scholarly journals Characterization of the ArsRS Regulon of Helicobacter pylori, Involved in Acid Adaptation

2006 ◽  
Vol 188 (10) ◽  
pp. 3449-3462 ◽  
Author(s):  
Michael Pflock ◽  
Nadja Finsterer ◽  
Biju Joseph ◽  
Hans Mollenkopf ◽  
Thomas F. Meyer ◽  
...  
Keyword(s):  
Helicobacter Pylori ◽  
Response Regulator ◽  
Transcriptional Profiling ◽  
Acid Resistance ◽  
Two Component System ◽  
Gene Encoding ◽  
Acid Adaptation ◽  
Genes Encoding ◽  
H Pylori ◽  
A Site

ABSTRACT The human gastric pathogen Helicobacter pylori is extremely well adapted to the highly acidic conditions encountered in the stomach. The pronounced acid resistance of H. pylori relies mainly on the ammonia-producing enzyme urease; however, urease-independent mechanisms are likely to contribute to acid adaptation. Acid-responsive gene regulation is mediated at least in part by the ArsRS two-component system consisting of the essential OmpR-like response regulator ArsR and the nonessential cognate histidine kinase ArsS, whose autophosphorylation is triggered in response to low pH. In this study, by global transcriptional profiling of an ArsS-deficient H. pylori mutant grown at pH 5.0, we define the ArsR∼P-dependent regulon consisting of 109 genes, including the urease gene cluster, the genes encoding the aliphatic amidases AmiE and AmiF, and the rocF gene encoding arginase. We show that ArsR∼P controls the acid-induced transcription of amiE and amiF by binding to extended regions located upstream of the −10 box of the respective promoters. In contrast, transcription of rocF is repressed by ArsR∼P at neutral, acidic, and mildly alkaline pH via high-affinity binding of the response regulator to a site overlapping the promoter of the rocF gene.

scholarly journals The Orphan Response Regulator HP1021 of Helicobacter pylori Regulates Transcription of a Gene Cluster Presumably Involved in Acetone Metabolism

2007 ◽  
Vol 189 (6) ◽  
pp. 2339-2349 ◽  
Author(s):  
Michael Pflock ◽  
Melanie Bathon ◽  
Jennifer Schär ◽  
Stefanie Müller ◽  
Hans Mollenkopf ◽  
...  
Keyword(s):  
Helicobacter Pylori ◽  
Gene Cluster ◽  
Response Regulator ◽  
Transcriptional Profiling ◽  
Acid Resistance ◽  
Housekeeping Genes ◽  
Open Reading Frames ◽  
Considerable Impact ◽  
Two Component Systems ◽  
H Pylori

ABSTRACT Helicobacter pylori is a gastric pathogen for which no nonhuman reservoir is known. In accordance with the tight adaptation to its unique habitat, the human stomach, H. pylori is endowed with a very restricted repertoire of regulatory proteins. Nevertheless, the three complete two-component systems of H. pylori were shown to be involved in the regulation of important virulence traits like motility and acid resistance and in the control of metal homeostasis. HP1021 is an orphan response regulator with an atypical receiver domain whose inactivation has a considerable impact on the growth of H. pylori. Here we report the identification of HP1021-regulated genes by whole-genome transcriptional profiling. We show that the transcription of the essential housekeeping genes nifS and nifU, which are required for the assembly of Fe-S clusters, is activated by HP1021. Furthermore, we demonstrate that the expression of a gene cluster comprising open reading frames hp0690 to hp0693 and hp0695 to hp0697 which is probably involved in acetone metabolism is strongly upregulated by HP1021. Evidence is provided for a direct regulation of the hp0695-to-hp0697 operon by the binding of HP1021 to its promoter region.

scholarly journals Transcriptional profiling of Helicobacter pylori Fur- and iron-regulated gene expression

Microbiology ◽  
2005 ◽  
Vol 151 (2) ◽  
pp. 533-546 ◽  
Author(s):  
Florian D. Ernst ◽  
Stefan Bereswill ◽  
Barbara Waidner ◽  
Jeroen Stoof ◽  
Ulrike Mäder ◽  
...  
Keyword(s):  
Helicobacter Pylori ◽  
Iron Homeostasis ◽  
Transcriptional Profiling ◽  
Northern Hybridization ◽  
Intracellular Iron ◽  
Iron Storage ◽  
Gastric Colonization ◽  
Genes Encoding ◽  
H Pylori ◽  
Regulated Gene Expression

