Fig. 6

Identification of functional elements and interactions. a–c The sensitivity of each position in the regulatory RNA RyhB to mutations [9] is profiled in order to identify functional elements. Known elements are highlighted, with dashed lines indicating paired nucleotides in stem-loops of the RNA molecule. a Enrichment ε for each single-mutation variant, computed by grouping the bottom two gates. b Quantitative change in fold-repression, estimated by the simple mean. For both measures the value for the WT (solid line) and non-functional variants (dotted line) are indicated. c The information footprint, or mutual information between the nucleotide at each position and the distribution of sort-seq reads. d Comparison of two measures of epistasis, the inferred interaction strength (IS) and the model-free K based on enrichment ratios. Four groups of mutation pairs previously identified as biologically significant [9] are highlighted