[URE3] prion propagation is abolished by a mutation of the primary cytosolic Hsp70 of budding yeast.
[URE3] and [PSI(+)] are infectious protein forms of the Saccharomyces cerevisiae Ure2p and Sup35p, respectively. We isolated an allele of SSA2, the primary cytosolic Hsp70, in a screen for mutants unable to maintain [URE3]. Designated ssa2-10, the mutation results in a leucine substitution for proline 395, a conserved residue of the peptide-binding domain. This allele also unexpectedly destabilizes [URE3] in newly formed heterozygotes: [URE3] is either absent in heterozygotes formed by crossing wild-type [URE3] cells with ssa2-10 mutants, or present and fully stable. SSA2 deletion mutants are weakly capable of maintaining [URE3]. The ssa2-10 allele is compatible with propagation of [PSI(+)]. However, in combination with a deletion of SSA1, ssa2-10 eliminates the nonsense-suppression phenotype of [PSI(+)] cells.
Roberts
B Tibor
BT
Laboratory of Biochemistry and Genetics, National Institute of Diabetes, Digestive and Kidney Diseases, National Institutes of Health, Bethesda, MD 20892-0830, USA.
Moriyama
Hiromitsu
H
Wickner
Reed B
RB
D003001:Cloning, Molecular; D004271:DNA, Fungal / Q000737:chemistry / Q000235:genetics; D005656:Fungal Proteins / Q000737:chemistry / Q000235:genetics* / Q000378:metabolism; D015966:Gene Expression Regulation, Fungal / Q000502:physiology*; D018840:HSP70 Heat-Shock Proteins / Q000737:chemistry / Q000235:genetics*; D017354:Point Mutation; D016133:Polymerase Chain Reaction; D011328:Prions / Q000235:genetics* / Q000378:metabolism; D012441:Saccharomyces cerevisiae / Q000235:genetics* / Q000378:metabolism; D029701:Saccharomyces cerevisiae Proteins; D013489:Suppression, Genetic
D004271:DNA, Fungal; D005656:Fungal Proteins; D018840:HSP70 Heat-Shock Proteins; D011328:Prions; C542288:SSA2 protein, S cerevisiae; D029701:Saccharomyces cerevisiae Proteins