Intracellular iron homeostasis is a necessity for almost all living organisms, since both iron restriction and iron overload can result in cell death. The ferric uptake regulator protein, Fur, controls iron homeostasis in most Gram-negative bacteria. In the human gastric pathogen Helicobacter pylori, Fur is thought to have acquired extra functions to compensate for the relative paucity of regulatory genes. To identify H. pylori genes regulated by iron and Fur, we used DNA array-based transcriptional profiling with RNA isolated from H. pylori 26695 wild-type and fur mutant cells grown in iron-restricted and iron-replete conditions. Sixteen genes encoding proteins involved in metal metabolism, nitrogen metabolism, motility, cell wall synthesis and cofactor synthesis displayed iron-dependent Fur-repressed expression. Conversely, 16 genes encoding proteins involved in iron storage, respiration, energy metabolism, chemotaxis, and oxygen scavenging displayed iron-induced Fur-dependent expression. Several Fur-regulated genes have been previously shown to be essential for acid resistance or gastric colonization in animal models, such as those encoding the hydrogenase and superoxide dismutase enzymes. Overall, there was a partial overlap between the sets of genes regulated by Fur and those previously identified as growth-phase, iron or acid regulated. Regulatory patterns were confirmed for five selected genes using Northern hybridization. In conclusion, H. pylori Fur is a versatile regulator involved in many pathways essential for gastric colonization. These findings further delineate the central role of Fur in regulating the unique capacity of H. pylori to colonize the human stomach.

scholarly journals Identification of Target Genes Regulated by the Two-Component System HP166-HP165 of Helicobacter pylori

2002 ◽  
Vol 184 (2) ◽  
pp. 350-362 ◽  
Author(s):  
Patricia Dietz ◽  
Gabriele Gerlach ◽  
Dagmar Beier
Keyword(s):  
Helicobacter Pylori ◽  
Target Genes ◽  
Essential Gene ◽  
Response Regulator ◽  
Transcriptional Level ◽  
Two Component System ◽  
Component System ◽  
Two Component ◽  
H Pylori ◽  
Target Promoters

ABSTRACT Two-component systems are signal transduction systems which enable bacteria to regulate cellular functions in response to changing environmental conditions. In most cases regulation is accomplished on the transcriptional level by a response regulator protein, which, according to the phosphorylation state of its receiver domain, displays different affinities for its target promoters. Here we describe identification of genes regulated by the two-component system HP166-HP165 of Helicobacter pylori and characterization of the corresponding target promoters. We demonstrated that expression of the HP166-HP165 two-component system is negatively autoregulated under conditions favoring autophosphorylation of the histidine kinase. Furthermore, we found that response regulator HP166 activates transcription of genes encoding a protein family with an unknown function present in H. pylori 26695, as well as an operon composed of five H. pylori-specific genes. While open reading frame HP166 is an essential gene, the target genes of the response regulator are not required for growth under in vitro culture conditions.

scholarly journals Intra- and Interspecies Signaling betweenStreptococcus salivarius and Streptococcus pyogenes Mediated by SalA and SalA1 Lantibiotic Peptides

2001 ◽  
Vol 183 (13) ◽  
pp. 3931-3938 ◽  
Author(s):  
M. Upton ◽  
J. R. Tagg ◽  
P. Wescombe ◽  
H. F. Jenkinson
Keyword(s):  
Streptococcus Pyogenes ◽  
Response Regulator ◽  
Genetic Locus ◽  
Two Component System ◽  
Peptide Modification ◽  
Insertional Inactivation ◽  
Two Component ◽  
Genes Encoding ◽  
Dose Dependent

