title: Oligopeptide repeats in the yeast protein Sup35p stabilize intermolecular prion interactions.
abstract: The nuclear-encoded Sup35p protein is responsible for the prion-like [PSI(+)] determinant of yeast, with Sup35p existing largely as a high molecular weight aggregate in [PSI(+)] strains. Here we show that the five oligopeptide repeats present at the N-terminus of Sup35p are responsible for stabilizing aggregation of Sup35p in vivo. Sequential deletion of the oligopeptide repeats prevented the maintenance of [PSI(+)] by the truncated Sup35p, although deletants containing only two repeats could be incorporated into pre-existing aggregates of wild-type Sup35p. The mammalian prion protein PrP also contains similar oligopeptide repeats and we show here that a human PrP repeat (PHGGGWGQ) is able functionally to replace a Sup35p oligopeptide repeat to allow stable [PSI(+)] propagation in vivo. Our data suggest a model in which the oligopeptide repeats in Sup35p stabilize intermolecular interactions between Sup35p proteins that initiate establishment of the aggregated state. Modulating repeat number therefore alters the rate of yeast prion conversion in vivo. Furthermore, there appears to be evolutionary conservation of function of the N-terminally located oligopeptide repeats in prion propagation.
authors.affiliation: Research School of Biosciences, University of Kent, Canterbury, Kent CT2 7NJ, UK.
authors.forename: S N
authors.initials: SN
authors.lastname: Parham
authors.forename: C G
authors.initials: CG
authors.lastname: Resende
authors.forename: M F
authors.initials: MF
authors.lastname: Tuite
mesh_terms: D001681:Biological Assay; D015153:Blotting, Western; D017124:Conserved Sequence; D019143:Evolution, Molecular; D005656:Fungal Proteins / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism*; D006801:Humans; D046911:Macromolecular Substances; D010454:Peptide Termination Factors; D010957:Plasmids / Q000235:genetics; D011328:Prions / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D011485:Protein Binding / Q000502:physiology; D011487:Protein Conformation; D020449:Repetitive Sequences, Amino Acid / Q000502:physiology; D012441:Saccharomyces cerevisiae; D029701:Saccharomyces cerevisiae Proteins; D017384:Sequence Deletion; D013329:Structure-Activity Relationship
chemical_list: D005656:Fungal Proteins; D046911:Macromolecular Substances; D010454:Peptide Termination Factors; D011328:Prions; C068068:SUP35 protein, S cerevisiae; D029701:Saccharomyces cerevisiae Proteins