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Strain‐specific effects of reducing agents on the cell‐free conversion of recombinant prion protein into a protease‐resistant form
Author(s) -
Imamura Morikazu,
Kato Nobuko,
Okada Hiroyuki,
Iwamaru Yoshifumi,
Shimizu Yoshihisa,
Mohri Shirou,
Yokoyama Takashi
Publication year - 2011
Publication title -
microbiology and immunology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.664
H-Index - 70
eISSN - 1348-0421
pISSN - 0385-5600
DOI - 10.1111/j.1348-0421.2011.00357.x
Subject(s) - recombinant dna , dithiothreitol , biology , cysteine , gene isoform , cell culture , strain (injury) , proteinase k , prion protein , mutant , biochemistry , microbiology and biotechnology , enzyme , gene , genetics , medicine , disease , anatomy , pathology
The pathogenic isoform (PrP Sc ) of the host‐encoded normal cellular prion protein (PrP C ) is believed to be the infectious agent of transmissible spongiform encephalopathies. Spontaneous conversion of α‐helix‐rich recombinant PrP into the PrP Sc ‐like β‐sheet‐rich form or aggregation of cytosolic PrP has been found to be accelerated under reducing conditions. However, the effect of reducing conditions on PrP Sc ‐mediated conversion of PrP C into PrP Sc has remained unknown. In this study, the effect of reducing conditions on the binding of bacterial recombinant mouse PrP (MoPrP) with PrP Sc and the conversion of MoPrP into proteinase K‐resistant PrP (PrP res ) using a cell‐free conversion assay was investigated. High concentrations of dithiothreitol did not inhibit either the binding or conversion reactions of PrP Sc from five prion strains. Indeed, dithiothreitol significantly accelerated mouse‐adapted BSE‐seeded conversion. These data suggest that conversion of PrP Sc derived from a subset of prion strains is accelerated under reducing conditions, as has previously been shown for spontaneous conversion. Furthermore, the five prion strains used could be classified into three groups according to their efficiency at binding and conversion of MoPrP and cysteine‐less mutants under both reducing and nonreducing conditions. The resulting classification is similar to that derived from biological and biochemical strain‐specific features.