Mechanism of ATPase-mediated Cu+ export and delivery to periplasmic chaperones: The interaction of Escherichia coli CopA and CusF

Teresita Padilla-Benavides, Alayna M.George Thompson, Megan M. McEvoy, José M. Argüello

Research output: Contribution to journalArticle

35 Scopus citations

Abstract

Cellular copper homeostasis requires transmembrane transport and compartmental trafficking while maintaining the cell essentially free of uncomplexed Cu2+/+. In bacteria, soluble cytoplasmic and periplasmic chaperones bind and deliver Cu+ to target transporters or metalloenzymes. Transmembrane Cu+-ATPases couple the hydrolysis of ATP to the efflux of cytoplasmic Cu+. Cytosolic Cu+ chaperones (CopZ) interact with a structural platform in Cu+-ATPases (CopA) and deliver copper into the ion permeation path. CusF is a periplasmic Cu+ chaperone that supplies Cu+ to the CusCBA system for efflux to the extracellular milieu. In this report, using Escherichia coli CopA and CusF, direct Cu+ transfer from the ATPase to the periplasmic chaperone was observed. This required the specific interaction of the Cu +-bound form of CopA with apo-CusF for subsequent metal transfer upon ATP hydrolysis. As expected, the reverse Cu+ transfer from CusF to CopA was not observed. Mutation of CopA extracellular loops or the electropositive surface of CusF led to a decrease in Cu+ transfer efficiency. On the other hand, mutation of Met and Glu residues proposed to be part of the metal exit site in the ATPase yielded enzymes with lower turnover rates, although Cu+ transfer was minimally affected. These results showhowsoluble chaperones obtainCu+ from transmembrane transporters. Furthermore, by explaining the movement of Cu+ from the cytoplasmic pool to the extracellular milieu, these data support a mechanism by which cytoplasmic Cu+ can be precisely directed to periplasmic targets via specific transporter-chaperone interactions.

Original languageEnglish (US)
Pages (from-to)20492-20501
Number of pages10
JournalJournal of Biological Chemistry
Volume289
Issue number30
DOIs
StatePublished - Jul 25 2014

ASJC Scopus subject areas

  • Biochemistry
  • Molecular Biology
  • Cell Biology

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