Hybrid transfer RNA genes in phage T4

We describe the isolation and characterization of two unusual amber suppressor forms of T4 tRNALeu. The sequences of the suppressor tRNAs can be described as hybrids of wild-type tRNALeu and suppressor tRNAGln molecules: the chain lengths and majority of the nucleotide residues corresponded to tRNALeu, but CUA anticodons flanked by 2-14 residues were identical to tRNAGln. The uncertainty as to the exact number of flanking residues correlated with tRNAGln is due to the similarity of the two tRNA sequences in this region. No evidence was found for changes in other T4 tRNAs. We propose that genes for the hybrid tRNAs were produced by mispairing of DNAs at anticodon segments of tRNALeu and tRNAGln with a double crossover flanking those segments.