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 Virulent Strains of Helicobacter pylori Demonstrate Delayed Phagocytosis and Stimulate Homotypic Phagosome Fusion in Macrophages

2000 ◽  
Vol 191 (1) ◽  
pp. 115-128 ◽  
Author(s):  
Lee-Ann H. Allen ◽  
Larry S. Schlesinger ◽  
Byoung Kang
Keyword(s):  
Helicobacter Pylori ◽  
Mononuclear Phagocytes ◽  
Gastric Epithelium ◽  
Type I ◽  
Causative Role ◽  
Type Ii ◽  
Duodenal Ulcers ◽  
H Pylori ◽  
Phagosome Fusion ◽  
Bacterial Protein Synthesis

Helicobacter pylori colonizes the gastric epithelium of ∼50% of the world's population and plays a causative role in the development of gastric and duodenal ulcers. H. pylori is phagocytosed by mononuclear phagocytes, but the internalized bacteria are not killed and the reasons for this host defense defect are unclear. We now show using immunofluorescence and electron microscopy that H. pylori employs an unusual mechanism to avoid phagocytic killing: delayed entry followed by homotypic phagosome fusion. Unopsonized type I H. pylori bound readily to macrophages and were internalized into actin-rich phagosomes after a lag of ∼4 min. Although early (10 min) phagosomes contained single bacilli, H. pylori phagosomes coalesced over the next ∼2 h. The resulting “megasomes” contained multiple viable organisms and were stable for 24 h. Phagosome–phagosome fusion required bacterial protein synthesis and intact host microtubules, and both chloramphenicol and nocodazole increased killing of intracellular H. pylori. Type II strains of H. pylori are less virulent and lack the cag pathogenicity island. In contrast to type I strains, type II H. pylori were rapidly ingested and killed by macrophages and did not stimulate megasome formation. Collectively, our data suggest that megasome formation is an important feature of H. pylori pathogenesis.

scholarly journals The fdxA Ferredoxin Gene Can Down-Regulate frxA Nitroreductase Gene Expression and Is Essential in Many Strains of Helicobacter pylori

2003 ◽  
Vol 185 (9) ◽  
pp. 2927-2935 ◽  
Author(s):  
Asish K. Mukhopadhyay ◽  
Jin-Yong Jeong ◽  
Daiva Dailidiene ◽  
Paul S. Hoffman ◽  
Douglas E. Berg
Keyword(s):  
Helicobacter Pylori ◽  
Metabolic Regulation ◽  
Metabolic Networks ◽  
Type I ◽  
Type Ii ◽  
Phenotypic Manifestation ◽  
Great Genetic Diversity ◽  
H Pylori ◽  
High Level ◽  
Homeostatic Mechanisms

ABSTRACT Very few examples of metabolic regulation are known in the gastric pathogen Helicobacter pylori. An unanticipated case was suggested, however, upon finding two types of metronidazole (Mtz)-susceptible strains: type I, in which frxA (which encodes a nitroreductase that contributes to Mtz susceptibility) is quiescent, and type II, in which frxA is well expressed. Here we report that inactivation of the fdxA ferredoxin gene (hp277) in type I strains resulted in high-level frxA expression (in effect, making them type II). However, fdxA null derivatives were obtained from only 6 of 32 type I strains tested that were readily transformed with an frxA::aphA marker. This suggested that fdxA is often essential. This essentiality was overcome in 4 of 20 strains by inactivating frxA, which suggested both that frxA overexpression is potentially deleterious and also that fdxA has additional, often vital roles. With type II strains, in contrast, fdxA null derivatives were obtained in 20 of 23 cases tested. Thus, fdxA is dispensable in most strains that normally exhibit (and tolerate) strong frxA expression. We propose that restraint of frxA expression helps maintain balanced metabolic networks in most type I strains, that other homeostatic mechanisms predominate in type II strains, and that these complex results constitute a phenotypic manifestation of H. pylori's great genetic diversity.

scholarly journals A retrospective study assessing the acceleration effect of type I Helicobacter pylori infection on the progress of atrophic gastritis

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Weidong Liu ◽  
Junjie Tian ◽  
Wenjia Hui ◽  
Wenjie Kong ◽  
Yan Feng ◽  
...  
Keyword(s):  
Helicobacter Pylori ◽  
Atrophic Gastritis ◽  
Control Group ◽  
Type I ◽  
Type Ii ◽  
Gastric Function ◽  
Infection Group ◽  
Group Type ◽  
H Pylori ◽  
And Control

