scholarly journals Structural Analyses of Helicobacter Pylori FolC Conducting Glutamation in Folate Metabolism

Crystals ◽  
2019 ◽  
Vol 9 (8) ◽  
pp. 429 ◽  
Author(s):  
Joon Sung Park ◽  
Hyoun Sook Kim ◽  
Sang Ho Park ◽  
Mi Seul Park ◽  
Sung-Min Kang ◽  
...  
Keyword(s):  
Helicobacter Pylori ◽  
Binding Site ◽  
Pathogenic Bacteria ◽  
Sequence Similarity ◽  
Diffraction Method ◽  
Folate Metabolism ◽  
Folylpolyglutamate Synthetase ◽  
Atp Binding Site ◽  
Crystallization Solution ◽  
H Pylori

FolC plays important roles in the folate metabolism of cells by attaching l-Glu to dihydropteroate (DHP) and folate, which are known activities of dihydrofolate synthetase (DHFS) and folylpolyglutamate synthetase (FPGS), respectively. Here, we determined the crystal structure of Helicobacter pylori FolC (HpFolC) at 1.95 Å resolution using the single-wavelength anomalous diffraction method. HpFolC has globular N- and C-terminal domains connected by a single loop, and a binding site for ATP is located between the two domains. Apo-HpFolC was crystallized in the presence of citrate in a crystallization solution, which was held in the ATP-binding site. Structural motifs such as the P-loop and Ω-loop of HpFolC for binding of ATP and two magnesium ions are well conserved in spite of the low overall sequence similarity to other FolC/FPGSs. The Ω-loop would also recognize a folate molecule, and the DHP-binding loop of HpFolC is expected to exhibit a unique recognition mode on DHP, compared with other FolCs. Because human FolC is known to only exhibit FPGS activity, the DHFS activity of bacterial FolC is an attractive target for the eradication of pathogenic bacteria. Consequently, our structural analyses of HpFolC provide a valuable foundation for a universal antibacterial strategy against H. pylori as well as other pathogenic bacteria.

scholarly journals Gastric Microenvironment—A Partnership between Innate Immunity and Gastric Microbiota Tricks Helicobacter pylori

2021 ◽  
Vol 10 (15) ◽  
pp. 3258
Author(s):  
Cristina Oana Mărginean ◽  
Lorena Elena Meliț ◽  
Maria Oana Săsăran
Keyword(s):  
Helicobacter Pylori ◽  
Immune System ◽  
Pathogenic Bacteria ◽  
T Regulatory Cells ◽  
Inflammatory Responses ◽  
Mucosal Barrier ◽  
Pathogen Recognition ◽  
Microenvironmental Factors ◽  
H Pylori ◽  
Major Factors

Helicobacter pylori (H. pylori) carcinogenicity depends on three major factors: bacterial virulence constituents, environmental factors and host’s genetic susceptibility. The relationship between microenvironmental factors and H. pylori virulence factors are incontestable. H. pylori infection has a major impact on both gastric and colonic microbiota. The presence of non-H. pylori bacteria within the gastric ecosystem is particularly important since they might persistently act as an antigenic stimulus or establish a partnership with H. pylori in order to augment the subsequent inflammatory responses. The gastric ecosystem, i.e., microbiota composition in children with H. pylori infection is dominated by Streptoccocus, Neisseria, Rothia and Staphylococcus. The impairment of this ecosystem enhances growth and invasion of different pathogenic bacteria, further impairing the balance between the immune system and mucosal barrier. Moreover, altered microbiota due to H. pylori infection is involved in increasing the gastric T regulatory cells response in children. Since gastric homeostasis is defined by the partnership between commensal bacteria and host’s immune system, this review is focused on how pathogen recognition through toll-like receptors (TLRs—an essential class of pathogen recognition receptors—PRRs) on the surface of macrophages and dendritic cells impact the immune response in the setting of H. pylori infection. Further studies are required for delineate precise role of bacterial community features and of immune system components.

scholarly journals In Vitro Analysis of Protein-Operator Interactions of the NikR and Fur Metal-Responsive Regulators of Coregulated Genes in Helicobacter pylori

