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Multiple biochemical similarities between infectious and non‐infectious aggregates of a prion protein carrying an octapeptide insertion
Author(s) -
Biasini Emiliano,
Medrano Andrea Z.,
Thellung Stefano,
Chiesa Roberto,
Harris David A.
Publication year - 2008
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.1471-4159.2007.05082.x
Subject(s) - infectivity , mutant , protease , prion protein , biology , virology , in vitro , immunoprecipitation , proteinase k , microbiology and biotechnology , chemistry , biochemistry , gene , virus , enzyme , pathology , medicine , disease
A nine‐octapeptide insertion in the prion protein (PrP) gene is associated with an inherited form of human prion disease. Transgenic (Tg) mice that express the mouse homolog of this mutation (designated PG14) spontaneously accumulate in their brains an insoluble and weakly protease‐resistant form of the mutant protein. This form (designated PG14 Spon ) is highly neurotoxic, but is not infectious in animal bioassays. In contrast, when Tg(PG14) mice are inoculated with the Rocky Mountain Laboratory (RML) strain of prions, they accumulate a different form of PG14 PrP (designated PG14 RML ) that is highly protease resistant and infectious in animal transmission experiments. We have been interested in characterizing the molecular properties of PG14 Spon and PG14 RML , with a view to identifying features that determine two, apparently distinct properties of PrP aggregates: their infectivity and their pathogenicity. In this paper, we have subjected PG14 Spon and PG14 RML to a panel of assays commonly used to distinguish infectious PrP (PrP Sc ) from cellular PrP (PrP C ), including immobilized metal affinity chromatography, precipitation with sodium phosphotungstate, and immunoprecipitation with PrP C ‐ and PrP Sc ‐specific antibodies. Surprisingly, we found that aggregates of PG14 Spon and PG14 RML behave identically to each other, and to authentic PrP Sc , in each of these biochemical assays. PG14 Spon however, in contrast to PG14 RML and PrP Sc , was unable to seed the misfolding of PrP C in an in vitro protein misfolding cyclic amplification reaction. Collectively, these results suggest that infectious and non‐infectious aggregates of PrP share common structural features accounting for their toxicity, and that self‐propagation of PrP involves more subtle molecular differences.