Fig. 3

Codon selection is under evolutionary pressure. A Percent distribution of WT codons in context of evolutionary conservation at the nucleotide level. B Some CcdB positions do not have the WT codon as the most conserved codon. Instead one of the synonymous counterparts is the most conserved codon. Histogram represents the frequency distribution of ES^CcdB scores for synonmous mutants with the most conserved codon for the corresponding WT amino acid. C Corresponding values of ES^CcdB (x-axis), ES^RelE (y-axis) and evolutionary conservation at the residue level (color bar) for each mutant of the N-terminal region is plotted. Percent conservation is proportional to the conservation level of the residue. Distribution of Codon Adaptation Index (CAI) ratios in wild-type (WT) ccdA and WT ccdB genes across different bacterial species: D Escherichia coli, E Klebsiella pneumoniae, F Salmonella enterica, and G Shigella flexneri. The CAI ratio provides insights into the codon usage of these genes within each respective species