A Novel Connection Between [PSI + ] Prion Formation and RNA Splicing in Saccharomyces cerevisiae

• Published in: The FASEB journal Vol. 36 Suppl 1
• Main Authors: Jones, Elizabeth A, Riccitelli, Audrey N, Cameron, Dale M, Kress, Tracy L
• Format: Journal Article
• Language: English
• Published: United States 01.05.2022
• ISSN: 1530-6860
• DOI: 10.1096/fasebj.2022.36.S1.R4569

Relatively new studies on prions in Saccharomyces cerevisiae show that some protein prion conformations may be beneficial to cell survival in response to environmental stress. Sup35, a translation termination release factor, forms the prion [PSI ]. When [PSI ] forms, translation termination efficiency decreases, which has been shown to result in the alteration of the abundance of cellular proteins, including splicing factor abundance. Therefore, we are testing the hypothesis that [PSI ] prion formation alters splicing efficiency in yeast. First, we employed quantitative RT-PCR and revealed that splicing efficiency improves upon [PSI ] prion formation. The proposed mechanisms for the effect of [PSI ] on protein abundance include nonsense suppression and non-stop decay. Non-stop decay would lead to degradation of the mRNA encoding a splicing protein and therefore would reduce splicing factor protein levels. Non-sense suppression, a result of translation readthrough, generates a C-terminally extended protein, which could alter the function of splicing factors, or alter protein levels. We are initiating RT-PCR and Western Blot analyses to test the contribution of the two mechanisms on splicing factor abundance. To further test the relationship between RNA splicing and [PSI ] prion formation, we used knockout PCR to create splicing factor deletion mutations in a [psi ] strain, as well as a weak [PSI ] strain or a strong [PSI ] strain. We found that the [PSI ] conformation can suppress the growth defect in a yeast strain with a deletion of the gene encoding SNU66, a component of the tri-snRNP. Similarly, the [PSI ] conformation can suppress the growth defect in a yeast strain with a deletion of the MUD2gene, which encodes a gene important for commitment complex formation. In addition, we found that [PSI ] can rescue the splicing defect observed in a mud2Δstrain, consistent with the suppressive growth phenotype. Together, the results show that [PSI ] formation impacts RNA splicing in S. cerevisiae and our future work will focus on determining the mechanisms that underlie this effect.