Direct Metal Transfer Between Periplasmic Proteins Identifies a Bacterial Copper Chaperone

Journal Article · Mon May 11 04:00:00 EDT 2009 · Biochem. 47:11408,2008

OSTI ID:958625

Bagai, I; Rensing, C; Blackburn, N; McEvoy, M M

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.

• Research Organization: Stanford Linear Accelerator Center (SLAC)
• Sponsoring Organization: USDOE
• DOE Contract Number: AC02-76SF00515
• OSTI ID: 958625
• Report Number(s): SLAC-REPRINT-2009-063
• Journal Information: Biochem. 47:11408,2008, Journal Name: Biochem. 47:11408,2008 Journal Issue: 44 Vol. 47; ISSN 0006-2960; ISSN BICHAW
• Country of Publication: United States
• Language: English

Related Subjects

59 BASIC BIOLOGICAL SCIENCES
ABSORPTION SPECTROSCOPY
AFFINITY
BACTERIA
CALORIMETRY
COPPER
CYTOPLASM
ESCHERICHIA COLI
EXPORTS
Other
BIO
CHEM
PROTEINS
TITRATION
TRANSITION ELEMENTS