title: [NSI (+)]: a novel non-Mendelian nonsense suppressor determinant in Saccharomyces cerevisiae.
abstract: Non-Mendelian determinants that control heritable traits in yeast are subdivided into two major groups-one that includes DNA- or RNA-based elements and another that comprises protein-based factors that are analogous to mammalian prion. All yeast non-Mendelian determinants show dominant inheritance, and some of them demonstrate cytoplasmic infectivity. Only prions, however, harbor-specific features, such as high frequency of induction following overproduction of prion-encoding protein, loss of the protein's normal function, and reversible curability. Here, we describe a novel nonchromosomal determinant that, in addition to [PSI (+)] and [ISP (+)], is involved in epigenetic control of nonsense suppression. This determinant, which we have designated [NSI (+)], causes nonsense suppression in the strains bearing the N-terminal-deleted or -modified SUP35 gene, but has no manifestation in the strains with the intact copy of SUP35. [NSI (+)] shows dominant non-Mendelian inheritance, reversible curability and may be transmitted by cytoduction, albeit with low frequency. Similar to yeast prions, this determinant can be cured by deletion or mutational inactivation of Hsp104. We have shown that [NSI (+)] does not correspond to the already identified yeast prions. Based on the data obtained, we hypothesize that [NSI (+)] is a novel prion factor involved in epigenetic control of nonsense suppression.
authors.affiliation: Vavilov Institute of General Genetics, Russian Academy of Science, St. Petersburg, Russia.
authors.forename: Alsu F
authors.initials: AF
authors.lastname: Saifitdinova
authors.forename: Anton A
authors.initials: AA
authors.lastname: Nizhnikov
authors.forename: Artem G
authors.initials: AG
authors.lastname: Lada
authors.forename: Alexandr A
authors.initials: AA
authors.lastname: Rubel
authors.forename: Zalina M
authors.initials: ZM
authors.lastname: Magomedova
authors.forename: Valentina V
authors.initials: VV
authors.lastname: Ignatova
authors.forename: Sergey G
authors.initials: SG
authors.lastname: Inge-Vechtomov
authors.forename: Alexey P
authors.initials: AP
authors.lastname: Galkin
mesh_terms: D015825:Chromosomes, Fungal; D018389:Codon, Nonsense; D044127:Epigenesis, Genetic; D015966:Gene Expression Regulation, Fungal; D016153:Genes, Suppressor; D005822:Genetic Vectors; D006360:Heat-Shock Proteins / Q000235:genetics / Q000378:metabolism; D010454:Peptide Termination Factors / Q000235:genetics / Q000378:metabolism; D011328:Prions / Q000235:genetics* / Q000378:metabolism; D012441:Saccharomyces cerevisiae / Q000235:genetics* / Q000378:metabolism; D029701:Saccharomyces cerevisiae Proteins / Q000235:genetics / Q000378:metabolism; D013489:Suppression, Genetic
chemical_list: D018389:Codon, Nonsense; D006360:Heat-Shock Proteins; D010454:Peptide Termination Factors; D011328:Prions; D029701:Saccharomyces cerevisiae Proteins; C070972:HsP104 protein, S cerevisiae