Stability of gene expression and inhibition strength as the function of the number and distribution of nucleation sites.
(A and B) Concentration profiles calculated for the [O]2-Gene-[O]2 (A) and [O]1-Gene-[O]1 (B) settings. The red dashed and gray continuous lines represent the solutions initiated with the two initial conditions. The two solutions overlap when GA is either weak or strong (thin and thick red-gray dashed lines). At intermediate GA, two distinct solutions evidenced the bistability (medium red dashed and gray dashed lines) for [O]2-Gene-[O]2. (C) Inhibition strength at single (upstream or downstream) and dual recruitment constructs. The inhibition strength is the average value for fold inhibition − 1 in the [0.06, 0.6] interval of GA. The total number of tet operators is indicated for each dual recruitment construct [tetO]1-GFP-[tetO]1 (n = 2), [tetO]1-GFP-[tetO]2 (n = 3), [tetO]2-GFP-[tetO]2 (n = 4), and [tetO]2-GFP-[tetO]4 (n = 6). Empty symbols stand for constructs that display bimodal gene expression.