MTSOD1s with full dismutase enzymatic activity (e.g., G37R) and without any enzymatic activity (e.g., G85R) cause FALS, demonstrating that the ability of MTSOD1 to cause FALS is not dependent on the dismutase activity; however, it remains unclear whether MTSOD1 dismutase activity can influence disease phenotype.
Here we used wild-type (WT) SOD and five FALS-related mutants (G37R, H46R, G85R, D90A, and L144F) to show that the metals contribute significantly to the kinetic stability of the protein, with demetalated (apo) SOD showing acid-induced unfolding rates about 60-fold greater than the metalated (holo) protein.
There is no significant asymmetry between the monomers in these dimers, in contrast to the subunit structures of the FALSG37R mutant of human SOD1 and in bovine Cu,Zn SOD.
Herein, we demonstrate that the entry of SOD1 into mitochondria depends on demetallation and that heat shock proteins (Hsp70, Hsp27, or Hsp25) block the uptake of the FALS-associated mutant SOD1 (G37R, G41D, or G93A), while having no effect on wild-type SOD1.
Transfection of these cell lines with DNA encoding two mutant SOD1 enzymes (G37R and G85R) associated with familial amyotrophic lateral sclerosis (FALS), produced similar, but more severe changes, i.e. even lower growth rates, higher lipid peroxidation, 3-nitrotyrosine and protein carbonyl levels, decreased GSH levels, raised GSSG levels and higher glutathione peroxidase activities.
To investigate the mechanism of toxicity induced by the mutant SOD1 associated with FALS, we generated transgenic Caenorhabditis elegans strains that contain wild-type and mutant human A4V, G37R and G93A SOD1 recombinant plasmids.
The X-ray crystal structure of a human copper/zinc superoxide dismutase mutant (G37R CuZnSOD) found in some patients with the inherited form of Lou Gehrig's disease (FALS) has been determined to 1.9 angstroms resolution.
We analyzed mutant superoxide dismutase-1 (SOD-1) in erythrocytes from patients with familial amyotrophic lateral sclerosis (FALS) by using ion exchange chromatography and HPLC/electrospray ionization mass spectrometry and were able to divide mutant SOD-1 proteins into a stable form including G37R and H46R, and an unstable form including I149T and a two base pair deletion mutant.