title: A mutation within the C-terminal domain of Sup35p that affects [PSI+] prion propagation.
abstract: The epigenetic factor [PSI+] in the yeast Saccharomyces cerevisiae is due to the prion form of Sup35p. The N-terminal domain of Sup35p (N), alone or together with the middle-domain (NM), assembles in vitro into fibrils that induce [PSI+] when introduced into yeast cells. The Sup35p C-terminal domain (C), involved in translation termination, is essential for growth. The involvement of Sup35p C-terminal domain into [PSI+] propagation is subject to debate. We previously showed that mutation of threonine 341 within Sup35p C-domain affects translation termination efficiency. Here, we demonstrate that mutating threonine 341 to aspartate or alanine results in synthetic lethality with [PSI+] and weakening of [PSI+] respectively. The corresponding Sup35D and Sup35A proteins assemble into wild-type like fibrils in vitro, but with a slower elongation rate. Moreover, cross-seeding between Sup35p and Sup35A is inefficient both in vivo and in vitro, suggesting that the point mutation alters the structural properties of Sup35p within the fibrils. Thus, Sup35p C-terminal domain modulates [PSI+] prion propagation, possibly through a functional interaction with the N and/or M domains of the protein. Our results clearly demonstrate that Sup35p C-terminal domain plays a critical role in prion propagation and provide new insights into the mechanism of prion conversion.
authors.affiliation: Laboratoire d'Enzymologie et Biochimie Structurales, CNRS, Bât. 34, Avenue de la Terrasse, F-91190 Gif-sur-Yvette, France. mehdi.kabani@lebs.cnrs-gif.fr
authors.forename: Mehdi
authors.initials: M
authors.lastname: Kabani
authors.forename: Bruno
authors.initials: B
authors.lastname: Cosnier
authors.forename: Luc
authors.initials: L
authors.lastname: Bousset
authors.forename: Jean-Pierre
authors.initials: JP
authors.lastname: Rousset
authors.forename: Ronald
authors.initials: R
authors.lastname: Melki
authors.forename: Céline
authors.initials: C
authors.lastname: Fabret
mesh_terms: D019943:Amino Acid Substitution; D050296:Microbial Viability; D050505:Mutant Proteins / Q000235:genetics / Q000378:metabolism; D020125:Mutation, Missense; D010454:Peptide Termination Factors / Q000235:genetics* / Q000378:metabolism*; D011328:Prions / Q000235:genetics* / Q000378:metabolism*; D011489:Protein Denaturation; D055503:Protein Multimerization; D012441:Saccharomyces cerevisiae / Q000235:genetics* / Q000378:metabolism*; D029701:Saccharomyces cerevisiae Proteins / Q000235:genetics* / Q000378:metabolism*
chemical_list: D050505:Mutant Proteins; D010454:Peptide Termination Factors; D011328:Prions; C068068:SUP35 protein, S cerevisiae; D029701:Saccharomyces cerevisiae Proteins