scholarly journals Pyrazolopyrimidinediones Are Selective Agents for Helicobacter pylori That Suppress Growth through Inhibition of Glutamate Racemase (MurI)

2009 ◽  
Vol 53 (8) ◽  
pp. 3331-3336 ◽  
Author(s):  
B. L. M. de Jonge ◽  
A. Kutschke ◽  
M. Uria-Nickelsen ◽  
H. D. Kamp ◽  
S. D. Mills
Keyword(s):  
Helicobacter Pylori ◽  
Peptidoglycan Biosynthesis ◽  
Glutamate Racemase ◽  
Selective Agents ◽  
Essential Enzyme ◽  
H Pylori ◽  
Selective Therapy ◽  
High Degree

ABSTRACT Pyrazolopyrimidinediones are a novel series of compounds that inhibit growth of Helicobacter pylori specifically. Using a variety of methods, advanced analogues were shown to suppress the growth of H. pylori through the inhibition of glutamate racemase, an essential enzyme in peptidoglycan biosynthesis. The high degree of selectivity of the series for H. pylori makes these compounds attractive candidates for novel H. pylori-selective therapy.

scholarly journals Pyridodiazepine Amines Are Selective Therapeutic Agents for Helicobacter pylori by Suppressing Growth through Inhibition of Glutamate Racemase but Are Predicted To Require Continuous Elevated Levels in Plasma To Achieve Clinical Efficacy

2015 ◽  
Vol 59 (4) ◽  
pp. 2337-2342 ◽  
Author(s):  
Boudewijn L. M. de Jonge ◽  
Amy Kutschke ◽  
Joseph V. Newman ◽  
Michael T. Rooney ◽  
Wei Yang ◽  
...  
Keyword(s):  
Helicobacter Pylori ◽  
Therapeutic Agents ◽  
Infection Model ◽  
Content Type ◽  
Peptidoglycan Biosynthesis ◽  
Glutamate Racemase ◽  
Mouse Infection Model ◽  
Exposure Levels ◽  
H Pylori ◽  
Extended Exposure

ABSTRACTA pyridodiazepine amine inhibitor ofHelicobacter pyloriglutamate racemase (MurI) was characterized. The compound was selectively active againstH. pylori, and growth suppression was shown to be mediated through the inhibition of MurI by several methods. In killing kinetics experiments, the compound showed concentration-independent activity, with about a 2-log loss of viability in 24 h. A demonstration of efficacy in a mouse infection model was attempted but not achieved, and this was attributed to the failure to attain extended exposure levels above the MIC for >95% of the time. This index and magnitude were derived from pharmacokinetic-pharmacodynamic (PK-PD) studies with amoxicillin, another inhibitor of peptidoglycan biosynthesis that showed slow killing kinetics similar to those of the pyridodiazepine amines. These studies indicate that MurI and other enzymes involved in peptidoglycan biosynthesis may be less desirable targets for monotherapy directed againstH. pyloriif once-a-day dosing is required.

scholarly journals Enzymes Associated with Reductive Activation and Action of Nitazoxanide, Nitrofurans, and Metronidazole in Helicobacter pylori

2002 ◽  
Vol 46 (7) ◽  
pp. 2116-2123 ◽  
Author(s):  
Gary Sisson ◽  
Avery Goodwin ◽  
Ausra Raudonikiene ◽  
Nicky J. Hughes ◽  
Asish K. Mukhopadhyay ◽  
...  
Keyword(s):  
Helicobacter Pylori ◽  
Reductase Activity ◽  
Loss Of Function ◽  
Reductive Activation ◽  
E Coli ◽  
Redox Active ◽  
Bactericidal Effects ◽  
Pyruvate Oxidoreductase ◽  
Essential Enzyme ◽  
H Pylori

ABSTRACT Nitazoxanide (NTZ) is a redox-active nitrothiazolyl-salicylamide prodrug that kills Helicobacter pylori and also many anaerobic bacterial, protozoan, and helminthic species. Here we describe development and use of a spectrophotometric assay, based on nitroreduction of NTZ at 412 nm, to identify H. pylori enzymes responsible for its activation and mode of action. Three enzymes that reduce NTZ were identified: two related NADPH nitroreductases, which also mediate susceptibility to metronidazole (MTZ) (RdxA and FrxA), and pyruvate oxidoreductase (POR). Recombinant His-tagged RdxA, FrxA, and POR, overexpressed in nitroreductase-deficient Escherichia coli, each rapidly reduced NTZ, whereas only FrxA and to a lesser extent POR reduced nitrofuran substrates (furazolidone, nitrofurantoin, and nitrofurazone). POR exhibited no MTZ reductase activity either in extracts of H. pylori or following overexpression in E. coli; RdxA exhibited no nitrofuran reductase activity, and FrxA exhibited no MTZ reductase activity. Analysis of mutation to rifampin resistance (Rifr) indicated that NTZ was not mutagenic and that nitrofurans were only weakly mutagenic. Alkaline gel DNA electrophoresis indicated that none of these prodrugs caused DNA breakage. In contrast, MTZ caused DNA damage and was strongly mutagenic. We conclude that POR, an essential enzyme, is responsible for most or all of the bactericidal effects of NTZ against H. pylori. While loss-of-function mutations in rdxA and frxA produce a Mtzr phenotype, they do not contribute much to the innate susceptibility of H. pylori to NTZ or nitrofurans.

