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Reversibility of Prion Misfolding: Insights from Constant-pH Molecular Dynamics Simulations.
MedLine Citation:
PMID:  22803931     Owner:  NLM     Status:  Publisher    
Abstract/OtherAbstract:
The prion protein (PrP) is the cause of a group of diseases known as transmissible spongiform encephalopathies (TSEs). Creutzfeldt-Jakob disease and bovine spongiform encephalopathy are examples of TSEs. Although the normal form of PrP (PrP(C)) is monomeric and soluble, it can misfold into a pathogenic form (PrP(Sc)) that has a high content of β-structure and can aggregate forming amyloid fibrils. The mechanism of conversion of PrP(C) into PrP(Sc) is not known but different triggers have been proposed. It can be catalyzed by a PrP(Sc) sample, or it can be induced by an external factor, such as low pH. The pH effect on the structure of PrP was recently studied by computational methods [Campos et al. J. Phys. Chem. B2010, 114, 12692-12700], and an evident trend of loss of helical structure was observed with pH decrease, together with a gain of β-structures. In particular, one simulation at pH 2 showed an evident misfolding transition. The main goal of the present work was to study the effects of a change in pH to 7 in several transient conformations of this simulation, in order to draw some conclusions about the reversibility of PrP misfolding. Although the most significant effect caused by the change of pH to 7 was a global stabilization of the protein structure, we could also observe that some conformational transitions induced by pH 2 were reversible in many of our simulations, namely those started from the early moments of the misfolding transition. This observation is in good agreement with experiments showing that, even at pH as low as 1.7, it is possible to revert the misfolding process [Bjorndahl et al. Biochemistry2011, 50, 1162-1173].
Authors:
Diogo Vila-Viçosa; Sara R R Campos; António M Baptista; Miguel Machuqueiro
Publication Detail:
Type:  JOURNAL ARTICLE     Date:  2012-7-17
Journal Detail:
Title:  The journal of physical chemistry. B     Volume:  -     ISSN:  1520-5207     ISO Abbreviation:  -     Publication Date:  2012 Jul 
Date Detail:
Created Date:  2012-7-18     Completed Date:  -     Revised Date:  -    
Medline Journal Info:
Nlm Unique ID:  101157530     Medline TA:  J Phys Chem B     Country:  -    
Other Details:
Languages:  ENG     Pagination:  -     Citation Subset:  -    
Affiliation:
Centro de Química e Bioquímica e Departamento de Química e Bioquímica, Faculdade de Ciências, Universidade de Lisboa , 1749-016 Lisboa, Portugal.
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