TY - JOUR
T1 - The octarepeat domain of the prion protein binds Cu(II) with three distinct coordination modes at pH 7.4
AU - Chattopadhyay, Madhuri
AU - Walter, Eric D.
AU - Newell, Dustin J.
AU - Jackson, Pilgrim J.
AU - Aronoff-Spencer, Eliah
AU - Peisach, Jack
AU - Gerfen, Gary J.
AU - Bennett, Brian
AU - Antholine, William E.
AU - Millhauser, Glenn L.
PY - 2005/9/14
Y1 - 2005/9/14
N2 - The prion protein (PrP) binds Cu2+ in its N-terminal octarepeat domain. This unusual domain is comprised of four or more tandem repeats of the fundamental sequence PHGGGWGQ. Previous work from our laboratories demonstrates that at full copper occupancy, each HGGGW segment binds a single Cu 2+. However, several recent studies suggest that low copper occupancy favors different coordination modes, possibly involving imidazoles from histidines in adjacent octapeptide segments. This is investigated here using a combination of X-band EPR, S-band EPR, and ESEEM, along with a library of modified peptides designed to favor different coordination interactions. At pH 7.4, three distinct coordination modes are identified. Each mode is fully characterized to reveal a series of copper-dependent octarepeat domain structures. Multiple His coordination is clearly identified at low copper stoichiometry. In addition, EPR detected copper-copper interactions at full occupancy suggest that the octarepeat domain partially collapses, perhaps stabilizing this specific binding mode and facilitating cooperative copper uptake. This work provides the first complete characterization of all dominant copper coordination modes at pH 7.4.
AB - The prion protein (PrP) binds Cu2+ in its N-terminal octarepeat domain. This unusual domain is comprised of four or more tandem repeats of the fundamental sequence PHGGGWGQ. Previous work from our laboratories demonstrates that at full copper occupancy, each HGGGW segment binds a single Cu 2+. However, several recent studies suggest that low copper occupancy favors different coordination modes, possibly involving imidazoles from histidines in adjacent octapeptide segments. This is investigated here using a combination of X-band EPR, S-band EPR, and ESEEM, along with a library of modified peptides designed to favor different coordination interactions. At pH 7.4, three distinct coordination modes are identified. Each mode is fully characterized to reveal a series of copper-dependent octarepeat domain structures. Multiple His coordination is clearly identified at low copper stoichiometry. In addition, EPR detected copper-copper interactions at full occupancy suggest that the octarepeat domain partially collapses, perhaps stabilizing this specific binding mode and facilitating cooperative copper uptake. This work provides the first complete characterization of all dominant copper coordination modes at pH 7.4.
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U2 - 10.1021/ja053254z
DO - 10.1021/ja053254z
M3 - Article
C2 - 16144413
AN - SCOPUS:24744456323
SN - 0002-7863
VL - 127
SP - 12647
EP - 12656
JO - Journal of the American Chemical Society
JF - Journal of the American Chemical Society
IS - 36
ER -