NR AVOE
AU Watzlawik,J.; Skora,L.; Frense,D.; Griesinger,C.; Zweckstetter,M.; Schulz-Schaeffer,W.J.; Kramer,M.L.
TI Prion protein helix1 promotes aggregation but is not converted into beta-sheet
QU The Journal of Biological Chemistry 2006 Oct 6; 281(40): 30242-50
PT comparative study; journal article; research support, non-u.s. gov't
AB Prion diseases are caused by the aggregation of the native alpha-helical prion protein PrPc into its pathological beta-sheet-rich isoform PrPsc. In current models of PrPsc, helix1 is assumed to be preferentially converted into beta-sheet during aggregation of PrPc. This was supported by the NMR structure of PrPc since, in contrast to the isolated helix1, helix2 and helix3 are connected by a small loop and are additionally stabilized by an interhelical disulfide bond. However, helix1 is extremely hydrophilic and has a high helix propensity. This prompted us to investigate the role of helix1 in prion aggregation using humPrP(23-159) including helix1 (144-156) compared with the C-terminal-truncated isoform humPrP(23-144) corresponding to the pathological human stop mutations Q160Stop and Y145Stop, respectively. Most unexpectedly, humPrP(23-159) aggregated significantly faster compared with the truncated fragment humPrP(23-144), clearly demonstrating that helix1 is involved in the aggregation process. However, helix1 is not resistant to digestion with proteinase K in fibrillar humPrP(23-159), suggesting that helix1 is not converted to beta-sheet. This is confirmed by Fourier transformation infrared spectroscopy since there is almost no difference in beta-sheet content of humPrP(23-159) fibrils compared with humPrP(23-144). In conclusion, we provide strong direct evidence that in contrast to earlier assumptions helix1 is not converted into beta-sheet during aggregation of PrPc to PrPsc.
MH Circular Dichroism; Drug Resistance/physiology; Electrostatics; Endopeptidase K/physiology; Humans; Magnetic Resonance Spectroscopy; Peptide Fragments; Prions/*chemistry/*physiology/ultrastructure; Protein Structure, Secondary; Spectroscopy, Fourier Transform Infrared
AD Prion and Dementia Research Unit, Institute of Neuropathology, University of Göttingen, 37075 Göttingen, Germany.
SP englisch
PO USA