Figure 4.

Hfq foci formation contributes to adapting E. coli cell function as N starvation ensues. A, representative PALM images of Hfq in E. coli cells as a function of time under N starvation (top panels). Images were taken at the indicated time points, and the arrows point to the Hfq foci. The images for N− and N–24 have been reused from Fig. 3 (B and C), respectively, to allow direct comparison. Graphs (bottom panels) with the optical density (A_{600 nm}) as a function of time of WT and Δhfq E. coli cells following infection with T7 phage are shown below each corresponding PALM image. The difference in time taken for the A_{600 nm} of the culture to decrease by ∼50% (T_lysis) between WT and Δhfq is indicated (ΔT_lysis). B, graphs showing the distribution of apparent diffusion coefficient of Hfq molecules at the different sampling time points and the corresponding %H_IM and ΔT_lysis values are shown in the inset (see text for details).