Formation of Soluble Oligomers and Amyloid Fibrils with Physical Properties of the Scrapie Isoform of the Prion Protein from the C-terminal Domain of Recombinant Murine Prion Protein mPrP-(121–231)

Samantha M. Martins, Dóris J. Frosoni, Ana M. Blanco Martinez, Fernanda G. De Felice, Sérgio T. Ferreira
2006 Journal of Biological Chemistry  
Prion diseases are fatal neurodegenerative disorders associated with conformational conversion of the cellular prion protein, PrP C , into a misfolded, protease-resistant form, PrP Sc . Here we show, for the first time, the oligomerization and fibrillization of the C-terminal domain of murine PrP, mPrP-(121-231), which lacks the entire unstructured N-terminal domain of the protein. In particular, the construct we used lacks amino acid residues 106 -120 from the so-called amyloidogenic core of
more » ... P (residues 106 -126). Amyloid formation was accompanied by acquisition of resistance to proteinase K digestion. Aggregation of mPrP-(121-231) was investigated using a combination of biophysical and biochemical techniques at pH 4.0, 5.5, and 7.0 and at 37 and 65°C. Under partially denaturing conditions (65°C), aggregates of different morphologies ranging from soluble oligomers to mature amyloid fibrils of mPrP-(121-231) were formed. Transmission electron microscopy analysis showed that roughly spherical aggregates were readily formed when the protein was incubated at pH 5.5 and 65°C for 1 h, whereas prolonged incubation led to the formation of mature amyloid fibrils. Samples incubated at 65°C at pH 4.0 or 7.0 presented an initial mixture of oligomers and protofibrils or fibrils. Electrophoretic analysis of samples incubated at 65°C revealed formation of sodium dodecyl sulfate-resistant oligomers (dimers, trimers, and tetramers) and higher molecular weight aggregates of mPrP-(121-231). These results demonstrate that formation of an amyloid form with physical properties of PrP Sc can be achieved in the absence of the flexible N-terminal domain and, in particular, of residues 106 -120 of PrP and does not require other cellular factors or a PrP Sc template.
doi:10.1074/jbc.m605367200 pmid:16844683 fatcat:j7xrro6rajc3dfeapk3hcl7hxm