Fig. 8: SegB exhibits short-range DNA compaction activity.

a Schematic of the segAB locus and upstream sites (1, 2, and 3) bound by SegB (top); schematic of the 289 bp DNA fragment with details of the three binding sites used for AFM experiments. b Representative AFM images of bare DNA fragment (289 bp) or SegB-DNA complexes formed upon adding 100, 300 and 700 nM SegB. Scale in panel (i) = 100 nm and in panel (ii) = 20 nm. Arrows point at the DNA sites that are occupied by SegB. The sites labelled 1, 2 and 3 on the images correspond to those shown in panel a. The bars on the right side of the images provide a colour gradient reference for the height of particles. c Schematic of the 289 bp DNA fragment with the three SegB sites (not to scale) (top); plot showing height traces of the individual single particle of bare DNA (in panel b ii, top left), of DNA-SegB (100 nM) (in panel b ii, top right), of DNA-SegB (300 nM) (in panel b ii, bottom left), and of DNA-SegB (700 nM) (in panel b ii, bottom right) (bottom). d Schematic of the 289 bp DNA fragment showing the three SegB binding sites (not to scale) (top); average height traces of bare DNA molecules (n = 100), DNA-SegB (100 nM) particles (n = 99), DNA-SegB (300 nM) particles (n = 95) and DNA-SegB (700 nM) particles (n = 100). e Histograms of the contour length of bare DNA molecules and the DNA in the DNA-SegB complexes at different SegB concentrations. The mean of the contour length is indicated in each plot. The coloured line represents nonlinear Gaussian fit. Three independent biological replicates were performed for each sample with similar results. For the graphs source data are provided as Source Data file.