Interaction of a Recombinant Prion Protein with Organo-Mineral Complexes as Assessed by FT-IR and CPMAS 13C NMR Analysis

Abstract

Prion proteins are considered as the main agents for the Transmissible Spongiform Encephalopathies (TSE). The misfolded form, PrP Sc , which is also indicated as the etiological agent for TSE, exhibits high resistance to degradation in environmental processes. Soil contamination by prion proteins is a real environmental issue since contaminated soils can become potential reservoir and diffuser for TSE infectivity. In this work, the interaction of prion protein with organomineral complexes was studied by using a recombinant non pathogenic prion protein and a model soil system. This latter was represented by a soil manganese mineral coated with polymerized catechol. FT-IR spectra showed amide I and II signals which revealed protein involvement in catechol polymers coating manganese oxide surface. CPMAS 13 C-NMR was applied to follow the complexation of the protein to the soil-like system. All the signals were attributed to C-N in peptidic bonds, alkyl chains and methyl groups. The NMR spectrum of the prion protein interacting directly with birnessite revealed disappearance of signals due to the paramagnetic nature of manganese oxide or protein abiotic degradation, while the presence of organic matter strongly reduced the disappearance of prion protein signals.

Prion Protein Interaction with Soil Humic Substances: Environmental Implications

“…However, it is plausible that encapsulated MoPrP retains its native folding, as observed in the fibrillization experiments where HS were not able to promote MoPrP conversion in β-sheet enriched structures. Moreover, previous experiments using Fourier infrared spectroscopy and cross-polarization magic angle spinning (CP MAS) 13 C-solid state NMR spectroscopy have reported no detectable conformational changes occurring on recPrP adsorbed in humic-like substances, in spite of large background noise given by carbon groups naturally present in HS [34] , [35] , [46] . HS also affect the resistance of MoPrP to biotic degradation, as reported in our controlled PK digestion experiments.…”