Metal-selective stability of Escherichia coli NikR.

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Escherichia coli NikR is a nickel-responsive transcription factor that regulates intracellular concentrations of nickel. To examine the unfolding of NikR and the effects of metal-binding on NikR"s thermodynamic stability, circular dichroism and electronic absorption spectroscopy were used to monitor the denaturation of NikR when induced by guanidine hydrochloride or by heat. Metal-binding stabilizes significantly both the full-length protein and its isolated metal-binding domain and this stabilization is greater for Ni(II) than any other metal tested, including Cu(II), Zn(II), Mn(II), Co(II) and Cd(II). Unexpectedly, the thermally denatured protein is capable of binding Ni(II) and Cu(II), however no metal-binding to the chemically unfolded protein was observed. Only the chemical denaturation of NikR was reversible, but this data could not be fit to a variety of two-state and three-state equilibrium models including dimer-monomers, tetramer-monomers, tetramer-dimers-monomers and linear denaturant binding models. The implications of these experiments on NikR"s role as a metalloregulator are discussed.

ContributionsUniversity of Toronto. Dept. of Chemistry.
The Physical Object
Pagination33 leaves.
ID Numbers
Open LibraryOL19512346M
ISBN 100612952347

NikR from Escherichia coli is a nickel-responsive transcription factor that regulates the expression of a nickel ion transporter. Metal analysis reveals that NikR can bind a variety of divalent transition metals, including Ni(II), Cu(II), Zn(II), Co(II), and Cd(II).Cited by: Selectivity of Metal Binding and Metal-Induced Stability of Escherichia coli NikR†.

Description Metal-selective stability of Escherichia coli NikR. FB2

Selectivity of Metal Binding and Metal-Induced Stability of Escherichia coli NikR †. NikR from Escherichia coli is a nickel-responsive transcription Metal-selective stability of Escherichia coli NikR.

book that regulates the expression of a. The NikR transcription factor from Escherichia coli is a Ni(II)-dependent repressor that regulates production of the nickel ion transporter encoded by the nik operon.

In the previous paper in this issue (Wang, S. C., Dias, A., Bloom, S. L., and Zamble, D. () Selectivity of Metal Binding and Metal-Induced Stability of Escherichia coli NikR, Biochemis −) we demonstrated Cited by: Escherichia coli cells that harbored H29A, H31A, and HA mutant genes exhibited less tolerance toward high concentrations of extracellular nickel ions than those with the wild-type gene.

MF_ NikR, 1 hit: InterPro i: View protein in InterPro IPR Acetolactate_synth/TF_NikR_C IPR Arc_rbn_hlx_hlx IPR CopG IPR Ni_resp_reg_NikR IPR Nickel_NikR_proteobac IPR Ribbon_hlx_hlx IPR TF_NikR_Ni-bd_C: Pfam i.

Functional sites Ni 2+-binding sites. Metal binding is required for measurable association of E. coli NikR to nik operator DNA in vitro.6, 9, 14 Metal binding stabilizes E.

coli NikR against both heat and chemical denaturation9, 10 as well as proteolytic cleavage. 15 This stabilization is likely related to a nickel-specific conformational change of the by: Metal binding studies have shown that nickel binds to NikR, at the C-terminus, with picomolar affinity (7–10 pM) [14, 18, 20•].

Interestingly, EcNikR has similar affinities for other divalent metal ions including zinc, copper and cobalt, although nickel confers greater conformational stability to Cited by:   The E. coli nickel sensor NikR has two binding sites, which have nickel affinities of 10 −12 molar and 10 −7 molar.

Occupancy of both metal sites gives a tighter DNA affinity than occupancy of Cited by: NikR, a nickel(II) ion responsive transcriptional regulator, controls nickel uptake in Gram-negative bacteria such as E. coli by regulating expression of a nickel-specific ATP-binding cassette (ABC) transporter encoded by the nik operon [24, 25].Cited by: In the previous paper in this issue Metal-selective stability of Escherichia coli NikR.

book, S. C., Dias, A., Bloom, S. L., and Zamble, D. () Selectivity of Metal Binding and Metal-Induced Stability of Escherichia coli NikR, Biochemistry. The Escherichia coli NikR is a kDa protein that negatively regulates transcription of the nikABCDE operon that encodes for an ATP-dependent Ni(II) permease.

Thermal and chemical denaturation. Metalloproteins and metal sensing. A subset of Escherichia coli manganese superoxide dismutase, metal co-repressors (Fur, NikR and Cited by: This perspective examines the metal-selective response of the Escherichia coli Ni(II)-responsive metalloregulator NikR.

Biochemical and structural studies of E. coli NikR reveal that the mechanism of metal-selective regulation is more complex than that defined by simple metal-binding thermodynamics.

Here we examine the metal-dependent allosteric changes on NikR structure that. coli NikR repressor binds operator DNA in a nickel-dependent fashion.

The pM affinity of NikR for nickel is mediated by its C-terminal 86 residues. Nickel binding induced additional secondary structure, decreased the compactness, and increased the stability of by: In the presence of excess nickel, Escherichia coli NikR regulates cellular nickel uptake by suppressing the transcription of the nik operon, which encodes the nickel uptake transporter, NikABCDE.

