Prion structure investigated in situ, ex vivo, and in vitro by FTIR spectroscopy

摘要

Syrian hamster nervous tissue was investigated by FTIR microspectroscopy with conventional and synchrotron infrared light sources. Various tissue structures from the cerebellum and medulla oblongata of sscrapie-infected and control hamsters were investigated at a spatial resolution of 50 μm. Single neurons in dorsal root ganglia of scrapie-infected hamsters were analyzed by raster scan mapping at 6 μm spatial resolution. These measurements enabled us to (ⅰ) scrutinize structural differences between infected and non-infected tissue and (ⅱ) analyze for the first time the distribution of different protein structures in situ within single nerve cells. Single nerve cells exhibited areas of increased β-sheet content, which co-localized consistently with accumulations of the pathological prion protein (PrP~(Sc)). Spectral data were also obtained from purified, partly proteinase K digested PrP~(Sc) isolated from scrapie-infected nervous tissue of hamsters to elucidate similarities/dissimilarities between prion structure in situ and ex vivo. A further comparison is drawn to the recombinant Syrian hamster prion protein SHaPrP~(90-232), whose in vitro transition from the predominantly α-helical isoform to β-sheet rich oligomeric structures was also investigated by FTIR spectroscopy.