The role of the N-terminal oligopeptide repeats of the yeast Sup35 prion protein in propagation and transmission of prion variants.
The cytoplasmic [PSI+] determinant of Saccharomyces cerevisiae is the prion form of the Sup35 protein. Oligopeptide repeats within the Sup35 N-terminal domain (PrD) presumably are required for the stable [PSI+] inheritance that in turn involves fragmentation of Sup35 polymers by the chaperone Hsp104. The nonsense suppressor [PSI+] phenotype can vary in efficiency probably due to different inheritable Sup35 polymer structures. Here we study the ability of Sup35 mutants with various deletions of the oligopeptide repeats to support [PSI+] propagation. We define the minimal region of the Sup35-PrD necessary to support [PSI+] as amino acids 1-64, which include the first two repeats, although a longer fragment, 1-83, is required to maintain weak [PSI+] variants. Replacement of wild-type Sup35 with deletion mutants decreases the strength of the [PSI+] phenotype. However, with one exception, reintroducing the wild-type Sup35 restores the original phenotype. Thus, the specific prion fold defining the [PSI+] variant can be preserved by the mutant Sup35 protein despite the change of phenotype. Coexpression of wild-type and mutant Sup35 containing three, two, one, or no oligopeptide repeats causes variant-specific [PSI+] elimination. These data suggest that [PSI+] variability is primarily defined by differential folding of the Sup35-PrD oligopeptide-repeat region.
Shkundina
Irina S
IS
Institute of Experimental Cardiology, Cardiology Research Center, Moscow, Russia.
Kushnirov
Vitaly V
VV
Tuite
Mick F
MF
Ter-Avanesyan
Michael D
MD
D001483:Base Sequence; D014644:Genetic Variation; D009842:Oligopeptides / Q000737:chemistry* / Q000235:genetics / Q000502:physiology*; D010454:Peptide Termination Factors; D010641:Phenotype; D010957:Plasmids; D011328:Prions / Q000737:chemistry* / Q000235:genetics / Q000502:physiology*; D017510:Protein Folding; D017434:Protein Structure, Tertiary / Q000235:genetics; D020449:Repetitive Sequences, Amino Acid / Q000235:genetics; D012441:Saccharomyces cerevisiae / Q000737:chemistry* / Q000235:genetics / Q000502:physiology*; D029701:Saccharomyces cerevisiae Proteins / Q000737:chemistry* / Q000235:genetics / Q000502:physiology*; D017384:Sequence Deletion
D009842:Oligopeptides; D010454:Peptide Termination Factors; D011328:Prions; C068068:SUP35 protein, S cerevisiae; D029701:Saccharomyces cerevisiae Proteins