The bacterial copper resistance protein CopG contains a cysteine-bridged tetranuclear copper cluster

Andrew C. Hausrath, Nicholas A. Ramirez, Alan T. Ly, Megan M. McEvoy

Research output: Contribution to journalArticlepeer-review

11 Scopus citations


CopG is an uncharacterized protein ubiquitous in Gram-negative bacteria whose gene frequently occurs in clusters of copper resistance genes and can be recognized by the presence of a conserved CxCC motif. To investigate its contribution to copper resistance, here we undertook a structural and biochemical characterization of the CopG protein from Pseudomonas aeruginosa. Results from biochemical analyses of CopG purified under aerobic conditions indicate that it is a green copper-binding protein that displays absorbance maxima near 411, 581, and 721 nm and is monomeric in solution. Determination of the three-dimensional structure by X-ray crystallography revealed that CopG consists of a thioredoxin domain with a C-terminal extension that contributes to metal binding. We noted that adjacent to the CxCC motif is a cluster of four copper ions bridged by cysteine sulfur atoms. Structures of CopG in two oxidation states support the assignment of this protein as an oxidoreductase. On the basis of these structural and spectroscopic findings and also genetic evidence, we propose that CopG has a role in interconverting Cu(I) and Cu(II) to minimize toxic effects and facilitate export by the Cus RND transporter efflux system.

Original languageEnglish (US)
Pages (from-to)11364-11376
Number of pages13
JournalJournal of Biological Chemistry
Issue number32
StatePublished - Aug 7 2020

ASJC Scopus subject areas

  • Biochemistry
  • Molecular Biology
  • Cell Biology


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