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Different structural stability and toxicity of PrP ARR and PrP ARQ sheep prion protein variants
Author(s) -
Paludi Domenico,
Thellung Stefano,
Chiovitti Katia,
Corsaro Alessandro,
Villa Valentina,
Russo Claudio,
Ianieri Adriana,
Bertsch Uwe,
Kretzschmar Hans A.,
Aceto Antonio,
Florio Tullio
Publication year - 2007
Publication title -
journal of neurochemistry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.75
H-Index - 229
eISSN - 1471-4159
pISSN - 0022-3042
DOI - 10.1111/j.1471-4159.2007.04934.x
Subject(s) - scrapie , toxicity , chemistry , prion protein , biophysics , biology , medicine , pathology , disease , organic chemistry
The polymorphisms at amino acid residues 136, 154, and 171 in ovine prion protein (PrP) have been associated with different susceptibility to scrapie: animals expressing PrP ARQ [PrP(Ala136/Arg154/Gln171)] show vulnerability, whereas those that express PrP ARR [PrP(Ala136/Arg154/Arg171)] are resistant to scrapie. The aim of this study was to evaluate the in vitro toxic effects of PrP ARR and PrP ARQ variants in relation with their structural characteristics. We show that both peptides cause cell death inducing apoptosis but, unexpectedly, the scrapie resistant PrP ARR form was more toxic than the scrapie susceptible PrP ARQ variant. Moreover, the α‐helical conformation of PrP ARR was less stable than that of PrP ARQ and the structural determinants responsible of these different conformational stabilities were characterized by spectroscopic analysis. We observed that PrP toxicity was inversely related to protein structural stability, being the unfolded conformation more toxic than the native one. However, the PrP ARQ variant displays a higher propensity to form large aggregates than PrP ARR . Interestingly, in the presence of small amounts of PrP ARR , PrP ARQ aggregability was reduced to levels similar to that of PrP ARR . Thus, in contrast to PrP ARR toxicity, scrapie transmissibility seems to reside in the more stable conformation of PrP ARQ that allows the formation of large amyloid fibrils.