2005 ◽  
Vol 187 (22) ◽  
pp. 7703-7715 ◽  
Author(s):  
Isabel Delany ◽  
Raffaele Ieva ◽  
Alice Soragni ◽  
Markus Hilleringmann ◽  
Rino Rappuoli ◽  
...  
Keyword(s):  
Helicobacter Pylori ◽  
Binding Site ◽  
Gene Networks ◽  
Iron Homeostasis ◽  
Molecular Mechanisms ◽  
Target Genes ◽  
Target Sequence ◽  
Gene Promoters ◽  
Direct Role ◽  
H Pylori

ABSTRACT Two important metal-responsive regulators, NikR and Fur, are involved in nickel and iron homeostasis and controlling gene expression in Helicobacter pylori. To date, they have been implicated in the regulation of sets of overlapping genes. We have attempted here dissection of the molecular mechanisms involved in transcriptional regulation of the NikR and Fur proteins, and we investigated protein-promoter interactions of the regulators with known target genes. We show that H. pylori NikR is a tetrameric protein and, through DNase I footprinting analysis, we have identified operators for NikR to which it binds with different affinities in a metal-responsive way. Mapping of the NikR binding site upstream of the urease promoter established a direct role for NikR as a positive regulator of transcription and, through scanning mutagenesis of this binding site, we have determined two subsites that are important for the binding of the protein to its target sequence. Furthermore, by alignment of the operators for NikR, we have shown that the H. pylori protein recognizes a sequence that is distinct from its well-studied orthologue in Escherichia coli. Moreover, we show that NikR and Fur can bind independently at distinct operators and also compete for overlapping operators in some coregulated gene promoters, adding another dimension to the previous suggested link between iron and nickel regulation. Finally, the importance of an interconnection between metal-responsive gene networks for homeostasis is discussed.

scholarly journals Carbonic Anhydrases: New Perspectives on Protein Functional Role and Inhibition in Helicobacter pylori

2021 ◽  
Vol 12 ◽  
Author(s):  
Cristina Campestre ◽  
Viviana De Luca ◽  
Simone Carradori ◽  
Rossella Grande ◽  
Vincenzo Carginale ◽  
...  
Keyword(s):  
Helicobacter Pylori ◽  
Pathogenic Bacteria ◽  
Acid Tolerance ◽  
Membrane Vesicles ◽  
Research Field ◽  
Outer Membrane Vesicles ◽  
Bacterial Toxin ◽  
Carbonic Anhydrases ◽  
Ph Homeostasis ◽  
H Pylori

Our understanding of the function of bacterial carbonic anhydrases (CAs, EC 4.2.1.1) has increased significantly in the last years. CAs are metalloenzymes able to modulate CO2, HCO3– and H+ concentration through their crucial role in catalysis of reversible CO2 hydration (CO2 + H2O ⇄ HCO3– + H+). In all living organisms, CA activity is linked to physiological processes, such as those related to the transport and supply of CO2 or HCO3–, pH homeostasis, secretion of electrolytes, biosynthetic processes and photosynthesis. These important processes cannot be ensured by the very low rate of the non-catalyzed reaction of CO2 hydration. It has been recently shown that CAs are important biomolecules for many bacteria involved in human infections, such as Vibrio cholerae, Brucella suis, Salmonella enterica, Pseudomonas aeruginosa, and Helicobacter pylori. In these species, CA activity promotes microorganism growth and adaptation in the host, or modulates bacterial toxin production and virulence. In this review, recent literature in this research field and some of the above-mentioned issues are discussed, namely: (i) the implication of CAs from bacterial pathogens in determining the microorganism growth and virulence; (ii) the druggability of these enzymes using classical CA inhibitors (CAIs) of the sulfonamide-type as examples; (iii) the role played by Helicobacter pylori CAs in the acid tolerance/adaptation of the microbe within the human abdomen; (iv) the role of CAs played in the outer membrane vesicles spawned by H. pylori in its planktonic and biofilm phenotypes; (v) the possibility of using H. pylori CAIs in combination with probiotic strains as a novel anti-ulcer treatment approach. The latter approach may represent an innovative and successful strategy to fight gastric infections in the era of increasing resistance of pathogenic bacteria to classical antibiotics.

