Direct metal transfer between periplasmic proteins identifies a bacterial copper chaperone

Ireena Bagai, Christopher Rensing, Ninian J. Blackburn, Megan McEvoy

Research output: Contribution to journalArticle

82 Citations (Scopus)

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)AAg(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.

Original languageEnglish (US)
Pages (from-to)11408-11414
Number of pages7
JournalBiochemistry
Volume47
Issue number44
DOIs
StatePublished - Nov 4 2008

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Periplasmic Proteins
Copper
Metals
Periplasm
Gram-Negative Bacteria
Metallochaperones
Bacteria
Selenomethionine
X-Ray Absorption Spectroscopy
X ray absorption spectroscopy
Calorimetry
Titration
Labeling
Escherichia coli
Transition metals
Proteins
Cytoplasm

ASJC Scopus subject areas

  • Biochemistry

Cite this

Direct metal transfer between periplasmic proteins identifies a bacterial copper chaperone. / Bagai, Ireena; Rensing, Christopher; Blackburn, Ninian J.; McEvoy, Megan.

In: Biochemistry, Vol. 47, No. 44, 04.11.2008, p. 11408-11414.

Research output: Contribution to journalArticle

Bagai, Ireena ; Rensing, Christopher ; Blackburn, Ninian J. ; McEvoy, Megan. / Direct metal transfer between periplasmic proteins identifies a bacterial copper chaperone. In: Biochemistry. 2008 ; Vol. 47, No. 44. pp. 11408-11414.
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