The <i>Helicobacter pylori</i> neutrophil‐activating protein is an iron‐binding protein with dodecameric structure

Tonello, Fiorella; Dundon, William G.; Satin, Barbara; Molinari, Maurizio; Tognon, Giuseppe; Grandi, Guido; Giudice, Giuseppe Del; Rappuoli, Rino; Montecucco, Cesare

doi:10.1046/j.1365-2958.1999.01584.x

Cited by 160 publications

(184 citation statements)

References 58 publications

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Section: And References Therein)mentioning

confidence: 99%

“…Consequently, the iron-storage capacity of these proteins is smaller, and ferritin dodecamers from Helicobacter pylori and Listeria innocua were reported to oxidize and sequester up to 500 iron atoms inside their cavity (9,12,13). Hereby, the main entry of iron and other ionic species into these members of the Dps subfamily is postulated to occur along pores that penetrate the protein shell at the threefold axes of symmetry (9,13), and that were also identified as entrance sites in the 24-mer ferritins (2). In the crystal structures of Dps proteins from E. coli (14), L. innocua (13), and Bacillus anthracis (15), these access channels are conserved, besides an interfacial iron-binding site that was assigned in these Dps-like ferritins as a di-iron ferroxidase center for catalytic iron oxidation.…”

Section: And References Therein)mentioning

confidence: 99%

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Iron-oxo clusters biomineralizing on protein surfaces: Structural analysis of Halobacterium salinarum DpsA in its low- and high-iron states

Zeth

Offermann

Essen

et al. 2004

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

107

122

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The crystal structure of the Dps-like (Dps, DNA-protecting protein during starvation) ferritin protein DpsA from the halophile Halobacterium salinarum was determined with low endogenous iron content at 1.6-Å resolution. The mechanism of iron uptake and storage was analyzed in this noncanonical ferritin by three highresolution structures at successively increasing iron contents. In the high-iron state of the DpsA protein, up to 110 iron atoms were localized in the dodecameric protein complex. For ultimate iron storage, the archaeal ferritin shell comprises iron-binding sites for iron translocation, oxidation, and nucleation. Initial iron-protein interactions occur through acidic residues exposed along the outer surface in proximity to the iron entry pore. This narrow pore permits translocation of ions toward the ferroxidase centers via two discrete steps. Iron oxidation proceeds by transient formation of tri-iron ferroxidase centers. Iron storage by biomineralization inside the ferritin shell occurs at two iron nucleation centers. Here, a single iron atom provides a structural seed for iron-oxide cluster formation. The clusters with up to five iron atoms adopt a geometry that is different from natural biominerals like magnetite but resembles iron clusters so far known only from bioinorganic model compounds.ferritin ͉ iron-binding ͉ inorganic cluster formation ͉ x-ray crystal structure

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Section: And References Therein)mentioning

confidence: 99%

Section: And References Therein)mentioning

confidence: 99%

Iron-oxo clusters biomineralizing on protein surfaces: Structural analysis of Halobacterium salinarum DpsA in its low- and high-iron states

Zeth

Offermann

Essen

et al. 2004

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

107

122

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“…H. pylori possess two iron storage proteins, NapA and Pfr. NapA is a homologue of bacterial DNA-protecting proteins, and its molecular structure has been determined (32,33). It has a dodecameric structure (12 subunits) that is capable of binding up to 500 iron atoms (32).…”

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

confidence: 99%

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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“…HP-NAP was cloned, expressed, and purified from Bacillus subtilis to avoid LPS contamination, as described previously (15). SB203580, tetramethyl benzidine, FITC-conjugated BSA, streptavidin-alkaline phosphatase, p-nitrophenyl phosphate, nonfat milk powder, acridine orange (AO), platelet-activating factor (PAF), HBSS, and biotin were purchased by Sigma-Aldrich.…”

Section: Reagentsmentioning

confidence: 99%

“…It is a dodecameric protein of 150 kDa with a structure similar to bacterioferritins, including a central cavity for iron accumulation (15,16). It was originally defined as PMN-activating protein because it stimulates PMNs to produce reactive oxygen radicals (17).…”

mentioning

confidence: 99%

The Neutrophil-Activating Protein of Helicobacter pylori Crosses Endothelia to Promote Neutrophil Adhesion In Vivo

Polenghi

Bossi

Fischetti

et al. 2007

The Journal of Immunology

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Helicobacter pylori induces an acute inflammatory response followed by a chronic infection of the human gastric mucosa characterized by infiltration of neutrophils/polymorphonuclear cells (PMNs) and mononuclear cells. The H. pylori neutrophil-activating protein (HP-NAP) activates PMNs, monocytes, and mast cells, and promotes PMN adherence to the endothelium in vitro. By using intravital microscopy analysis of rat mesenteric venules exposed to HP-NAP, we demonstrated, for the first time in vivo, that HP-NAP efficiently crosses the endothelium and promotes a rapid PMN adhesion. This HP-NAP-induced adhesion depends on the acquisition of a high affinity state of β2 integrin on the plasma membrane of PMNs, and this conformational change requires a functional p38 MAPK. We also show that HP-NAP stimulates human PMNs to synthesize and release a number of chemokines, including CXCL8, CCL3, and CCL4. Collectively, these data strongly support a central role for HP-NAP in the inflammation process in vivo: indeed, HP-NAP not only recruits leukocytes from the vascular lumen, but also stimulates them to produce messengers that may contribute to the maintenance of the flogosis associated with the H. pylori infection.

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The Helicobacter pylori neutrophil‐activating protein is an iron‐binding protein with dodecameric structure

Cited by 160 publications

References 58 publications

Iron-oxo clusters biomineralizing on protein surfaces: Structural analysis of Halobacterium salinarum DpsA in its low- and high-iron states

Iron-oxo clusters biomineralizing on protein surfaces: Structural analysis of Halobacterium salinarum DpsA in its low- and high-iron states

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

The Neutrophil-Activating Protein of Helicobacter pylori Crosses Endothelia to Promote Neutrophil Adhesion In Vivo

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