Human SOD1 before harboring the catalytic metal: solution structure of copper-depleted, disulfide-reduced form.
SOD1 has to undergo several post-translational modifications before reaching its mature form. The protein requires insertion of zinc and copper atoms, followed by the formation of a conserved S-S bond between Cys-57 and Cys-146 (human numbering), which makes the protein fully active. In this report an NMR structural investigation of the reduced SH-SH form of thermostable E,Zn-as-SOD1 (E is empty; as is C6A, C111S) is reported, characterizing the protein just before the last step leading to the mature form. The structure is compared with that of the oxidized S-S form as well as with that of the yeast SOD1 complexed with its copper chaperone, CCS. Local conformational rearrangements upon disulfide bridge reduction are localized in the region near Cys-57 that is completely exposed to the solvent in the present structure, at variance with the oxidized forms. There is a local disorder around Cys-57 that may serve for protein-protein recognition and may possibly be involved in intermolecular S-S bonds in familial amyotrophic lateral sclerosis-related SOD1 mutants. The structure allows us to further discuss the copper loading mechanism in SOD1.
Banci
Lucia
L
Magnetic Resonance Center, University of Florence, Via Luigi Sacconi 6, 50019 Sesto Fiorentino, Florence, Italy.
Bertini
Ivano
I
Cantini
Francesca
F
D'Amelio
Nicola
N
Gaggelli
Elena
E
D000690:Amyotrophic Lateral Sclerosis / Q000378:metabolism; D002384:Catalysis; D003300:Copper / Q000737:chemistry*; D003545:Cysteine / Q000737:chemistry; D004220:Disulfides / Q000737:chemistry; D004926:Escherichia coli / Q000378:metabolism; D006801:Humans; D009682:Magnetic Resonance Spectroscopy; D008954:Models, Biological; D008958:Models, Molecular; D015233:Models, Statistical; D008968:Molecular Conformation; D009154:Mutation; D011487:Protein Conformation; D011506:Proteins / Q000737:chemistry; D013482:Superoxide Dismutase / Q000737:chemistry / Q000502:physiology*; D000072105:Superoxide Dismutase-1
D004220:Disulfides; D011506:Proteins; C000606290:SOD1 protein, human; D003300:Copper; D013482:Superoxide Dismutase; D000072105:Superoxide Dismutase-1; D003545:Cysteine