title: Copper alters aggregation behavior of prion protein and induces novel interactions between its N- and C-terminal regions.
abstract: Copper is reported to promote and prevent aggregation of prion protein. Conformational and functional consequences of Cu(2+)-binding to prion protein (PrP) are not well understood largely because most of the Cu(2+)-binding studies have been performed on fragments and truncated variants of the prion protein. In this context, we set out to investigate the conformational consequences of Cu(2+)-binding to full-length prion protein (PrP) by isothermal calorimetry, NMR, and small angle x-ray scattering. In this study, we report altered aggregation behavior of full-length PrP upon binding to Cu(2+). At physiological temperature, Cu(2+) did not promote aggregation suggesting that Cu(2+) may not play a role in the aggregation of PrP at physiological temperature (37 °C). However, Cu(2+)-bound PrP aggregated at lower temperatures. This temperature-dependent process is reversible. Our results show two novel intra-protein interactions upon Cu(2+)-binding. The N-terminal region (residues 90-120 that contain the site His-96/His-111) becomes proximal to helix-1 (residues 144-147) and its nearby loop region (residues 139-143), which may be important in preventing amyloid fibril formation in the presence of Cu(2+). In addition, we observed another novel interaction between the N-terminal region comprising the octapeptide repeats (residues 60-91) and helix-2 (residues 174-185) of PrP. Small angle x-ray scattering studies of full-length PrP show significant compactness upon Cu(2+)-binding. Our results demonstrate novel long range inter-domain interactions of the N- and C-terminal regions of PrP upon Cu(2+)-binding, which might have physiological significance.
authors: Centre for Cellular and Molecular Biology, Council of Scientific and Industrial Research, Uppal Road, Hyderabad 500 007, India.
authors: Abhay Kumar
authors: AK
authors: Thakur
authors: Department of Chemical Sciences, Tata Institute of Fundamental Research, Homi Bhabha Road, Colaba, Mumbai 400 005, India.
authors: Atul Kumar
authors: AK
authors: Srivastava
authors: Centre for Cellular and Molecular Biology, Council of Scientific and Industrial Research, Uppal Road, Hyderabad 500 007, India.
authors: Volety
authors: V
authors: Srinivas
authors: Department of Chemical Sciences, Tata Institute of Fundamental Research, Homi Bhabha Road, Colaba, Mumbai 400 005, India.
authors: Kandala Venkata Ramana
authors: KVR
authors: Chary
authors: Centre for Cellular and Molecular Biology, Council of Scientific and Industrial Research, Uppal Road, Hyderabad 500 007, India. Electronic address: mohan@ccmb.res.in.
authors: Chintalagiri Mohan
authors: CM
authors: Rao
mesh_terms: D000818:Animals; D001665:Binding Sites; D002151:Calorimetry / Q000379:methods; D003300:Copper / Q000737:chemistry*; D006639:Histidine / Q000737:chemistry; D006801:Humans; D009682:Magnetic Resonance Spectroscopy / Q000379:methods; D051379:Mice; D008968:Molecular Conformation; D017096:Prion Diseases / Q000378:metabolism; D011328:Prions / Q000737:chemistry*; D017434:Protein Structure, Tertiary; D012542:Scattering, Radiation; D013053:Spectrophotometry / Q000379:methods; D013696:Temperature; D014965:X-Rays
chemical_list: D011328:Prions; D006639:Histidine; D003300:Copper