Competitive Inhibition of Quercetin and Apigenin at the ATP Binding site of D-Alanine-D-Alanine Ligase of Helicobacter pylori – A Molecular Modeling Approach

2019 ◽  
Vol 7 (5) ◽  
pp. 340-348 ◽  
Author(s):  
Salam Pradeep Singh ◽  
Chandrabose Selvaraj ◽  
Bolin Kumar Knowar ◽  
Sanjeev Kumar Singh ◽  
Chingakham Brajakishor Singh ◽  
...  
Keyword(s):  
Helicobacter Pylori ◽  
Molecular Modeling ◽  
Binding Site ◽  
Competitive Inhibition ◽  
Atp Binding ◽  
Atp Binding Site ◽  
Modeling Approach

scholarly journals Characterization of a recombinant type II 3-deoxy-D-arabino-heptulosonate-7-phosphate synthase from Helicobacter pylori

2005 ◽  
Vol 390 (1) ◽  
pp. 223-230 ◽  
Author(s):  
Celia J. Webby ◽  
Mark L. Patchett ◽  
Emily J. Parker
Keyword(s):  
Helicobacter Pylori ◽  
Sequence Similarity ◽  
Condensation Reaction ◽  
Enzyme Reaction ◽  
Single Type ◽  
Type I ◽  
Type Ii ◽  
Recombinant Type ◽  
H Pylori ◽  
Phosphate Synthase

DAH7P (3-Deoxy-D-arabino-heptulosonate 7-phosphate) synthase catalyses the condensation reaction between phosphoenolpyruvate (PEP) and D-erythrose 4-phosphate (E4P) as the first committed step in the biosynthesis of aromatic compounds in plants and micro-organisms. Previous work has identified two families of DAH7P synthases based on sequence similarity and molecular mass, with the majority of the mechanistic and structural studies being carried out on the type I paralogues from Escherichia coli. Whereas a number of organisms possess genes encoding both type I and type II DAH7P synthases, the pathogen Helicobacter pylori has only a single, type II, enzyme. Recombinant DAH7P synthase from H. pylori was partially solubilized by co-expression with chaperonins GroEL/GroES in E. coli, and purified to homogeneity. The enzyme reaction follows an ordered sequential mechanism with the following kinetic parameters: Km (PEP), 3 μM; Km (E4P), 6 μM; and kcat, 3.3 s−1. The enzyme reaction involves interaction of the si face of PEP with the re face of E4P. H. pylori DAH7P synthase is not inhibited by phenylalanine, tyrosine, tryptophan or chorismate. EDTA inactivates the enzyme, and activity is restored by a range of bivalent metal ions, including (in order of decreasing effectiveness) Co2+, Mn2+, Ca2+, Mg2+, Cu2+ and Zn2+. Analysis of type II DAH7P synthase sequences reveals several highly conserved motifs, and comparison with the type I enzymes suggests that catalysis by these two enzyme types occurs on a similar active-site scaffold and that the two DAH7P synthase families may indeed be distantly related.

scholarly journals 16S rRNA Mutations That Confer Tetracycline Resistance in Helicobacter pylori Decrease Drug Binding in Escherichia coli Ribosomes

2005 ◽  
Vol 187 (11) ◽  
pp. 3708-3712 ◽  
Author(s):  
Lisa Nonaka ◽  
Sean R. Connell ◽  
Diane E. Taylor
Keyword(s):  
Escherichia Coli ◽  
Helicobacter Pylori ◽  
16S Rrna ◽  
Binding Site ◽  
Tetracycline Resistance ◽  
Drug Binding ◽  
Multicopy Plasmid ◽  
Wild Type ◽  
E Coli ◽  
H Pylori

ABSTRACT Tetracycline resistance in clinical isolates of Helicobacter pylori has been associated with nucleotide substitutions at positions 965 to 967 in the 16S rRNA. We constructed mutants which had different sequences at 965 to 967 in the 16S rRNA gene present on a multicopy plasmid in Escherichia coli strain TA527, in which all seven rrn genes were deleted. The MICs for tetracycline of all mutants having single, double, or triple substitutions at the 965 to 967 region that were previously found in highly resistant H. pylori isolates were higher than that of the mutant exhibiting the wild-type sequence of tetracycline-susceptible H. pylori. The MIC of the mutant with the 965TTC967 triple substitution was 32 times higher than that of the E. coli mutant with the 965AGA967 substitution present in wild-type H. pylori. The ribosomes extracted from the tetracycline-resistant E. coli 965TTC967 variant bound less tetracycline than E. coli with the wild-type H. pylori sequence at this region. The concentration of tetracycline bound to the ribosome was 40% that of the wild type. The results of this study suggest that tetracycline binding to the primary binding site (Tet-1) of the ribosome at positions 965 to 967 is influenced by its sequence patterns, which form the primary binding site for tetracycline.

