Journal of Biological Chemistry
Volume 275, Issue 43, 27 October 2000, Pages 33771-33776
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METABOLISM AND BIOENERGETICS
Copper Activation of Superoxide Dismutase 1 (SOD1) in Vivo: ROLE FOR PROTEIN-PROTEIN INTERACTIONS WITH THE COPPER CHAPERONE FOR SOD1*

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Insertion of copper into superoxide dismutase 1 (SOD1) in vivo requires the copper chaperone for SOD1 (CCS). CCS encompasses three protein domains: copper binding Domains I and III at the amino and carboxyl termini, and a central Domain II homologous to SOD1. Using a yeast interaction mating system, yeast CCS was seen to physically interact with SOD1, and this interaction required sequences at the predicted dimer interface of CCS Domain II. Interactions with SOD1 also required sequences of Domain III, but not Domain I. Mutations were introduced at the dimer interface of yeast SOD1, and the corresponding mutant failed to interact with CCS. When loaded with copper independent of CCS, this mutant SOD1 exhibited superoxide scavenging activity, but was normally inactive in vivo because CCS failed to recognize the enzyme. Activation of SOD1 by CCS was also examined using an in vivo assay for copper incorporation into SOD1. Yeast CCS was observed to insert copper into a pre-existing pool of apoSOD1 without the need for new SOD1 synthesis or for protein unfolding by the major SSA cytosolic heat shock proteins. Our data are consistent with a model in which prefolded dimers of apoSOD1 serve as substrate for the CCS copper chaperone.

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Published, JBC Papers in Press, August 15, 2000, DOI 10.1074/jbc.M006254200

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This work was supported in part by the Johns Hopkins University National Institute of Environmental Health Sciences center, by Grant GM50016 (to V. C. C.) from the National Institutes of Health (NIH), and by a grant from the Amyotrophic Lateral Sclerosis Association (to C. K.).The costs of publication of this article were defrayed in part by the payment of page charges. The article must therefore be hereby marked “advertisement” in accordance with 18 U.S.C. Section 1734 solely to indicate this fact.

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Supported by NIH Training Grant ES-07141.