Familial amyotrophic lateral sclerosis mutants of copper/zinc superoxide dismutase are susceptible to disulfide reduction
Department of Neurology
Amino Acid Substitution; Animals; Binding Sites; Cysteine; Disulfides; Dithiothreitol; Humans; Iodoacetamide; Kinetics; Mice; Motor Neuron Disease; Mutagenesis, Site-Directed; *Mutation; Organ Specificity; Oxidation-Reduction; Protein Structure, Secondary; Recombinant Proteins; Superoxide Dismutase
Life Sciences | Medicine and Health Sciences
We observed that 14 biologically metallated mutants of copper/zinc superoxide dismutase (SOD1) associated with familial amyotrophic lateral sclerosis all exhibited aberrantly accelerated mobility during partially denaturing PAGE and increased sensitivity to proteolytic digestion compared with wild type SOD1. Decreased metal binding site occupancy and exposure to the disulfide-reducing agents dithiothreitol, Tris(2-carboxyethyl)phosphine (TCEP), or reduced glutathione increased the fraction of anomalously migrating mutant SOD1 proteins. Furthermore, the incubation of mutant SOD1s with TCEP increased the accessibility to iodoacetamide of cysteine residues that normally participate in the formation of the intrasubunit disulfide bond (Cys-57 to Cys-146) or are buried within the core of the beta-barrel (Cys-6). SOD1 enzymes in spinal cord lysates from G85R and G93A mutant but not wild type SOD1 transgenic mice also exhibited abnormal vulnerability to TCEP, which exposed normally inaccessible cysteine residues to modification by maleimide conjugated to polyethylene glycol. These results implicate SOD1 destabilization under cellular disulfide-reducing conditions at physiological pH and temperature as a shared property that may be relevant to amyotrophic lateral sclerosis mutant neurotoxicity.
DOI of Published Version
J Biol Chem. 2003 Feb 21;278(8):5984-92. Epub 2002 Nov 27. Link to article on publisher's site
The Journal of biological chemistry
Tiwari, Ashutosh and Hayward, Lawrence J., "Familial amyotrophic lateral sclerosis mutants of copper/zinc superoxide dismutase are susceptible to disulfide reduction" (2002). Open Access Articles. 723.