In situ photodegradation of incorporated polyanion does not alter prion infectivity

Single-stranded polyanions ≥40 bases in length facilitate the formation of hamster scrapie prions in vitro,and polyanions co-localize with prpsc aggregates in vivo [1,2]. to test the hypothesis that intact polyanionic molecules might serve as a structural backbone essential for maintaining the infectious conformation(s) of prpsc,we produced synthetic prions using a photocleavable,100-base oligonucleotide (pc-oligo). in serial protein misfolding cyclic amplification (spmca) reactions using purified prpc substrate,pc-oligo was incorporated into physical complexes with prpsc molecules that were resistant to benzonase digestion. exposure of these nuclease-resistant prion complexes to long wave ultraviolet light (315 nm) induced degradation of pc-oligo into 5 base fragments. light-induced photolysis of incorporated pc-oligo did not alter the infectivity of in vitro-generated prions,as determined by bioassay in hamsters and brain homogenate spmca assays. neuropathological analysis also revealed no significant differences in the neurotropism of prions containing intact versus degraded pc-oligo. these results show that polyanions >5 bases in length are not required for maintaining the infectious properties of in vitro-generated scrapie prions,and indicate that such properties are maintained either by short polyanion remnants,other co-purified cofactors,or by prpsc molecules alone. © 2011 piro et al.