽  
...  
Keyword(s):  
Helicobacter Pylori ◽  
Stem Cell ◽  
Progenitor Cells ◽  
Intrinsic Factor ◽  
Secretion System ◽  
Lineage Tracing ◽  
Host Cells ◽  
Dependent Manner ◽  
Cell Marker ◽  
H Pylori

Helicobacter pylori-induced gastritis is the strongest risk factor for gastric adenocarcinoma, a malignancy preceded by a series of well-defined histological stages, including metaplasia. One microbial constituent that augments cancer risk is the cag type 4 secretion system (T4SS), which translocates the oncoprotein CagA into host cells. Aberrant stem cell activation is linked to carcinogenesis, and Lrig1 (leucine-rich repeats and Ig-like domains 1) marks a distinct population of progenitor cells. We investigated whether microbial effectors with carcinogenic potential influence Lrig1 progenitor cells ex vivo and via lineage expansion within H. pylori-infected gastric mucosa. Lineage tracing was induced in Lrig1-CreERT2/+;R26R-YFP/+ (Lrig1/YFP) mice that were uninfected or subsequently infected with cag+H. pylori or an isogenic cagE− mutant (nonfunctional T4SS). In contrast to infection with wild-type (WT) H. pylori for 2 wk, infection for 8 wk resulted in significantly increased inflammation and proliferation in the corpus and antrum compared with uninfected or mice infected with the cagE− mutant. WT H. pylori-infected mice harbored significantly higher numbers of Lrig1/YFP epithelial cells that coexpressed UEA1 (surface cell marker). The number of cells coexpressing intrinsic factor (chief cell marker), YFP (lineage marker), and GSII lectin (spasmolytic polypeptide-expressing metaplasia marker) were increased only by WT H. pylori. In human samples, Lrig1 expression was significantly increased in lesions with premalignant potential compared with normal mucosa or nonatrophic gastritis. In conclusion, chronic H. pylori infection stimulates Lrig1-expressing progenitor cells in a cag-dependent manner, and these reprogrammed cells give rise to a full spectrum of differentiated cells.

scholarly journals Modification of the Gastric Mucosal Microbiota by a Strain-Specific Helicobacter pylori Oncoprotein and Carcinogenic Histologic Phenotype

mBio ◽  
2019 ◽  
Vol 10 (3) ◽  
Author(s):  
Jennifer M. Noto ◽  
Joseph P. Zackular ◽  
Matthew G. Varga ◽  
Alberto Delgado ◽  
Judith Romero-Gallo ◽  
...  
Keyword(s):  
Gastric Cancer ◽  
Helicobacter Pylori ◽  
Community Structure ◽  
Microbial Community ◽  
Iron Deficiency ◽  
Dependent Manner ◽  
Content Type ◽  
Β Diversity ◽  
H Pylori ◽  
Gastric Microbiota

