%0 Journal Article
%T Dissociation of Infectivity from Seeding Ability in Prions with Alternate Docking Mechanism
%A Michael B. Miller
%A James C. Geoghegan
%A Surachai Supattapone
%J PLOS Pathogens
%D 2011
%I Public Library of Science (PLoS)
%R 10.1371/journal.ppat.1002128
%X Previous studies identified two mammalian prion protein (PrP) polybasic domains that bind the disease-associated conformer PrPSc, suggesting that these domains of cellular prion protein (PrPC) serve as docking sites for PrPSc during prion propagation. To examine the role of polybasic domains in the context of full-length PrPC, we used prion proteins lacking one or both polybasic domains expressed from Chinese hamster ovary (CHO) cells as substrates in serial protein misfolding cyclic amplification (sPMCA) reactions. After ~5 rounds of sPMCA, PrPSc molecules lacking the central polybasic domain (ĶĪC) were formed. Surprisingly, in contrast to wild-type prions, ĶĪC-PrPSc prions could bind to and induce quantitative conversion of all the polybasic domain mutant substrates into PrPSc molecules. Remarkably, ĶĪC-PrPSc and other polybasic domain PrPSc molecules displayed diminished or absent biological infectivity relative to wild-type PrPSc, despite their ability to seed sPMCA reactions of normal mouse brain homogenate. Thus, ĶĪC-PrPSc prions interact with PrPC molecules through a novel interaction mechanism, yielding an expanded substrate range and highly efficient PrPSc propagation. Furthermore, polybasic domain deficient PrPSc molecules provide the first example of dissociation between normal brain homogenate sPMCA seeding ability from biological prion infectivity. These results suggest that the propagation of PrPSc molecules may not depend on a single stereotypic mechanism, but that normal PrPC/PrPSc interaction through polybasic domains may be required to generate prion infectivity.
%U http://www.plospathogens.org/article/info%3Adoi%2F10.1371%2Fjournal.ppat.1002128