Effects of 16S ram mutations on overall miscoding in various contexts. Control and mutant 70SICs (color-coded, as indicated) programmed with various near-cognate codons in the A site were mixed with the TC under conditions that facilitate reassembly of the TC, and apparent rates of miscoding were measured. Misincorporation rates for Phe (A, E, I), Tyr (B, F, J), Lys (C, G, K), and Glu (D, H, L) in the presence of various first-position (A–D) or third-position (E–L) codon-anticodon mismatches were compared. The codon programmed in the A site of each ribosome complex is indicated above each graph, with the mismatched base colored red. Anticodon sequences for each tRNA are indicated at the top of the figure. Data in panels A–J represent the mean ± SEM from three or more independent experiments. For panels K and L, rates were measured using a quench-flow machine, and reported values and their standard errors come from the curve fits.
