Recombinant Saccharomyces cerevisiae Superoxide dismutase [Cu-Zn] (SOD1)

Recombinant Production and Activation Pathways

Recombinant SOD1 is expressed in heterologous systems (e.g., E. coli or yeast) and purified for biochemical studies. Its activation involves two distinct pathways:

CCS-Dependent vs. CCS-Independent Activation

• Yeast-Specific Dependency: S. cerevisiae SOD1 activation is strictly CCS-dependent due to a unique Pro144 residue that enforces disulfide regulation .

• Mammalian Flexibility: Mammalian SOD1 retains partial activity in CCS-knockout models, suggesting alternative Cu sources under high copper availability .

Proteomic Changes in SOD1 Knockout Yeast (Δsod1)

Deletion of SOD1 alters expression of 18 proteins involved in:

• Carbon Metabolism: Downregulation of glycolytic enzymes (e.g., Tdh3p) .

• Antioxidant Defense: Reduced thioredoxin and glutathione peroxidase levels .

• Amino Acid Biosynthesis: Methionine auxotrophy linked to oxidative inactivation of biosynthetic enzymes .

Functional Consequences

Role in Amyotrophic Lateral Sclerosis (ALS)

• Toxic Gain-of-Function: Mutant SOD1 in ALS acquires aberrant Cu-mediated reactivity, generating toxic radicals (e.g., peroxynitrite) .

• Therapeutic Insights: CCS-knockout mice show reduced SOD1 activity but remain viable, suggesting CCS inhibition as a strategy to mitigate mutant SOD1 toxicity .

Comparative Analysis Across Species

Key Data from Metabolic Studies

• 64Cu Labeling: CCS-deficient mice show >80% reduction in SOD1 activity, confirming CCS’s essential role in Cu incorporation .

• Enzyme Activity: Liver and kidney retain 30% SOD1 activity in CCS knockouts, suggesting tissue-specific Cu availability .