Poster abstracts

Poster number 98 submitted by Jeremy Monroe

Translation is altered by the presence of N1-methylpseudouridine and 7-methylguanosine in mRNA coding regions

Jeremy Monroe (Department of Chemistry, University of Michigan), Kristin S. Koutmou (Department of Chemistry, University of Michigan)

Abstract:
Translation is altered by the presence of N1-methylpseudouridine and 7-methylguanosine in mRNA coding regions
Jeremy Monroe and Kristin S. Koutmou
Department of Chemistry, University of Michigan, 930 N University, Ann Arbor, MI 48109

Chemical modifications to mRNAs have the potential to impact every step in the life cycle of an mRNA after transcription to modulate protein expression. Initial in vitro studies of varying resolution by ourselves and others on a limited set of mRNA modifications indicate that they can alter the overall rate and fidelity of protein synthesis. However, there is still not a broad molecular level picture of how modifications change ribosome decoding. Establishing this basic knowledge will be vital as we work to discern the biological consequences of mRNA modifications. We are working fill this key gap in understanding by systematically varying the chemical moieties on mRNA nucleobases to directly establish the contributions of individual nucleobase positions and functional groups to mRNA decoding. Towards this goal, we have tested how two unique modifications, N1-methyl-pseudouridine (m1Ψ) and N-7-methylguanosine (m7G), impact protein synthesis in a fully-reconstituted in vitro E. coli translation system. These modifications were chosen for study because of their recent discovery (m7G) in eukaryotic mRNAs coding regions, and their incorporation into mRNA-based drugs (m1Ψ). Our early work reveals that m1Ψ slows amino acid addition when inserted into the first position of a phenylalanine (Phe) codon (m1Ψ UU), and promotes the incorporation of non-cognate isoleucine and leucine amino acids on a Phe codon. In contrast, m7G modification impedes translation termination by releaser factor 2. These findings provide further evidence that mRNA modification has consequences for translation, and suggest that individual modifications are likely to have discrete effects on the mechanism of protein synthesis.

Keywords: translation, mRNA modifications