title: Cell division is essential for elimination of the yeast [PSI+] prion by guanidine hydrochloride.
abstract: Guanidine hydrochloride (Gdn.HCl) blocks the propagation of yeast prions by inhibiting Hsp104, a molecular chaperone that is absolutely required for yeast prion propagation. We had previously proposed that ongoing cell division is required for Gdn.HCl-induced loss of the [PSI+] prion. Subsequently, Wu et al.[Wu Y, Greene LE, Masison DC, Eisenberg E (2005) Proc Natl Acad Sci USA 102:12789-12794] claimed to show that Gdn.HCl can eliminate the [PSI+] prion from alpha-factor-arrested cells leading them to propose that in Gdn.HCl-treated cells the prion aggregates are degraded by an Hsp104-independent mechanism. Here we demonstrate that the results of Wu et al. can be explained by an unusually high rate of alpha-factor-induced cell death in the [PSI+] strain (780-1D) used in their studies. What appeared to be no growth in their experiments was actually no increase in total cell number in a dividing culture through a counterbalancing level of cell death. Using media-exchange experiments, we provide further support for our original proposal that elimination of the [PSI+] prion by Gdn.HCl requires ongoing cell division and that prions are not destroyed during or after the evident curing phase.
authors.affiliation: Protein Science Group, Department of Biosciences, University of Kent, Canterbury CT2 7NJ, United Kingdom.
authors.forename: Lee J
authors.initials: LJ
authors.lastname: Byrne
authors.forename: Brian S
authors.initials: BS
authors.lastname: Cox
authors.forename: Diana J
authors.initials: DJ
authors.lastname: Cole
authors.forename: Martin S
authors.initials: MS
authors.lastname: Ridout
authors.forename: Byron J T
authors.initials: BJ
authors.lastname: Morgan
authors.forename: Mick F
authors.initials: MF
authors.lastname: Tuite
mesh_terms: D002455:Cell Division / Q000502:physiology*; D019791:Guanidine / Q000494:pharmacology*; D000072235:Mating Factor; D008954:Models, Biological; D010455:Peptides / Q000502:physiology; D011328:Prions / Q000187:drug effects*; D012441:Saccharomyces cerevisiae / Q000166:cytology* / Q000187:drug effects* / Q000502:physiology
chemical_list: D010455:Peptides; D011328:Prions; D000072235:Mating Factor; D019791:Guanidine