The yeast prion Ure2p native-like assemblies are toxic to mammalian cells regardless of their aggregation state.
The yeast prion Ure2p assembles in vitro into oligomers and fibrils retaining the alpha-helix content and binding properties of the soluble protein. Here we show that the different forms of Ure2p native-like assemblies (dimers, oligomers, and fibrils) are similarly toxic to murine H-END cells when added to the culture medium. Interestingly, the amyloid fibrils obtained by heat treatment of the toxic native-like fibrils appear harmless. Moreover, the Ure2p C-terminal domain, lacking the N-terminal segment necessary for aggregation but containing the glutathione binding site, is not cytotoxic. This finding strongly supports the idea that Ure2p toxicity depends on the structural properties of the flexible N-terminal prion domain and can therefore be considered as an inherent feature of the protein, unrelated to its aggregation state but rather associated with a basic toxic fold shared by all of the Ure2p native-like assemblies. Indeed, the latter are able to interact with the cell surface, leading to alteration of calcium homeostasis, membrane permeabilization, and oxidative stress, whereas the heat-treated amyloid fibrils do not. Our results support the idea of a general mechanism of toxicity of any protein/peptide aggregate endowed with structural features, making it able to interact with cell membranes and to destabilize them. This evidence extends the widely accepted view that the toxicity by protein aggregates is restricted to amyloid prefibrillar aggregates and provides new insights into the mechanism by which native-like oligomers compromise cell viability.
Department of Biochemical Sciences, Interuniversity Centre for the Study of the Molecular Basis of Neurodegenerative Diseases, University of Florence, Florence 50134, Italy.
Laura
L
Pieri
Monica
M
Bucciantini
Daniele
D
Nosi
Lucia
L
Formigli
Jimmy
J
Savistchenko
Ronald
R
Melki
Massimo
M
Stefani
D000818:Animals; D017209:Apoptosis / Q000187:drug effects; D002118:Calcium / Q000378:metabolism; D002460:Cell Line; D002470:Cell Survival / Q000187:drug effects; D005979:Glutathione Peroxidase; D051379:Mice; D008854:Microscopy, Electron; D008954:Models, Biological; D046912:Multiprotein Complexes; D009336:Necrosis; D010084:Oxidation-Reduction; D011328:Prions / Q000737:chemistry* / Q000235:genetics / Q000472:pathogenicity / Q000633:toxicity*; D011994:Recombinant Proteins / Q000737:chemistry / Q000235:genetics / Q000633:toxicity; D029701:Saccharomyces cerevisiae Proteins / Q000737:chemistry* / Q000235:genetics / Q000633:toxicity*; D012995:Solubility
D046912:Multiprotein Complexes; D011328:Prions; D011994:Recombinant Proteins; D029701:Saccharomyces cerevisiae Proteins; D005979:Glutathione Peroxidase; C067020:URE2 protein, S cerevisiae; D002118:Calcium