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Virus-induced amyloidosis in scrapie involves a change in covalent linkages in the preamyloid
H Diringer1, H Blode, U Oberdieck
1Robert-Koch-Institut des Bundesgesundheitsamtes, Berlin, Federal Republic of Germany.
Abstract:
Preparations of the preamyloid and the amyloid protein from normal and scrapie hamster brains show different solubilization behaviours towards Triton X-114 extraction. The normal isoform is completely extractable from microsomal membranes by the detergent, whereas the pathological one is not. Both forms can be isolated using preparative SDS electrophoresis as the final step in order to remove all non-covalently associated materials. After removal of the SDS these purified proteins retain their solubility differences against Triton X-114. This demonstrates that at least one distinct modification of the preamyloid protein--which has to be covalent in nature--must have occurred to account for the strong aggregation tendency of the pathological isoform.
Insights
Scrapie and normal hamster brain proteins exhibit distinct solubilization behaviors. This difference, linked to covalent modification, explains the pathological protein
Area of Science:
- Neuroscience
- Biochemistry
- Protein Chemistry
Background:
- Scrapie is a transmissible spongiform encephalopathy.
- The disease involves the misfolding and aggregation of the prion protein.
- Understanding the biochemical differences between normal and pathological prion protein is crucial.
Purpose of the Study:
- To investigate the differential solubilization behavior of normal (preamyloid) and pathological (amyloid) prion protein isoforms.
- To identify the nature of modifications leading to the aggregation tendency of the pathological isoform.
Main Methods:
- Differential extraction of proteins from normal and scrapie hamster brains using Triton X-114.
- Isolation of protein isoforms using preparative SDS-PAGE.
- Analysis of protein solubility after SDS removal.
Main Results:
- Normal prion protein is fully extractable by Triton X-114 from microsomal membranes.
- Pathological prion protein shows significantly reduced extractability.
- Purified proteins retain their differential solubility, indicating inherent modifications.
Conclusions:
- A covalent modification of the preamyloid protein underlies the aggregation propensity of the pathological isoform.
- These findings provide insights into the structural changes driving prion disease pathogenesis.