It has long been known that mutations in the body of the tRNA can affect translational fidelity, but how? The crystal structures of the 70S ribosome complexed to EF-Tu and wild type and mutant aminoacyl-tRNAs bound to cognate and near-cognate codons now show that the mutants cause miscoding by different means. The so-called Hirsh suppressor (G24A) promotes an additional internal interaction while the A9C mutant enhances tRNA flexibility, but they both decrease the energetic penalty for tRNA distortion.
- T Martin Schmeing
- Rebecca M Voorhees
- V Ramakrishnan
