The Influence of Competing tRNA Abundance on Translation: Quantifying the Efficiency of Sense Codon Reassignment at Rarely Used Codons

Making sense: We quantitatively evaluate the effect of the abundance of competing endogenous tRNAs on the ability of orthogonal tRNA variants to reassign E. coli sense codons. For rarely used codons, a strong correlation exists between tRNA abundance and reassignment efficiency. Our measurements suggest that the Ile AUA codon is a particularly good target for genetic code expansion.