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Cu(I) Affinities of the Domain 1 and 3 Sites in the Human Metallochaperone for Cu,Zn-Superoxide Dismutase

Lookup NU author(s): Stephen Allen, Dr Adriana Badarau, Professor Christopher Dennison

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Abstract

The delivery of copper by the human metallochaperone CCS is a key step in the activation of Cu,Zn-superoxide dismutase (SOD1). CCS is a three-domain protein with Cu(I)-binding CXXC and CXC motifs in domains 1 and 3, respectively. A detailed analysis of the binding of copper to CCS, including variants in which the Cys residues from domains 1 and 3 have been mutated to Ser, and also using separate domain 1 and 3 constructs, demonstrates that CCS is able to bind 1 equiv of Cu(I) in both of these domains. The Cu(I) affinity of domain 1 is approximately 5 X 10(17) M-1 at pH 7.5, while that of domain 3 is at least 1 order of magnitude weaker. The CXXC site will therefore be preferentially loaded with Cu(I), suggesting that domain 1 plays a role in the acquisition of the metal. The delivery of copper to the target occurs via domain 3 whose structural flexibility and ability to be transiently metalated during copper delivery appear to be more important than the Cu(I) affinity of its CXC motif The Cu(I) affinity of domain 1 of CCS is comparable to that of HAH1, another cytosolic copper metallochaperone. CCS and HAH1 readily exchange Cu(I), providing a mechanism whereby cross-talk can occur between copper trafficking pathways.

Publication metadata

Author(s): Allen S, Badarau A, Dennison C

Publication type: Article

Publication status: Published

Journal: Biochemistry

Year: 2012

Volume: 51

Issue: 7

Pages: 1439–1448

Print publication date: 09/02/2012

ISSN (print): 0006-2960

ISSN (electronic): 1520-4995

Publisher: American Chemical Society

URL: http://dx.doi.org/10.1021/bi201370r

DOI: 10.1021/bi201370r

PubMed id: 22320662

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