ABSTRACT Streptococcus salivarius 20P3 produces a 22-amino-acid residue lantibiotic, designated salivaricin A (SalA), that inhibits the growth of a range of streptococci, including all strains ofStreptococcus pyogenes. Lantibiotic production is associated with the sal genetic locus comprisingsalA, the lantibiotic structural gene; salBCTXgenes encoding peptide modification and export machinery proteins; andsalYKR genes encoding a putative immunity protein and two-component sensor-regulator system. Insertional inactivation ofsalB in S. salivarius 20P3 resulted in abrogation of SalA peptide production, of immunity to SalA, and ofsalA transcription. Addition of exogenous SalA peptide tosalB mutant cultures induced dose-dependent expression ofsalA mRNA (0.2 kb), demonstrating that SalA production was normally autoregulated. Inactivation of salR encoding the response regulator of the SalKR two-component system led to reduced production of, and immunity to, SalA. The sal genetic locus was also present in S. pyogenes SF370 (M type 1), but because of a deletion across the salBCT genes, the corresponding lantibiotic peptide, designated SalA1, was not produced. However, in S. pyogenes T11 (M type 4) the sallocus gene complement was apparently complete, and active SalA1 peptide was synthesized. Exogenously added SalA1 peptide from S. pyogenes T11 induced salA1 transcription in S. pyogenes SF370 and in an isogenic S. pyogenes T11salB mutant and salA transcription in S. salivarius 20P3 salB. Thus, SalA and SalA1 are examples of streptococcal lantibiotics whose production is autoregulated. These peptides act as intra- and interspecies signaling molecules, modulating lantibiotic production and possibly influencing streptococcal population ecology in the oral cavity.

scholarly journals Basal Body Structures Differentially Affect Transcription of RpoN- and FliA-Dependent Flagellar Genes in Helicobacter pylori

2015 ◽  
Vol 197 (11) ◽  
pp. 1921-1930 ◽  
Author(s):  
Jennifer Tsang ◽  
Timothy R. Hoover
Keyword(s):  
Helicobacter Pylori ◽  
Basal Body ◽  
Protein Interactions ◽  
Transcript Levels ◽  
Content Type ◽  
Genes Encoding ◽  
H Pylori ◽  
Flagellar Biogenesis ◽  
Flagellar Genes

ABSTRACTFlagellar biogenesis inHelicobacter pyloriis regulated by a transcriptional hierarchy governed by three sigma factors, RpoD (σ80), RpoN (σ54), and FliA (σ28), that temporally coordinates gene expression with the assembly of the flagellum. Previous studies showed that loss of flagellar protein export apparatus components inhibits transcription of flagellar genes. The FlgS/FlgR two-component system activates transcription of RpoN-dependent genes though an unknown mechanism. To understand better the extent to which flagellar gene regulation is coupled to flagellar assembly, we disrupted flagellar biogenesis at various points and determined how these mutations affected transcription of RpoN-dependent (flaBandflgE) and FliA-dependent (flaA) genes. The MS ring (encoded byfliF) is one of the earliest flagellar structures assembled. Deletion offliFresulted in the elimination of RpoN-dependent transcripts and an ∼4-fold decrease inflaAtranscript levels. FliH is a cytoplasmic protein that functions with the C ring protein FliN to shuttle substrates to the export apparatus. Deletions offliHand genes encoding C ring components (fliMandfliY) decreased transcript levels offlaBandflgEbut had little or no effect on transcript levels offlaA. Transcript levels offlaBandflgEwere elevated in mutants where genes encoding rod proteins (fliEandflgBC) were deleted, while transcript levels offlaAwas reduced ∼2-fold in both mutants. We propose that FlgS responds to an assembly checkpoint associated with the export apparatus and that FliH and one or more C ring component assist FlgS in engaging this flagellar structure.IMPORTANCEThe mechanisms used by bacteria to couple transcription of flagellar genes with assembly of the flagellum are poorly understood. The results from this study identified components of theH. pyloriflagellar basal body that either positively or negatively affect expression of RpoN-dependent flagellar genes. Some of these basal body proteins may interact directly with regulatory proteins that control transcription of theH. pyloriRpoN regulon, a hypothesis that can be tested by examining protein-protein interactionsin vitro.

scholarly journals Small Molecule Inhibitors of the Response Regulator ArsR Exhibit Bactericidal Activity against Helicobacter pylori

