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Title: Direct Metal Transfer Between Periplasmic Proteins Identifies a Bacterial Copper Chaperone

Abstract

Transition metals require exquisite handling within cells to ensure that cells are not harmed by an excess of free metal species. In Gram-negative bacteria, copper is required in only small amounts in the periplasm, not in the cytoplasm, so a key aspect of protection under excess metal conditions is to export copper from the periplasm. Additional protection could be conferred by a periplasmic chaperone to limit the free metal species prior to export. Using isothermal titration calorimetry, we have demonstrated that two periplasmic proteins, CusF and CusB, of the Escherichia coli Cu(I)/Ag(I) efflux system undergo a metal-dependent interaction. Through the development of a novel X-ray absorption spectroscopy approach using selenomethionine labeling to distinguish the metal sites of the two proteins, we have demonstrated transfer of Cu(I) occurs between CusF and CusB. The interaction between these proteins is highly specific, as a homologue of CusF with a 51% identical sequence and a similar affinity for metal, did not function in metal transfer. These experiments establish a metallochaperone activity for CusF in the periplasm of Gram-negative bacteria, serving to protect the periplasm from metal-mediated damage.

Authors:
; ; ;
Publication Date:
Research Org.:
SLAC National Accelerator Lab., Menlo Park, CA (United States)
Sponsoring Org.:
USDOE
OSTI Identifier:
958625
Report Number(s):
SLAC-REPRINT-2009-063
Journal ID: ISSN 0006-2960; BICHAW; TRN: US201001%%773
DOE Contract Number:  
AC02-76SF00515
Resource Type:
Journal Article
Journal Name:
Biochem. 47:11408,2008
Additional Journal Information:
Journal Volume: 47; Journal Issue: 44; Journal ID: ISSN 0006-2960
Country of Publication:
United States
Language:
English
Subject:
59 BASIC BIOLOGICAL SCIENCES; ABSORPTION SPECTROSCOPY; AFFINITY; BACTERIA; CALORIMETRY; COPPER; CYTOPLASM; ESCHERICHIA COLI; EXPORTS; PROTEINS; TITRATION; TRANSITION ELEMENTS; Other,BIO, CHEM

Citation Formats

Bagai, I, Rensing, C, Blackburn, N, and McEvoy, M M. Direct Metal Transfer Between Periplasmic Proteins Identifies a Bacterial Copper Chaperone. United States: N. p., 2009. Web.
Bagai, I, Rensing, C, Blackburn, N, & McEvoy, M M. Direct Metal Transfer Between Periplasmic Proteins Identifies a Bacterial Copper Chaperone. United States.
Bagai, I, Rensing, C, Blackburn, N, and McEvoy, M M. 2009. "Direct Metal Transfer Between Periplasmic Proteins Identifies a Bacterial Copper Chaperone". United States.
@article{osti_958625,
title = {Direct Metal Transfer Between Periplasmic Proteins Identifies a Bacterial Copper Chaperone},
author = {Bagai, I and Rensing, C and Blackburn, N and McEvoy, M M},
abstractNote = {Transition metals require exquisite handling within cells to ensure that cells are not harmed by an excess of free metal species. In Gram-negative bacteria, copper is required in only small amounts in the periplasm, not in the cytoplasm, so a key aspect of protection under excess metal conditions is to export copper from the periplasm. Additional protection could be conferred by a periplasmic chaperone to limit the free metal species prior to export. Using isothermal titration calorimetry, we have demonstrated that two periplasmic proteins, CusF and CusB, of the Escherichia coli Cu(I)/Ag(I) efflux system undergo a metal-dependent interaction. Through the development of a novel X-ray absorption spectroscopy approach using selenomethionine labeling to distinguish the metal sites of the two proteins, we have demonstrated transfer of Cu(I) occurs between CusF and CusB. The interaction between these proteins is highly specific, as a homologue of CusF with a 51% identical sequence and a similar affinity for metal, did not function in metal transfer. These experiments establish a metallochaperone activity for CusF in the periplasm of Gram-negative bacteria, serving to protect the periplasm from metal-mediated damage.},
doi = {},
url = {https://www.osti.gov/biblio/958625}, journal = {Biochem. 47:11408,2008},
issn = {0006-2960},
number = 44,
volume = 47,
place = {United States},
year = {Mon May 11 00:00:00 EDT 2009},
month = {Mon May 11 00:00:00 EDT 2009}
}