Phenylalanyl-tRNA synthetase editing defects result in efficient mistranslation of phenylalanine codons as tyrosine

Tyrosylation of E. coli tRNA^Phe (5 μM) by PheRS variants (0.5 μM each) in the presence (filled bars) and absence (open bars) of EF-Tu (5 μM). The Y-axis represents the end levels of Tyr-tRNA^Phe synthesized after 6 min. PheRS variants contain either a wild-type editing site (WT) or mutations in the β subunit that reduce the editing activity (Ling et al. 2007). Relative post-transfer editing activities determined previously are shown in the figure. Data sets are the average of three independent experiments.