2020 ◽  
Vol 8 (4) ◽  
pp. 503 ◽  
Author(s):  
Andrés González ◽  
Javier Casado ◽  
Eduardo Chueca ◽  
Sandra Salillas ◽  
Adrián Velázquez-Campoy ◽  
...  
Keyword(s):  
Helicobacter Pylori ◽  
Antibiotic Resistance ◽  
High Throughput Screening ◽  
Lithocholic Acid ◽  
Response Regulator ◽  
Bacterial Pathogen ◽  
Antimicrobial Effect ◽  
Chemical Library ◽  
Secondary Bile Acid ◽  
H Pylori

Helicobacter pylori is considered the most prevalent bacterial pathogen in humans. The increasing antibiotic resistance evolved by this microorganism has raised alarm bells worldwide due to the significant reduction in the eradication rates of traditional standard therapies. A major challenge in this antibiotic resistance crisis is the identification of novel microbial targets whose inhibitors can overcome the currently circulating resistome. In the present study, we have validated the use of the essential response regulator ArsR as a novel and promising therapeutic target against H. pylori infections. A high-throughput screening of a repurposing chemical library using a fluorescence-based thermal shift assay identified several ArsR binders. At least four of these low-molecular weight compounds noticeably inhibited the DNA binding activity of ArsR and showed bactericidal effects against antibiotic-resistant strains of H. pylori. Among the ArsR inhibitors, a human secondary bile acid, lithocholic acid, quickly destroyed H. pylori cells and exhibited partial synergistic action in combination with clarithromycin or levofloxacin, while the antimicrobial effect of this compound against representative members of the normal human microbiota such as Escherichia coli and Staphylococcus epidermidis appeared irrelevant. Our results enhance the battery of novel therapeutic tools against refractory infections caused by multidrug-resistant H. pylori strains.

scholarly journals Expanding Allelic Diversity of Helicobacter pylori vacA

1998 ◽  
Vol 36 (9) ◽  
pp. 2597-2603 ◽  
Author(s):  
Leen-Jan van Doorn ◽  
Céu Figueiredo ◽  
Ricardo Sanna ◽  
Salvador Pena ◽  
Peter Midolo ◽  
...  
Keyword(s):  
Helicobacter Pylori ◽  
Direct Sequencing ◽  
Allelic Diversity ◽  
Pcr Primers ◽  
Epidemiological Studies ◽  
Sequence Alignments ◽  
Gene Encoding ◽  
The World ◽  
Probe Assay ◽  
H Pylori

The diversity of the gene encoding the vacuolating cytotoxin (vacA) of Helicobacter pylori was analyzed in 98 isolates obtained from different geographic locations. The studies focused on variation in the previously defined s and m regions ofvacA, as determined by PCR and direct sequencing. Phylogenetic analysis revealed the existence of four distinct types of s-region alleles: aside from the previously described s1a, s1b, and s2 allelic types, a novel subtype, designated s1c, was found. Subtype s1c was observed exclusively in isolates from East Asia and appears to be the major s1 allele in that part of the world. Three different allelic forms (m1, m2a, and m2b) were detected in the m region. On the basis of sequence alignments, universal PCR primers that allow effective amplification of the s and m regions from H. pyloriisolates from all over the world were defined. Amplimers were subsequently analyzed by reverse hybridization onto a line probe assay (LiPA) that allows the simultaneous and highly specific hybridization of the different vacA s- and m-region alleles and tests for the presence of the cytotoxin-associated gene (cagA). This PCR-LiPA method permits rapid analysis of the vacA andcagA status of H. pylori strains for clinical and epidemiological studies and will facilitate identification of any further variations.

scholarly journals Identification of novel bacterial urease inhibitors through molecular shape and structure based virtual screening approaches

RSC Advances ◽  
2020 ◽  
Vol 10 (27) ◽  
pp. 16061-16070
Author(s):  
Muhammad Imran ◽  
Saba Waqar ◽  
Koji Ogata ◽  
Mahmood Ahmed ◽  
Zobia Noreen ◽  
...  
Keyword(s):  
Helicobacter Pylori ◽  
Virtual Screening ◽  
Acid Resistance ◽  
Molecular Shape ◽  
Urease Inhibitors ◽  
H Pylori ◽  
Screening Approaches

