NR AFOM
AU Hornemann,S.; Glockshuber,R.
TI A scrapie-like unfolding intermediate of the prion protein domain PrP(121-231) induced by acidic pH
QU Proceedings of the National Academy of Sciences of the United States of America 1998 May 26; 95(11): 6010-4
PT journal article
AB The infectious agent of transmissible spongiform encephalopathies is believed to consist of an oligomeric isoform, PrPsc, of the monomeric cellular prion protein, PrPc. The conversion of PrPc to PrPsc is characterized by a decrease in alpha-helical structure, an increase in beta-sheet content, and the formation of PrPsc amyloid. Whereas the N-terminal part of PrPc comprising residues 23-120 is flexibly disordered, its C-terminal part, PrP(121-231), forms a globular domain with three alpha-helices and a small beta-sheet. Because the segment of residues 90-231 is protease-resistant in PrPsc, it is most likely structured in the PrPsc form. The conformational change of the segment containing residues 90-120 thus constitutes the minimal structural difference between PrPc and a PrPsc monomer. To test whether PrP(121-231) is also capable to undergo conformational transitions, we analyzed its urea-dependent unfolding transitions at neutral and acidic pH. We identified an equilibrium unfolding intermediate of PrP(121-231) that is exclusively populated at acidic pH and shows spectral characteristics of a beta-sheet protein. The intermediate is in rapid equilibrium with native PrP(121-231), significantly populated in the absence of urea at pH 4.0, and may have important implications for the presumed formation of PrPsc during endocytosis.
MH Animal; Base Sequence; Endocytosis; Escherichia coli; Hydrogen-Ion Concentration; Mice; Molecular Sequence Data; Peptide Fragments/*chemistry/genetics/metabolism; *Prion Diseases; Prions/*chemistry/genetics/metabolism; *Protein Folding; Support, Non-U.S. Gov't
AD Institut für Molekularbiologie und Biophysik, Eidgenössische Technische Hochschule Hönggerberg, CH-8093 Zürich, Switzerland.
SP englisch
PO USA