Seminar

Amyloid proteins and protein folding studied by solid state NMR spectroscopy at high sensitivity

Henrike Heise, PhD

Protein misfolding and amyloid formation are connected to a variety of diseases, like the neurodegenerative disorders Alzheimer’s disease, Parkinson’s disease and sponigiform encephalopaties or other disease associated amyloidosis [1]. Here, Dr. Heise presents results obtained on fibrils of the 37-residue peptide hormone IAPP, and Abeta(1-42). Site-specific resonance assignments could be obtained for all residues in both peptides. For IAPP, the secondary structure is in rough agreement with previous findings [2-4], although some differences to previous results can be seen, whereas for Abeta major differences toward previously found results [6,7] are observed. The ovine prion protein in its infectious form, PrPSc, is the causative agent of the fatal disease scrapie in sheep. Dr. Heise’s group report preliminary site-specific resonance assignments for fibrils obtained by seeding with brain-derived fibrils and compare results from different seeding protocols. Their data indicate a semi-flexibile N-terminus and a distinct ?-sheet core C terminal of residue ?155.7 [5]. Furthermore, they show first results obtained on fibrils with a high level of deuteration. Finally, they used DNP enhancement to overcome the inherently low sensitivity of magnetic resonance spectroscopy by transferring high polarization of unpaired electrons to nuclei. Low temperature NMR spectra usually suffer from severe line broadenings due to freezing out different conformations [8]. While this is usually accounted for as an unwanted side-effect of DNP-NMR, however, these inhomogeneously broadened lines also contain valuable information about conformational ensembles of (disordered) proteins. They applied this method not only to the investigation of mature amyloid fibrils, but also to the study of conformational ensembles in intrinsically disordered proteins in frozen solution. [1] Hoyer, W.; Heise, H. In Amyloid Fibrils and Prefibrillar Aggregates; Otzen, D., Ed.; Wiley-VCH Verlag GmbH & Co. KGaA: 2013, p 39. [2] Luca, S.; Yau, W. M.; Leapman, R.; Tycko, R. Biochemistry 2007, 46, 13505. [3] Alexandrescu, A. T. Plos One 2013, 8, 8. [4] Bedrood, S.; Li, Y.; Isas, J. M.; Hegde, B. G.; Baxa, U.; Haworth, I. S.; Langen, R. J. Biol. Chem. 2012, 287, 5235. [5] Müller, H.; Brener, O.; Andreoletti, O.; Piechatzek, T.; Willbold, D.; Legname, G.; Heise, H. Prion 2014, 8, 344. [6] Xiao, Y.; Ma, B.; McElheny, D.; Parthasarathy, S.; Long, F.; Hoshi, M.; Nussinov, R.; Ishii, Y. Nat. Struct. Mol. Biol. 2015, 22, 499. [7] Colvin, M. T.; Silvers, R.; Frohm, B.; Su, Y.; Linse, S.; Griffin, R. G. J. Am. Chem. Soc. 2015, 137, 7509. [8] Tycko R. NMR at Low and Ultralow Temperatures. Accounts of chemical research 2013;46:1923-32