title: Importance of low-oligomeric-weight species for prion propagation in the yeast prion system Sup35/Hsp104.
abstract: The [PSI+] determinant of Saccharomyces cerevisiae, consisting of the cytosolic translation termination factor Sup35, is a prion-type genetic element that induces an inheritable conformational change and converts the Sup35 protein into amyloid fibers. The molecular chaperone Hsp104 is required to maintain self-replication of [PSI+]. We observe in vitro that addition of catalytic amounts of Hsp104 to the prion-determining region of the NM domain of Sup35, Sup355-26, results in the dissociation of oligomeric Sup35 into monomeric species. Several intermediates of Sup355-26 could be detected during this process. Strong interactions are found between Hsp104 and hexameric/tetrameric Sup355-26, whereas the intermediate and monomeric "release" forms show a decreased affinity with respect to Hsp104, as monitored by saturation transfer difference and diffusion-ordered NMR spectroscopic experiments. Interactions are mediated mostly by the side chains of Gln, Asn, and Tyr residues in Sup355-26. No interaction can be detected between Hsp104 and higher oligomeric states (>/=8) of Sup355-26. Taking into account the fact that Hsp104 is required for maintenance of [PSI+], we suggest that low-oligomeric-weight species of Sup35 are important for prion propagation in yeast.
authors.affiliation: Institut für Organische Chemie und Biochemie and Lehrstuhl für Biotechnologie, Technische Universität München, Lichtenbergstrasse 4, 85747 Garching, Germany.
authors.forename: Saravanakumar
authors.initials: S
authors.lastname: Narayanan
authors.forename: Benjamin
authors.initials: B
authors.lastname: Bösl
authors.forename: Stefan
authors.initials: S
authors.lastname: Walter
authors.forename: Bernd
authors.initials: B
authors.lastname: Reif
mesh_terms: D001216:Asparagine / Q000737:chemistry; D003600:Cytosol / Q000378:metabolism; D005656:Fungal Proteins / Q000737:chemistry*; D005973:Glutamine / Q000737:chemistry; D006360:Heat-Shock Proteins / Q000737:chemistry*; D009682:Magnetic Resonance Spectroscopy; D008954:Models, Biological; D010452:Peptide Biosynthesis; D010454:Peptide Termination Factors; D010455:Peptides / Q000737:chemistry; D011328:Prions / Q000737:chemistry*; D011485:Protein Binding; D011487:Protein Conformation; D012441:Saccharomyces cerevisiae / Q000378:metabolism; D029701:Saccharomyces cerevisiae Proteins / Q000737:chemistry*; D013997:Time Factors; D014443:Tyrosine / Q000737:chemistry
chemical_list: D005656:Fungal Proteins; D006360:Heat-Shock Proteins; D010454:Peptide Termination Factors; D010455:Peptides; D011328:Prions; C068068:SUP35 protein, S cerevisiae; D029701:Saccharomyces cerevisiae Proteins; D005973:Glutamine; C070972:HsP104 protein, S cerevisiae; D014443:Tyrosine; D001216:Asparagine