AbstractBased on the antibody typing classification, Helicobacter pylori infection can be divided into type I H. pylori infection and type II H. pylori infection. To observe the effects of different H. pylori infection types on the distribution of histopathological characteristics and the levels of three items of serum gastric function (PG I, PG II, G-17). 1175 cases from October 2018 to February 2020 were collected with ratio 1:2. All patients were performed with 14C-Urea breath test (14C-UBT), H. pylori antibody typing classification, three items of serum gastric function detection, painless gastroscopy, pathological examination, etc. According to H. pylori antibody typing classification, patients were divided into three groups: type I H. pylori infection group, type II H. pylori infection group and control group. Significant difference existed among type I H. pylori infection group, type II H. pylori infection group and control group in inflammation and activity (χ2 = 165.43, 354.88, P all < 0.01). The proportion of three groups in OLGA staging had statistic difference (χ2 = 67.99, P all < 0.01); Compared with type II H. pylori infection group and control group, the level of pepsinogen I, pepsinogen II, gastrin17 in type I H. pylori infection group increased, and PG I/PG II ratio (PG I/PG II ratio, PGR) decreased, which was statistically significant (χ2 = 35.08, 166.24, 134.21, 141.19; P all < 0.01). Type I H. pylori infection worsened the severity of gastric mucosal inflammation and activity. H. pylori infection was prone to induce atrophy of gastric mucosa, while type I H. pylori infection played a key role in promoting the progress of atrophic gastritis and affected the level of serum gastric function. The study indicated that the eradication of H. pylori should be treated individually.

scholarly journals Effects of Infections of Helicobacter Pylori With Different Virulent Factors on Severity of Gastrointestinal Diseases

2021 ◽  
Author(s):  
Yan Zhang ◽  
Xiang-ming Fang ◽  
Kui Tian
Keyword(s):  
Helicobacter Pylori ◽  
Bacterial Infections ◽  
Gastrointestinal Diseases ◽  
Ulcer Bleeding ◽  
Type I ◽  
Peptic Ulcers ◽  
Type Ii ◽  
Type Iii ◽  
Significant Difference ◽  
H Pylori

Abstract Background: Helicobacter Pylori (H. pylori) infection, one of the most common chronic bacterial infections, has been considered as a major cause of diseases such as lymphoma, gastritis, peptic ulcers, and stomach cancer. Here, we aimed to determine whether H. pylori strains with different virulence contribute to the gastrointestinal diseases differentially in clinical settings, which may provide future direction for eradication of H. pylori infection. Methods: We recruited 501 patients with gastrointestinal disorders for analysis of antibody types of H. pylori infection. Correlation analysis was done to determine the association of different virulence of H. pylori with patients’ baseline parameters and personal disease history. Next, subjects with each type of anti- H. pylori infection antibody were subjected to esophagogastro duodenoscopy（EGD) and colonoscopy examinations. The pathological diagnosis was also conducted in endoscopic samples. Chi-squared test was employed to compare the differences in endoscopic assessments and pathological findings among three types of H. pylori infection determined by the presence of antibodies to virulent factors. Results: There were 296 cases with Type I H. pylori infection, 120 cases with Type II H. pylori infection, and 85 cases without H. pylori infection (negative, Type III). No correlation was found between different virulence of H. pylori and participants’ baseline data (P > 0.05). EGD results showed that the incidences of peptic ulcer, bleeding and malignant lesions in Type I group were significantly higher than that in Type II and Type III (P＜0.05). Despite of increased trends of incidences of precancerous alterations and the malignance in Type I group compared with type II and III groups, there was no significant difference (P > 0.05). In addition, coloscopic features were similar among three groups. On the other hand, infections of H. pylori with cytotoxin-associated gene A (CagA) and/or vacuolating cytotoxin A (VacA) virulent factors resulted in more severe histopathological diseases than that with only Ure A/B factor and without infection (P < 0.05). Conclusions: Infections of H. pylori strains with CagA/VacA are likely to cause development of severe gastrointestinal diseases. These results are helpful to treat for H. pylori infection clinically.

Split spinal cord malformations in children

1998 ◽  
Vol 88 (1) ◽  
pp. 57-65 ◽  
Author(s):  
Yusuf Ersşahin ◽  
Saffet Mutluer ◽  
Sevgül Kocaman ◽  
Eren Demirtasş
Keyword(s):  
Spinal Cord ◽  
Neurological Deficits ◽  
Single Type ◽  
Type I ◽  
Type Ii ◽  
Content Type ◽  
Spinal Lesion ◽  
The Mean ◽  
Fine Print

