Solution structure of a 142-residue recombinant prion protein corresponding to the infectious fragment of the scrapie isoform

Abstract

The scrapie prion protein (PrP Sc ) is the major, and possibly the only, component of the infectious prion; it is generated from the cellular isoform (PrP C ) by a conformational change. N-terminal truncation of PrP Sc by limited proteolysis produces a protein of Ϸ142 residues designated PrP 27-30, which retains infectivity. A recombinant protein (rPrP) corresponding to Syrian hamster PrP 27-30 was expressed in Escherichia coli and purified. After refolding rPrP into an ␣-helical form resembling PrP C , the structure was solved by multidimensional heteronuclear NMR, revealing many structural features of rPrP that were not found in two shorter PrP fragments studied previously. Extensive side-chain interactions for residues 113-125 characterize a hydrophobic cluster, which packs against an irregular ␤-sheet, whereas residues 90-112 exhibit little defined structure. Although identifiable secondary structure is largely lacking in the N terminus of rPrP, paradoxically this N terminus increases the amount of secondary structure in the remainder of rPrP. The surface of a long helix (residues 200-227) and a structured loop (residues 165-171) form a discontinuous epitope for binding of a protein that facilitates PrP Sc formation. Polymorphic residues within this epitope seem to modulate susceptibility of sheep and humans to prion disease. Conformational heterogeneity of rPrP at the N terminus may be key to the transformation of PrP C into PrP Sc , whereas the discontinuous epitope near the C terminus controls this transition.

Genetic Mapping of Activity Determinants within Cellular Prion Proteins

“…Distinct from the analogous region of PrP, the NMR structure of this region of Dpl reveals a kink, dividing it into ␣B and ␣BЈ helices of 16 (residues 101-116) and 9 (residues 117-125) residues, respectively (14,15,78,79). In our genetic analyses, the region including residues 101-125 can exert a pro-apoptotic effect in the absence of ␣A or ␣C (Fig.…”

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

“…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 yeast prion protein Ure2: Structure, function and folding

“…The relationship between domain structure and function for the PrP protein is more complex. The PrP protein has a flexible N-terminal tail [23,24] containing an octapeptide repeat region involved in copper binding [25], but this flexible region only partially overlaps with the segment that is required for infectivity (see Fig. 1).…”

“…The Ure2 system is therefore a useful model not only to investigate the prion concept, but also to understand the properties of Gln/ Asn-repeat proteins and hence the molecular basis of the related diseases. [27,29,58], Sup35 [114,115], Rnq1 [13], Het-s [22] and PrP [23,24,116,117]. The functional regions are as indicated.…”