Conserved residues modulate copper release in human copper chaperone Atox1.

Abstract

It is unclear how the human copper (Cu) chaperone Atox1 delivers Cu to metal-binding domains of Wilson and Menkes disease proteins in the cytoplasm. To begin to address this problem, we have characterized Cu(I) release from wild-type Atox1 and two point mutants (Met(10)Ala and Lys(60)Ala). The dynamics of Cu(I) displacement from holo-Atox1 were measured by using the Cu(I) chelator bicinchonic acid (BCA) as a metal acceptor. BCA removes Cu(I) from Atox1 in a three-step process involving the bimolecular formation of an initial Atox1-Cu-BCA complex followed by dissociation of Atox1 and the binding of a second BCA to generate apo-Atox1 and Cu-BCA(2). Both mutants lose Cu(I) more readily than wild-type Atox1 because of more rapid and facile displacement of the protein from the Atox1-Cu-BCA intermediate by the second BCA. Remarkably, Cu(I) uptake from solution by BCA is much slower than the transfer from holo-Atox1, presumably because of slow dissociation of DTT-Cu complexes. These results suggest that Cu chaperones play a key role in making Cu(I) rapidly accessible to substrates and that the activated protein-metal-chelator complex may kinetically mimic the ternary chaperone-metal-target complex involved in Cu(I) transfer in vivo.

• Authors: Faiza Hussain, John S Olson, Pernilla Wittung-Stafshede
• Journal: Proceedings of the National Academy of Sciences of the United States of America (Proc Natl Acad Sci U S A) Vol. 105 Issue 32 Pg. 11158-63 (Aug 12 2008) ISSN: 1091-6490 [Electronic] United States
• PMID: 18685091 (Publication Type: Journal Article, Research Support, N.I.H., Extramural, Research Support, Non-U.S. Gov't)

Chemical References

• ATOX1 protein, human
• Cation Transport Proteins
• Chelating Agents
• Copper Transport Proteins
• Metallochaperones
• Molecular Chaperones
• Multiprotein Complexes
• Quinolines
• Serum Albumin, Bovine
• Copper
• bicinchoninic acid
• Adenosine Triphosphatases
• Copper-Transporting ATPases

Topics

• Adenosine Triphosphatases (chemistry, genetics, metabolism)
• Animals
• Cation Transport Proteins (chemistry, genetics, metabolism)
• Cattle
• Chelating Agents (chemistry)
• Copper (chemistry, metabolism)
• Copper Transport Proteins
• Copper-Transporting ATPases
• Humans
• Kinetics
• Metallochaperones
• Models, Chemical
• Molecular Chaperones (chemistry, genetics, metabolism)
• Multiprotein Complexes (chemistry, genetics, metabolism)
• Point Mutation
• Protein Binding (physiology)
• Quinolines (chemistry)
• Serum Albumin, Bovine (chemistry, genetics, metabolism)