Supporting the structural basis of prion strains: induction and identification of [PSI] variants11Edited by F. E. Cohen

King, Chih-Yen

doi:10.1006/jmbi.2001.4542

Cited by 111 publications

(112 citation statements)

References 39 publications

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“…Variants of [PSI ϩ ], differing in prion stability, in the intensity of the nonsense-suppression phenotype, or in the range of Sup35 prion domain sequences that can propagate them, have been described (10,53). These phenotypic differences reflect structural variations in the Sup35p fibrils that transmit the trait (11,12), but the precise nature of structural variations is not known.…”

Section: Discussionmentioning

confidence: 99%

“…Sup35p consists of three domains: a C-terminal domain with translation termination function (C), a highly charged middle domain (M), and an N-terminal domain necessary and sufficient for the propagation of the [PSI ϩ ] prion (N) (8). Variants of the [PSI ϩ ] prion (also called strains) can be distinguished by their stability of propagation, the degree to which Sup35p is inactivated (9), and compatibility with point mutants of the Sup35 prion domain sequence (10). Experiments on infection with amyloid fibrils of recombinant Sup35p show that different amyloid forms of Sup35p are responsible for the different [PSI ϩ ] variants (11,12).…”

Section: T He Nonchromosomal Gene [Psi ϩ ] Of Saccharomyces Cerevisiaementioning

confidence: 99%

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Amyloid of the prion domain of Sup35p has an in-register parallel β-sheet structure

Shewmaker¹,

Wickner²,

Tycko

2006

Proc. Natl. Acad. Sci. U.S.A.

272

302

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The [PSI ؉ ] prion of Saccharomyces cerevisiae is a self-propagating amyloid form of Sup35p, a subunit of the translation termination factor. Using solid-state NMR we have examined the structure of amyloid fibrils formed in vitro from purified recombinant Sup35 1-253 , consisting of the glutamine-and asparagine-rich Nterminal 123-residue prion domain (N) and the adjacent 130-residue highly charged M domain. Measurements of magnetic dipole-dipole couplings among 13 C nuclei in a series of Sup35NM fibril samples, 13 C-labeled at backbone carbonyl sites of Tyr, Leu, or Phe residues or at side-chain methyl sites of Ala residues, indicate intermolecular 13 C-13 C distances of Ϸ0.5 nm for nearly all sites in the N domain. Certain sites in the M domain also exhibit intermolecular distances of Ϸ0.5 nm. These results indicate that an in-register parallel ␤-sheet structure underlies the [PSI ؉ ] prion phenomenon. The Sup35p prion domain (Sup35N, residues 1-123) is asparagine-and glutamine-rich, is poor in charged residues, and has five imperfect nine-residue repeats with consensus YQQYN-PQGG. Sequence shuffling shows that the repeats are not necessary for prion generation or propagation and that amino acid content of the prion domain (not the sequence) determines whether a protein can form a prion (13). Certain point mutations in the prion domain can block propagation of [PSI ϩ ] introduced with the wild sequence (14, 15), although the mutant sequence may itself form a prion (16). Thus, propagation of an existing prion is very sequence-specific, as in the species barriers of mammalian prion diseases (reviewed in ref. 17).Amyloid fibrils are filamentous protein aggregates exhibiting ''cross-␤'' x-ray fiber diffraction patterns, indicating the presence of ␤-sheets formed by ␤-strands that are oriented approximately perpendicular to the fiber axis, with interstrand hydrogen bonds approximately parallel to the fiber axis (reviewed in ref. 18). The fact that the prion domains of Ure2p (another yeast prion protein with an N-terminal prion domain rich in asparagine and glutamine) and Sup35p can be shuffled and yet still form prions and amyloid (13,19) suggests that the amyloid on which these prions are based has an in-register parallel ␤-sheet structure (20, 21). A prion amyloid structure based on antiparallel ␤-sheets or ␤-helices would necessarily be stabilized by interactions among specific sets of unlike residues. These interactions would likely be destroyed by shuffling the sequence. In contrast, an in-register parallel ␤-sheet structure can be stabilized by intermolecular hydrophobic interactions (22,23) or polar side chain interactions [e.g., the ''polar zipper'' interactions suggested by Perutz et al. (24)] among like residues. Shuffling the sequence would still allow like residues to align and interact in such a structure. Thus, shuffleability of a prion domain suggests an in-register parallel ␤-sheet structure.The molecular structures of amyloid fibrils, particularly those formed by bona fide proteins, are difficult t...

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Section: Discussionmentioning

confidence: 99%

Section: T He Nonchromosomal Gene [Psi ϩ ] Of Saccharomyces Cerevisiaementioning

confidence: 99%

Amyloid of the prion domain of Sup35p has an in-register parallel β-sheet structure

Shewmaker¹,

Wickner²,

Tycko

2006

Proc. Natl. Acad. Sci. U.S.A.

