Increased [PSI+] Appearance by Fusion of Rnq1 with the Prion Domain of Sup35 in Saccharomyces cerevisiae

Department of Biological Sciences, Laboratory of Macromolecular Interactions, and Institute of Microbiology, Seoul National University, Seoul 151-742, Korea.
Eukaryotic Cell (Impact Factor: 3.18). 06/2009; 8(7):968-76. DOI: 10.1128/EC.00353-08
Source: PubMed


During propagation, yeast prions show a strict sequence preference that confers the specificity of prion assembly. Although
propagations of [PSI+] and [RNQ+] are independent of each other, the appearance of [PSI+] is facilitated by the presence of [RNQ+]. To explain the [RNQ+] effect on the appearance of [PSI+], the cross-seeding model was suggested, in which Rnq1 aggregates act as imperfect templates for Sup35 aggregation. If cross-seeding
events take place in the cytoplasm of yeast cells, the collision frequency between Rnq1 aggregates and Sup35 will affect the
appearance of [PSI+]. In this study, to address whether cross-seeding occurs in vivo, a new [PSI+] induction method was developed that exploits a protein fusion between the prion domain of Sup35 (NM) and Rnq1. This fusion
protein successfully joins preexisting Rnq1 aggregates, which should result in the localization of NM around the Rnq1 aggregates
and hence in an increased collision frequency between NM and Rnq1 aggregates. The appearance of [PSI+] could be induced very efficiently, even with a low expression level of the fusion protein. This study supports the occurrence
of in vivo cross-seeding between Sup35 and Rnq1 and provides a new tool that can be used to dissect the mechanism of the de
novo appearance of prions.

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Available from: Yeong-Jae Seok, Jul 25, 2014
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    • "Under normal cellular conditions, efficient formation, but not maintenance, of [PSI 1 ] requires the presence of [PIN tively substitute for [PIN 1 ], allowing [PSI 1 ] formation in cells lacking [PIN 1 ] (Derkatch et al. 2001; Osherovich and Weissman 2001). In vitro and in vivo evidence suggest that the ability of [PIN 1 ] to facilitate [PSI 1 ] formation is the result of a direct interaction between Rnq1p aggregates and Sup35p (Derkatch et al. 2004; Bardill and True 2009; Choe et al. 2009). [PIN 1 ] also increases the frequency of [URE3] formation, while [PSI 1 ] inhibits [URE3] formation (Bradley et al. 2002; Schwimmer and Masison 2002). "
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