title: Distinct amino acid compositional requirements for formation and maintenance of the [PSI⁺] prion in yeast.
abstract: Multiple yeast prions have been identified that result from the structural conversion of proteins into a self-propagating amyloid form. Amyloid-based prion activity in yeast requires a series of discrete steps. First, the prion protein must form an amyloid nucleus that can recruit and structurally convert additional soluble proteins. Subsequently, maintenance of the prion during cell division requires fragmentation of these aggregates to create new heritable propagons. For the Saccharomyces cerevisiae prion protein Sup35, these different activities are encoded by different regions of the Sup35 prion domain. An N-terminal glutamine/asparagine-rich nucleation domain is required for nucleation and fiber growth, while an adjacent oligopeptide repeat domain is largely dispensable for prion nucleation and fiber growth but is required for chaperone-dependent prion maintenance. Although prion activity of glutamine/asparagine-rich proteins is predominantly determined by amino acid composition, the nucleation and oligopeptide repeat domains of Sup35 have distinct compositional requirements. Here, we quantitatively define these compositional requirements in vivo. We show that aromatic residues strongly promote both prion formation and chaperone-dependent prion maintenance. In contrast, nonaromatic hydrophobic residues strongly promote prion formation but inhibit prion propagation. These results provide insight into why some aggregation-prone proteins are unable to propagate as prions.
authors.affiliation: Department of Biochemistry and Molecular Biology, Colorado State University, Fort Collins, Colorado, USA.
authors.forename: Kyle S
authors.initials: KS
authors.lastname: MacLea
authors.affiliation: Department of Biochemistry and Molecular Biology, Colorado State University, Fort Collins, Colorado, USA.
authors.forename: Kacy R
authors.initials: KR
authors.lastname: Paul
authors.affiliation: Graduate Program in Cell and Molecular Biology, Colorado State University, Fort Collins, Colorado, USA.
authors.forename: Zobaida
authors.initials: Z
authors.lastname: Ben-Musa
authors.affiliation: Department of Biochemistry and Molecular Biology, Colorado State University, Fort Collins, Colorado, USA.
authors.forename: Aubrey
authors.initials: A
authors.lastname: Waechter
authors.affiliation: Department of Biochemistry and Molecular Biology, Colorado State University, Fort Collins, Colorado, USA.
authors.forename: Jenifer E
authors.initials: JE
authors.lastname: Shattuck
authors.affiliation: Department of Biochemistry and Molecular Biology, Colorado State University, Fort Collins, Colorado, USA.
authors.forename: Margaret
authors.initials: M
authors.lastname: Gruca
authors.affiliation: Department of Biochemistry and Molecular Biology, Colorado State University, Fort Collins, Colorado, USA Graduate Program in Cell and Molecular Biology, Colorado State University, Fort Collins, Colorado, USA Eric.Ross@ColoState.Edu.
authors.forename: Eric D
authors.initials: ED
authors.lastname: Ross
mesh_terms: D000595:Amino Acid Sequence; D000596:Amino Acids / Q000737:chemistry*; D000682:Amyloid / Q000737:chemistry; D015723:Gene Library; D008969:Molecular Sequence Data; D009154:Mutation; D009842:Oligopeptides / Q000737:chemistry; D010454:Peptide Termination Factors / Q000737:chemistry*; D011328:Prions / Q000737:chemistry*; D011489:Protein Denaturation; D017510:Protein Folding; D017433:Protein Structure, Secondary; D017434:Protein Structure, Tertiary; D012441:Saccharomyces cerevisiae / Q000737:chemistry*; D029701:Saccharomyces cerevisiae Proteins / Q000737:chemistry*; D014443:Tyrosine / Q000737:chemistry
chemical_list: D000596:Amino Acids; D000682:Amyloid; D009842:Oligopeptides; D010454:Peptide Termination Factors; D011328:Prions; C068068:SUP35 protein, S cerevisiae; D029701:Saccharomyces cerevisiae Proteins; D014443:Tyrosine