scholarly journals PCR-RFLP typing of ureC from Helicobacter pylori isolated in Argentina from gastric biopsies before and after treatment with clarithromycin

1997 ◽  
Vol 118 (2) ◽  
pp. 119-124 ◽  
Author(s):  
G. G. STONE ◽  
D. SHORTRIDGE ◽  
R. K. FLAMM ◽  
J. BEYER ◽  
D. STAMLER ◽  
...  
Keyword(s):  
Helicobacter Pylori ◽  
Duodenal Ulcers ◽  
Rflp Type ◽  
Pcr Rflp ◽  
Before And After ◽  
Gastric Biopsies ◽  
Non Ulcer Dyspepsia ◽  
H Pylori ◽  
High Degree ◽  
Rflp Typing

A clinical trial was conducted in Argentina to determine the efficacy of clarithromycin plus lansoprazole for the treatment of Helicobacter pylori in duodenal ulcers and non-ulcer dyspepsia. PCR–RFLP was conducted on an 820-bp amplified product of the ureC gene of H. pylori to determine the genetic heterogeneity of 83 pretreatment and 21 post-treatment isolates. Twelve different restriction patterns were observed when digested with Sau 3A or Hha I, resulting in 40 different RFLP types. Comparison of isolates before treatment to after treatment showed that 20 of 20 patients had the same RFLP type. In addition, the presence of the cytotoxin-associated gene (cagA) and the vacuolating gene (vacA) were determined. All pretreatment isolates were positive for vacA whereas 75% of the pretreatment isolates were positive for cagA. The results of this study indicate that a high degree of heterogeneity exists among H. pylori and that infection is not limited to a small number of RFLP types.

scholarly journals Structure-Based Inhibitors Exhibit Differential Activities againstHelicobacter pyloriandEscherichia coliUndecaprenyl Pyrophosphate Synthases

2008 ◽  
Vol 2008 ◽  
pp. 1-6 ◽  
Author(s):  
Chih-Jung Kuo ◽  
Rey-Ting Guo ◽  
I-Lin Lu ◽  
Hun-Ge Liu ◽  
Su-Ying Wu ◽  
...  
Keyword(s):  
Helicobacter Pylori ◽  
Gastric Epithelium ◽  
Peptic Ulcers ◽  
Farnesyl Pyrophosphate ◽  
Isopentenyl Pyrophosphate ◽  
E Coli ◽  
Peptidoglycan Biosynthesis ◽  
New Antibiotics ◽  
H Pylori ◽  
Bacterial Peptidoglycan

Helicobacter pyloricolonizes the human gastric epithelium and causes diseases such as gastritis, peptic ulcers, and stomach cancer. Undecaprenyl pyrophosphate synthase (UPPS), which catalyzes consecutive condensation reactions of farnesyl pyrophosphate with eight isopentenyl pyrophosphate to form lipid carrier for bacterial peptidoglycan biosynthesis, represents a potential target for developing new antibiotics. In this study, we solved the crystal structure ofH. pyloriUPPS and performed virtual screening of inhibitors from a library of 58,635 compounds. Two hits were found to exhibit differential activities againstHelicobacter pyloriandEscherichia coliUPPS, giving the possibility of developing antibiotics specially targeting pathogenicH. pyloriwithout killing the intestinalE. coli.

scholarly journals Helicobacter pylori Expresses an Autolytic Enzyme: Gene Identification, Cloning, and Theoretical Protein Structure

2002 ◽  
Vol 184 (22) ◽  
pp. 6270-6279 ◽  
Author(s):  
Eleonora Marsich ◽  
Pierfrancesco Zuccato ◽  
Sonia Rizzi ◽  
Amedeo Vetere ◽  
Enrico Tonin ◽  
...  
Keyword(s):  
Helicobacter Pylori ◽  
Bacteriophage T4 ◽  
Three Dimensional ◽  
Gene Identification ◽  
Gram Negative Bacteria ◽  
Hypothetical Gene ◽  
Autolytic Enzyme ◽  
Genetic Features ◽  
H Pylori ◽  
High Degree

