Chaperones of Nickel Metabolism

Quiroz, Soledad; Kim, Jong K.; Mulrooney, Scott B.; Hausinger, Robert P.

doi:10.1002/9780470028131.ch14

Cited by 12 publications

(14 citation statements)

References 110 publications

(167 reference statements)

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“…The apo-enzyme is modified in several successive steps that require a dedicated set of accessory proteins, usually comprising UreD, UreF, UreG and UreE. [8] This process leads to carbamylation of the active site lysine and incorporation of the binuclear metallic active site, with consequent enzyme activation (Scheme 2). The activity of urease is strictly required for the survival and growth of bacterial pathogens that colonize human and animal gastric mucosa as well as intestinal and urinary tracts, and therefore both the enzyme and the accessory proteins represent targets for drug development.…”

Section: Introductionmentioning

confidence: 99%

Crystallographic and X-ray absorption spectroscopic characterization of Helicobacter pylori UreE bound to Ni2+ and Zn2+ reveals a role for the disordered C-terminal arm in metal trafficking

Banaszak

Martin‐Diaconescu

Bellucci

et al. 2012

Biochemical Journal

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The survival and growth of the pathogen Helicobacter pylori in the gastric acidic environment is ensured by the activity of urease, an enzyme containing two essential Ni2+ ions in the active site. The metallo-chaperone UreE facilitates in vivo Ni2+ insertion into the apo-enzyme. Crystals of apo-HpUreE and its Ni2+ and Zn2+ bound forms were obtained from protein solutions in the absence and presence of the metal ions. The crystal structures of the homodimeric protein, determined at 2.00 Å (apo), 1.59 Å (Ni) and 2.52 Å (Zn) resolution, show the conserved proximal and solvent-exposed His102 residues from two adjacent monomers invariably involved in metal binding. The C-terminal regions of the apo-protein are disordered in the crystal, but acquire significant ordering in the presence of the metal ions due to the binding of His152. The analysis of X-ray absorption spectral data obtained on solutions of Ni2+- and Zn2+-HpUreE provided accurate information of the metal ion environment in the absence of solid-state effects. These results reveal the role of the histidine residues at the protein C-terminus in metal ion binding, and the mutual influence of protein framework and metal ion stereo-electronic properties in establishing coordination number and geometry leading to metal selectivity.

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Section: Introductionmentioning

confidence: 99%

Crystallographic and X-ray absorption spectroscopic characterization of Helicobacter pylori UreE bound to Ni2+ and Zn2+ reveals a role for the disordered C-terminal arm in metal trafficking

Banaszak

Martin‐Diaconescu

Bellucci

et al. 2012

Biochemical Journal

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“…24,25 The generally accepted hypothesis for the role of UreG in vivo is the hydrolysis of GTP concomitant with the activation of urease, the latter process entailing the insertion, in the active site, of two essential Ni 21 ions bridged by a lysine-carbamate residue. 26 Previous studies on UreG isolated from Bacillus pasteurii, Klebsiella aerogenes, and M. tuberculosis have indicated that a distinct trait of this protein resides in its unstructured behavior, 7,27 including UreG among the very few enzymes that so far can be ascribed to the class of intrinsically unfolded proteins. 28 The current comprehension of the relationships between the molecular properties of UreG and its function suggests that multiple factors may concur in the determination of the GTPase activity of UreG in vivo, ranging from multiprotein complex formation, disorderto-order folding transition, monomer-to-dimer equilibria, apo-to-holo metal-binding processes, and GTP/GDP binding/release mechanisms.…”

Section: Introductionmentioning

confidence: 99%

“…The generally accepted hypothesis for the role of UreG in vivo is the hydrolysis of GTP concomitant with the activation of urease, the latter process entailing the insertion, in the active site, of two essential Ni 2+ ions bridged by a lysine‐carbamate residue 26. Previous studies on UreG isolated from Bacillus pasteurii , Klebsiella aerogenes , and M. tuberculosis have indicated that a distinct trait of this protein resides in its unstructured behavior,7, 27 including UreG among the very few enzymes that so far can be ascribed to the class of intrinsically unfolded proteins 28.…”

