1. Mouse Prion Protein Domain PrP(121-231) Andreas Razen Geometric Computations in Molecular Biology 2 May 2007

2. Prion Protein  Located in cell surface (brain, nervous system)  Protects cell against oxidative stress (free radicals lacking electrons)  PrP C = Prion Protein Cellular (normal form)  PrP Sc = Scrapie form (infectious form)  Change of conformation (chain reaction) sporadic genetic infection

3. Protein Only Hypothesis  „A modified form of normal prion protein triggers infectious neurodegenerative diseases“  Prion Diseases affect brain and nervous system of humans and mammals – not treatable – fatal; Creutzfeldt-Jakob disease (CJD) (Human) Bovine spongiform encephalopathy (BSE) (Cattle) Scrapie (Sheep) Feline spongiform encephalopathy (FSE) (Cats)  PrP Sc resistant to conventional sterilization methods (heat, radiation) – in contrast to PrP C

4. Structure of Mouse PrP(121-231)  3 right-handed α -helices and 1 two-stranded anti- parallel β-sheet  Most point mutation sites are located in second and third helix (all are identical with human PrP)

5. Structure Elucidation – PrP(121-231)  Riek, Hornemann, Wider, Billeter, Glockshuber & Wüthrich (1996)  NMR: Nuclei with magnetic spin align in very powerful external (static) magnetic field Alignment is perturbed by an additional electromagnetic field Magnetic nuclei absorb its energy („resonance“) Depending on local chemical environment nuclei resonate at slightly different frequencies Structural information

6. Ramachandran Plot

7. Locations of selected residues  Red: Mutation related to prion deseases  Blue: Residues involved in species barrier  Green: solvent-accessible glycosilation sites (enhances solubility of protein)

8. Same primary structure – different secondary structure  Presence of β-sheet in PrP C in contrast with model predictions (important for transition?)  PrP occurs in two conformations not much differing in energy  Dimer of PrP C PrP Sc might form, destabilizing PrP C, causing conformational shift

9. Conformation change

10. Protein Aggregation Diseases

11. Thank you!