Self-assembling transfer RNA has potential for nanoparticle arrays

Transfer RNAs (tRNAs) are small, stable, L-shaped RNA molecules that transfer amino acids to the growing polypeptide chain during protein synthesis. Exploiting the similarity in shape between tRNA and H2O molecules, our aim has been to produce a tRNA building block that will self-assemble into higher aggregates, with a goal of 3D arrays, for possible application as molecular sieves or scaffolds. Some tRNAs can form dimers by intermolecular base-pairing of their single-stranded loops. The glycine tRNA (GCC) gene from Escherichia coli has been used in a pilot study. Modern molecular biology techniques were utilized to produce variants of the glycine tRNA with additional complementarity in a specific loop (T loop). Initial aggregation studies showed two of five variant tRNAs tested form dimers at neutral pH in the presence of spermine and magnesium and sodium chloride ions, in contrast to the starting tRNA. One forms dimers rapidly, the other more slowly, possibly due to the need for structural rearrangement to disrupt intramolecular interactions before dimerization can occur. Surprisingly, with the variant where arrays were possible there was a lack of higher aggregates, which may be due to steric hindrance around the elbow region formed from the 3D folding of this tRNA.