Programme 6

Structural characterisation of mammalian prions

Aims

Mammalian prions are hypothesised to be fibrillar or amyloid forms of prion protein (PrP), which self-propagate by means of seeded protein polymerisation. It is increasingly recognised that similar seeding processes may be involved in Alzheimer’s disease and other neurodegenerative conditions. To-date the three-dimensional (3D) structure of mammalian prions and how this differs from non-infectious amyloid fibrils remains unknown. The aim of this project is to contribute to our understanding of the 3D structure of infectious prions isolated ex vivo from multiple prion strains.

Methods

Recently we developed novel methods to obtain exceptionally pure preparations of prions from prion-infected murine brain and have shown that pathogenic PrP in these high-titre preparations is assembled into rod-like assemblies. These preparations contain very high titres of infectious prions which faithfully transmit prion strain-specific phenotypes when inoculated into mice making them eminently suitable for detailed structural analysis. This project will contribute to the 3D structural characterisation of these prion assemblies. Extensive training will be provided in the biochemical methods used for prion purification and bioassay of prions in cell culture together with training in electron microscopy, electron tomography and other biophysical methods (see references listed below for more details).

Rotation project

This 3-month project will allow the student to become familiar with the methods used for purification of prions from mouse brain and the determination of infectious prion titre in cell culture. The student will learn multiple techniques in protein biochemistry and become competent in working in microbiological containment level 3 laboratories.

PhD project

The 3-month project will have enabled the student to independently produce purified prions for structural characterisation. The PhD studies will  focus upon understanding the 3D structure of prions.

This study will provide an exciting opportunity to contribute to our knowledge of the structure of mammalian prions and how prions differ from non-infectious amyloid assemblies. Findings from this study are likely to have very wide relevance to understanding other diseases involving the aggregation or polymerisation of misfolded host proteins.

References

Wenborn, A., Terry, C., Gros, N., Joiner, S., D’Castro, L., Panico, S., Sells, J., Cronier, S., Linehan, J.M., Brandner, S., Saibil, H.R., Collinge, J. and Wadsworth, J.D.F. (2015) A novel and rapid method for obtaining high titre intact prion strains from mammalian brain Sci. Rep. 5, 10062.

Terry, C., Wenborn, A., Gros, N., Sells, J., Joiner, S., Hosszu, L.L.P., Tattum, M.H., Panico, S., Clare, D.K., Collinge, J., Saibil, H.R., and Wadsworth, J.D.F. (2016) Ex vivo mammalian prions are formed of paired double helical prion protein fibrils. Open Biol. 6, 160035.