Structural study of an in vitro propagated recombinant prion

Introduction: Previous in vitro recombinant prion protein (recPrP) aggregation studies have reported various types of misfolded self-replicating recPrP fibrils, some of which can cause prion diseases in animal models; therefore, they are termed recPrPSc. In the RML prion-seeded PMCA reactions, we recently produced recPrPSc that was highly infectious to wild-type mice. Strain characterization analyses confirmed that these animals succumbed to the RML prion disease.

Objective: We propose that recPrPSc also preserves structural features of the native RML prion.

Methods: We validate our biological findings through cryo-electron microscopy (cryo-EM) analyses.

Results/discussion: Cryo-EM analyses revealed that recPrPSc possesses a distinct V-shaped architecture, which closely mirrors the previously published structure of the native RML prion. At present, we are actively building an atomic model into the density map to gain deeper insights into the molecular organization of these recPrPSc fibrils. Preliminary observations indicate that the overall fold and structural features are highly consistent between the amplified and ex vivo forms. Once model building is complete, we will perform a quantitative comparison of the two structures by calculating their root-mean-square deviation (RMSD), which will allow us to assess the degree of structural conservation at the atomic level.

Conclusion: PMCA can faithfully preserve both key biological and structural properties of the native prion.