Structural Basis for Metal Sensing by CnrX

Trepreau, Juliette; Girard, Éric; Maillard, Antoine P.; Rosny, Eve de; Petit-Haertlein, I.; Kahn, Richard; Covès, Jacques

doi:10.1016/j.jmb.2011.03.014

Cited by 36 publications

(102 citation statements)

References 51 publications

(89 reference statements)

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“…This situation is similar to what has been recently determined for the Ni(II)/Co(II) responsive membrane-bound periplasmic regulator CnrX. 46, 86–88 Mutational studies on CnrX indicate that binding of Met123 pulls the protein into a signal propagating active conformation. Non-cognate metals do not bind this residue and thus cannot facilitate this conformational change.…”

Section: Discussionsupporting

confidence: 85%

Glutamate Ligation in the Ni(II)- and Co(II)-Responsive Escherichia coli Transcriptional Regulator, RcnR

et al. 2017

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Escherichia coli RcnR (resistance to cobalt and nickel regulator, EcRcnR), is a metal-responsive repressor of the genes encoding the Ni(II) and Co(II) exporter proteins RcnAB by binding to PrcnAB. DNA-binding affinity is weakened when the cognate ions Ni(II) or Co(II) bind to EcRcnR in a six-coordinate site that features a (N/O)5S ligand donor-atom set in distinct sites: while both metal ions are bound by the N-terminus, Cys35, and His64, Co(II) is additionally bound by His3. On the other hand, the non-cognate Zn(II) and Cu(I) ions feature a lower coordination number, have a solvent-accessible binding site, and coordinate protein ligands that do not include the N-terminal amine. A molecular model of apo-EcRcnR suggested potential roles for Glu34 and Glu63 in binding Ni(II) and Co(II) to EcRcnR. The roles of Glu34 and Glu63 in metal binding, metal selectivity and function were therefore investigated using a structure/function approach. X-ray absorption spectroscopy (XAS) was used to assess the structural changes in the Ni(II), Co(II), and Zn(II) binding sites of Glu → Ala and Glu → Cys variants at both positions. The effect of these structural alterations on the regulation of PrcnA by EcRcnR in response to metal binding was explored using LacZ reporter assays. These combined studies indicate that while Glu63 is a ligand for both metal ions, Glu34 is a ligand for Co(II) but possibly not for Ni(II). The Glu34 variants affect the structure of the cognate metal sites, but they have no effect on the transcriptional response. In contrast, the Glu63 variants affect both the structure and transcriptional response, although they do not completely abolish the function of EcRcnR. The structure of the Zn(II) site is not significantly perturbed by any of the Glu variations. The spectroscopic and functional data obtained on the mutants were used to calculate models of the metal site structures of EcRcnR bound to Ni(II), Co(II) and Zn(II). The results are interpreted in terms of a switch mechanism, in which a subset of the metal binding ligands is responsible for the allosteric response required for DNA release.

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Section: Discussionsupporting

confidence: 85%

Glutamate Ligation in the Ni(II)- and Co(II)-Responsive Escherichia coli Transcriptional Regulator, RcnR

et al. 2017

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“…The expression of CnrX is preferentially induced in response to Ni 2+ ions and, to a lesser extent, to Co 2+ and Cu 2+ ions, while Zn 2+ is a very poor inducer (Trepreau et al 2011). Similar results were reported in transcriptomic studies in addition to cnrX upregulation in the presence of Cd 2+ (Monchy et al 2007;Monsieurs et al 2011).…”

Section: Cnrxsupporting

confidence: 81%

“…This efflux system mediates nickel and cobalt resistance in C. metallidurans CH34 (Liesegang et al 1993;Collard et al 1993). Transcription of cnrCBA is not regulated by a two-component regulatory system as for most HME-RND-driven systems but through the ECF sigma factor CnrH and the membrane bound anti-sigma factor complex CnrYX (see volume I, chapter 3) (Grass et al 2000;Tibazarwa et al 2000;Grass et al 2005a;Trepreau et al 2011Trepreau et al , 2014. The high resolution three-dimensional structures of these regulatory proteins will be reviewed below (Sect 3.3).…”

Section: Hme2 Subfamilymentioning

confidence: 99%

Metal Response in Cupriavidus metallidurans

Vandenbussche

Mergeay

2015

SpringerBriefs in Molecular Science

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“…There is significant support for the hypothesis that distinct coordination environments of cognate vs. non-cognate metal complexes in metal sensor proteins of widely disparate structures is a key determinant of the functional selectivity in the cell. 25,35,40,62–68 This may not, however, be the case for all metallosensors 36,51,69 and in these cases, the influence of cellular metal bioavailability is likely a major factor that controls metal sensing so that illegitimate cross-talk between metal homeostasis systems can be avoided. 2,51,57,70,71 This hypothesis predicts that Mn(II) would adopt a coordination geometry that is distinct from that of Zn(II).…”

Section: Discussionmentioning

confidence: 99%

Physical Characterization of the Manganese-Sensing Pneumococcal Surface Antigen Repressor from Streptococcus pneumoniae

Lisher¹,

Higgins²,

Maroney

et al. 2013

Biochemistry

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Transition metals, including manganese, are required for proper virulence and persistence of many pathogenic bacteria. In Streptococcus pneumoniae (Spn), manganese homeostasis is controlled by a high affinity Mn(II) uptake complex, PsaBCA, and a constitutively expressed efflux transporter, MntE. PsaBCA expression is transcriptionally regulated by the DtxR/MntR family metalloregulatory protein pneumococcal surface antigen repressor (PsaR) in Spn. Here, we present a comprehensive analysis of the metal and DNA-binding properties of PsaR. PsaR is a homodimer in the absence and presence of metals and binds two manganese or zinc per protomer (four per dimer) in two pairs of structurally distinct sites, termed site 1 and site 2. Site 1 is likely filled with Zn(II) in vivo (KZn1≥1013 M−1; KMn1≈108 M−1). The Zn(II)-site 1 complex adopts a pentacoordinate geometry by x-ray absorption spectroscopy containing a single cysteine, and appears analogous to the Cd(II) site observed in S. gordonii ScaR. Site 1 is necessary but not sufficient for full positive allosteric activation of DNA operator binding by metals as measured by ΔGc, the allosteric coupling free energy, since mutants in site 1 show intermediate ΔGc. Site 2 is the primary regulatory site and governs specificity for Mn(II) over Zn(II) in PsaR, with ΔGcZn,Mn>>ΔGcZn,Zn despite the fact that Zn(II) binds site 2 with 40-fold higher affinity relative to Mn(II), i.e., KZn2>KMn2. Mutational studies reveal that Asp7 in site 2 is a critical ligand for Mn(II)-dependent allosteric activation of DNA binding. These findings are discussed in the context of other well-studied DtxR/MntR Mn(II)/Fe(II) metallorepressors.

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Structural Basis for Metal Sensing by CnrX

Cited by 36 publications

References 51 publications

Glutamate Ligation in the Ni(II)- and Co(II)-Responsive Escherichia coli Transcriptional Regulator, RcnR

Glutamate Ligation in the Ni(II)- and Co(II)-Responsive Escherichia coli Transcriptional Regulator, RcnR

Metal Response in Cupriavidus metallidurans

Physical Characterization of the Manganese-Sensing Pneumococcal Surface Antigen Repressor from Streptococcus pneumoniae

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