Submitted to: Proceedings of the National Academy of Sciences
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 6/20/2005
Publication Date: 7/20/2005
Citation: Nakayashiki, T., Kurtzman, C.P., Edskes, H.K., Wickner, R.B. 2005. Evidence that the yeast prions [URE3] and [PSI+] are diseases. Proceedings of the National Academy of Sciences. 102(30):10575-10580. Interpretive Summary: The yeast Saccharomyces was used as a model system to determine if prion-like genetic particles are maintained in yeast cells from generation to generation or whether they are lethal. Three types of prions were examined. The prion [PIN+] is maintained in isolates from various worldwide locations, but prions [URE3] and [PSI+] were absent from worldwide collections, indicating that they are lethal to the yeasts that carry them. This appears to be the first report of prions causing a disease in microorganisms, and the results may be useful in understanding prion infections in higher organisms.
Technical Abstract: Viruses, plasmids and prions can spread in nature in spite of being a burden to their hosts. Because a prion arises de novo in >1 in 10(to the 6th degree) cells and spreads to all offspring in meiosis, its absence in wild strains would imply it has a net deleterious effect on its host. Among 70 wild Saccharomyces strains, we found the [PIN+] prion in 11 strains, but the [URE3] and [PSI+] prions were uniformly absent. In contrast, the ‘selfish’ 2u'DNA was in 38 wild strains and the ‘selfish’ RNA replicons L BC, 20S and 23S were found in 8, 14 and 1 strains, respectively. The absence of [URE3] and [PSI+] in wild strains indicates that each has a net deleterious effect on its host.