Influence of <i>β</i>-galactosidase overexpression on codon-specific elongation rates.

<p>(A) Codon usages of all sense codons in wild type <i>E. coli</i> cells growing at a specific rate of 2.5 h⁻¹ compared to codon usages in <i>E. coli</i> cells overexpressing <i>β</i>-galactosidase. The largest changes are obtained for the codon usages of AAA and UGG. (B) Elongation rates of all 61 sense codons in wild type <i>E. coli</i> cells growing at a specific rate of 2.5 h⁻¹ compared to codon-specific elongation rates in <i>E. coli</i> cells overexpressing <i>β</i>-galactosidase encoded by the lacZ gene, calculated for the 2-1-2 pathway (blue) and the 2-3-2 pathway (orange) of E-site tRNA release. Note that the elongation rates of the codons AAA and AAG are almost identical for both the 2-1-2 pathway (blue) and the 2-3-2 pathway (orange). Except for the codon usages, all parameters used to calculate the elongation rates were identical in all four calculations; in particular, all calculations used the same set of total concentrations of all tRNA species.