272

302

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“…Sup35NM-Because fusion of several proteins to the C terminus of Sup35NM does not significantly impair its ability to form fibers (5,8,22,23), we introduced fluorescent dyes at the C-terminal cysteine of Sup35NM. Fiber formation was started by diluting the labeled Sup35NM in 8 M guanidine HCl into buffer.…”

Section: Polarity Of Fiber Growth Tested With Red and Green-mentioning

confidence: 99%

Strong Growth Polarity of Yeast Prion Fiber Revealed by Single Fiber Imaging

Inoue¹,

Kishimoto²,

Hirao

et al. 2001

Journal of Biological Chemistry

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Using the yeast prion as a model, we have developed a novel system to observe the growth of individual prion fibers directly. NM fragments, the prion-determining region of the yeast protein Sup35p, were labeled by either red or green fluorescent dyes, and the fiber growth was observed under a fluorescence microscope. When greenSup35NM was added to the preformed fibers made of red-Sup35NM, 70 -97% of green fibers grew unidirectionally, from only one end of individual red fibers, whereas the remainder grew from both ends. Similarly, the majority of red fibers grew from only one end of green fibers when the order of addition was reversed. Sonication of preformed fibers to expose fresh ends did not change the results, excluding a possibility of occasional deformation of one end as the reason of the apparent unidirectional growth. These results indicate the polarity of Sup35 prion fibers and impose constraints on the models of fiber growth.

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“…Mutations within this region have profound effects on the efficiency of prion propagation in vivo, ranging from phenotypic masking of the prion state, as we have observed for NatA mutants, to curing (Young and Cox, 1971;DePace et al, 1998;King, 2001). The substrate specificities of the N ␣ -acetyltransferases are determined in large part by the second amino acid of target proteins (Polevoda et al, 1999), with proteins containing penultimate residues with a small radius of gy- ration such as Ser, Gly, Thr, and Ala generally targeted for modification by NatA after removal of the initiator methionine.…”

Section: Nata Does Not Alter the Prion Phenotype By Modifying Known Rmentioning

confidence: 77%

The NatA Acetyltransferase Couples Sup35 Prion Complexes to the [PSI⁺] Phenotype

Pezza

Langseth

Yamamoto

et al. 2009

MBoC

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Protein-only (prion) epigenetic elements confer unique phenotypes by adopting alternate conformations that specify new traits. Given the conformational flexibility of prion proteins, protein-only inheritance requires efficient self-replication of the underlying conformation. To explore the cellular regulation of conformational self-replication and its phenotypic effects, we analyzed genetic interactions between [PSI ؉ ], a prion form of the S. cerevisiae Sup35 protein (Sup35 [PSI ؉ ] ), and the three N ␣ -acetyltransferases, NatA, NatB, and NatC, which collectively modify ϳ50% of yeast proteins. Although prion propagation proceeds normally in the absence of NatB or NatC, the [PSI ؉ ] phenotype is reversed in strains lacking NatA. Despite this change in phenotype, [PSI ؉ ] NatA mutants continue to propagate heritable Sup35 [PSI ؉ ] . This uncoupling of protein state and phenotype does not arise through a decrease in the number or activity of prion templates (propagons) or through an increase in soluble Sup35. Rather, NatA null strains are specifically impaired in establishing the translation termination defect that normally accompanies Sup35 incorporation into prion complexes. The NatA effect cannot be explained by the modification of known components of the [PSI ؉ ] prion cycle including Sup35; thus, novel acetylated cellular factors must act to establish and maintain the tight link between Sup35 [PSI ؉ ] complexes and their phenotypic effects. INTRODUCTIONThe transmission of phenotypes from one individual to another is a fundamental process in biology. Much of our understanding of these events arises from decades of study on nucleic acid metabolism, but new traits may also be passed between individuals without changes in nucleic acid content through a number of epigenetic mechanisms. One particularly intriguing example of such a process is the prion phenomenon, in which the activity of a protein is altered in a heritable way to transmit a new phenotype. How is such a feat accomplished? In 1967, Griffith proposed that some proteins, now known as prions (Prusiner, 1982), can adopt more than one stable form in vivo (Griffith, 1967). Since a protein's structure determines its function, two cells containing the same protein but in diffrent physical states will have distinct phenotypes. This protein-based process has been linked to a number of previously inexplicable events, including the development and spread of the transmissible spongiform encephalopathies in mammals (Prusiner, 1982) and the non-Mendelian inheritance of some traits in fungi (Wickner, 1994).Protein-based traits can only become transmissible, however, if the inherent structural flexibility of prion proteins can be constrained by regulatory mechanisms to create an epigenetic element. For example, if each newly synthesized prion polypeptide chain independently folded to a unique form, all cells would display the same phenotype, which would reflect the average of the accessible states. The appearance of distinct protein-based phenotypes suggests that ...

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Supporting the structural basis of prion strains: induction and identification of [PSI] variants11Edited by F. E. Cohen

Cited by 111 publications

References 39 publications

Amyloid of the prion domain of Sup35p has an in-register parallel β-sheet structure

Amyloid of the prion domain of Sup35p has an in-register parallel β-sheet structure

Strong Growth Polarity of Yeast Prion Fiber Revealed by Single Fiber Imaging

The NatA Acetyltransferase Couples Sup35 Prion Complexes to the [PSI⁺] Phenotype

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Supporting the structural basis of prion strains: induction and identification of [PSI] variants11Edited by F. E. Cohen

Cited by 111 publications

References 39 publications

Amyloid of the prion domain of Sup35p has an in-register parallel β-sheet structure

Amyloid of the prion domain of Sup35p has an in-register parallel β-sheet structure

Strong Growth Polarity of Yeast Prion Fiber Revealed by Single Fiber Imaging

The NatA Acetyltransferase Couples Sup35 Prion Complexes to the [PSI+] Phenotype

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The NatA Acetyltransferase Couples Sup35 Prion Complexes to the [PSI⁺] Phenotype