title: Prion nucleation site unmasked by transient interaction with phospholipid cofactor.
abstract: Infectious mammalian prions can be formed de novo from purified recombinant prion protein (PrP) substrate through a pathway that requires the sequential addition of 1-palmitoyl-2-oleoyl-sn-glycero-3-phosphoglycerol (POPG) and RNA cofactor molecules. Recent studies show that the initial interaction between PrP and POPG causes widespread and persistent conformational changes to form an insoluble intermediate species, termed PrP(Int1). Here, we characterize the mechanism and functional consequences of the interaction between POPG and PrP. Negative-stain electron microscopy of PrP(Int1) revealed the presence of amorphous aggregates. Pull-down and photoaffinity label experiments indicate that POPG induces the formation of a PrP(C) polybasic-domain-binding neoepitope within PrP(Int1). The ongoing presence of POPG is not required to maintain PrP(Int1) structure, as indicated by the absence of stoichiometric levels of POPG in solid-state NMR measurements of PrP(Int1). Together, these results show that a transient interaction with POPG cofactor unmasks a PrP(C) binding site, leading to PrP(Int1) aggregation.
authors: Departments of Biochemistry and ‡Medicine, Geisel School of Medicine at Dartmouth , Hanover, New Hampshire 03755, United States.
authors: Ashley A
authors: AA
authors: Zurawel
authors: Daniel J
authors: DJ
authors: Walsh
authors: Sean M
authors: SM
authors: Fortier
authors: Tamutenda
authors: T
authors: Chidawanyika
authors: Suvrajit
authors: S
authors: Sengupta
authors: Kurt
authors: K
authors: Zilm
authors: Surachai
authors: S
authors: Supattapone
mesh_terms: D000818:Animals; D051379:Mice; D019906:Nuclear Magnetic Resonance, Biomolecular; D010715:Phosphatidylglycerols / Q000737:chemistry*; D011328:Prions / Q000737:chemistry*; D011487:Protein Conformation; D017510:Protein Folding; D020836:Protein Structure, Quaternary; D011994:Recombinant Proteins / Q000737:chemistry
chemical_list: D010715:Phosphatidylglycerols; D011328:Prions; D011994:Recombinant Proteins; C060037:1-palmitoyl-2-oleoylglycero-3-phosphoglycerol