A peptide corresponding to the third helical region within the PrPC protein, from residues 198 to 218 (helix-3), was synthesised with and without the familial 210-Val to Ile Creutzfeldt-Jakob disease mutation. The NMR structure of PrPC predicts no global variation in stability for this mutation, indicating that local sequence rather than global structural factors are involved in the pathological effects of this mutation. 1H NMR analysis of peptides with and without this mutation indicated that it had no significant effect on local helical structure. Temperature denaturation studies monitored by CD showed that the mutation increased the helical content within this region (helical propensity), but did not stabilise the helix toward denaturation (helical stability). Aggregation data indicated that, in addition to increasing helical propensity, this mutation increased the aggregation propensity of this sequence. CD and NMR data indicate that helical interactions, stabilised by the Val-210-Ile mutation, may precede the formation of β-sheet aggregates in this peptide sequence. Therefore, this pathological mutation probably does not facilitate PrPC to PrPSc conversion by directly destabilising the helical structure of PrPC, but may preferentially stabilise PrPSc by facilitating β-sheet formation within this sequence region of PrP. In addition, helical interactions between helix-3 in two or more PrPC molecules may promote conversion to PrPSc.
|Number of pages||13|
|Journal||Biochimica et Biophysica Acta (BBA) - Protein Structure and Molecular Enzymology|
|Publication status||Published - 12 Jan 2001|
- Circular dichroism
- Nuclear magnetic resonance
- Pathogenic mutation