Role of the Chaperone Protein Hsp104 in Propagation of the Yeast Prion-Like Factor [ <i>psi</i> ⁺ ]

The yeast non-Mendelian factor [ psi + ] has been suggested to be a self-modified protein analogous to mammalian prions. Here it is reported that an intermediate amount of the chaperone protein Hsp104 was required for the propagation of the [ psi + ] factor. Overproduction or inactivation of Hsp104 caused the loss of [ psi + ]. These results suggest that chaperone proteins play a role in prion-like phenomena, and that a certain level of chaperone expression can cure cells of prions without affecting viability. This may lead to antiprion treatments that involve the alteration of chaperone amounts or activity.