Medical College of Wisconsin
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Copper coordination in the full-length, recombinant prion protein. Biochemistry 2003 Jun 10;42(22):6794-803

Date

06/05/2003

Pubmed ID

12779334

Pubmed Central ID

PMC2905145

DOI

10.1021/bi027138+

Scopus ID

2-s2.0-0037646939 (requires institutional sign-in at Scopus site)   269 Citations

Abstract

The prion protein (PrP) binds divalent copper at physiologically relevant conditions and is believed to participate in copper regulation or act as a copper-dependent enzyme. Ongoing studies aim at determining the molecular features of the copper binding sites. The emerging consensus is that most copper binds in the octarepeat domain, which is composed of four or more copies of the fundamental sequence PHGGGWGQ. Previous work from our laboratory using PrP-derived peptides, in conjunction with EPR and X-ray crystallography, demonstrated that the HGGGW segment constitutes the fundamental binding unit in the octarepeat domain [Burns et al. (2002) Biochemistry 41, 3991-4001; Aronoff-Spencer et al. (2000) Biochemistry 39, 13760-13771]. Copper coordination arises from the His imidazole and sequential deprotonated glycine amides. In this present work, recombinant, full-length Syrian hamster PrP is investigated using EPR methodologies. Four copper ions are taken up in the octarepeat domain, which supports previous findings. However, quantification studies reveal a fifth binding site in the flexible region between the octarepeats and the PrP globular C-terminal domain. A series of PrP peptide constructs show that this site involves His96 in the PrP(92-96) segment GGGTH. Further examination by X-band EPR, S-band EPR, and electron spin-echo envelope spectroscopy, demonstrates coordination by the His96 imidazole and the glycine preceding the threonine. The copper affinity for this type of binding site is highly pH dependent, and EPR studies here show that recombinant PrP loses its affinity for copper below pH 6.0. These studies seem to provide a complete profile of the copper binding sites in PrP and support the hypothesis that PrP function is related to its ability to bind copper in a pH-dependent fashion.

Author List

Burns CS, Aronoff-Spencer E, Legname G, Prusiner SB, Antholine WE, Gerfen GJ, Peisach J, Millhauser GL



MESH terms used to index this publication - Major topics in bold

Animals
Binding Sites
Copper
Cricetinae
Electron Spin Resonance Spectroscopy
Glycine
Histidine
Hydrogen-Ion Concentration
Models, Molecular
Prions
Protein Structure, Tertiary
Recombinant Proteins
Repetitive Sequences, Amino Acid