MCB
Home Help [Feedback] [For Subscribers] [Archive] [Search] [Contents]
This Article
Right arrow Full Text
Right arrow Full Text (PDF)
Right arrow Alert me when this article is cited
Right arrow Alert me if a correction is posted
Services
Right arrow Similar articles in this journal
Right arrow Similar articles in PubMed
Right arrow Alert me to new issues of the journal
Right arrow Download to citation manager
Right arrowReprints and Permissions
Right arrow Copyright Information
Right arrow Books from ASM Press
Right arrow MicrobeWorld
Citing Articles
Right arrow Citing Articles via HighWire
Right arrow Citing Articles via Google Scholar
Google Scholar
Right arrow Articles by Ness, F.
Right arrow Articles by Tuite, M. F.
Right arrow Search for Related Content
PubMed
Right arrow PubMed Citation
Right arrow Articles by Ness, F.
Right arrow Articles by Tuite, M. F.

 Previous Article  |  Next Article 

Molecular and Cellular Biology, August 2002, p. 5593-5605, Vol. 22, No. 15
0270-7306/02/$04.00+0     DOI: 10.1128/MCB.22.15.5593-5605.2002
Copyright © 2002, American Society for Microbiology. All Rights Reserved.

Guanidine Hydrochloride Inhibits the Generation of Prion "Seeds" but Not Prion Protein Aggregation in Yeast

Frédérique Ness, Paulo Ferreira, Brian S. Cox, and Mick F. Tuite*

Department of Biosciences, University of Kent, Canterbury, Kent CT2 7NJ, United Kingdom

Received 12 December 2001/ Returned for modification 6 February 2002/ Accepted 25 April 2002

[PSI+] strains of the yeast Saccharomyces cerevisiae replicate and transmit the prion form of the Sup35p protein but can be permanently cured of this property when grown in millimolar concentrations of guanidine hydrochloride (GdnHCl). GdnHCl treatment leads to the inhibition of the replication of the [PSI+] seeds necessary for continued [PSI+] propagation. Here we demonstrate that the rate of incorporation of newly synthesized Sup35p into the high-molecular-weight aggregates, diagnostic of [PSI+] strains, is proportional to the number of seeds in the cell, with seed number declining (and the levels of soluble Sup35p increasing) in the presence of GdnHCl. GdnHCl does not cause breakdown of preexisting Sup35p aggregates in [PSI+] cells. Transfer of GdnHCl-treated cells to GdnHCl-free medium reverses GdnHCl inhibition of [PSI+] seed replication and allows new prion seeds to be generated exponentially in the absence of ongoing protein synthesis. Following such release the [PSI+] seed numbers double every 20 to 22 min. Recent evidence (P. C. Ferreira, F. Ness, S. R. Edwards, B. S. Cox, and M. F. Tuite, Mol. Microbiol. 40:1357-1369, 2001; G. Jung and D. C. Masison, Curr. Microbiol. 43:7-10, 2001), together with data presented here, suggests that curing yeast prions by GdnHCl is a consequence of GdnHCl inhibition of the activity of molecular chaperone Hsp104, which in turn is essential for [PSI+] propagation. The kinetics of elimination of [PSI+] by coexpression of a dominant, ATPase-negative allele of HSP104 were similar to those observed for GdnHCl-induced elimination. Based on these and other data, we propose a two-cycle model for "prionization" of Sup35p in [PSI+] cells: cycle A is the GdnHCl-sensitive (Hsp104-dependent) replication of the prion seeds, while cycle B is a GdnHCl-insensitive (Hsp104-independent) process that converts these seeds to pelletable aggregates.


* Corresponding author. Mailing address: Department of Biosciences, University of Kent, Canterbury, Kent CT2 7NJ, United Kingdom. Phone: (44)(0) 1227 823699. Fax: (44)(0) 1227 763912. E-mail: M.F.Tuite{at}ukc.ac.uk.


Molecular and Cellular Biology, August 2002, p. 5593-5605, Vol. 22, No. 15
0022-538X/02/$04.00+0     DOI: 10.1128/MCB.22.15.5593-5605.2002
Copyright © 2002, American Society for Microbiology. All Rights Reserved.




This article has been cited by other articles:




Home Help [Feedback] [For Subscribers] [Archive] [Search] [Contents]
J. Bacteriol. J. Virol. Eukaryot. Cell
Microbiol. Mol. Biol. Rev. Clin. Vaccine Immunol. All ASM Journals

Copyright © 2002 by the American Society for Microbiology. All rights reserved.