Dynamic properties of the G93A mutant of copper-zinc superoxide dismutase as detected by NMR spectroscopy: implications for the pathology of familial amyotrophic lateral sclerosis.
The backbone assignment of the copper-zinc superoxide dismutase amyotrophic lateral sclerosis G93A mutant was performed on an (15)N-enriched protein sample. (15)N R(1), R(2), and R(1)(rho) and (15)N-(1)H NOE experiments were then carried out at 600 MHz on G93A Cu(2)Zn(2)SOD and the values compared to the dynamics data for the "wild-type" protein. In addition, (15)N and (1)H chemical shift comparisons between wild-type Cu(2)Zn(2)SOD and its G93A mutant were also made. G93A exhibits a higher mobility than wild-type Cu(2)Zn(2)SOD, particularly in loops III and V, on a time scale faster than the rate of protein tumbling. There are also distinct chemical shift and NOE differences in residues 35-42 and 92-95, which comprise these loops. These two regions of Cu(2)Zn(2)SOD form the end of the beta-barrel termed the "beta-barrel plug" [Tainer, J. A., Getzoff, E. D., Beem, K. M., Richardson, J. S., and Richardson, D. C. (1982) J. Mol. Biol. 160, 181-217]. The increased mobility and reduction of the number of observed NOEs in this region indicate an opening of the beta-barrel that may lead to amyloid fibrillogenesis. Alternatively, a motor neuron-specific substrate may bind this region of the protein, leading to deleterious modifications and/or reactions.
Shipp
Eric L
EL
Magnetic Resonance Center (CERM), University of Florence, Via Luigi Sacconi 6, 50019 Sesto Fiorentino, Italy.
Cantini
Francesca
F
Bertini
Ivano
I
Valentine
Joan Selverstone
JS
Banci
Lucia
L
D000409:Alanine / Q000235:genetics*; D000690:Amyotrophic Lateral Sclerosis / Q000201:enzymology* / Q000235:genetics / Q000473:pathology*; D003300:Copper / Q000737:chemistry; D005998:Glycine / Q000235:genetics*; D006801:Humans; D008958:Models, Molecular; D019906:Nuclear Magnetic Resonance, Biomolecular / Q000379:methods; D010957:Plasmids; D011487:Protein Conformation; D017510:Protein Folding; D011994:Recombinant Proteins / Q000737:chemistry / Q000235:genetics / Q000302:isolation & purification; D013482:Superoxide Dismutase / Q000737:chemistry* / Q000235:genetics* / Q000302:isolation & purification; D013816:Thermodynamics; D015032:Zinc / Q000737:chemistry
D011994:Recombinant Proteins; D003300:Copper; C109415:SOD1 G93A protein; D013482:Superoxide Dismutase; D015032:Zinc; D000409:Alanine; D005998:Glycine