Caister Academic Press

CIMB Abstract

Curr. Issues Mol. Biol. (2000) 2: 51-59.

[URE3] and [PSI] are Prions of Yeast and Evidence for New Fungal Prions

Daniel C. Masison, Herman K. Edskes, Marie-Lise Maddelein, Kimberly L. Taylor and Reed B. Wickner

[URE3] and [PSI] are two non-Mendelian genetic elements discovered over 25 years ago and never assigned to a nucleic acid replicon. Their genetic properties led us to propose that they are prions, altered self-propagating forms of Ure2p and Sup35p, respectively, that cannot properly carry out the normal functions of these proteins. Ure2p is partially protease-resistant in [URE3] strains and Sup35p is aggregated specifically in [PSI] strains supporting this idea. Overexpression of Hsp104 cures [PSI], as does the absence of this protein, suggesting that the prion change of Sup35p in [PSI] strains is aggregation. Strains of [PSI], analogous to those described for scrapie, have now been described as well as an in vitro system for [PSI] propagation. Recently, two new potential prions have been described, one in yeast and the other in the filamentous fungus, Podospora.

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