NR ALBT
AU Speransky,V.V.; Taylor,K.L.; Edskes,H.K.; Wickner,R.B.; Steven,A.C.
TI Prion filament networks in [URE3] cells of Saccharomyces cerevisiae
QU Journal of Cell Biology 2001 Jun 11; 153(6): 1327-36
PT journal article
AB The [URE3] prion (infectious protein) of yeast is a self-propagating, altered form of Ure2p that cannot carry out its normal function in nitrogen regulation. Previous data have shown that Ure2p can form protease-resistant amyloid filaments in vitro, and that it is aggregated in cells carrying the [URE3] prion. Here we show by electron microscopy that [URE3] cells overexpressing Ure2p contain distinctive, filamentous networks in their cytoplasm, and demonstrate by immunolabeling that these networks contain Ure2p. In contrast, overexpressing wild-type cells show a variety of Ure2p distributions: usually, the protein is dispersed sparsely throughout the cytoplasm, although occasionally it is found in multiple small, focal aggregates. However, these distributions do not resemble the single, large networks seen in [URE3] cells, nor do the control cells exhibit cytoplasmic filaments. In [URE3] cell extracts, Ure2p is present in aggregates that are only partially solubilized by boiling in SDS and urea. In these aggregates, the NH(2)-terminal prion domain is inaccessible to antibodies, whereas the COOH-terminal nitrogen regulation domain is accessible. This finding is consistent with the proposal that the prion domains stack to form the filament backbone, which is surrounded by the COOH-terminal domains. These observations support and further specify the concept of the [URE3] prion as a self-propagating amyloid.
MH Amyloid/metabolism; Cytoskeleton/*metabolism; Epitopes/metabolism; Fungal Proteins/metabolism; Gene Expression; Microfilaments/metabolism; Models, Biological; Prions/*metabolism; Recombinant Fusion Proteins/metabolism; Saccharomyces cerevisiae/metabolism
AD Laboratory of Structural Biology, National Institute of Arthritis and Musculoskeletal and Skin Diseases, National Institutes of Health, Bethesda, MD 20892, USA
SP englisch
PO USA