title: Locating folds of the in-register parallel β-sheet of the Sup35p prion domain infectious amyloid.
abstract: The [PSI+] prion is a self-propagating amyloid of the translation termination factor, Sup35p, of Saccharomyces cerevisiae. The N-terminal 253 residues (NM) of this 685-residue protein normally function in regulating mRNA turnover but spontaneously form infectious amyloid in vitro. We converted the three Ile residues in Sup35NM to Leu and then replaced 16 single residues with Ile, one by one, and prepared Ile-1-(13)C amyloid of each mutant, seeding with amyloid formed by the reference sequence Sup35NM. Using solid-state NMR, we showed that 10 of the residues examined, including six between residues 30 and 90, showed the ∼0.5-nm distance between labels diagnostic of the in-register parallel amyloid architecture. The five scattered N domain residues with wider spacing may be in turns or loops; one is a control at the C terminus of M. All mutants, except Q56I, showed little or no [PSI+] transmission barrier from the reference sequence, suggesting that they could assume a similar amyloid architecture in vitro when seeded with filaments of reference sequence Sup35NM. Infection of yeast cells expressing the reference SUP35 gene sequence with amyloid of several mutants produced [PSI+] transfectants with similar efficiency as did reference sequence Sup35NM amyloid. Our work provides a stringent demonstration that the Sup35 prion domain has the folded in-register parallel β-sheet architecture and suggests common locations of the folds. This architecture naturally suggests a mechanism of inheritance of conformation, the central mystery of prions.
authors.affiliation: Laboratories of Biochemistry and Genetics and.
authors.forename: Anton
authors.initials: A
authors.lastname: Gorkovskiy
authors.affiliation: Chemical Physics, National Institute of Diabetes and Digestive and Kidney Diseases, National Institutes of Health, Bethesda, MD 20892.
authors.forename: Kent R
authors.initials: KR
authors.lastname: Thurber
authors.affiliation: Chemical Physics, National Institute of Diabetes and Digestive and Kidney Diseases, National Institutes of Health, Bethesda, MD 20892.
authors.forename: Robert
authors.initials: R
authors.lastname: Tycko
authors.affiliation: Laboratories of Biochemistry and Genetics and wickner@helix.nih.gov.
authors.forename: Reed B
authors.initials: RB
authors.lastname: Wickner
mesh_terms: D000595:Amino Acid Sequence; D000682:Amyloid / Q000737:chemistry*; D066241:Carbon-13 Magnetic Resonance Spectroscopy; D008969:Molecular Sequence Data; D050505:Mutant Proteins / Q000737:chemistry; D010454:Peptide Termination Factors / Q000737:chemistry*; D011328:Prions / Q000737:chemistry*; D017433:Protein Structure, Secondary; D012441:Saccharomyces cerevisiae / Q000378:metabolism*; D029701:Saccharomyces cerevisiae Proteins / Q000737:chemistry*; D014162:Transfection
chemical_list: D000682:Amyloid; D050505:Mutant Proteins; D010454:Peptide Termination Factors; D011328:Prions; C068068:SUP35 protein, S cerevisiae; D029701:Saccharomyces cerevisiae Proteins
keywords: Sup35; [PSI+] prion; amyloid; dipolar recoupling; solid-state NMR