Amyloid Core Formed of Full-Length Recombinant Mouse Prion Protein Involves Sequence 127–143 but Not Sequence 107–126

Biswanath Chatterjee,Chao-Li Huang,Rita P.-Y Chen,Chen Lin,Chung-Yu Lee,Chien-Chih Yang,Eric H.-L Chen

doi:10.1371/journal.pone.0067967

Biswanath Chatterjee, Chao-Li Huang + Show 5 more

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https://doi.org/10.1371/journal.pone.0067967

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Abstract

The principal event underlying the development of prion disease is the conversion of soluble cellular prion protein (PrPC) into its disease-causing isoform, PrPSc. This conversion is associated with a marked change in secondary structure from predominantly α-helical to a high β-sheet content, ultimately leading to the formation of aggregates consisting of ordered fibrillar assemblies referred to as amyloid. In vitro, recombinant prion proteins and short prion peptides from various species have been shown to form amyloid under various conditions and it has been proposed that, theoretically, any protein and peptide could form amyloid under appropriate conditions. To identify the peptide segment involved in the amyloid core formed from recombinant full-length mouse prion protein mPrP(23–230), we carried out seed-induced amyloid formation from recombinant prion protein in the presence of seeds generated from the short prion peptides mPrP(107–143), mPrP(107–126), and mPrP(127–143). Our results showed that the amyloid fibrils formed from mPrP(107–143) and mPrP(127–143), but not those formed from mPrP(107–126), were able to seed the amyloidogenesis of mPrP(23–230), showing that the segment residing in sequence 127–143 was used to form the amyloid core in the fibrillization of mPrP(23–230).

Highlights

Transmissible spongiform encephalopathies (TSEs) are a group of fatal neurodegenerative disorders which affect many mammalian species such as human, bovine, sheep, deer, mink, cat etc [1,2,3,4]
20 mM NaOAc, pH 3.7, and by mPrP(107–126) in 20 mM HEPES buffer, pH 7.4, containing 100 mM NaCl and 0.01% NaN3 was monitored by measuring the fluorescence emission of the amyloid fibril-Thioflavin T (ThT) complex at 487 nm over time (Figure 2)
In the case of the full-length protein mPrP(23–230), 1 M guanidine hydrochloride (GdnHCl) and 3 M urea were required to destabilize the native structure to facilitate its conversion into fibrils, and shaking was necessary to increase the chance of protein contact [36], [37]

Summary

Introduction

Transmissible spongiform encephalopathies (TSEs) are a group of fatal neurodegenerative disorders which affect many mammalian species such as human, bovine, sheep, deer, mink, cat etc [1,2,3,4]. The principle pathogenic event in TSE is the formation of an abnormally folded isoform, known as PrPSc from a normal cellular protein called PrPC [5]. As estimated by circular dichroism spectroscopy and Fourier transformed infrared spectroscopy, PrPSc has a b-sheet content of 43% compared to the 4% b-sheet content of PrPC, estimated from its NMR structure [9,10,11]. The conversion of PrPC to PrPSc leads to a conformational change associated with an increase in b-sheet content [12], [13]. PrPSc has the ability to induce misfolding of PrPC, leading to the maintenance, propagation, and manifestation of disease phenotype in the host organism, with the result that, unlike other neurodegenerative disorders, prion diseases are transmissible.

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