ABSTRACT Helicobacter pylori is the strongest risk factor for gastric adenocarcinoma; however, most infected individuals never develop this malignancy. Strain-specific microbial factors, such as the oncoprotein CagA, as well as environmental conditions, such as iron deficiency, augment cancer risk. Importantly, dysbiosis of the gastric microbiota is also associated with gastric cancer. To investigate the combinatorial effects of these determinants in an in vivo model of gastric cancer, Mongolian gerbils were infected with the carcinogenic cag+ H. pylori strain 7.13 or a 7.13 cagA isogenic mutant, and microbial DNA extracted from gastric tissue was analyzed by 16S rRNA sequencing. Infection with H. pylori significantly increased gastric inflammation and injury, decreased α-diversity, and altered microbial community structure in a cagA-dependent manner. The effect of iron deficiency on gastric microbial communities was also investigated within the context of infection. H. pylori-induced injury was augmented under conditions of iron deficiency, but despite differences in gastric pathology, there were no significant differences in α- or β-diversity, phyla, or operational taxonomic unit (OTU) abundance among infected gerbils maintained on iron-replete or iron-depleted diets. However, when microbial composition was stratified based solely on the severity of histologic injury, significant differences in α- and β-diversity were present among gerbils harboring premalignant or malignant lesions compared to gerbils with gastritis alone. This study demonstrates that H. pylori decreases gastric microbial diversity and community structure in a cagA-dependent manner and that as carcinogenesis progresses, there are corresponding alterations in community structure that parallel the severity of disease. IMPORTANCE Microbial communities are essential for the maintenance of human health, and when these communities are altered, hosts can become susceptible to inflammation and disease. Dysbiosis contributes to gastrointestinal cancers, and specific bacterial species are associated with this phenotype. This study uses a robust and reproducible animal model to demonstrate that H. pylori infection induces gastric dysbiosis in a cagA-dependent manner and further that dysbiosis and altered microbial community structure parallel the severity of H. pylori-induced gastric injury. Ultimately, such models of H. pylori infection and cancer that can effectively evaluate multiple determinants simultaneously may yield effective strategies for manipulating the gastric microbiota to prevent the development of gastric cancer.

scholarly journals l-Arginine Availability Regulates Inducible Nitric Oxide Synthase-Dependent Host Defense against Helicobacter pylori

2007 ◽  
Vol 75 (9) ◽  
pp. 4305-4315 ◽  
Author(s):  
Rupesh Chaturvedi ◽  
Mohammad Asim ◽  
Nuruddeen D. Lewis ◽  
Holly M. Scott Algood ◽  
Timothy L. Cover ◽  
...  
Keyword(s):  
Nitric Oxide ◽  
Helicobacter Pylori ◽  
Protein Expression ◽  
Translation Initiation Factor ◽  
No Production ◽  
Dependent Manner ◽  
Inos Protein ◽  
Inos Protein Expression ◽  
H Pylori ◽  
Inducible Nitric Oxide

ABSTRACT Helicobacter pylori infection of the stomach causes an active immune response that includes stimulation of inducible nitric oxide (NO) synthase (iNOS) expression. Although NO can kill H. pylori, the bacterium persists indefinitely, suggesting that NO production is inadequate. We determined if the NO derived from iNOS in macrophages was dependent on the availability of its substrate, l-arginine (l-Arg). Production of NO by H. pylori-stimulated RAW 264.7 cells was dependent on the l-Arg concentration in the culture medium, and the 50% effective dose for l-Arg was 220 μM, which is above reported plasma l-Arg levels. While iNOS mRNA induction was l-Arg independent, iNOS protein increased in an l-Arg-dependent manner that did not involve changes in iNOS protein degradation. l-Lysine, an inhibitor of l-Arg uptake, attenuated H. pylori-stimulated iNOS protein expression, translation, NO levels, and killing of H. pylori. While l-Arg starvation suppressed global protein translation, at concentrations of l-Arg at which iNOS protein was only minimally expressed in response to H. pylori, global translation was fully restored and eukaryotic translation initiation factor α was dephosphorylated. H. pylori lacking the gene rocF, which codes for a bacterial arginase, induced higher levels of NO production by increasing iNOS protein levels. When murine gastric macrophages were activated with H. pylori, supraphysiologic levels of l-Arg were required to permit iNOS protein expression and NO production. These findings indicate that l-Arg is rate limiting for iNOS translation and suggest that the levels of l-Arg that occur in vivo do not permit sufficient NO generation by the host to kill H. pylori.

scholarly journals Helicobacter pylori induces intracellular galectin-8 aggregation around damaged lysosomes within gastric epithelial cells in a host O-glycan-dependent manner