Section: Introductionmentioning

confidence: 99%

Zn²⁺‐linked dimerization of UreG from Helicobacter pylori, a chaperone involved in nickel trafficking and urease activation

et al. 2008

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The biosynthesis of the active metal-bound form of the nickel-dependent enzyme urease involves the formation of a lysine-carbamate functional group concomitantly with the delivery of two Ni(2+) ions into the precast active site of the apoenzyme and with GTP hydrolysis. In the urease system, this role is performed by UreG, an accessory protein belonging to the group of homologous P-loop GTPases, often required to complete the biosynthesis of nickel-enzymes. This study is focused on UreG from Helicobacter pylori (HpUreG), a bacterium responsible for gastric ulcers and cancer, infecting large part of the human population, and for which urease is a fundamental virulence factor. The soluble HpUreG was expressed in E. coli and purified to homogeneity. On-line size exclusion chromatography and light scattering indicated that apo-HpUreG exists as a monomer in solution. Circular dichroism, which demonstrated the presence of a well-defined secondary structure, and NMR spectroscopy, which revealed a large number of residues that appear structured on the basis of their backbone amide proton chemical shift dispersion, indicated that, at variance with other UreG proteins so far characterized, this protein is significantly folded in solution. The amino acid sequence of HpUreG is 29% identical to that of HypB from Methanocaldococcus jannaschii, a dimeric zinc-binding GTPase involved in the in vivo assembly of [Ni,Fe]-hydrogenase. A homology-based molecular model of HpUreG was calculated, which allowed us to identify structural and functional features of the protein. Isothermal titration microcalorimetry demonstrated that HpUreG specifically binds 0.5 equivalents of Zn(2+) per monomer (K(d) = 0.33 +/- 0.03 microM), whereas it has 20-fold lower affinity for Ni(2+) (K(d) = 10 +/- 1 microM). Zinc ion binding (but not Ni(2+) binding) causes protein dimerization, as confirmed using light scattering measurements. The structural rearrangement occurring upon Zn(2+)-binding and consequent dimerization was evaluated using circular dichroism and fluorescence spectroscopy. Fully conserved histidine and cysteine residues were identified and their role in zinc binding was verified by site-directed mutagenesis and microcalorimetry. The results are analyzed and discussed with respect to analogous examples of GTPases in nickel metabolism.

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“…In the living organisms, metal‐binding proteins play various roles. For example, they are involved in metal homeostasis (uptake, transport, delivery or storage of metals), regulational pathways (for example, metal‐dependent transcription factors) or detoxification processes (sequestration and removal of toxic metals) . In some proteins and enzymes, metal ions play structural or catalytic roles .…”

Section: Discussionmentioning

confidence: 99%

Structure and properties of AB21, a novel Agaricus bisporus protein with structural relation to bacterial pore‐forming toxins

et al. 2018

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We report the characterization of the dimeric protein AB21 from Agaricus bisporus, one of the most commonly and widely consumed mushrooms in the world. The protein shares no significant sequence similarity with any protein of known function, and it is the first characterized member of its protein family. The coding sequence of the ab21 gene was determined and the protein was expressed in E. coli in a recombinant form. We demonstrated a high thermal and pH stability of AB21 and proved the weak affinity of the protein to divalent ions of some transition metals (nickel, zinc, cadmium, and cobalt). The reported crystallographic structure exhibits an interesting rod-like helical bundle fold with structural similarity to bacterial toxins of the ClyA superfamily. By immunostaining, we demonstrated an abundance of AB21 in the fruiting bodies of A. bisporus.

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Chaperones of Nickel Metabolism

Cited by 12 publications

References 110 publications

Crystallographic and X-ray absorption spectroscopic characterization of Helicobacter pylori UreE bound to Ni2+ and Zn2+ reveals a role for the disordered C-terminal arm in metal trafficking

Crystallographic and X-ray absorption spectroscopic characterization of Helicobacter pylori UreE bound to Ni2+ and Zn2+ reveals a role for the disordered C-terminal arm in metal trafficking

Zn²⁺‐linked dimerization of UreG from Helicobacter pylori, a chaperone involved in nickel trafficking and urease activation

Structure and properties of AB21, a novel Agaricus bisporus protein with structural relation to bacterial pore‐forming toxins

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Chaperones of Nickel Metabolism

Cited by 12 publications

References 110 publications

Crystallographic and X-ray absorption spectroscopic characterization of Helicobacter pylori UreE bound to Ni2+ and Zn2+ reveals a role for the disordered C-terminal arm in metal trafficking

Crystallographic and X-ray absorption spectroscopic characterization of Helicobacter pylori UreE bound to Ni2+ and Zn2+ reveals a role for the disordered C-terminal arm in metal trafficking

Zn2+‐linked dimerization of UreG from Helicobacter pylori, a chaperone involved in nickel trafficking and urease activation

Structure and properties of AB21, a novel Agaricus bisporus protein with structural relation to bacterial pore‐forming toxins

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Zn²⁺‐linked dimerization of UreG from Helicobacter pylori, a chaperone involved in nickel trafficking and urease activation