Helicobacter pylori catalase

Hazell, Stuart L.; Evans, Doyle J.; Graham, David Y.

doi:10.1099/00221287-137-1-57

Cited by 112 publications

(99 citation statements)

References 25 publications

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“…Determination of Catalase Activity-The quantitative catalase activity of H. pylori cell extract or purified catalase protein was determined following the method described by Hazell et al (20). Briefly, catalase activity was measured spectrophotometrically at 25°C by following the decrease in absorbance at 240 nm (⑀ 240 nm ϭ 43.48 M Ϫ1 cm Ϫ1 ) of 13 mM H 2 O 2 in phosphate-buffered saline.…”

Section: Methodsmentioning

confidence: 99%

“…A unique property of H. pylori catalase is that it has a pI of Ͼ9. Another property of H. pylori catalase, which is distinct from other typical catalases, is its stability at very high concentrations of H 2 O 2 (20). H. pylori cells were shown to be resistant to a high concentration (ϳ100 mM) of H 2 O 2 , and this resistance was abolished in katA Ϫ mutants (24).…”

mentioning

confidence: 97%

“…In addition to a high pI (Ͼ9), H. pylori catalase has another property distinct from other typical catalases in that it is stable at very high concentrations of H 2 O 2 (20). In the presence of excess H 2 O 2 , typical catalases can form an intermediate (compound II (Fe(IV)) as a result of one-electron oxidation; this intermediate does not react with H 2 O 2 , and thus the accumulation of compound II leads to the deactivation of catalase (39).…”

Section: Fig 2 Catalase Activities and The Epr Signals In Various Hmentioning

confidence: 99%

“…Hazell et al (20) reported that catalase accounts for ϳ1% of the total protein of the cell in H. pylori. The proteome analysis of Jungblut et al (19) showed that AhpC (also called TsaA) is the third most abundant protein in H. pylori.…”

Section: Monitoring Kata and Ahpc Proteins In H Pylori Cell Extract mentioning

confidence: 99%

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Role of a Bacterial Organic Hydroperoxide Detoxification System in Preventing Catalase Inactivation

Wang¹,

Conover

Benoit³

et al. 2004

Journal of Biological Chemistry

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In the gastric pathogen Helicobacter pylori, catalase (KatA) and alkyl hydroperoxide reductase (AhpC) are two highly abundant enzymes that are crucial for oxidative stress resistance and survival of the bacterium in the host. Here we report a connection unidentified previously between the two stress resistance enzymes. We observed that the catalase in ahpC mutant cells in comparison with the parent strain is inactivated partially (approximately 50%). The decrease of catalase activity is well correlated with the perturbation of the heme environment in catalase, as detected by electron paramagnetic resonance spectroscopy. To understand the reason for this catalase inactivation, we examined the inhibitory effects of hydroperoxides on H. pylori catalase (either present in cell extracts or added to the purified enzyme) by monitoring the enzyme activity and the EPR signal of catalase. H. pylori catalase is highly resistant to its own substrate, without the loss of enzyme activity by treatment with a molar ratio of 1:3000 H 2 O 2 . However, it is inactivated by lower concentrations of organic hydroperoxides (the substrate of AhpC). Treatment with a molar ratio of 1:400 t-butyl hydroperoxide resulted in an inactivation of catalase by approximately 50%. UV-visible absorption spectra indicated that the catalase inactivation by organic hydroperoxides is caused by the formation of a catalytically incompetent compound II species. To further support the idea that organic hydroperoxides, which accumulate in the ahpC mutant cells, are responsible for the inactivation of catalase, we compared the level of lipid peroxidation found in ahpC mutant cells with that found in wild type cells. The results showed that the total amount of extractable lipid hydroperoxides in the ahpC mutant cells is approximately three times that in the wild type cells. Our findings reveal a novel role of the organic hydroperoxide detoxification system in preventing catalase inactivation.

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Section: Methodsmentioning

confidence: 99%

mentioning

confidence: 97%

Section: Fig 2 Catalase Activities and The Epr Signals In Various Hmentioning

confidence: 99%

Section: Monitoring Kata and Ahpc Proteins In H Pylori Cell Extract mentioning

confidence: 99%

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Role of a Bacterial Organic Hydroperoxide Detoxification System in Preventing Catalase Inactivation

Wang¹,

Conover

Benoit³

et al. 2004

Journal of Biological Chemistry

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“…Single colonies were picked after a 3-5 day incubation at 37°C in CampyPakPlus envelopes (Becton Dickinson) and recultured. Isolates were identified as H. pylori by their morphology and their production of urease and catalase (12).…”

Section: Methodsmentioning

confidence: 99%

Epithelial attachment alters the outcome of Helicobacter pylori infection

Guruge

Falk

Lorenz

et al. 1998

Proc. Natl. Acad. Sci. U.S.A.

270

167

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Genetically defined in vivo models are needed to assess the importance of target cell attachment in bacterial pathogenesis. Gastric colonization by Helicobacter pylori in human populations is common and persistent, and has various outcomes including peptic ulcers and cancer. The impact of attachment on the course of infection was examined in transgenic mice expressing a human receptor for H. pylori in their gastric epithelium. Persistent infection by a clinical isolate occurred at comparable microbial densities in transgenic and nontransgenic littermates. However, microbial attachment in transgenic mice resulted in production of autoantibodies to Lewis x carbohydrate epitopes shared by bacteria and acid-secreting parietal cells, chronic gastritis, and parietal cell loss. This model should help identify bacterial and host genes that produce attachment-related pathology.

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Heme binding and peroxidase activity of a secreted minicatalase

et al. 2016

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Microbial pathogens often require efficient and robust H O scavenger activities to survive in the presence of reactive oxygen species generated by inflammatory responses. In addition to catalases and peroxidases, enzymes known to scavenge H O , a novel class of secreted minicatalases is found in diderm bacteria. Here, we characterize the Helicobacter pylori (Hp) minicatalase: a monomeric hemoprotein with catalase core homology. Overexpression of Hp minicatalase rescued a catalase/peroxidase-deficient Escherichia coli phenotype under aerobic conditions and limited H O stress. The purified enzyme lacks catalase activity, but has strong (k > 100 s ) H O -dependent peroxidase activity toward a variety of organic substrates. Our investigations into heme binding revealed that the heme cofactor is assembled in the periplasm to form the functional holoprotein. Furthermore, we observed the presence of a disulfide bond near the heme cavity of Hp minicatalase, which is conserved in secreted minicatalases and, therefore, may play a role in heme binding.

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Helicobacter pylori catalase

Cited by 112 publications

References 25 publications

Role of a Bacterial Organic Hydroperoxide Detoxification System in Preventing Catalase Inactivation

Role of a Bacterial Organic Hydroperoxide Detoxification System in Preventing Catalase Inactivation

Epithelial attachment alters the outcome of Helicobacter pylori infection

Heme binding and peroxidase activity of a secreted minicatalase

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