title: Pharmacological chaperone for the structured domain of human prion protein.
abstract: In prion diseases, the misfolded protein aggregates are derived from cellular prion protein (PrP(C)). Numerous ligands have been reported to bind to human PrP(C) (huPrP), but none to the structured region with the affinity required for a pharmacological chaperone. Using equilibrium dialysis, we screened molecules previously suggested to interact with PrP to discriminate between those which did not interact with PrP, behaved as nonspecific polyionic aggregates or formed a genuine interaction. Those that bind could potentially act as pharmacological chaperones. Here we report that a cationic tetrapyrrole [Fe(III)-TMPyP], which displays potent antiprion activity, binds to the structured region of huPrP. Using a battery of biophysical techniques, we demonstrate that Fe(III)-TMPyP forms a 11 complex via the structured C terminus of huPrP with a K(d) of 4.5 ± 2 μM, which is in the range of its IC(50) for curing prion-infected cells of 1.6 ± 0.4 μM and the concentration required to inhibit protein-misfolding cyclic amplification. Therefore, this molecule tests the hypothesis that stabilization of huPrP(C), as a principle, could be used in the treatment of human prion disease. The identification of a binding site with a defined 3D structure opens up the possibility of designing small molecules that stabilize huPrP and prevent its conversion into the disease-associated form.
authors.affiliation: Department of Neurodegenerative Disease and Medical Research Council Prion Unit, University College of London Institute of Neurology, Queen Square, London WCN1 3BG, United Kingdom.
authors.forename: Andrew J
authors.initials: AJ
authors.lastname: Nicoll
authors.forename: Clare R
authors.initials: CR
authors.lastname: Trevitt
authors.forename: M Howard
authors.initials: MH
authors.lastname: Tattum
authors.forename: Emmanuel
authors.initials: E
authors.lastname: Risse
authors.forename: Emma
authors.initials: E
authors.lastname: Quarterman
authors.forename: Amaurys Avila
authors.initials: AA
authors.lastname: Ibarra
authors.forename: Connor
authors.initials: C
authors.lastname: Wright
authors.forename: Graham S
authors.initials: GS
authors.lastname: Jackson
authors.forename: Richard B
authors.initials: RB
authors.lastname: Sessions
authors.forename: Mark
authors.initials: M
authors.lastname: Farrow
authors.forename: Jonathan P
authors.initials: JP
authors.lastname: Waltho
authors.forename: Anthony R
authors.initials: AR
authors.lastname: Clarke
authors.forename: John
authors.initials: J
authors.lastname: Collinge
mesh_terms: D001665:Binding Sites / Q000235:genetics; D001703:Biophysics / Q000379:methods; D002942:Circular Dichroism; D055808:Drug Discovery / Q000379:methods*; D006801:Humans; D009682:Magnetic Resonance Spectroscopy; D008958:Models, Molecular; D017096:Prion Diseases / Q000188:drug therapy*; D011328:Prions / Q000737:chemistry / Q000378:metabolism*; D011485:Protein Binding; D017510:Protein Folding; D045725:Tetrapyrroles / Q000378:metabolism*; D014461:Ultracentrifugation
chemical_list: D011328:Prions; D045725:Tetrapyrroles