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Adaptive Evolution of the Lactose Utilization Network in Experimentally Evolved Populations of Escherichia coli

Figure 6

Contribution of lac mutations to evolved inducer responses.

A) Inducer response histograms for reconstructed lacIΔTGGC and lacO1G11A mutants. The lacI mutation confers constitutive lac expression, whereas the lacO1 mutation confers a lower induction threshold and a graded response to inducer. B) Effect of the lacO1 mutation on the maximum lac expression level. Mean Plac-GFP expression levels during growth in saturating levels of inducer (100 µM TMG) are shown for the ancestor, evolved clone G+L3-1, lacO1G11A single mutant and the G+L3-1 clone with lacO1 reverted to the ancestral sequence (G+L3-1 lacO1anc). Standard error is shown, n = 4.

Figure 6