scholarly journals Helicobacter pylori infection and inflammatory bowel diseases

2021 ◽  
Vol 11 (1) ◽  
pp. 68-78
Author(s):  
Yu. P. Uspenskiy ◽  
N. V. Baryshnikova ◽  
A. N. Suvorov ◽  
A. V. Svarval
Keyword(s):  
Helicobacter Pylori ◽  
Gastric Mucosa ◽  
Inflammatory Bowel Diseases ◽  
Pathogenic Bacteria ◽  
T Cell Response ◽  
Aminosalicylic Acid ◽  
Bowel Diseases ◽  
Inflammatory Bowel ◽  
H Pylori

Helicobacter pylori is detected in the human intestine on average in 35% of clinical cases, but the question about its etiopathogenetic role in intestinal diseases has not been fully investigated. Many scientists study a relationship between the H. pylori persistence and development of various bowel diseases. Diverse viewpoints have been proposed regarding a potential link between H. pylori and inflammatory bowel diseases (IBD). Here we review the data from domestic and foreign studies aimed at examining potential role of H. pylori both as a trigger and protector resulting in the pathogenetic alterations leading to developing Crohn‘s disease and ulcerative colitis. The former is favored by the hypothesis wherein H. pylori may trigger IBD due to potential connection between extragastric infection and its direct damaging action as well as indirect effects contributing to the initiation of oxidative stress, autoimmune aggression and development of intestinal dysbiosis. In addition, the effects of enterohepatic Helicobacter spp. promoting IBD pathogenesis are discussed. The mechanisms underlying the protective role of H. pylori infection may be driven via differentially expressed acute and/or chronic local inflammatory mucosal response able to downmodulate systemic immune responses and suppress autoimmune reactions, as well as skewing host immune response from a pro-inflammatory Th1/Th17 cell-mediated towards regulatory T-cell response. Moreover, it was found that H. pylori may induce production of antibacterial peptides counteracting potentially pathogenic bacteria involved in IBD pathogenesis. In particular, it was found that IBD patients are dominated with moderate active antral gastritis coupled to atrophy, with the peak intensity observed in patients under 30 years of age. Intensity of intestinal metaplasia in the gastric mucosa of IBD patients accounted for by the duration of the disease course. Basal IBD therapy with 5-aminosalicylic acid lowers severity and activity of gastritis, degree of atrophy as well as magnitude H. pylori invasion in the gastric mucosa. There is evidence that 5-aminosalicylic acid-containing drugs may result in a so-called “spontaneous eradication” of H. pylori infection. Extended investigations are required to examine a role of H. pylori in IBD pathogenesis.

scholarly journals T4SS-dependent TLR5 activation by Helicobacter pylori infection

2019 ◽  
Vol 10 (1) ◽  
Author(s):  
Suneesh Kumar Pachathundikandi ◽  
Nicole Tegtmeyer ◽  
Isabelle Catherine Arnold ◽  
Judith Lind ◽  
Matthias Neddermann ◽  
...  
Keyword(s):  
Helicobacter Pylori ◽  
Epithelial Cells ◽  
Pathogenic Bacteria ◽  
Type Iv Secretion ◽  
Downstream Signaling ◽  
Type Iv ◽  
Efficient Control ◽  
H Pylori ◽  
Highly Virulent

AbstractToll-like receptor TLR5 recognizes a conserved domain, termed D1, that is present in flagellins of several pathogenic bacteria but not in Helicobacter pylori. Highly virulent H. pylori strains possess a type IV secretion system (T4SS) for delivery of virulence factors into gastric epithelial cells. Here, we show that one of the H. pylori T4SS components, protein CagL, can act as a flagellin-independent TLR5 activator. CagL contains a D1-like motif that mediates adherence to TLR5+ epithelial cells, TLR5 activation, and downstream signaling in vitro. TLR5 expression is associated with H. pylori infection and gastric lesions in human biopsies. Using Tlr5-knockout and wild-type mice, we show that TLR5 is important for efficient control of H. pylori infection. Our results indicate that CagL, by activating TLR5, may modulate immune responses to H. pylori.

