Disease-associated mutations at copper ligand histidine residues of superoxide dismutase 1 diminish the binding of copper and compromise dimer stability

Jiou Wang, Amy Caruano-Yzermans, Angela Rodriguez, Jonathan P. Scheurmann, Hilda H. Slunt, Xiaohang Cao, Jonathan Gitlin, P. John Hart, David R. Borchelt

Research output: Contribution to journalArticle

Abstract

A subset of superoxide dismutase 1 (Cu/Zn-SOD1) mutants that cause familial amyotrophic lateral sclerosis (FALS) have heightened reactivity with -ONOO and H2O2 in vitro. This reactivity requires a copper ion bound in the active site and is a suggested mechanism of motor neuron injury. However, we have found that transgenic mice that express SOD1-H46R/H48Q, which combines natural FALS mutations at ligands for copper and which is inactive, develop motor neuron disease. Using a direct radioactive copper incorporation assay in transfected cells and the established tools of single crystal x-ray diffraction, we now demonstrate that this variant does not stably bind copper. We find that single mutations at copper ligands, including H46R, H48Q, and a quadruple mutant H46R/H48Q/H63G/H120G, also diminish the binding of radioactive copper. Further, using native polyacrylamide gel electrophoresis and a yeast two-hybrid assay, the binding of copper was found to be related to the formation of the stable dimeric enzyme. Collectively, our data demonstrate a relationship between copper and assembly of SOD1 into stable dimers and also define disease-causing SOD1 mutants that are unlikely to robustly produce toxic radicals via copper-mediated chemistry.

Original languageEnglish (US)
Pages (from-to)345-352
Number of pages8
JournalJournal of Biological Chemistry
Volume282
Issue number1
DOIs
StatePublished - Jan 5 2007

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ASJC Scopus subject areas

  • Biochemistry
  • Molecular Biology
  • Cell Biology

Cite this

Wang, J., Caruano-Yzermans, A., Rodriguez, A., Scheurmann, J. P., Slunt, H. H., Cao, X., Gitlin, J., Hart, P. J., & Borchelt, D. R. (2007). Disease-associated mutations at copper ligand histidine residues of superoxide dismutase 1 diminish the binding of copper and compromise dimer stability. Journal of Biological Chemistry, 282(1), 345-352. https://doi.org/10.1074/jbc.M604503200