Functional Analysis of RNA Exosome Mutants Linked to Disease Using a Saccharomyces cerevisiae Model System

The RNA exosome complex is a key component of RNA processing and quality control that both degrades and processes many classes of RNA. This complex is highly conserved among eukaryotes and was first identified and studied in budding yeast ( S. cerevisiae ). Mutations in the human EXOSC2 gene, which encodes a cap subunit of the RNA exosome, have been linked to a novel syndrome characterized by retinitis pigmentosa, progressive hearing loss, premature aging, short stature, mild intellectual disability and distinctive gestalt. While the amino acid substitutions in EXOSC2 that cause this syndrome are known, how these amino acid changes impact RNA exosome function is not. The goal of my project is to analyze the functional consequences of retinitis pigmentosa‐linked amino acid substitutions modeled in the budding yeast ortholog of EXOSC2, Rrp4. The two variants I have analyzed, rrp4‐G58V and rrp4‐G226D , correspond to patient mutations G30V and G198D, respectively. I first assessed growth of the mutant strains compared to wildtype yeast cells, which revealed that rrp4‐G226D mutant cells exhibit a growth defect at 37°C, whereas the rrp4‐G58V mutant cells grow normally. To assess whether these amino acid substitutions affect Rrp4 protein levels, I used immunoblotting. Results of this analysis reveal that the rrp4‐G58V and rrp4‐G226D proteins are expressed, but at somewhat reduced level compared to wildtype Rrp4. In the future, I will continue characterization of the mutants by using biochemical approaches to study the assembly of the RNA exosome complex and genetic analysis of rrp4 mutant interactions with RNA exosome cofactors. Support or Funding Information EMORY INITIATIVE TO MAXIMIZE STUDENT DEVELOPMENT Emory Initiative to Maximize Student Development: R25 GM125598 Neurodevelopmental Role of an RNA Binding Protein Required for Cognitive Function: R01 MH107305 This abstract is from the Experimental Biology 2019 Meeting. There is no full text article associated with this abstract published in The FASEB Journal .