Object. The authors reviewed and analyzed information on 74 patients with split spinal cord malformations (SSCMs) treated between January 1, 1980 and December 31, 1996 at their institution with the aim of defining and classifying the malformations according to the method of Pang, et al. Methods. Computerized tomography myelography was superior to other radiological tools in defining the type of SSCM. There were 46 girls (62%) and 28 boys (38%) ranging in age from less than 1 day to 12 years (mean 33.08 months). The mean age (43.2 months) of the patients who exhibited neurological deficits and orthopedic deformities was significantly older than those (8.2 months) without deficits (p = 0.003). Fifty-two patients had a single Type I and 18 patients a single Type II SSCM; four patients had composite SSCMs. Sixty-two patients had at least one associated spinal lesion that could lead to spinal cord tethering. After surgery, the majority of the patients remained stable and clinical improvement was observed in 18 patients. Conclusions. The classification of SSCMs proposed by Pang, et al., will eliminate the current chaos in terminology. In all SSCMs, either a rigid or a fibrous septum was found to transfix the spinal cord. There was at least one unrelated lesion that caused tethering of the spinal cord in 85% of the patients. The risk of neurological deficits resulting from SSCMs increases with the age of the patient; therefore, all patients should be surgically treated when diagnosed, especially before the development of orthopedic and neurological manifestations.

scholarly journals A Novel Line Immunoassay Based on Recombinant Virulence Factors Enables Highly Specific and Sensitive Serologic Diagnosis of Helicobacter pylori Infection

2013 ◽  
Vol 20 (11) ◽  
pp. 1703-1710 ◽  
Author(s):  
Luca Formichella ◽  
Laura Romberg ◽  
Christian Bolz ◽  
Michael Vieth ◽  
Michael Geppert ◽  
...  
Keyword(s):  
Helicobacter Pylori ◽  
Immune Responses ◽  
Virulence Factors ◽  
Gastrointestinal Disease ◽  
Individual Risk ◽  
Enzyme Linked Immunosorbent Assay ◽  
Type I ◽  
Serologic Test ◽  
Content Type ◽  
H Pylori

ABSTRACTHelicobacter pyloricolonizes half of the world's population, and infection can lead to ulcers, gastric cancer, and mucosa-associated lymphoid tissue (MALT) lymphoma. Serology is the only test applicable for large-scale, population-based screening, but current tests are hampered by a lack of sensitivity and/or specificity. Also, no serologic test allows the differentiation of type I and type II strains, which is important for predicting the clinical outcome.H. pylorivirulence factors have been associated with disease, but direct assessment of virulence factors requires invasive methods to obtain gastric biopsy specimens. Our work aimed at the development of a highly sensitive and specific, noninvasive serologic test to detect immune responses to importantH. pylorivirulence factors. This line immunoassay system (recomLine) is based on recombinant proteins. For this assay, six highly immunogenic virulence factors (CagA, VacA, GroEL, gGT, HcpC, and UreA) were expressed inEscherichia coli, purified, and immobilized to nitrocellulose membranes to detect serological immune responses in patient's sera. For the validation of the line assay, a cohort of 500 patients was screened, of which 290 (58.0%) wereH. pylorinegative and 210 (42.0%) were positive by histology. The assay showed sensitivity and specificity of 97.6% and 96.2%, respectively, compared to histology. In direct comparison to lysate blotting and enzyme-linked immunosorbent assay (ELISA), therecomLine assay had increased discriminatory power. For the assessment of individual risk for gastrointestinal disease, the test must be validated in a larger and defined patient cohort. Taking the data together, therecomLine assay provides a valuable tool for the diagnosis ofH. pyloriinfection.

Molecular characterization of an inward rectifier channel (IKir) found in avian vestibular hair cells: cloning and expression of pKir2.1

2004 ◽  
Vol 19 (2) ◽  
pp. 155-169 ◽  
Author(s):  
Manning J. Correia ◽  
Thomas G. Wood ◽  
Deborah Prusak ◽  
Tianxiang Weng ◽  
Katherine J. Rennie ◽  
...  
Keyword(s):  
Hair Cells ◽  
Cho Cells ◽  
Dwell Time ◽  
Single Channel ◽  
Cloning And Expression ◽  
Single Type ◽  
Type I ◽  
Type Ii ◽  
Vestibular Hair Cells ◽  
Inwardly Rectifying

