Extended Data Fig. 3. Fitness effects of an ftsZ mutation on populations of Mycoplasma mycoides.
We reengineered the nonsense mutation ftsZ E315* and quantified its effect on relative fitness in both the non-minimal and minimal cells using head-to-head competition assays. The ftsZ E315* nonsense mutation had a significant effect on Mycoplasma cell size that depended on cell type (two-way ANOVA, F1,32 = 7.45, P = 0.010). Compared to the wild type (non-evolved ancestor), the mutation increased relative fitness by 25% in the non-minimal cell and 14% in the minimal cell. Dark-coloured symbols represent the mean ± SEM. Light-coloured symbols represent values for each replicate population. Samples sizes are as follows: wild-type minimal cell, n = 12; ftsZ E315* minimal, n = 12; wild-type non-minimal cell, n = 5; ftsZ E315* non-minimal, n = 5.