title: Genetic study of interactions between the cytoskeletal assembly protein sla1 and prion-forming domain of the release factor Sup35 (eRF3) in Saccharomyces cerevisiae.
abstract: Striking similarities between cytoskeletal assembly and the "nucleated polymerization" model of prion propagation suggest that similar or overlapping sets of proteins may assist in both processes. We show that the C-terminal domain of the yeast cytoskeletal assembly protein Sla1 (Sla1C) specifically interacts with the N-terminal prion-forming domain (Sup35N) of the yeast release factor Sup35 (eRF3) in the two-hybrid system. Sla1C and several other Sup35N-interacting proteins also exhibit two-hybrid interactions with the poly-Gln-expanded N-proximal fragment of human huntingtin, which promotes Huntington disease-associated aggregation. The Sup35N-Sla1C interaction is inhibited by Sup35N alterations that make Sup35 unable to propagate the [PSI(+)] state and by the absence of the chaperone protein Hsp104, which is essential for [PSI] propagation. In a Sla1(-) background, [PSI] curing by dimethylsulfoxide or excess Hsp104 is increased, while translational readthrough and de novo [PSI] formation induced by excess Sup35 or Sup35N are decreased. These data show that, in agreement with the proposed function of Sla1 during cytoskeletal formation, Sla1 assists in [PSI] formation and propagation, but is not required for these processes. Sla1(-) strains are sensitive to some translational inhibitors, and some sup35 mutants, obtained in a Sla1(-) background, are sensitive to Sla1, suggesting that the interaction between Sla1 and Sup35 proteins may play a role in the normal function of the translational apparatus. We hypothesize that Sup35N is involved in regulatory interactions with intracellular structural networks, and [PSI] prion may be formed as a by-product of this process.
authors.affiliation: School of Biology, Georgia Institute of Technology, Atlanta, Georgia 30332-0230, USA.
authors.forename: P A
authors.initials: PA
authors.lastname: Bailleul
authors.forename: G P
authors.initials: GP
authors.lastname: Newnam
authors.forename: J N
authors.initials: JN
authors.lastname: Steenbergen
authors.forename: Y O
authors.initials: YO
authors.lastname: Chernoff
mesh_terms: D002352:Carrier Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D002934:Cinnamates; D003001:Cloning, Molecular; D003598:Cytoskeletal Proteins; D003599:Cytoskeleton / Q000378:metabolism*; D005656:Fungal Proteins / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism*; D005800:Genes, Fungal / Q000235:genetics / Q000502:physiology; D016153:Genes, Suppressor / Q000235:genetics; D006360:Heat-Shock Proteins / Q000235:genetics / Q000378:metabolism; D006801:Humans; D000071058:Huntingtin Protein; D006921:Hygromycin B / Q000031:analogs & derivatives / Q000494:pharmacology; D008826:Microbial Sensitivity Tests; D008954:Models, Biological; D009154:Mutation; D009419:Nerve Tissue Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism; D009687:Nuclear Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism; D010303:Paromomycin / Q000494:pharmacology; D010454:Peptide Termination Factors; D011328:Prions / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D011485:Protein Binding; D014176:Protein Biosynthesis / Q000187:drug effects / Q000235:genetics; D012441:Saccharomyces cerevisiae / Q000166:cytology / Q000187:drug effects / Q000235:genetics* / Q000378:metabolism; D029701:Saccharomyces cerevisiae Proteins
chemical_list: D002352:Carrier Proteins; D002934:Cinnamates; D003598:Cytoskeletal Proteins; D005656:Fungal Proteins; C086055:HTT protein, human; D006360:Heat-Shock Proteins; D000071058:Huntingtin Protein; D009419:Nerve Tissue Proteins; D009687:Nuclear Proteins; D010454:Peptide Termination Factors; D011328:Prions; C082265:SLA1 protein, S cerevisiae; C068068:SUP35 protein, S cerevisiae; D029701:Saccharomyces cerevisiae Proteins; C070972:HsP104 protein, S cerevisiae; D006921:Hygromycin B; C026273:hygromycin A; D010303:Paromomycin