title: Amino acid residue 184 of yeast Hsp104 chaperone is critical for prion-curing by guanidine, prion propagation, and thermotolerance.
abstract: Inactivation of Hsp104 by guanidine is contended to be the mechanism by which guanidine cures yeast prions. We now find an Hsp104 mutation (D184N) that confers resistance to guanidine-curing of the yeast [PSI(+)] prion. In an independent screen we isolated an HSP104 allele altered in the same residue (D184Y) that dramatically impairs [PSI(+)] propagation in a temperature-dependent manner. Directed mutagenesis of HSP104 produced additional alleles that conferred varying degrees of resistance to guanidine-curing or impaired [PSI(+)] propagation. The mutations similarly affected propagation of the [URE3] prion. Basal and induced abundance of all mutant proteins was normal. Thermotolerance of cells expressing mutant proteins was variably resistant to guanidine, and the degree of thermotolerance did not correlate with [PSI(+)] stability. We thus show that guanidine cures yeast prions by inactivating Hsp104 and identify a highly conserved Hsp104 residue that is critical for yeast prion propagation. Our data suggest that Hsp104 activity can be reduced substantially without affecting [PSI(+)] stability, and that Hsp104 interacts differently with prion aggregates than with aggregates of thermally denatured protein.
authors.affiliation: Laboratory of Biochemistry and Genetics, National Institute of Diabetes, Digestive, and Kidney Diseases, National Institutes of Health, Building 8, Room 407, Bethesda, MD 20892-0851, USA.
authors.forename: Giman
authors.initials: G
authors.lastname: Jung
authors.forename: Gary
authors.initials: G
authors.lastname: Jones
authors.forename: Daniel C
authors.initials: DC
authors.lastname: Masison
mesh_terms: D000251:Adenosine Triphosphatases / Q000737:chemistry / Q000235:genetics*; D000595:Amino Acid Sequence; D019943:Amino Acid Substitution; D019791:Guanidine / Q000494:pharmacology*; D006360:Heat-Shock Proteins / Q000737:chemistry / Q000235:genetics*; D016297:Mutagenesis, Site-Directed; D010957:Plasmids; D011328:Prions / Q000187:drug effects / Q000502:physiology*; D012441:Saccharomyces cerevisiae / Q000235:genetics*; D029701:Saccharomyces cerevisiae Proteins / Q000737:chemistry / Q000235:genetics*; D013696:Temperature
chemical_list: D006360:Heat-Shock Proteins; D011328:Prions; D029701:Saccharomyces cerevisiae Proteins; C070972:HsP104 protein, S cerevisiae; D000251:Adenosine Triphosphatases; D019791:Guanidine