Zinc-mediated interaction of copper chaperones through their heavy-metal associated domains

J Trace Elem Med Biol. 2023 Jan;75:127111. doi: 10.1016/j.jtemb.2022.127111. Epub 2022 Nov 23.


Background: A copper chaperone CCS is a multi-domain protein that supplies a copper ion to Cu/Zn-superoxide dismutase (SOD1). Among the domains of CCS, the N-terminal domain (CCSdI) belongs to a heavy metal-associated (HMA) domain, in which a Cys-x-x-Cys (CxxC) motif binds a heavy metal ion. It has hence been expected that the HMA domain in CCS has a role in the metal trafficking; however, the CxxC motif in the domain is dispensable for supplying a copper ion to SOD1, leaving an open question on roles of CCSdI in CCS.

Methods: To evaluate protein-protein interactions of CCS through CCSdI, yeast two-hybrid assay, a pull-down assay using recombinant proteins, and the analysis with fluorescence resonance energy transfer were performed.

Results: We found that CCS specifically interacted with another copper chaperone HAH1, a HMA domain protein, through CCSdI. The interaction between CCSdI and HAH1 was not involved in the copper supply from CCS to SOD1 but was mediated by a zinc ion ligated with Cys residues of the CxxC motifs in CCSdI and HAH1.

Conclusion: While physiological significance of the interaction between copper chaperones awaits further investigation, we propose that CCSdI would have a role in the metal-mediated interaction with other proteins including heterologous copper chaperones.

Keywords: Copper; Copper chaperone; Heavy-metal associated domain; SOD1; Yeast two-hybrid; Zinc.

MeSH terms

  • Copper*
  • Zinc*


  • Zinc
  • Copper