title: The prion model for [URE3] of yeast: spontaneous generation and requirements for propagation.
abstract: The genetic properties of the non-Mendelian element, [URE3], suggest that it is a prion (infectious protein) form of Ure2p, a mediator of nitrogen regulation in Saccharomyces cerevisiae. Into a ure2Delta strain (necessarily lacking [URE3]), we introduced a plasmid overproducing Ure2p. This induced the frequent "spontaneous generation" of [URE3], with properties identical to the original [URE3]. Altering the translational frame only in the prion-inducing domain of URE2 shows that it is Ure2 protein (and not URE2 RNA) that induces appearance of [URE3]. The proteinase K-resistance of Ure2p is unique to [URE3] strains and is not seen in nitrogen regulation of normal strains. The prion-inducing domain of Ure2p (residues 1-65) can propagate [URE3] in the absence of the C-terminal part of the molecule. In contrast, the C-terminal part of Ure2p cannot be converted to the prion (inactive) form without the prion-inducing domain covalently attached. These experiments support the prion model for [URE3] and extend our understanding of its propagation.
authors.affiliation: Laboratory of Biochemistry and Genetics, National Institute of Diabetes and Digestive and Kidney Diseases, Building 8, Room 225, National Institutes of Health, 8 Center Drive MSC0830, Bethesda, MD 20892-0830, USA.
authors.forename: D C
authors.initials: DC
authors.lastname: Masison
authors.forename: M L
authors.initials: ML
authors.lastname: Maddelein
authors.forename: R B
authors.initials: RB
authors.lastname: Wickner
mesh_terms: D000595:Amino Acid Sequence; D005656:Fungal Proteins / Q000235:genetics*; D015966:Gene Expression Regulation, Fungal; D005979:Glutathione Peroxidase; D008969:Molecular Sequence Data; D011328:Prions / Q000235:genetics*; D012441:Saccharomyces cerevisiae / Q000235:genetics* / Q000254:growth & development; D029701:Saccharomyces cerevisiae Proteins
chemical_list: D005656:Fungal Proteins; D011328:Prions; D029701:Saccharomyces cerevisiae Proteins; D005979:Glutathione Peroxidase; C067020:URE2 protein, S cerevisiae