NMR solution structure of the human prion protein

Abstract

The NMR structures of the recombinant human prion protein, hPrP(23-230), and two C-terminal fragments, hPrP(90 -230) and hPrP(121-230), include a globular domain extending from residues 125-228, for which a detailed structure was obtained, and an N-terminal flexibly disordered ''tail.'' The globular domain contains three ␣-helices comprising the residues 144 -154, 173-194, and 200 -228 and a short anti-parallel ␤-sheet comprising the residues 128 -131 and 161-164. Within the globular domain, three polypeptide segments show increased structural disorder: i.e., a loop of residues 167-171, the residues 187-194 at the end of helix 2, and the residues 219 -228 in the C-terminal part of helix 3. The local conformational state of the polypeptide segments 187-193 in helix 2 and 219 -226 in helix 3 is measurably influenced by the length of the N-terminal tail, with the helical states being most highly populated in hPrP(23-230). When compared with the previously reported structures of the murine and Syrian hamster prion proteins, the length of helix 3 coincides more closely with that in the Syrian hamster protein whereas the disordered loop 167-171 is shared with murine PrP. These species variations of local structure are in a surface area of the cellular form of PrP that has previously been implicated in intermolecular interactions related both to the species barrier for infectious transmission of prion disease and to immune reactions. P rion proteins (PrP) are associated with transmissible spongiform encephalopathies (TSE), which are invariably fatal diseases characterized by loss of motor control, dementia, and paralysis wasting (1, 2). Human TSEs include Creutzfeldt-Jakob disease, fatal familial insomnia, the Gerstmann-Sträussler-Scheinker syndrome, and kuru, and there is bovine spongiform encephalopathy in cattle and scrapie in sheep. The ''proteinonly'' hypothesis (3, 4) proposes that TSEs are caused by the conversion of a ubiquitous ''cellular form'' of PrP (PrP C ) into an aggregated ''scrapie form'' (PrP Sc ). According to this model, the prion protein (PrP) would at the same time be target and infectious agent in TSEs, which could explain that this class of diseases can be traced to infectious, inherited, and spontaneous origins (2, 5). PrP Sc is characterized by a high ␤-sheet content, insolubility in detergents, and resistance to proteolysis in its aggregated form (6-8) whereas PrP C is a soluble protein with a high content of ␣-helices (8, 9) and high susceptibility to proteolytic digestion. No chemical modifications have as yet been identified by which the two PrP forms would differ (10).Considering that the protein-only hypothesis suggests a change of protein conformation as a possible cause of the onset of TSEs, the three-dimensional prion protein structures have attracted keen interest. So far, nuclear magnetic resonance (NMR) solution studies have been described for monomeric, cellular forms of PrP of the two most widely used laboratory animals in prion research, the mouse (m) and the Syrian hamster (sh)...

Dynamics of a truncated prion protein, PrP(113–231), from 15N NMR relaxation: Order parameters calculated and slow conformational fluctuations localized to a distinct region

“…45 However, here we allow s c to vary per residue, which therefore compensates for the effect of an anisotropic rotational diffusion within PrP C , as shown in Supporting Figure S3 The similarities between structures of mammalian PrP species are well documented. 8 Sequence comparison of mouse and Syrian hamster shows a 94.2% homology in this fragment, there are six largely conservative substitutions. It is clear from this study that mouse and hamster PrP have very similar dynamical properties.…”

“…Mature PrP C is then tethered to the cell surface via a glycosyl-phosphatidylinositol anchor at the C-terminus. 1 Three dimensional NMR solution structures of non-glycosolated PrP C from a number of mammalian species have been determined, including mouse, 4 Syrian hamster, [5][6][7] human, 8 bovine, 9 cats, dogs, pigs, sheep, chicken, turtles, frogs, and elk. [10][11][12] There has been some recent progress in defining the molecular architecture of prion amyloid fibers.…”

The toxicity of antiprion antibodies is mediated by the flexible tail of the prion protein

“…7). Comparisons with published structures 2,10,13,14 indicate that F(ab) 1 POM1 binding did not cause conformational distortions in the GD. We also studied the binding interface of scFv POM1 complexed with full-length recombinant mouse PrP (residues 23-230, rmPrP ) by solution nuclear magnetic resonance (NMR) spectroscopy.…”

Camelid single-domain antibody fragments: Uses and prospects to investigate protein misfolding and aggregation, and to treat diseases associated with these phenomena

“…PrP C might also be involved in numerous biological activities including cell-signalling, neurogenesis, neuroprotection and synpaptic transmission [121]. PrP C is composed of two domains [122] (Fig. 6A): (i) a flexible disordered N-terminal domain (residues 23e124) including several octapeptide repeats (60e91) and a positively charged segment (residues 96e111), and (ii) a structured globular C-terminus (residues 125e231) containing three a-helices, two of them being linked by a disulphide bridge and two very short anti-parallel b-strands.…”