Figure 1.

Intracellular mobility of diverse types of DNA-binding proteins in live E. coli cells is highly variable and unrelated to their molecular weight

(A) Illustration of photoactivated single-molecule tracking, showing example fluorescence images and trajectories of a mobile and an immobile molecule. Scale bar, 1 μm. The measured localizations reflect the average position of a molecule during a frame exposure. Apparent diffusion coefficients (D^∗) report the frequency and duration of DNA interactions by measuring the average displacements over the course of a trajectory.

(B) D^∗ histograms for diverse DNA-binding proteins, fitted with a two-species model (black dashed line) of a mixture of immobile (red) and mobile molecules (blue). The number of cells (n_c) and the numbers of tracks (n_t) are indicated.

(C) Percentages of immobile molecules obtained from fitting the D^∗ histograms in (B) with a two-species model. Error bars represent 95% CI.

(D) D_mobile^∗ values for the mobile molecule populations.

(E) D_mobile^∗ plotted against the cubic root of the molecular weight of the protein complex.

See also Figure S1.