The enzyme urease is an essential colonizing factor of the notorious carcinogenic pathogen Helicobacter pylori (H. pylori), conferring acid resistance to the bacterium.

scholarly journals Colonization and Inflammation Deficiencies in Mongolian Gerbils Infected by Helicobacter pylori Chemotaxis Mutants

2005 ◽  
Vol 73 (3) ◽  
pp. 1820-1827 ◽  
Author(s):  
David J. McGee ◽  
Melanie L. Langford ◽  
Emily L. Watson ◽  
J. Elliot Carter ◽  
Yu-Ting Chen ◽  
...  
Keyword(s):  
Helicobacter Pylori ◽  
Immune Cell ◽  
Response Regulator ◽  
Critical Role ◽  
Mongolian Gerbils ◽  
Wild Type ◽  
In The Wild ◽  
H Pylori

ABSTRACT Helicobacter pylori causes disease in the human stomach and in mouse and gerbil stomach models. Previous results have shown that motility is critical for H. pylori to colonize mice, gerbils, and other animal models. The role of chemotaxis, however, in colonization and disease is less well understood. Two genes in the H. pylori chemotaxis pathway, cheY and tlpB, which encode the chemotaxis response regulator and a methyl-accepting chemoreceptor, respectively, were disrupted. The cheY mutation was complemented with a wild-type copy of cheY inserted into the chromosomal rdxA gene. The cheY mutant lost chemotaxis but retained motility, while all other strains were motile and chemotactic in vitro. These strains were inoculated into gerbils either alone or in combination with the wild-type strain, and colonization and inflammation were assessed. While the cheY mutant completely failed to colonize gerbil stomachs, the tlpB mutant colonized at levels similar to those of the wild type. With the tlpB mutant, there was a substantial decrease in inflammation in the gerbil stomach compared to that with the wild type. Furthermore, there were differences in the numbers of each immune cell in the tlpB-mutant-infected stomach: the ratio of lymphocytes to neutrophils was about 8 to 1 in the wild type but only about 1 to 1 in the mutant. These results suggest that the TlpB chemoreceptor plays an important role in the inflammatory response while the CheY chemotaxis regulator plays a critical role in initial colonization. Chemotaxis mutants may provide new insights into the steps involved in H. pylori pathogenesis.

scholarly journals GadY, a Small-RNA Regulator of Acid Response Genes in Escherichia coli

2004 ◽  
Vol 186 (20) ◽  
pp. 6698-6705 ◽  
Author(s):  
Jason A. Opdyke ◽  
Ju-Gyeong Kang ◽  
Gisela Storz
Keyword(s):  
Escherichia Coli ◽  
Stationary Phase ◽  
Small Rna ◽  
Acid Resistance ◽  
Base Pairs ◽  
Gene Encoding ◽  
Mrna Accumulation ◽  
Long Form ◽  
Genes Encoding ◽  
Opposite Strand

ABSTRACT A previous bioinformatics-based search for small RNAs in Escherichia coli identified a novel RNA named IS183. The gene encoding this small RNA is located between and on the opposite strand of genes encoding two transcriptional regulators of the acid response, gadX (yhiX) and gadW (yhiW). Given that IS183 is encoded in the gad gene cluster and because of its role in regulating acid response genes reported here, this RNA has been renamed GadY. We show that GadY exists in three forms, a long form consisting of 105 nucleotides and two processed forms, consisting of 90 and 59 nucleotides. The expression of this small RNA is highly induced during stationary phase in a manner that is dependent on the alternative sigma factor σS. Overexpression of the three GadY RNA forms resulted in increased levels of the mRNA encoding the GadX transcriptional activator, which in turn caused increased levels of the GadA and GadB glutamate decarboxylases. A promoter mutation which abolished gadY expression resulted in a reduction in the amount of gadX mRNA during stationary phase. The gadY gene was shown to overlap the 3′ end of the gadX gene, and this overlap region was found to be necessary for the GadY-dependent accumulation of gadX mRNA. We suggest that during stationary phase, GadY forms base pairs with the 3′-untranslated region of the gadX mRNA and confers increased stability, allowing for gadX mRNA accumulation and the increased expression of downstream acid resistance genes.

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