Fig. 2. Selection coefficients (s) of amino acid changes depend on promoter activity.

(A) Selection coefficient (s) of individual amino acid mutants at non-optimal levels of promoter activity compared to the optimal level for the WT, which is used as a reference point for comparisons. Spearman correlation coefficients are shown. Lines indicate LOESS regressions. Horizontal error bars indicate the SEMs observed across biological replicates at optimal promoter activity level for the WT. Vertical error bars indicate the SEMs observed across biological replicates at non-optimal promoter activity levels. (B) Distributions of s for individual mutants across promoter activity levels show reduced spread and increasing average of individual values. The larger blue dots with white crosses indicate the means of the distributions. (C) Clusters showing patterns of changes of s for individual mutants across promoter activity levels. Colored lines indicate mutants from the different clusters (k-means, k = 4). Number of mutants in each cluster: (1) 446, (2) 291, (3) 218, and (4) 581.