The structural basis for specific decoding of AUA by isoleucine tRNA on the ribosome

Abstract

Post-translational modifications of tRNAs can alter their decoding specificity. A molecular basis for altered codon specificity is now provided by the crystal structure of the archaeal tRNA2Ile modified with agmatidine at the wobble cytidine residue in complex with the AUA codon on the ribosome. Decoding of the AUA isoleucine codon in bacteria and archaea requires modification of a C in the anticodon wobble position of the isoleucine tRNA. Here, we report the crystal structure of the archaeal tRNA2Ile, which contains the modification agmatidine in its anticodon, in complex with the AUA codon on the 70S ribosome. The structure illustrates how agmatidine confers codon specificity for AUA over AUG.