Glycobiology ◽  
2018 ◽  
Vol 29 (2) ◽  
pp. 151-162 ◽  
Author(s):  
Fang-Yen Li ◽  
I-Chun Weng ◽  
Chun-Hung Lin ◽  
Mou-Chieh Kao ◽  
Ming-Shiang Wu ◽  
...  
Keyword(s):  
Helicobacter Pylori ◽  
Epithelial Cells ◽  
Rhesus Macaques ◽  
Dependent Manner ◽  
Gastric Epithelial Cells ◽  
Vacuolating Cytotoxin ◽  
Infected Cells ◽  
H Pylori ◽  
Autophagy Activity ◽  
Binding Lectin

Abstract Galectin-8, a beta-galactoside-binding lectin, is upregulated in the gastric tissues of rhesus macaques infected with Helicobacter pylori. In this study, we found that H. pylori infection triggers intracellular galectin-8 aggregation in human-derived AGS gastric epithelial cells, and that these aggregates colocalize with lysosomes. Notably, this aggregation is markedly reduced following the attenuation of host O-glycan processing. This indicates that H. pylori infection induces lysosomal damage, which in turn results in the accumulation of cytosolic galectin-8 around damaged lysosomes through the recognition of exposed vacuolar host O-glycans. H. pylori-induced galectin-8 aggregates also colocalize with autophagosomes, and galectin-8 ablation reduces the activation of autophagy by H. pylori. This suggests that galectin-8 aggregates may enhance autophagy activity in infected cells. We also observed that both autophagy and NDP52, an autophagy adapter, contribute to the augmentation of galectin-8 aggregation by H. pylori. Additionally, vacuolating cytotoxin A, a secreted H. pylori cytotoxin, may contribute to the increased galectin-8 aggregation and elevated autophagy response in infected cells. Collectively, these results suggest that H. pylori promotes intracellular galectin-8 aggregation, and that galectin-8 aggregation and autophagy may reciprocally regulate each other during infection.

Low concentrations of A23187 increase calcium uptake by cardiac sarcoplasmic reticulum

1985 ◽  
Vol 249 (6) ◽  
pp. H1211-H1215
Author(s):  
J. J. Murray ◽  
A. V. Kuzmin ◽  
P. W. Reed ◽  
D. O. Levitsky
Keyword(s):  
Sarcoplasmic Reticulum ◽  
Calcium Uptake ◽  
Atp Hydrolysis ◽  
Ionophore A23187 ◽  
Uptake System ◽  
Dependent Manner ◽  
Concentration Dependent Manner ◽  
Cardiac Sarcoplasmic Reticulum ◽  
Calcium Dependent ◽  
Uptake Measurement

The divalent cation ionophore A23187 at a concentration of 1 nM produced an increased rate of oxalate-supported calcium uptake by isolated cardiac sarcoplasmic reticulum as determined by absorbance changes of the calcium-sensitive dye murexide. Addition of a higher concentration of A23187 (0.1 microM) produced a decreased rate of calcium uptake. Measurement of the time during which ATPase was activated by calcium addition also suggested an increased rate of calcium uptake in the presence of 1 nM A23187 and an inhibition of calcium uptake at a higher concentration of the ionophore (0.1 microM). Ca2+-stimulated ATPase activity and incorporation of 32Pi from [gamma-32P]ATP into sarcoplasmic reticular proteins were increased by A23187 at concentrations of 1 nM or greater. An increased coupling of calcium uptake to ATP hydrolysis was observed at 1 nM A23187, while concentrations of the ionophore greater than or equal to 10 nM produced a decreased coupling. Addition of an inhibitor of cyclic AMP-dependent protein kinase decreased the rate of calcium uptake, and this inhibition was reversed in a concentration-dependent manner by 0.01–1 nM A23187. These data suggest that A23187 can activate a mechanism involving the calcium-dependent phosphorylation of protein that may regulate the activity of the calcium uptake system of the sarcoplasmic reticulum. These observations appear to provide an explanation for some of the contractile effects of A23187 in intact cardiac muscle that suggest that treatment with the ionophore results in an increased sequestration of calcium from the cytoplasm.

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