Fig. 2: Klf4 foci on λ-DNA switch from an adsorbed state to a condensed state via a prewetting-like transition at positions predicted by a Klf4 position weight matrix.

a, Confocal images (top) and intensity profiles (bottom) of Klf4-GFP on λ-DNA. Light and dark green, adsorbed and condensed intensity ranges. b, Probability density of the logarithm of intensities; N = 37 experiments. Black line, fit to the sum of two normal distributions. Intersection (658.5 counts) defines the threshold between adsorbed (light green, Ads.) and condensed (dark green, Cond.) states (Methods and Extended Data Fig. 7). c, Same as b as a function of time. Top: N = 60 (Extended Data Fig. 4g and Supplementary Video 3). d, Fraction of DNA occupied by the condensed state. Light dots, individual experiments; red circles, binned medians; error bars, 95% confidence interval (bootstrapping); red line, fit to the heterogeneous two-state model. e, Phase diagram for a binary fluid in the presence of a surface^17,54. In the coexistence regime (dark green, liquid–liquid phase separation (LLPS)) and close to the surface, the dense phase transits from partial to complete wetting when the system crosses a characteristic temperature (yellow dashed line). This first-order transition extends into the single-phase region through the prewetting line (solid yellow line). f, Crossing the prewetting line (at C_PW) leads to condensation from a thin adsorbed layer (left and middle). Above the saturation concentration C_SAT, liquid droplets spontaneously appear in the bulk (right). g, Consensus recognition motif of Klf4 in vivo²⁶ and probability of binding to a given sequence along λ-DNA relative to the consensus motif (Methods and Extended Data Fig. 8). h, Blue and colour map, binding energy landscape h_i (kT is the unit of energy, where k is the Boltzmann constant, and T is the temperature), coarse grained over 1 kb (Methods and Extended Data Fig. 9a). Red, average Klf4 intensity along λ-DNA ([Klf4-GFP]: 8–281 nM, N = 79). Shaded area, standard error of the mean at 95% confidence.