Multimodal Response to Copper Binding in Superoxide Dismutase Dynamics
Résumé
Copper/zinc superoxide dismutase (SOD) is a homodimeric metalloenzyme which has been extensively studied as a benchmark for structure-function relationships in proteins, in particular because of its implication in the familial form of the neurodegenerative disease amyotrophic lateral sclerosis. Here, we investigate microcrystalline preparations of two differently metallated forms of SOD, namely the fully mature functional Cu I ,Zn state and the E,Zn-SOD state in which the Cu site is empty. By using solid-state NMR with fast magic-angle spinning (MAS) at high magnetic fields (1 H Larmor frequency of 800-1000 MHz), we quantify motions spanning a dynamic range from ns to ms. We determine that metal ion uptake does not act as a rigidification element but as a switch redistributing motional processes on different timescales, with coupling of the dynamics of histidine sidechains and those of remote key backbone elements of the protein.
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