Poster abstracts
Poster number 34 submitted by Amelia Cochran
Investigation of Pus4 Substrate Selection
Amelia Cochran (Chemistry, University of Michigan), Jacqueline Anthenien (Chemistry, University of Michigan), Kristin Koutmou (Chemistry, University of Michigan), Markos Koutmos (Chemistry, University of Michigan)
Abstract:
Pseudouridine synthase (Pus) enzymes catalyze the isomerization of uridine (U) to pseudouridine (Ψ), a common modification known to impact RNA stability and structure. Originally characterized as modifiers of non-coding RNAs, some Pus enzymes are now also known to target mRNA. Because Ψ has been shown to impact mRNA processing, translation, and stability, these mRNA-modifying Pus enzymes may participate in regulation of gene expression. But how and why specific mRNA targets are selected is not yet fully understood. Pus4, which modifies U55 in the T-loop of most tRNAs, is one of the major mRNA-modifying Pus enzymes. Though it has been proposed that Pus4 only modifies mRNAs with similarities to its native tRNA targets, recent studies suggest that Pus4 can bind to and modify RNAs that differ from these native substrates. To fully understand how RNA features impact Pus4 substrate selection, we are working to characterize Pus4’s ability to bind to and modify RNAs of different sequences and structures in vitro. Additionally, we aim to understand how Pus4’s structural features contribute to its substrate selection, and how structural differences between prokaryotic and eukaryotic Pus4 homologs influence apparent differences in specificity. Our initial findings show a lack of selectivity in RNA binding in eukaryotic Pus4, pointing to the possibility of enzyme promiscuity and reliance on factors outside of protein-RNA interaction for mRNA target selection.
Keywords: Pseudouridine, RNA modifications , RNA binding proteins