Abstract
Metallochaperones are a diverse family of trafficking molecules that provide metal ions to protein targets for use as cofactors. The copper chaperone for superoxide dismutase (Ccs1) activates immature copper-zinc superoxide dismutase (Sod1) by delivering copper and facilitating the oxidation of the Sod1 intramolecular disulfide bond. Here, we present structural, spectroscopic, and cell-based data supporting a novel copper-induced mechanism for Sod1 activation. Ccs1 binding exposes an electropositive cavity and proposed "entry site" for copper ion delivery on immature Sod1. Copper-mediated sulfenylation leads to a sulfenic acid intermediate that eventually resolves to form the Sod1 disulfide bond with concomitant release of copper into the Sod1 active site. Sod1 is the predominant disulfide bond-requiring enzyme in the cytoplasm, and this copper-induced mechanism of disulfide bond formation obviates the need for a thiol/disulfide oxidoreductase in that compartment.
Keywords:
X-ray crystallography; chaperone; copper; enzyme activation; metalloenzyme; superoxide dismutase (SOD).
© 2017 by The American Society for Biochemistry and Molecular Biology, Inc.
Publication types
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Research Support, Non-U.S. Gov't
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Research Support, U.S. Gov't, Non-P.H.S.
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Research Support, N.I.H., Extramural
MeSH terms
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Amino Acid Substitution
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Apoenzymes / chemistry
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Apoenzymes / genetics
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Apoenzymes / metabolism
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Binding Sites
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Copper / metabolism*
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Crystallography, X-Ray
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Cysteine / metabolism
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Cystine / metabolism*
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Enzyme Activation
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Enzyme Stability
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Humans
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Ligands
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Models, Molecular*
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Molecular Chaperones / chemistry
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Molecular Chaperones / genetics
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Molecular Chaperones / metabolism*
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Mutagenesis, Site-Directed
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Mutation
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Oxidation-Reduction
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Protein Conformation
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Protein Interaction Domains and Motifs
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Protein Processing, Post-Translational*
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Recombinant Proteins / chemistry
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Recombinant Proteins / metabolism
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Saccharomyces cerevisiae Proteins / chemistry
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Saccharomyces cerevisiae Proteins / genetics
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Saccharomyces cerevisiae Proteins / metabolism*
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Superoxide Dismutase / chemistry
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Superoxide Dismutase / genetics
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Superoxide Dismutase / metabolism*
Substances
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Apoenzymes
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CCS1 protein, S cerevisiae
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Ligands
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Molecular Chaperones
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Recombinant Proteins
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Saccharomyces cerevisiae Proteins
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Cystine
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Copper
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LYS7 protein, S cerevisiae
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Superoxide Dismutase
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Cysteine
Associated data
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PDB/5U9M
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PDB/1JK9
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PDB/1OZU