Fig. 4
From: Unraveling the causes of adaptive benefits of synonymous mutations in TEM-1 β-lactamase
Resistance landscape of four beneficial synonymous mutations: R9*, A17*, G87*, and E89*. All error bars indicate the standard error of the mean (N = 3 for a, N = 2 for c). In a, resistance to CTX (IC99.99) is shown for all alleles in the fitness landscape. In b, the same data are represented, but with the number of mutations on the x-axis and resistance on the y-axis. If the resistance increases as an extra mutation is added, the connecting line is black, whereas if resistance decreases the line is red. In c, TEM expression data for a number of selected alleles are given. TEM messenger levels are indicated by white bars, whereas TEM protein levels are indicated by gray bars. For the low-resistance alleles R9*/G87* and R9*/G87*/E89*, TEM protein expression levels appear to drop, whereas protein levels are high for the quadruple mutant with high resistance
