title: Biophysical and physiological characterization of ZraP from Escherichia coli, the periplasmic accessory protein of the atypical ZraSR two-component system.
abstract: The ZraSR system belongs to the family of TCSs (two-component signal transduction systems). In Escherichia coli, it was proposed to participate in zinc balance and to protect cytoplasmic zinc overload by sequestering this metal ion into the periplasm. This system controls the expression of the accessory protein ZraP that would be a periplasmic zinc scavenger. ZraPSR is functionally homologous with CpxPAR that integrates signals of envelope perturbation, including misfolded periplasmic proteins. The auxiliary periplasmic regulator CpxP inhibits the Cpx pathway by interacting with CpxA. Upon envelope stress sensing, the inhibitory function of CpxP is relieved, resulting in CpxR activation. Similarly to CpxPAR, ZraPSR probably plays a role in envelope stress response as a zinc-dependent chaperone activity was demonstrated for ZraP in Salmonella. We have purified ZraP from E. coli and shown that it is an octamer containing four interfacial metal-binding sites contributing to dimer stability. These sites are located close to the N-terminus, whereas the C-terminus is involved in polymerization of the protein to form a tetramer of dimers. In vitro, ZraP binds copper with a higher affinity than zinc and displays chaperone properties partially dependent on zinc binding. In vivo, zinc-bound ZraP is a repressor of the expression of the zraPSR operon. However, we have demonstrated that none of the Zra proteins are involved in zinc or copper resistance. We propose an integrated mechanism in which zinc is a marker of envelope stress perturbation and ZraPSR TCS is a sentinel sensing and responding to zinc entry into the periplasm.
authors.affiliation: Institut de Biologie Structurale, Campus EPN, CS 10090, 71 Avenue des Martyrs, 38044 Grenoble cedex 9, France.
authors.forename: Isabelle
authors.initials: I
authors.lastname: Petit-Härtlein
authors.affiliation: Université de Lyon, Lyon, F-69003, France INSA de Lyon, 20 Avenue Albert Einstein, F-69621 Villeurbanne Cedex, France CNRS, UMR5240, Microbiologie, Adaptation et Pathogénie, Université Lyon 1, Villeurbanne F-69622, France.
authors.forename: Kevin
authors.initials: K
authors.lastname: Rome
authors.affiliation: Institut de Biologie Structurale, Campus EPN, CS 10090, 71 Avenue des Martyrs, 38044 Grenoble cedex 9, France.
authors.forename: Eve
authors.initials: E
authors.lastname: de Rosny
authors.affiliation: Université Grenoble Alpes, DCM UMR 5250, F-38000 Grenoble, France.
authors.forename: Florian
authors.initials: F
authors.lastname: Molton
authors.affiliation: Université Grenoble Alpes, DCM UMR 5250, F-38000 Grenoble, France.
authors.forename: Carole
authors.initials: C
authors.lastname: Duboc
authors.affiliation: Université de Lyon, Lyon, F-69003, France INSA de Lyon, 20 Avenue Albert Einstein, F-69621 Villeurbanne Cedex, France CNRS, UMR5240, Microbiologie, Adaptation et Pathogénie, Université Lyon 1, Villeurbanne F-69622, France.
authors.forename: Erwan
authors.initials: E
authors.lastname: Gueguen
authors.affiliation: Université de Lyon, Lyon, F-69003, France INSA de Lyon, 20 Avenue Albert Einstein, F-69621 Villeurbanne Cedex, France CNRS, UMR5240, Microbiologie, Adaptation et Pathogénie, Université Lyon 1, Villeurbanne F-69622, France.
authors.forename: Agnès
authors.initials: A
authors.lastname: Rodrigue
authors.affiliation: Institut de Biologie Structurale, Campus EPN, CS 10090, 71 Avenue des Martyrs, 38044 Grenoble cedex 9, France jacques.coves@ibs.fr.
authors.forename: Jacques
authors.initials: J
authors.lastname: Covès
mesh_terms: D065567:Absorption, Physiological; D000595:Amino Acid Sequence; D001665:Binding Sites; D055592:Biophysical Phenomena; D002352:Carrier Proteins / Q000737:chemistry / Q000235:genetics / Q000302:isolation & purification / Q000378:metabolism; D003300:Copper / Q000378:metabolism; D048168:Escherichia coli K12 / Q000502:physiology*; D029968:Escherichia coli Proteins / Q000737:chemistry / Q000235:genetics / Q000302:isolation & purification / Q000378:metabolism*; D015964:Gene Expression Regulation, Bacterial; D007700:Kinetics; D018832:Molecular Chaperones / Q000737:chemistry / Q000235:genetics / Q000302:isolation & purification / Q000378:metabolism*; D008969:Molecular Sequence Data; D009154:Mutation; D009876:Operon; D033903:Periplasmic Proteins / Q000737:chemistry / Q000235:genetics / Q000302:isolation & purification / Q000378:metabolism*; D055550:Protein Stability; D020836:Protein Structure, Quaternary; D011994:Recombinant Proteins; D015398:Signal Transduction; D015534:Trans-Activators / Q000235:genetics / Q000378:metabolism; D015032:Zinc / Q000378:metabolism*
chemical_list: D002352:Carrier Proteins; D029968:Escherichia coli Proteins; D018832:Molecular Chaperones; D033903:Periplasmic Proteins; D011994:Recombinant Proteins; D015534:Trans-Activators; C114106:zraP protein, E coli; C423908:zraR protein, E coli; C423907:zraS protein, E coli; D003300:Copper; D015032:Zinc
keywords: Escherichia coli; ZraPSR; chaperone; two-component system (TCS); zinc resistance