Fig. 5.

Nucleoid and HU dynamics in live D. radiodurans. a Reconstructed PALM image of HU-PAmCherry-expressing cells (stack of 15,000 frames with 50 ms frametime and acquired with constant 1 kW cm⁻² 561 nm laser and increasing 405 nm laser power). Several of the nucleoid morphologies illustrated in Fig. 3 can be seen in this image, but without a significative improvement in the perceived spatial resolution, due to the dynamics of nucleoids in live cells that change conformation in the second-to-minute timescale (Supplementary Movie 5). b Distribution of the apparent diffusion coefficients of 1355 single tracks of HU-PAmCherry measured by single-particle-tracking PALM in live, exponentially growing HU-PAmCherry-expressing D. radiodurans. Inset: mean square deviation (MSD) plot of the HU-PAmCherry tracks (Δt = 30 ms). The curve indicates that the molecules are confined with a confinement radius of 400 nm. The mean apparent diffusion coefficient derived from these 1355 tracks is of 0.32 µm²/s. c, d Ensemble measurements of HU-mCherry mobility probed by fluorescence recovery after photobleaching (FRAP) on HU-mCherry-expressing live D. radiodurans cells. c Examples of HU-mCherry-labelled nucleoids used for FRAP experiments. The photobleached region (ROI1) is indicated with a white box. Scale bar: 1 µm. d Analysis of the recovery of the fluorescence signal of HU-mCherry after photobleaching. Fitting this full-scale normalized data reveals that 99 ± 1% of HU-mCherry molecules are mobile exhibiting a half-life of 1.03 ± 0.06 s. Presented data are the mean values ± SD (N = 10). Source data are provided as a Source Data file