ABSTRACT Helicobacter pylori is an important pathogen of the gastric system. The clinical outcome of infection is thought to be correlated with some genetic features of the bacterium. However, due to the extreme genetic variability of this organism, it is hard to draw definitive conclusions concerning its virulence factors. Here we describe a novel H. pylori gene which expresses an autolytic enzyme that is also capable of degrading the cell walls of both gram-positive and gram-negative bacteria. We designated this gene lys. We found this gene and observed its expression in a number of unrelated clinical strains, a fact that suggests that it is well conserved in the species. A comparison of the nucleotide sequences of lys and the hypothetical gene HP0339 from H. pylori strain ATCC 26695 revealed almost total identity, except for the presence of an insertion consisting of 24 nucleotides in the lys sequence. The coding sequences of lys and HP0339 show a high degree of homology with the coding sequence of bacteriophage T4 lysozyme. Because of this similarity, it was possible to model the three-dimensional structures of both the lys and HP0339 products.

scholarly journals A RecB-Like Helicase in Helicobacter pylori Is Important for DNA Repair and Host Colonization

2008 ◽  
Vol 77 (1) ◽  
pp. 286-291 ◽  
Author(s):  
Ge Wang ◽  
Robert J. Maier
Keyword(s):  
Dna Damage ◽  
Helicobacter Pylori ◽  
Mutant Strain ◽  
Dna Recombination ◽  
Acid Stress ◽  
Infection Model ◽  
Mouse Infection Model ◽  
Genes Encoding ◽  
H Pylori ◽  
High Degree

ABSTRACT The human gastric pathogen Helicobacter pylori encounters frequent oxidative and acid stress in its specific niche, and this causes bacterial DNA damage. H. pylori exhibits a very high degree of DNA recombination, which is required for repairing both DNA double-stranded (ds) breaks and blocked replication forks. Nevertheless, few genes encoding components of DNA recombinational repair processes have been identified in H. pylori. An H. pylori mutant defective in a putative helicase gene (HP1553) was constructed and characterized herein. The HP1553 mutant strain was much more sensitive to mitomycin C than the WT strain, indicating that HP1553 is required for repair of DNA ds breaks. Disruption of HP1553 resulted in a significant decrease in the DNA recombination frequency, suggesting that HP1553 is involved in DNA recombination processes, probably functioning as a RecB-like helicase. HP1553 was shown to be important for H. pylori protection against oxidative stress-induced DNA damage, as the exposure of the HP1553 mutant cells to air for 6 h caused significant fragmentation of genomic DNA and led to cell death. In a mouse infection model, the HP1553 mutant strain displayed a greatly reduced ability to colonize the host stomachs, indicating that HP1553 plays a significant role in H. pylori survival/colonization in the host.

scholarly journals Decrypting a cryptic allosteric pocket in H. pylori glutamate racemase

2021 ◽  
Vol 4 (1) ◽  
Author(s):  
Pratik Rajesh Chheda ◽  
Grant T. Cooling ◽  
Sondra F. Dean ◽  
Jonah Propp ◽  
Kathryn F. Hobbs ◽  
...  
Keyword(s):  
Life Cycle ◽  
Experimental Methods ◽  
Mechanisms Of Action ◽  
Allosteric Inhibitors ◽  
Coupled Motion ◽  
Glutamate Racemase ◽  
Wide Range ◽  
Essential Enzyme ◽  
H Pylori ◽  
Drug Leads

AbstractOne of our greatest challenges in drug design is targeting cryptic allosteric pockets in enzyme targets. Drug leads that do bind to these cryptic pockets are often discovered during HTS campaigns, and the mechanisms of action are rarely understood. Nevertheless, it is often the case that the allosteric pocket provides the best option for drug development against a given target. In the current studies we present a successful way forward in rationally exploiting the cryptic allosteric pocket of H. pylori glutamate racemase, an essential enzyme in this pathogen’s life cycle. A wide range of computational and experimental methods are employed in a workflow leading to the discovery of a series of natural product allosteric inhibitors which occupy the allosteric pocket of this essential racemase. The confluence of these studies reveals a fascinating source of the allosteric inhibition, which centers on the abolition of essential monomer-monomer coupled motion networks.

scholarly journals Evidence for a Conjugation-Like Mechanism of DNA Transfer in Helicobacter pylori

