Wild-type Cu/Zn superoxide dismutase stabilizes mutant variants by heterodimerization

Mutations in the gene encoding Cu/Zn superoxide dismutase (SOD1) are responsible for a subset of amyotrophic lateral sclerosis cases presumably by the acquisition of as yet unknown toxic properties. Additional overexpression of wild-type SOD1 in mutant SOD1 transgenic mice did not improve but rather accelerated the disease course. Recently, it was documented that the presence of wild-type SOD1 (SOD(WT)) reduced the aggregation propensity of mutant SOD1 by the formation of heterodimers between mutant and SOD1(WT) and that these heterodimers displayed at least a similar toxicity in cellular and animal models. In this study we investigated the biochemical and biophysical properties of obligate…