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Title: Proteinase K and the structure of PrPse: the good, the bad, and the ugly

item Silva, Christopher - Chris
item VÁZQUEZ-FERNÁNDEZ, ESTER - University Of Alberta
item ONIKSO, BRUCE - Oni Pro Biosciences
item REQUENA, JESÚS - University Of Santiago De Compostela

Submitted to: Virus Research
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 3/20/2015
Publication Date: 3/24/2015
Publication URL:
Citation: Silva, C.J., Vázquez-Fernández, E., Onikso, B., Requena, J.R. 2015. Proteinase K and the structure of PrPse: the good, the bad, and the ugly. Virus Research. doi: 10.1016/j.virusres.2015.03.008.

Interpretive Summary: Proteinase K (PK) is a hardy enzyme that has been used to study prions. Prions are the cause of a set of fatal diseases in animals and humans called transmissible spongiform encephalopathies (TSEs). PK is used to diagnose prion diseases, because PK completely digests the normal cellular protein, but only a small portion of the prion. In this way prions can be detected without interference from the normal cellular prion protein. The recent discovery that the characteristic shape of a prion is determined by a distinct feature referred to as a '-sheet means that PK can also be used to help determine the shape of prions. Prions were partially digested with PK to reveal the location of these '-sheets. In addition this approach also revealed the exposed areas of the prion that connected the '-sheets. This information was used to construct a model of the structure of a prion. This model will help researchers locate the features that will help identify prions and determine why they cause disease.

Technical Abstract: Infectious proteins (prions) are, ironically, defined by their resistance to proteolytic digestion. A defining characteristic of the transmissible isoform of the prion protein (PrPSc) is its partial resistance to proteinase K (PK) digestion. Diagnosis of prion disease typically relies upon immunodetection of PK-digested PrPSc by Western blot, ELISA or immunohistochemical detection. PK digestion has also been used to detect differences in prion strains. Thus, PK has been a crucial tool to detect and, thereby, control the spread of prions. PK has also been used as a tool to probe the structure of PrPSc. Mass spectrometry and antibodies have been used to identify PK cleavage sites in PrPSc. These results have been used to identify the more accessible, flexible stretches connecting the ß-strand components in PrPSc. These data, combined with physical constraints imposed by spectroscopic results, were used to propose a qualitative model for the structure of PrPSc. Assuming that PrPSc is a four rung ß-solenoid, we have threaded the PrP sequence to satisfy the PK proteolysis data and other experimental constraints.