Generation of Infectious Prions Amenable to Site-specific Click Chemistry.

Prion diseases are a group of fatal neurodegenerative diseases that proceed through the templated conversion of the normal PrP C protein to a self-propagating and infectious form, termed PrP Sc . This conversion process is central to disease progression. However, due to difficulties in producing functional PrP Sc molecules that can be selectively modified with chemical probes, many aspects of PrP Sc biology cannot be directly studied. To overcome this limitation, we substituted p-azido-L-phenylalanine (AzF), a small click chemistry-reactive amino acid, for tryptophan residue 99 of PrP C . W99AzF PrP C substrate can efficiently and faithfully propagate either infectious or non-infectious PrP Sc conformers in vitro . Critically, W99AzF PrP Sc amyloid fibrils remain amenable to click chemistry by various ligands after the prion conversion process. Through the combination of site-specific substitution, the modularity of click chemistry, and the functional diversity of click labels, a multitude of modified prions can now be produced to ask targeted questions about the biochemical and biological basis of prion infectivity.