Fig. 2: Pairwise epistasis.
From: Origins and breadth of pairwise epistasis in an α-helix of β-lactamase TEM-1
a Log-fitness of effects of double mutants, against the sum of the single mutants’ log-fitness. Gray mutants of observed log-fitness and predicted log-fitness based on single mutants lower than −0.6 cannot give reliable values for the epistasis. The colors of the other points represent the form of epistasis detected using the color code defined in Fig. 1 (a). b Distribution of epistasis using the same color code, excluding mutants with non-measurable epistasis; histograms are stacked. c Categorization of epistasis for all mutations, pairs of deleterious (A−/B−), pairs involving one deleterious and one beneficial (A+/B−), or pairs of beneficial (A+/B+). d Relative log-fitness effect of all mutations against the log-fitness of the different backgrounds in which they were found. The values for three focal mutations, L122A, R120K, and S124E, are highlighted in blue, green, and red, respectively. Blue shaded area corresponds to double mutants with fitness effects below the threshold, salmon shaded area corresponds to double mutant with log-fitness value higher than the threshold despite having a single mutant below it. e The fraction of mutations falling into unconditionally inactivating, deleterious with context-dependency, no context dependency, and beneficial with context-dependency is presented. Source data are provided as a Source Data file.
