[PSI] and [URE3] as yeast prions

Authors

  • Reed B. Wickner,

    Corresponding author
    1. Section on Genetics of Simple Eukaryotes, National Institute of Diabetes, Digestive and Kidney Diseases, Bldg. 8, Room 225, NIH, Bethesda, MD 20892–0830, U.S.A.
    • Bldg. 8, Room 225, 8 Center Dr., MSC 0830, National Institutes of Health, Bethesda, MD 20892–0830, U.S.A. Telephone: (301) 496–3452; Telefax: (301) 402–0240
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  • Daniel C. Masison,

    1. Section on Genetics of Simple Eukaryotes, National Institute of Diabetes, Digestive and Kidney Diseases, Bldg. 8, Room 225, NIH, Bethesda, MD 20892–0830, U.S.A.
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  • Herman K. Edskes

    1. Section on Genetics of Simple Eukaryotes, National Institute of Diabetes, Digestive and Kidney Diseases, Bldg. 8, Room 225, NIH, Bethesda, MD 20892–0830, U.S.A.
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Abstract

[URE3] is a non-Mendelian genetic element that mimics recessive mutations in the chromosomal URE2 gene making cells derepressed for nitrogen catabolic enzymes. [PSI] is a non-Mendelian enhancer of readthrough of translational termination similar in its effects to some mutations in the chromosomal SUP35 gene. Three lines of evidence led to the proposal75 that both [URE3] and [PSI] are prions, infectious proteins analogous to the scrapie agent mediating transmissible spongiform encephalopathies of mammals. (1) Both [PSI] and [URE3] are reversibly curable. (2) [PSI] propagation requires SUP35 and [URE3] propagation requires URE2 with recessive chromosomal mutants having the same phenotypes as the presence of the respective dominant non-Mendelian element. (3) Overproduction of Sup35p and Ure2p increases the frequency of cells acquiring [PSI] or [URE3], respectively.

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