ABSTRACT
Introduction Originally, the term prion was coined to stress the “protein only” nature of an infectious
agent causing transmissible spongiform encephalopathies in mammals.1 All variations of this disease in humans and animals were linked to abnormal self-propagating conformations of just one cellular protein, PrP. The intriguing but controversial idea that a protein conformation could be infectious gained considerable support in 1994 when Reed Wickner showed that the prion model could explain the inheritance and behavior of the yeast [URE3] cytoplasmic fac tor and postulated that another yeast cytoplasmic factor, [PSP], was also a prion.2 Soon, the discovery that the prion form of [Het-s] has a defined cellular activity in the fungus Podospora anserina,, indicated that prions could have functional roles,3,4 whereas the determination that the Hspl04 chaperone is required for the propagation of all known yeast prions showed that cellular machinery has a role in prion replication.5'8 Now the protein only nature of these fungal cytoplasmic determinants has been definitively proven by demonstrating the infectivity of prion-like particles made in vitro from respective recombinant proteins.9'12
The list of prions and the number of prion-carrying species has expanded, but Saccharomy ces cerevisiae is the only species in which several prions have been identified: [PST], [URE3] and [P/AT] (also known as [RN(£]). This makes yeast uniquely suited to study interactions
Corresponding Author: Irina L. Derkatch-Department of Microbiology, New York University School of Medicine, NYU Medical Center, 530 First Avenue, New York, New York 10016, U.S.A. Email: irina.derkatch@med.nyu.edu
Protein-Based Inheritance, edited by Yury O. Chernoff. ©2007 Landes Bioscience.
