One octarepeate expansion to the human prion protein alters both the Zn2+ and Cu2+ coordination environments within the octarepeate domain |
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Authors: | Shearer Jason Rosenkoetter Kyle E Callan Paige E Pham Chi |
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Affiliation: | Department of Chemistry/216, University of Nevada, Reno, Reno, Nevada 89557, United States. shearer@unr.edu |
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Abstract: | The influence of a single octarepeat expansion on the Cu(II) and Zn(II) coordination environments within the octarepeat domain of the human prion protein is examined. Using X-ray absorption spectroscopy and diethyl pyrocarbonate labeling studies, we find that at low copper concentrations the "normal" octarepeat domain (four PHGGGWGQ repeats) coordinates Zn(II) in an (N/O)(6) coordination environment with two histidine residues and Cu(II) in a redox-inactive (N/O)(4) coordination environment using one imidazole residue. Expansion of the octarepeat region by one repeat (five PHGGGWGQ repeats) yields a three-histidine (N/O)(6) coordination environment for Zn(II) and a two-histidine (N/O)(4) coordination environment for Cu(II) at low copper concentrations. This Cu(II)[(N/O)(2)-histidine(2)] coordination motif is redox-active and capable of generating H(2)O(2) under reducing aerobic conditions. |
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