The yeast Sup35 protein is a subunit of the translation termination factor, and its conversion to the [PSI ⁺] prion state leads to more translational read-through. Although extensive studies have been done on [PSI ⁺], changes at the proteomic level have not been performed exhaustively. We therefore used a SILAC-based quantitative mass spectrometry approach and identified 4187 proteins from both [psi ^-] and [PSI ⁺] strains. Surprisingly, there was very little difference between the two proteomes under standard growth conditions. We found however that several [PSI ⁺] strains harbored an additional chromosome, such as chromosome I. Albeit, we found no evidence to support that [PSI ⁺] induces chromosomal instability (CIN). Instead we hypothesized that the selective pressure applied during the establishment of [PSI ⁺]-containing strains could lead to a supernumerary chromosome due to the presence of the ade1-14 selective marker for translational read-through. We therefore verified that there was no prevalence of disomy among newly generated [PSI ⁺] strains in absence of strong selection pressure. We also noticed that low amounts of adenine in media could lead to higher levels of mitochondrial DNA in [PSI ⁺] in ade1-14 cells. Our study has important significance for the establishment and manipulation of yeast strains with the Sup35 prion.

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Journal Article | Research Support, N.I.H., Extramural | Research Support, Non-U.S. Gov't

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Chan PHW, Lee L, Kim E, Hui T, Stoynov N, Nassar R, Moksa M, Cameron DM, Hirst M, Gsponer J, ... Show all

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