Poster abstracts
Poster number 50 submitted by Rachel Giles
Guanosine mRNA modifications impact translation speed
Rachel Giles (Chemistry, University of Michigan), Tyler Smith (Chemistry, University of Michigan), Kristin Koutmou (Chemistry, University of Michigan)
Abstract:
Cells chemically modify all three major classes of biomolecules (DNA, RNA and protein) to control their structure, function and stability. In RNAs, nucleoside modifications are incorporated either enzymatically or as the result of RNA damage. Regardless of how they are added, the insertion of chemical modifications into mRNA coding sequences can influence how the ribosome decodes rate of translation elongation and termination. Here we investigate the consequences of recently discovered guanosine mRNA modifications, N1-methyl guanosine (m1G) and N2-methyl guanosine (m2G), and a well-established adenosine mRNA modification, inosine (I),on protein synthesis. All four of these modifications alter the hydrogen bonding potential between codon and anticodon nucleotides as well potential stereochemical interactions between codons and their cognate amino-acyl tRNAs. We find that inclusion of modifications around varied positions of the guanosine purine base (m1G, m2G, I, 2,6 – diaminopurine (DAP), and 2-aminopurine (2AP)) in mRNA codons (GUG, CGU, UGA and UAG) impact translation elongation and termination in a fully reconstituted E. coli translation system. Our findings indicate that these modifications alter the rates of translation elongation and termination in a context dependent manner, with modifications in the first and second positions of the codon slowing elongation the most. These data support the growing body of evidence indicating that mRNA modifications can alter protein production by the ribosome.
Keywords: Translation, RNA modifications