Metal-binding properties of Hpn from Helicobacter pylori and implications for the therapeutic activity of bismuth

Wegner, Seraphine V.; Ertem, Elif; Sünbül, Murat; He, Chuan

doi:10.1039/c0sc00411a

Cited by 13 publications

(16 citation statements)

References 52 publications

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“…Previous studies have shown that it plays an important role in nickel homeostasis, though there are new functions that need to be explored. [25] Our work demonstrates that the Hpnl protein not only coordinates with Ni II , but also binds Cu II , Co II , and Zn II with moderate affinities. Due to the detoxification ability of Hpnl to excess amounts of external nickel ions, [12] the effects of Cu II , Zn II , and Co II on the growth of E. coli cells that harbor the hpnl gene were also examined in minimum medium M9 by the same procedures as we previously performed for Ni II (see Figure S4 in (Figure 4).…”

Section: Discussionmentioning

confidence: 94%

Metal‐Binding Properties of an Hpn‐Like Histidine‐Rich Protein

Zeng

Yang

Sun

2011

Chemistry A European J

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The Hpn-like protein (Hpnl), a histidine- and glutamine-rich protein, is critical for Helicobacter pylori colonization in human gastric muscosa. In this study, the thermodynamic properties of Ni(II), Cu(II), Co(II), and Zn(II) toward Hpnl were studied by isothermal titration calorimetry (ITC). We found that Hpnl exhibits two independent binding sites for Ni(II) as opposed to one site for Cu(II), Co(II), and Zn(II). Protease digestion and chemical denaturation analysis further revealed that Ni(II) confers a higher stability upon Hpnl than other divalent metal ions. The potential Ni(II) binding sites are localized in the His-rich domain of Hpnl as confirmed by mutagenesis in combination with modification of histidine residues of the protein. We also demonstrated that the single mutants (H29A and H31A) and tetrameric mutant (H29-32A) cut nearly half of the binding capacity of Hpnl towards nickel ions, whereas other histidine residues (His30, 32, 38, 39, 40, and 41) are nonessential for nickel coordination. Escherichia coli cells that harbored H29A, H31A, and H29-32A mutant genes exhibited less tolerance toward high concentrations of extracellular nickel ions than those with the wild-type gene. Our combined data indicated that the conserved histidine residues, His29 and His31 in the His-rich domain of Hpnl, are critical for nickel binding, and such a binding is important for Hpnl protein to fulfill its biological functions.

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Section: Discussionmentioning

confidence: 94%

Metal‐Binding Properties of an Hpn‐Like Histidine‐Rich Protein

Zeng

Yang

Sun

2011

Chemistry A European J

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“…Recently, fluorescence resonance energy transfer (FRET) approach has allowed studies of metal binding properties of Hpn (where the protein sequence is inserted between the FRET partners CFP and YFP) both in vitro and in vivo. It was found that when Hpn-FRET was expressed in a model system, for example, E. coli, FRET change was only observed with addition of bismuth subsalicylate (Pepto Bismol) but not Ni 2+ and Zn 2+ , clearly indicating that Hpn is a potential target for bismuth in vivo [50 ]. The binding of bismuth to the protein may therefore interfere with its normal functions.…”

Section: Potential Protein Targets Of Bismuth Drugsmentioning

confidence: 99%

Recent advances in bioinorganic chemistry of bismuth

Sun

2012

Current Opinion in Chemical Biology

160

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Bismuth has been used in medicine for over two centuries for the treatment of various diseases, in particular for gastrointestinal disorders, owing to its antimicrobial activity. Recent structural characterization of bismuth drugs provides an insight into assembly and pharmacokinetic pathway of the drugs. Mining potential protein targets inside the pathogen via metallomic/metalloproteomic approach and further characterization on the interactions of bismuth drugs with these targets laid foundation in understanding the mechanism of action of bismuth drugs. Such studies would be beneficial in rational design of new potential drugs.

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“…The metal-binding capacity of Hpn and Hpn-2 has been addressed in vivo by FRET in E . coli using overexpressed engineered recombinant fluorescent proteins [ 39 , 40 ]. These studies revealed that Hpn did not bind nickel or zinc in E .…”

Section: Introductionmentioning

confidence: 99%

Evolution of Helicobacter: Acquisition by Gastric Species of Two Histidine-Rich Proteins Essential for Colonization

et al. 2015

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Metal acquisition and intracellular trafficking are crucial for all cells and metal ions have been recognized as virulence determinants in bacterial pathogens. Virulence of the human gastric pathogen Helicobacter pylori is dependent on nickel, cofactor of two enzymes essential for in vivo colonization, urease and [NiFe] hydrogenase. We found that two small paralogous nickel-binding proteins with high content in Histidine (Hpn and Hpn-2) play a central role in maintaining non-toxic intracellular nickel content and in controlling its intracellular trafficking. Measurements of metal resistance, intracellular nickel contents, urease activities and interactomic analysis were performed. We observed that Hpn acts as a nickel-sequestration protein, while Hpn-2 is not. In vivo, Hpn and Hpn-2 form homo-multimers, interact with each other, Hpn interacts with the UreA urease subunit while Hpn and Hpn-2 interact with the HypAB hydrogenase maturation proteins. In addition, Hpn-2 is directly or indirectly restricting urease activity while Hpn is required for full urease activation. Based on these data, we present a model where Hpn and Hpn-2 participate in a common pathway of controlled nickel transfer to urease. Using bioinformatics and top-down proteomics to identify the predicted proteins, we established that Hpn-2 is only expressed by H. pylori and its closely related species Helicobacter acinonychis. Hpn was detected in every gastric Helicobacter species tested and is absent from the enterohepatic Helicobacter species. Our phylogenomic analysis revealed that Hpn acquisition was concomitant with the specialization of Helicobacter to colonization of the gastric environment and the duplication at the origin of hpn-2 occurred in the common ancestor of H. pylori and H. acinonychis. Finally, Hpn and Hpn-2 were found to be required for colonization of the mouse model by H. pylori. Our data show that during evolution of the Helicobacter genus, acquisition of Hpn and Hpn-2 by gastric Helicobacter species constituted a decisive evolutionary event to allow Helicobacter to colonize the hostile gastric environment, in which no other bacteria persistently thrives. This acquisition was key for the emergence of one of the most successful bacterial pathogens, H. pylori.

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Metal-binding properties of Hpn from Helicobacter pylori and implications for the therapeutic activity of bismuth

Cited by 13 publications

References 52 publications

Metal‐Binding Properties of an Hpn‐Like Histidine‐Rich Protein

Metal‐Binding Properties of an Hpn‐Like Histidine‐Rich Protein

Recent advances in bioinorganic chemistry of bismuth

Evolution of Helicobacter: Acquisition by Gastric Species of Two Histidine-Rich Proteins Essential for Colonization

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