Prion protein misfolding the structural biology of prion diseases

Lead Research Organisation: Queen Mary, University of London
Department Name: Sch of Biological and Chemical Sciences

Abstract

The proposal would fund two research workers for 3 years to address fundamental molecular processes associated with Prion diseases, which include CJD in humans and mad-cow disease in cattle. A key feature of this fatal neurodegenerative disease is the accumulation of a small molecule, the prion protein within the brain. The prion protein changes shape in the diseased form and then clumps together to form the insoluble plaques found in the brains of patients with prion disease. It is the ability of the prion protein to change shape and misfold that will be studied. The interaction of the prion protein with physiological levels of the essential mineral copper will also be investigated, looking into how for example copper influences the shape (structure) and misfolding of the prion protein. These studies will inform drug design and assist in the development of medicines for the disease. Prion diseases have similarities with the more prevalent neurodegenerative disease Alzheimer's and knowledge gained in this study will increase our understanding of both diseases.

Technical Summary

The prion protein (PrP) is a Cu(II) binding cell surface glyco-protein. Misfolding of PrP into a b-sheet rich conformation is responsible for neurodegenerative diseases such as CJD in humans and BSE (mad cow disease) in cattle. We propose to study the structure and misfolding of PrPC, in particular the copper loaded forms of PrP. Copper bound forms of PrP are physiologically relevant and those studying the folding and fibrillisation of PrP should certainly consider the effect of Cu(II) ions on the biophysical properties of PrPC. We will use a range of spectroscopic and biophysical techniques to investigate how Cu(II) ions influence the structure and fibrillisation of PrP. In particular, we will use NMR, CD and EPR for which we have proven experience. For example, 15N HSQC NMR data will be used to monitor misfolding and backbone dynamics of PrP. Ni(II) will be used as a diamagnetic replacement ion to probe the effect of metal binding to PrP by NMR methods. CD will be used to monitor the folding transitions and stability of PrP when exposed to changes in solvent environment and in the presence of Cu(II) ions. Visible-CD and complementary Cu-EPR and ESEEM will be used to study the coordination geometry of the Cu(II) complexes formed. The studies will use various recombinant and synthetic fragments of the prion protein. The proposal represents a step towards understanding the misfolding processes of the prion protein.

Publications

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Brazier MW (2008) Manganese binding to the prion protein. in The Journal of biological chemistry

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Klewpatinond M (2008) Deconvoluting the Cu2+ binding modes of full-length prion protein. in The Journal of biological chemistry

 
Description With more that twelve original research articles published directly from this project we have made a world leading contribution to understanding the structure and misfolding of the prion protein (PrPC).
1) With implications for prion function and diseases, we have completed an extensive study of Cu2+ binding to full-length prion protein, resolving many controversies surrounding the sequential loading of Cu2+ ions, their coordination geometry and affinity. Additionally investigating the influence of Cu2+ ions on the prion protein's fold and stability.
2) We have characterized the copper bound PrPC redox system and shown that oxidative modification of PrPC perturbs its hydrophobic core and destabilises the native fold, providing an explanation for the high proportion of oxidized PrP within scrapie isolates.
3) To understand the misfolding pathway and oligomerization of PrPC, we have characterized the low pH folding intermediate and studied the structure and dynamics of this soluble oligomer using 3D-NMR spectroscopy.
Exploitation Route We have make an important contribution to the interpretation of Visible CD spectra with copper and nickel bound to proteins and peptides Published in 2007 Empirical rules for rationalising visible circular dichroism of Cu2+ and Ni2+ histidine complexes: Klewpatinond M and Viles JH (2007) Febs Lett 581, 1430-1434
Sectors Pharmaceuticals and Medical Biotechnology

 
Description general public and was discussed on BBC Radio 4 with a Nobel Laureate, Prof Harry Kroto, speaking 
Form Of Engagement Activity A talk or presentation
Part Of Official Scheme? No
Geographic Reach National
Primary Audience Public/other audiences
Results and Impact I have organised an international meeting hosted at Queen Mary, "Metals in Neuro-degenerative Disease". Part of the meeting was open to the general public and was discussed on BBC Radio 4 with a Nobel Laureate, Prof Harry Kroto, speaking.
Year(s) Of Engagement Activity 2006
 
Description sub-committee within the Department for Environment Food & Rural Affairs (DEFRA) 
Form Of Engagement Activity A formal working group, expert panel or dialogue
Part Of Official Scheme? No
Geographic Reach National
Primary Audience Policymakers/politicians
Results and Impact I have presented to a sub-committee within the Department for Environment Food & Rural Affairs (DEFRA) on prion protein (BSE) contamination, link with (SEAC) Spongiform Encephalopathy Advisory Committee
Year(s) Of Engagement Activity 2006