Skip to main content
ARS Home » Pacific West Area » Albany, California » Western Regional Research Center » Produce Safety and Microbiology Research » Research » Publications at this Location » Publication #419439
Research Project: Rapid Antemortem Tests for the Early Detection of Transmissible Spongiform Encephalopathies and Other Animal Diseases

Location: Produce Safety and Microbiology Research

Title: Comparing the extent of methionine oxidation in the prion and native conformations of PrP

Author
item Silva, Christopher
item Erickson-Beltran, Melissa
item REQUENA, JESUS - University Of Santiago De Compostela

Submitted to: ACS Omega
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 12/18/2024
Publication Date: 1/3/2025
Citation: Silva, C.J., Erickson-Beltran, M.L., Requena, J.R. 2025. Comparing the extent of methionine oxidation in the prion and native conformations of PrP. ACS Omega. 10(1): 1320-1330. https://doi.org/10.1021/acsomega.4c08892.
DOI: https://doi.org/10.1021/acsomega.4c08892

Interpretive Summary: Scrapie is a disease of sheep. Scrapie replicates by inducing a protein to adopt the infectious scrapie shape. Scrapie contains more methionines than is typical for mammalian proteins. Measuring how much methionines are oxidized reveals information about the infectious shape of scrapie. Sheep scrapie was oxidized with hydrogen peroxide and analyzed. The extent of methionine oxidation was different from that predicted from other proposed scrapie structures. The structure of the sheep scrapie is different from those of hamster and mouse prions.

Technical Abstract: Scrapie is a prion disease of sheep and goats. Prions (PrPSc) replicate by inducing a natively expressed protein (PrPC) to refold into the prion conformation. PrPC and PrPSc contain a disproportionately large number of methionines. Surface exposed methionines are more prone to chemical oxidation. Chemical oxidation is a means of measuring the surface exposure of the methionines in a prion, as these covalent changes are retained after an oxidized prion is denatured prior to analysis. Scrapie prions and recombinant sheep prion protein were oxidized in 0, 10, 20, or 50 mM solutions of hydrogen peroxide. The samples were digested with trypsin or trypsin followed by chymotrypsin to yield a set of peptides (TNMK, MLGSAMSR, ENMYR, IMER,VVEQMCITQYQR) containing the methionines present in sheep PrP. The mass spectrometry based multiple reaction monitoring (MRM) method was used to analyze these peptides. Analysis of the rPrP samples showed that surface exposed methionines (132, 137,and 157) were more oxidized than those less surface exposed (209 and 216). The extent of methionine oxidation in sheep scrapie PrPSc is 216 > 137 > 132 > 157 > 209 > 112. These results demonstrate that this approach can be used to map the surface exposure of the methionines in order to distinguish among PrP conformations and effect a kind of conformational sequence.