Dimerization, oligomerization, and aggregation of human amyotrophic lateral sclerosis copper/zinc superoxide dismutase 1 protein mutant forms in live cells

J Biol Chem. 2014 May 23;289(21):15094-103. doi: 10.1074/jbc.M113.542613. Epub 2014 Apr 1.

Abstract

More than 100 copper/zinc superoxide dismutase 1 (SOD1) genetic mutations have been characterized. These mutations lead to the death of motor neurons in ALS. In its native form, the SOD1 protein is expressed as a homodimer in the cytosol. In vitro studies have shown that SOD1 mutations impair the dimerization kinetics of the protein, and in vivo studies have shown that SOD1 forms aggregates in patients with familial forms of ALS. In this study, we analyzed WT SOD1 and 9 mutant (mt) forms of the protein by non-invasive fluorescence techniques. Using microscopic techniques such as fluorescence resonance energy transfer, fluorescence complementation, image-based quantification, and fluorescence correlation spectroscopy, we studied SOD1 dimerization, oligomerization, and aggregation. Our results indicate that SOD1 mutations lead to an impairment in SOD1 dimerization and, subsequently, affect protein aggregation. We also show that SOD1 WT and mt proteins can dimerize. However, aggregates are predominantly composed of SOD1 mt proteins.

Keywords: Fluorescence Resonance Energy Transfer (FRET); Fluorescence correlation Spectroscopy; Mutant; Protein Aggregation; Protein Misfolding; Superoxide Dismutase (SOD).

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Amyotrophic Lateral Sclerosis / enzymology*
  • Fluorescence Resonance Energy Transfer
  • HEK293 Cells
  • Humans
  • Liver / cytology
  • Liver / enzymology*
  • Luminescent Proteins / genetics
  • Luminescent Proteins / metabolism
  • Microscopy, Confocal
  • Models, Molecular
  • Mutant Proteins / chemistry
  • Mutant Proteins / genetics
  • Mutation*
  • Protein Multimerization*
  • Protein Structure, Quaternary
  • Spectrometry, Fluorescence
  • Superoxide Dismutase / chemistry*
  • Superoxide Dismutase / genetics*
  • Superoxide Dismutase-1

Substances

  • Luminescent Proteins
  • Mutant Proteins
  • SOD1 protein, human
  • Superoxide Dismutase
  • Superoxide Dismutase-1