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Title: Nickel-Specific Response in the Transcriptional Regulator, Escherichia coli NikR

Abstract

Studies of the transcriptional repression of the Ni-specific permease encoded by the P{sub nik} operon by Escherichia coli NikR using a LacZ reporter assay establish that the NikR response is specific to nickel in vivo. Toward understanding this metal ion-specific response, X-ray absorption spectroscopy (XAS) analysis of various M-NikR complexes (M = Co(II), Ni(II), Cu(II), Cu(I), and Zn(II)) was used to show that each high-affinity binding site metal adopts a unique structure, with Ni(II) and Cu(II) being the only two metal ions to feature planar four-coordinate complexes. The results are consistent with an allosteric mechanism whereby the geometry and ligand selection of the metal present in the high-affinity site induce a unique conformation in NikR that subsequently influences DNA binding. The influence of the high-affinity metal on protein structure was examined using hydrogen/deuterium (H/D) exchange detected by liquid chromatography-electrospray ionization mass spectrometry (LC-ESI-MS). Each NikR complex gives rise to differing amounts of H/D exchange; Zn(II)- and Co(II)-NikR are most like apo-NikR, while the exchange time course is substantially different for Ni(II) and to a lesser extent for Cu(II). In addition to the high-affinity metal binding site, E. coli NikR has a low-affinity metal-binding site that affects DNA binding affinity. Wemore » have characterized this low-affinity site using XAS in heterobimetallic complexes of NikR. When Cu(II) occupies the high-affinity site and Ni(II) occupies the low-affinity site, the Ni K-edge XAS spectra show that the Ni site is composed of six N/O-donors. A similar low-affinity site structure is found for the NikR complex when Co(II) occupies the low-affinity site and Ni(II) occupies the high-affinity site, except that one of the Co(II) ligands is a chloride derived from the buffer.« less

Authors:
; ; ; ;
Publication Date:
Research Org.:
Brookhaven National Laboratory (BNL) National Synchrotron Light Source
Sponsoring Org.:
Doe - Office Of Science
OSTI Identifier:
930361
Report Number(s):
BNL-81080-2008-JA
Journal ID: ISSN 0002-7863; JACSAT; TRN: US200904%%651
DOE Contract Number:  
DE-AC02-98CH10886
Resource Type:
Journal Article
Resource Relation:
Journal Name: Journal of the American Chemical Society; Journal Volume: 129
Country of Publication:
United States
Language:
English
Subject:
59 BASIC BIOLOGICAL SCIENCES; ABSORPTION SPECTROSCOPY; AFFINITY; CHLORIDES; DNA; ESCHERICHIA COLI; IN VIVO; IONIZATION; MASS SPECTROSCOPY; NICKEL; PROTEIN STRUCTURE; SPECTRA; X-RAY SPECTROSCOPY; national synchrotron light source

Citation Formats

Leitch,S., Bradley, M., Rowe, J., Chivers, P., and Maroney, M. Nickel-Specific Response in the Transcriptional Regulator, Escherichia coli NikR. United States: N. p., 2007. Web. doi:10.1021/ja068505y.
Leitch,S., Bradley, M., Rowe, J., Chivers, P., & Maroney, M. Nickel-Specific Response in the Transcriptional Regulator, Escherichia coli NikR. United States. doi:10.1021/ja068505y.
Leitch,S., Bradley, M., Rowe, J., Chivers, P., and Maroney, M. Mon . "Nickel-Specific Response in the Transcriptional Regulator, Escherichia coli NikR". United States. doi:10.1021/ja068505y.
@article{osti_930361,
title = {Nickel-Specific Response in the Transcriptional Regulator, Escherichia coli NikR},
author = {Leitch,S. and Bradley, M. and Rowe, J. and Chivers, P. and Maroney, M.},
abstractNote = {Studies of the transcriptional repression of the Ni-specific permease encoded by the P{sub nik} operon by Escherichia coli NikR using a LacZ reporter assay establish that the NikR response is specific to nickel in vivo. Toward understanding this metal ion-specific response, X-ray absorption spectroscopy (XAS) analysis of various M-NikR complexes (M = Co(II), Ni(II), Cu(II), Cu(I), and Zn(II)) was used to show that each high-affinity binding site metal adopts a unique structure, with Ni(II) and Cu(II) being the only two metal ions to feature planar four-coordinate complexes. The results are consistent with an allosteric mechanism whereby the geometry and ligand selection of the metal present in the high-affinity site induce a unique conformation in NikR that subsequently influences DNA binding. The influence of the high-affinity metal on protein structure was examined using hydrogen/deuterium (H/D) exchange detected by liquid chromatography-electrospray ionization mass spectrometry (LC-ESI-MS). Each NikR complex gives rise to differing amounts of H/D exchange; Zn(II)- and Co(II)-NikR are most like apo-NikR, while the exchange time course is substantially different for Ni(II) and to a lesser extent for Cu(II). In addition to the high-affinity metal binding site, E. coli NikR has a low-affinity metal-binding site that affects DNA binding affinity. We have characterized this low-affinity site using XAS in heterobimetallic complexes of NikR. When Cu(II) occupies the high-affinity site and Ni(II) occupies the low-affinity site, the Ni K-edge XAS spectra show that the Ni site is composed of six N/O-donors. A similar low-affinity site structure is found for the NikR complex when Co(II) occupies the low-affinity site and Ni(II) occupies the high-affinity site, except that one of the Co(II) ligands is a chloride derived from the buffer.},
doi = {10.1021/ja068505y},
journal = {Journal of the American Chemical Society},
number = ,
volume = 129,
place = {United States},
year = {Mon Jan 01 00:00:00 EST 2007},
month = {Mon Jan 01 00:00:00 EST 2007}
}