1998 ◽  
Vol 180 (11) ◽  
pp. 2901-2905 ◽  
Author(s):  
Ernst J. Kuipers ◽  
Dawn A. Israel ◽  
Johannes G. Kusters ◽  
Martin J. Blaser
Keyword(s):  
Helicobacter Pylori ◽  
Genetic Variation ◽  
Dna Transfer ◽  
Cell Contact ◽  
Rapd Pcr ◽  
Dnase Treatment ◽  
H Pylori ◽  
High Degree ◽  
Dna Pcr

ABSTRACT Many strains of Helicobacter pylori are naturally competent for transformation in vitro. Since there is a high degree of genetic variation among H. pylori strains, we sought to determine whether mechanisms of DNA exchange other than transformation exist in these organisms. Studies were done with H. pyloricells that each were resistant to two different antibiotics; the procedure used involved mating of cells on plates or in broth, in the absence or presence of DNase. In each experiment, such matings produced progeny with the markers of both parents. Examination of the full resistance profile and random arbitrarily primed DNA PCR (RAPD-PCR) profiles of the progeny indicated that DNA transfer was bidirectional. DNase treatment reduced but did not eliminate transfer; only the presence of both DNase and a membrane separating the cells did so. For progeny derived from matings in the presence of DNase, antibiotic resistance and RAPD profiles indicated that transfer was unidirectional. DNase-treated cell-free supernatants also did not transform, ruling out transduction. These experiments indicate that both a DNase-sensitive mechanism (transformation) and a DNase-resistant conjugation-like mechanism involving cell-to-cell contact may contribute to DNA transfer between H. pylori cells.

scholarly journals MODERN ASPECTS TO THE PROBLEM OF THE PREVALENCE OF HELICOBACTER PYLORI ASSOCIATED STOMACH DISEASES IN UZBEKISTAN

2021 ◽  
Vol 1 (2) ◽  
pp. 28-30
Author(s):  
Jadida Akhmedjanovna Ismailova ◽  
Akhrorbek A. Yusupbekov
Keyword(s):  
Helicobacter Pylori ◽  
Peptic Ulcer ◽  
Peptic Ulcer Disease ◽  
Eradication Therapy ◽  
Type B ◽  
Genetic Characteristics ◽  
Ulcer Disease ◽  
Stomach Diseases ◽  
H Pylori ◽  
High Degree

Introduction. We studied the regional epidemiological and genetic characteristics of the prevalence of Helicobacter pylori among the population of Uzbekistan. The work is based on the totality of the results of clinical, biochemical, immunological, genetic and instrumental research methods. Materials and Methods. It was established that Uzbekistan belongs to the regions with a high degree of H. pylori infection of the population (80%). 84% of the population of Uzbekistan have a mixed IceA1- / IceA2-genotype CagA. In peptic ulcer disease, the pathogenic strain CagA + VacA s1, VacA m2 and IceA 1,2 prevails, in chronic gastritis (type B) associated with H. pylori, the strain Cag + VacA s1, VacA m2 and IceA 1. Results and Discussion. The level of resistance of H. pylori strains to clarithromycin reaches 13.3%. Prolongation of eradication therapy up to 10 days and the addition of BTD to it makes it possible to increase the efficiency of H. pylori eradication up to 95%. Conclusion. Due to the presence of HP resistance to clarithromycin in 13.3% of cases and taking into account the low effectiveness of triadotherapy (72.5%), it is advisable to use quadritherapy with the inclusion of BTD in the standard of treatment, which contributes to an increase in the eradication efficiency up to 95%.

The rod-to-coccoid body transformation in cultures of Helicobacter pylori

1990 ◽  
Vol 48 (3) ◽  
pp. 626-627
Author(s):  
A. R. Crooker ◽  
W. G. Kraft ◽  
T. L. Beard ◽  
M. C. Myers
Keyword(s):  
Helicobacter Pylori ◽  
Growth Cycle ◽  
Negative Bacterium ◽  
Body Formation ◽  
Coccoid Form ◽  
Spiral Form ◽  
Prolonged Culture ◽  
H Pylori ◽  
Upper Gastrointestinal

Helicobacter pylori is a microaerophilic, gram-negative bacterium found in the upper gastrointestinal tract of humans. There is strong evidence that H. pylori is important in the etiology of gastritis; the bacterium may also be a major predisposing cause of peptic ulceration. On the gastric mucosa, the organism exists as a spiral form with one to seven sheathed flagella at one (usually) or both poles. Short spirals were seen in the first successful culture of the organism in 1983. In 1984, Marshall and Warren reported a coccoid form in older cultures. Since that time, other workers have observed rod and coccal forms in vitro; coccoid forms predominate in cultures 3-7 days old. We sought to examine the growth cycle of H. pylori in prolonged culture and the mode of coccoid body formation.

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