"Prion-proof" for [PIN+]: infection with in vitro-made amyloid aggregates of Rnq1p-(132-405) induces [PIN+].
Prions are self-propagating, infectious protein conformations. The mammalian prion, PrP(Sc), responsible for neurodegenerative diseases like bovine spongiform encephalopathy (BSE; "mad cow" disease) and Creutzfeldt-Jakob's disease, appears to be a beta-sheet-rich amyloid conformation of PrP(c) that converts PrP(c) into PrP(Sc). However, an unequivocal demonstration of "protein-only" infection by PrP(Sc) is still lacking. So far, protein only infection has been proven for three prions, [PSI(+)], [URE3] and [Het-s], all of fungal origin. Considerable evidence supports the hypothesis that another protein, the yeast Rnq1p, can form a prion, [PIN(+)]. While Rnq1p does not lose any known function upon prionization, [PIN(+)] has interesting positive phenotypes: facilitating the appearance and destabilization of other prions as well as the aggregation of polyglutamine extensions of the Huntingtin protein. Here, we polymerize a Gln/Asn-rich recombinant fragment of Rnq1p into beta-sheet-rich amyloid-like aggregates. While the method used for [PSI(+)] and [URE3] infectivity assays did not yield protein-only infection for the Rnq1p aggregates, we did successfully obtain protein-only infection by modifying the protocol. This work proves that [PIN(+)] is a prion mediated by amyloid-like aggregates of Rnq1p, and supports the hypothesis that heterologous prions affect each other's appearance and propagation through interaction of their amyloid-like regions.
Patel
Basant K
BK
Department of Biological Sciences, Laboratory of Molecular Biology, University of Illinois, Chicago, IL 60607, USA.
Liebman
Susan W
SW
D000595:Amino Acid Sequence; D000682:Amyloid / Q000378:metabolism*; D007700:Kinetics; D011328:Prions / Q000737:chemistry* / Q000378:metabolism*; D020836:Protein Structure, Quaternary; D011994:Recombinant Proteins / Q000378:metabolism; D012441:Saccharomyces cerevisiae / Q000166:cytology / Q000378:metabolism*; D029701:Saccharomyces cerevisiae Proteins / Q000737:chemistry* / Q000378:metabolism*; D013696:Temperature; D014170:Transformation, Genetic
D000682:Amyloid; D011328:Prions; C404807:RNQ1 protein, S cerevisiae; D011994:Recombinant Proteins; D029701:Saccharomyces cerevisiae Proteins