scholarly journals Anti-Helicobacter pylori Activity of a Lactobacillus sp. PW-7 Exopolysaccharide

Foods ◽  
2021 ◽  
Vol 10 (10) ◽  
pp. 2453
Author(s):  
Jingfei Hu ◽  
Xueqing Tian ◽  
Tong Wei ◽  
Hangjie Wu ◽  
Jing Lu ◽  
...  
Keyword(s):  
Helicobacter Pylori ◽  
Hydroxyl Radicals ◽  
Pathogenic Bacteria ◽  
Inhibitory Concentration ◽  
Structural Characteristics ◽  
Reducing Power ◽  
Superoxide Anions ◽  
Dpph Radical ◽  
Approximate Molecular Weight ◽  
H Pylori

Helicobacter pylori is a cause of gastric cancer. We extracted the exopolysaccharide (EPS) of Lactobacillus plajomi PW-7 for antibacterial activity versus H. pylori, elucidating its biological activity and structural characteristics. The minimum inhibitory concentration (MIC) of EPS against H. pylori was 50 mg/mL. Disruption of the cell membranes of pathogenic bacteria by EPS was indicated via the antibacterial mechanism test and confirmed through electron microscopy. EPS also has antioxidant capacity. The IC50 of EPS for 2,2-Diphenyl-1-picrylhydrazyl (DPPH) radical, superoxide anions, and hydroxyl radicals were 300 μg/mL, 180 μg/mL, and 10 mg/mL, respectively. The reducing power of EPS was 2 mg/mL, equivalent to 20 μg/mL of ascorbic acid. EPS is a heteropolysaccharide comprising six monosaccharides, with an approximate molecular weight of 2.33 × 104 Da. Xylose had a significant effect on H. pylori. EPS from L. plajomi PW-7 showed potential as an antibacterial compound and antioxidant, laying a foundation for the development of EPS-based foods.

scholarly journals Isolation of Helicobacter pylori Genes That Modulate Urease Activity

1999 ◽  
Vol 181 (8) ◽  
pp. 2477-2484 ◽  
Author(s):  
David J. McGee ◽  
Carrie A. May ◽  
Rachel M. Garner ◽  
Janette M. Himpsl ◽  
Harry L. T. Mobley
Keyword(s):  
Helicobacter Pylori ◽  
Pathogenic Bacteria ◽  
Urease Activity ◽  
Regulatory Gene ◽  
Dna Helicase ◽  
E Coli ◽  
Dna Library ◽  
Flagellar Biosynthesis ◽  
H Pylori ◽  
High Level

ABSTRACT Helicobacter pylori urease, a nickel-requiring metalloenzyme, hydrolyzes urea to NH3 and CO2. We sought to identify H. pylori genes that modulate urease activity by constructing pHP8080, a plasmid which encodes both H. pylori urease and the NixA nickel transporter. Escherichia coli SE5000 and DH5α transformed with pHP8080 resulted in a high-level urease producer and a low-level urease producer, respectively. An H. pylori DNA library was cotransformed into SE5000 (pHP8080) and DH5α (pHP8080) and was screened for cotransformants expressing either lowered or heightened urease activity, respectively. Among the clones carrying urease-enhancing factors, 21 of 23 contained hp0548, a gene that potentially encodes a DNA helicase found within the cag pathogenicity island, and hp0511, a gene that potentially encodes a lipoprotein. Each of these genes, when subcloned, conferred a urease-enhancing activity in E. coli (pHP8080) compared with the vector control. Among clones carrying urease-decreasing factors, 11 of 13 clones contained the flbA (also known asflhA) flagellar biosynthesis/regulatory gene (hp1041), an lcrD homolog. The LcrD protein family is involved in type III secretion and flagellar secretion in pathogenic bacteria. Almost no urease activity was detected in E. coli (pHP8080) containing the subcloned flbA gene. Furthermore, there was significantly reduced synthesis of the urease structural subunits in E. coli (pHP8080) containing the flbA gene, as determined by Western blot analysis with UreA and UreB antiserum. Thus, flagellar biosynthesis and urease activity may be linked in H. pylori. These results suggest that H. pylori genes may modulate urease activity.

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