A fast inwardly rectifying current has been observed in some of the sensory cells (hair cells) of the inner ear of several species. While the current was presumed to be an IKir current, contradictory evidence existed as to whether the cloned channel actually belonged to the Kir2.0 subfamily of potassium inward rectifiers. In this paper, we report for the first time converging evidence from electrophysiological, biochemical, immunohistochemical, and genetic studies that show that the Kir2.1 channel carries the fast inwardly rectifying currents found in pigeon vestibular hair cells. Following cytoplasm extraction from single type II and multiple pigeon vestibular hair cells, mRNA was reverse transcribed, amplified, and sequenced. The open reading frame (ORF), consisting of a 1,284-bp nucleotide sequence, showed 94, 85, and 83% identity with Kir2.1 subunit sequences from chick lens, Kir2 sequences from human heart, and a mouse macrophage cell line, respectively. Phylogenetic analyses revealed that pKir2.1 formed an immediate node with hKir2.1 but not with hKir2.2–2.4. Hair cells (type I and type II) and supporting cells in the sensory epithelium reacted positively with a Kir2.1 antibody. The whole cell current recorded in oocytes and CHO cells, transfected with pigeon hair cell Kir2.1 (pKir2.1), demonstrated blockage by Ba2+ and sensitivity to changing K+ concentration. The mean single-channel linear slope conductance in transfected CHO cells was 29 pS. The open dwell time was long (∼300 ms at −100 mV), and the closed dwell time was short (∼34 ms at −100 mV). Multistates ranging from 3–6 were noted in some single-channel responses. All of the above features have been described for other Kir2.1 channels. Current clamp studies of native pigeon vestibular hair cells illustrated possible physiological roles of the channel and showed that blockage of the channel by Ba2+ depolarized the resting membrane potential by ∼30 mV. Negative currents hyperpolarized the membrane ∼20 mV before block but ∼60 mV following block. RT-PCR studies revealed that the pKir2.1 channels found in pigeon vestibular hair cells were also present in pigeon vestibular nerve, vestibular ganglion, lens, neck muscle, brain (brain stem, cerebellum and optic tectum), liver, and heart.

scholarly journals The Cloninger Type I/Type II Typology: Configurations and Personality Profiles in Socially Stable Alcohol Dependent Patients

2014 ◽  
Vol 2014 ◽  
pp. 1-5 ◽  
Author(s):  
Peter Wennberg ◽  
Kristina Berglund ◽  
Ulf Berggren ◽  
Jan Balldin ◽  
Claudia Fahlke
Keyword(s):  
Longitudinal Study ◽  
Alcohol Dependence ◽  
Single Type ◽  
Type I ◽  
Type Ii ◽  
Novelty Seeking ◽  
Personality Profiles ◽  
Study Population ◽  
Males And Females ◽  
Alcohol Dependent

Many attempts have been made to derive alcohol use typologies or subtypes of alcohol dependence and this study aimed at validating the type I/type II typology in a treatment sample of socially stable alcohol dependent males and females. A second aim was to compare the two types with respect to their temperament profiles. Data was part of a larger ongoing longitudinal study, the Gothenburg Alcohol Research Project, and included 269 alcohol dependent males and females recruited from three treatment centers. The results showed that type II alcoholism occurred as a more homogenous type than type I alcoholism, and type I alcoholism seemed too heterogeneous to be summarized into one single type. When adapting a strict classification, less than a third of the study population could be classified in accordance with the typology, suggesting that the typology is not applicable, at least in socially stable individuals with alcohol dependence. The results also showed that type II alcoholics showed higher levels of novelty seeking than did the individuals that were classified as type I alcoholics. Quite surprisingly, the individuals classified as type II alcoholics also showed higher levels of harm avoidance than did the individuals that were classified as type I alcoholics.

scholarly journals Cloning, sequencing, expression, purification and preliminary characterization of a type II dehydroquinase from Helicobacter pylori

1996 ◽  
Vol 319 (2) ◽  
pp. 559-565 ◽  
Author(s):  
Joanna R BOTTOMLEY ◽  
Christopher L. CLAYTON ◽  
Peter A. CHALK ◽  
Colin KLEANTHOUS
Keyword(s):  
Helicobacter Pylori ◽  
Sequence Data ◽  
Shikimate Pathway ◽  
Cosmid Library ◽  
Type Ii ◽  
Gene Encoding ◽  
Heat Stable ◽  
Plasmid Construct ◽  
H Pylori ◽  
Type Ii Dehydroquinase

A heat-stable dehydroquinase was purified to near homogeneity from a plate-grown suspension of the Gram-negative stomach pathogen Helicobacter pylori, and shown from both its subunit and native molecular masses to be a member of the type II family of dehydroquinases. This was confirmed by N-terminal amino acid sequence data. The gene encoding this activity was isolated following initial identification, by random sequencing of the H. pylori genome, of a 96 bp fragment, the translated sequence of which showed strong identity to a C-terminal region of other type II enzymes. Southern blot analysis of a cosmid library identified several potential clones, one of which complemented an Escherichia coliaroD point mutant strain deficient in host dehydroquinase. The gene encoding the H. pylori type II dehydroquinase (designated aroQ) was sequenced. The translated sequence was identical to the N-terminal sequence obtained directly from the purified protein, and showed strong identity to other members of the type II family of dehydroquinases. The enzyme was readily expressed in E. coli from a plasmid construct from which several milligrams of protein could be isolated, and the molecular mass of the protein was confirmed by electrospray MS. The aroQ gene in H. pylori may function in the central biosynthetic shikimate pathway of this bacterium, thus opening the way for the construction of attenuated strains as potential vaccines as well as offering a new target for selective enzyme inhibition.

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