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Unusual Cu(I)/Ag(I) coordination of Escherichia coli CusF as revealed by atomic resolution crystallography and X‐ray absorption spectroscopy
Author(s) -
Loftin Isabell R.,
Franke Sylvia,
Blackburn Ninian J.,
McEvoy Megan M.
Publication year - 2007
Publication title -
protein science
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 3.353
H-Index - 175
eISSN - 1469-896X
pISSN - 0961-8368
DOI - 10.1110/ps.073021307
Subject(s) - periplasmic space , copper , x ray absorption spectroscopy , chemistry , extended x ray absorption fine structure , crystallography , escherichia coli , histidine , metal , absorption (acoustics) , absorption spectroscopy , inorganic chemistry , materials science , biochemistry , amino acid , organic chemistry , physics , quantum mechanics , composite material , gene
Elevated levels of copper or silver ions in the environment are an immediate threat to many organisms. Escherichia coli is able to resist the toxic effects of these ions through strictly limiting intracellular levels of Cu(I) and Ag(I). The CusCFBA system is one system in E. coli responsible for copper/silver tolerance. A key component of this system is the periplasmic copper/silver‐binding protein, CusF. Here the X‐ray structure and XAS data on the CusF–Ag(I) and CusF–Cu(I) complexes, respectively, are reported. In the CusF–Ag(I) structure, Ag(I) is coordinated by two methionines and a histidine, with a nearby tryptophan capping the metal site. EXAFS measurements on the CusF–Cu(I) complex show a similar environment for Cu(I). The arrangement of ligands effectively sequesters the metal from its periplasmic environment and thus may play a role in protecting the cell from the toxic ion.