Arthi Chandran, Samuel Kadavakollu, Shawn White, Kiran K Andra,Naveen M Singh, Rahul Vemula
Background: Translational errors can give rise to an accumulation of unfolded proteins leading to the activation of the unfolded protein response. Among the various mechanisms that exist to reduce these errors, uracil modifications, specifically 5-methoxycarbonylmethyluridine (mcm5U), 5-methoxycarbonylmethyl-2- thiouridine (mcm5s2U) and 5-carbamoylmethyluridine (ncm5U), in tRNA increase fidelity by improving binding to A-ending codons in mixed codon boxes. Dph3 is a protein involved in diphthamide synthesis, but also plays a role with the elongator complex. Results: Activation of ER-stress response was observed through the presence of increased splicing of HAC1 mRNA in dph3 mutants Cell viability was decreased in mutants stressed by paromomycin as demonstrated using cytotoxic assays. Dph3 mutants were partially rescued from cell stress by the complementation of DPH3. lacZ reporter assays showed an increased unfolded protein response in mutants lacking Dph3 under both basal and stressed conditions. Conclusion: This experiment revealed the critical role of Dph3 in normal cell?s ability to produce proteins accurately especially when under external stressors. The results showed that the DPH3 gene in Saccharomyces cerevisiae was involved in the prevention of translational errors and the presence of Dph3 lowered ERstress response factors.
