ZraP, the most prominent zinc protein under zinc stress conditions has no direct role in in-vivo zinc tolerance in Escherichia coli

Journal Article (2019)
Author(s)

L van der Weel (TU Delft - BT/Biocatalysis)

Karel S. As (Student TU Delft)

Wijb J.C. Dekker (TU Delft - BT/Industriele Microbiologie)

Lieke van den Eijnden (Student TU Delft)

W. Van Helmond (TU Delft - OLD ChemE/Organic Materials and Interfaces)

Christo Schiphorst (Student TU Delft)

Wilfred R. Hagen (TU Delft - BT/Biocatalysis)

Peter Hagedoorn (TU Delft - BT/Biocatalysis)

Research Group
BT/Industriele Microbiologie
DOI related publication
https://doi.org/10.1016/j.jinorgbio.2018.12.013
More Info
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Publication Year
2019
Language
English
Research Group
BT/Industriele Microbiologie
Volume number
192
Pages (from-to)
98-106

Abstract

Escherichia coli ZraP (zinc resistance associated protein) is the major Zn containing soluble protein under Zn stress conditions. ZraP is the accessory protein of a bacterial two-component, Zn2+ sensitive signal transduction system ZraSR. ZraP has also been reported to act as a Zn2+ dependent molecular chaperone. An explanation why ZraP is the major Zn protein under the stress condition of Zn2+ overload (0.2 mM) has remained elusive. We have recombinantly produced E. coli ZraP and measured Zn2+ and Cu2+ affinity in-vitro using Isothermal Titration Calorimetry. ZraP has a significantly higher affinity for Cu2+ than for Zn2+. Mutation of the conserved Cys102 to Ala or Ser resulted in a change of the oligomeric state of the protein. Mutation of the conserved His107 to Ala did not affect the zinc binding affinity or the oligomeric state of the protein. Deletion of the ZraP coding gene from the E. coli genome resulted in a phenotype with tolerance to very high zinc concentrations (up to 2.5 mM) that were lethal to wild type E. coli. These results exclude a direct role for ZraP in Zn2+ tolerance in E. coli.

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