Recent advances suggest that self-replication of protein physical states directs both the development and spread of the Transmissible Spongiform Encephalopathies and the inheritance of some phenotypic traits in lower eukaryotes. This novel biological process, known as the prion hypothesis, predicts that a uniquegroup of proteins has the capacity to adopt multiple conformational states with distinct physiological consequences in vivo. Since one-fold-one-function proteins are unableto act in roles that have historically been linked to nucleic acids such as infectivity and inheritance, understandinghow a prion protein's structure can be constrained to allow the faithful propagation of associated phenotypes but remain sufficiently flexible to allow occasional transitions in state is crucial to understanding the physiological consequences of the protein- only hypothesis. The prion cycles of lower eukaryotesprovide experimentally tractable model systems for studyingprion cycle regulation in vivo. For example, the Sup35 protein of S. cerevisiae is a component of the translation termination complex whose function is reversibly modulatedby a prion cycle. In the non-prion state, Sup35 facilitates efficient termination ( pst] phenotype), but in the prion form, Sup35's activity is compromised leading to stop codon read-through ([PSI+] phenotype). While the [PSI+] and [pst] phenotypes are largely stable, they spontaneous interconvert (~1 cell/million) and can be induced to quantitatively switch by chemical and molecular stimuli. Using this system, we will begin to elucidate the molecular mechanism underlyingthe near-faithful propagation of prion forms in vivo by focusing on two contributingfactors: the interplay of distinct forms when present in the same cell and the trans regulators of efficient prion conversion. Toward this end, we will 1) determine the molecular basis of prion variant dominance in vivo,2) elucidate the molecular mechanisms by which knownregulators of the Sup35/[PS/+] prion cycle modulatepropagation and phenotypic transitions, and 3) screen for and characterize novel prion regulators. Together, these lines of investigation will build a framework for understandingprotein-only phenotypic propagation in terms of prion protein biogenesis. A strong foundation of previous work indicates that the knowledge gleaned from prion studies in lower eukaryotes is clearly and directly applicable to our understandingof prion mechanisms and their physiological consequences in mammals.

Agency
National Institute of Health (NIH)
Institute
National Institute of General Medical Sciences (NIGMS)
Type
Research Project (R01)
Project #
5R01GM069802-05
Application #
7763235
Study Section
Membrane Biology and Protein Processing (MBPP)
Program Officer
Maas, Stefan
Project Start
2006-02-01
Project End
2011-08-31
Budget Start
2010-02-01
Budget End
2011-08-31
Support Year
5
Fiscal Year
2010
Total Cost
$281,256
Indirect Cost
Name
Brown University
Department
Biochemistry
Type
Schools of Medicine
DUNS #
001785542
City
Providence
State
RI
Country
United States
Zip Code
02912
Holmes, William M; Klaips, Courtney L; Serio, Tricia R (2014) Defining the limits: Protein aggregation and toxicity in vivo. Crit Rev Biochem Mol Biol 49:294-303
Pezza, John A; Villali, Janice; Sindi, Suzanne S et al. (2014) Amyloid-associated activity contributes to the severity and toxicity of a prion phenotype. Nat Commun 5:4384
Holmes, William M; Mannakee, Brian K; Gutenkunst, Ryan N et al. (2014) Loss of amino-terminal acetylation suppresses a prion phenotype by modulating global protein folding. Nat Commun 5:4383
DiSalvo, Susanne; Serio, Tricia R (2011) Insights into prion biology: integrating a protein misfolding pathway with its cellular environment. Prion 5:76-83
DiSalvo, Susanne; Derdowski, Aaron; Pezza, John A et al. (2011) Dominant prion mutants induce curing through pathways that promote chaperone-mediated disaggregation. Nat Struct Mol Biol 18:486-92
Derdowski, Aaron; Sindi, Suzanne S; Klaips, Courtney L et al. (2010) A size threshold limits prion transmission and establishes phenotypic diversity. Science 330:680-3
Tuite, Mick F; Serio, Tricia R (2010) The prion hypothesis: from biological anomaly to basic regulatory mechanism. Nat Rev Mol Cell Biol 11:823-33
Pezza, John A; Langseth, Sara X; Raupp Yamamoto, Rochele et al. (2009) The NatA acetyltransferase couples Sup35 prion complexes to the [PSI+] phenotype. Mol Biol Cell 20:1068-80
Sindi, Suzanne S; Serio, Tricia R (2009) Prion dynamics and the quest for the genetic determinant in protein-only inheritance. Curr Opin Microbiol 12:623-30
Satpute-Krishnan, Prasanna; Langseth, Sara X; Serio, Tricia R (2007) Hsp104-dependent remodeling of prion complexes mediates protein-only inheritance. PLoS Biol 5:e24

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