Previously published in vitro studies have shown that NikR is capable of binding a range of divalent transition metal ions in addition to Ni 2+, including Co 2+, Cu 2+, Zn 2+, and Cd 2+.Cited by: Abstract. Using in vivo translational gene fusion in Escherichia coli K we identified a gene that is specifically induced by heavy metals, cadmium, mercury and zinc, at nmolar concentrations.

This gene was identified by homology to known zinc and cadmium transporters. We created a disruption of the gene that resulted only in a minor increase in sensitivity to cadmium, suggesting that the Cited by:   The X-ray structure of the E.

coli NikR C-domain 6 first identified the high affinity nickel-binding sites, located at the interface between two NikR dimers (see Figure 1).

The Ni 2+ sites are roughly ~40 Å distant from the β sheet in the N-terminus that Cited by: In Escherichia coli and other bacteria, nickel uptake is regulated by the transcription factor NikR. Nickel binding at high-affinity sites in E. coli NikR (EcNikR) facilitates EcNikR binding to the.

E. coli NikR, for example, has three types of metal binding sites: high-affinity nickel binding sites, potassium binding sites, and low-affinity nickel binding sites.

Details Metal-selective stability of Escherichia coli NikR. FB2

While prior work has outlined the location and role of the stoichiometric or high-affinity nickel sites Cited by:   NikR is a nickel-responsive ribbon-helix-helix transcription factor present in many bacteria and archaea. The DNA binding properties of Escherichia coli and Helicobacter pylori NikR (factors EcNikR and HpNikR, respectively) have revealed variable features of DNA recognition.

EcNikR represses a single operon by binding to a perfect inverted repeat sequence, whereas HpNikR binds to promoters Cited by: Nickel-specific response in the transcriptional regulator, Escherichia coli NikR.

Journal of the American Chemical Society (16): Benanti, E.L. & Chivers, P. To determine whether NarL- and NikR-dependent regulation of P nik expression were independent, LacZ levels were measured in nikR-deficient and nikR narLX-deficient strains containing wild-type NikR or a mutant protein, the Cys95Ala protein, which lacks high-affinity nickel-binding activity and shows no DNA binding in vitro with up to 1 μM NiCl by: Escherichia coli NikR, a repressor with homologs in other bacteria and archaea, was identified as a potential new member of the ribbon-helix-helix (beta-alpha-alpha) family of transcription factors in profile based sequence searches and in structure prediction by:   The Pyrococcus horikoshii OT3 genome contains a gene (PH or nikR) encoding a protein (PhNikR) that shares % amino acid sequence identity with Escherichia coli nickel responsive repressor NikR (EcNikR), including many residues that are functionally important in the E.

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coli ortholog. We succeeded in crystallization and structural characterization of PhNikR in the apo Cited by: Abstract In Escherichia coli and other bacteria, nickel uptake is regulated by the transcription factor NikR. Nickel binding at high-affinity sites in E.

coli NikR (EcNikR) facilitates EcNikR binding to the nik operon, where it then suppresses transcription of genes encoding the nickel uptake transporter, NikABCDE.

In E. coli, nickel overload is avoided via the repressor NikR, which binds to the promoter region of the nikABCDE operon when nickel is present (11, 19). NikR has both strong (in the pM range) and weak (nM) Ni-binding sites, allowing sensing of nickel at concentrations corresponding to the range from 1 to molecules per cell (6, 12).Cited by: Structural Basis of Low-Affinity Nickel Binding to the Nickel-Responsive Transcription Factor NikR from Escherichia coliCited by:   Structural and mechanistic insights into Helicobacter pylori NikR C.

Fauquant, K. Schauer, H. de Reuse, L. Terradot, I. Michaud-Soret, Structural and mechanistic insights into Helicobacter pylori NikR activation, Nucleic Acids Research, Volume 38 Selectivity of metal binding and metal-induced stability of Escherichia coli by:   The relatively stable MBD of NikR and two rotatable DBDs of NikR can adapt roughly three different main conformations (straight, trans or cis) whose stability seems to be related to both nickel and DNA by: 9.

Abstract. In Escherichia coli, the peptidoglycan cell wall is synthesized by bifunctional penicillin-binding proteins such as PBP1b that have both transpeptidase and transglycosylase PBP1b transpeptidase domain is a major target of β-lactams, and therefore it is important to attain a detailed understanding of its by:   Three Escherichia coli mutants defective in formate-dependent nitrite reduction (Nrf activity) were characterised.

Two of the mutants, JCB and JCB, synthesized all five c-type cytochromes previously characterised in anaerobic cultures of E. coli. The third mutant, JCB, was defective for both cytochrome b and cytochrome c synthesis, but only during anaerobic by:   The NikR protein is a nickel-dependent regulatory protein which is a member of the ribbon-helix-helix family of transcriptional regulators.

The gastric pathogen Helicobacter pylori expresses a NikR ortholog, which was previously shown to mediate regulation of metal metabolism and urease expression, but the mechanism governing the diverse regulatory effects had not been described until Cited by: