Figure 4. MeCP2 exerts stabilization and recruitment functions at nucleosomes.

a, A representative kymograph of a nucleosome-containing unmethylated DNA tether bound with Cy3-MeCP2 and pulled to high forces by gradually increasing the inter-bead distance. Vertical dotted line denotes the time when the tether ruptured. Arrows denote nucleosome positions. b, A representative force-distance curve of a MeCP2-bound nucleosome-containing DNA tether showing force-induced nucleosome unwrapping transitions. Inset shows a zoom-in view of two example transitions for which the distance changes (ΔL) and the transition forces are recorded. c, Distribution of transition forces recorded from force-distance curves of nucleosomal DNA tethers with no MeCP2 or H1 bound (n = 84), or bound with WT MeCP2 (n = 107), MeCP2^R270X (n = 68), H1 (n = 106), or with both WT MeCP2 and H1 (n = 81). Box boundaries represent 25^th to 75^th percentiles, middle bar represents median, and whiskers represent minimum and maximum values. d, A representative kymograph of an unmethylated DNA tether containing AF488-labeled nucleosomes and incubated with Cy5-labeled MeCP2 and Cy3-labeled H1. Lasers were alternated on and off to confirm signal from each fluorescence channel. Arrows denote nucleosome positions. Inset shows a zoom-in view of individual fluorescence channels at a nucleosome site where both MeCP2 and H1 colocalized. e, A representative kymograph of a methylated DNA tether incubated with Cy3-labeled MeCP2 and LD655-labeled TBLR1. f, Apparent on rate for TBLR1 binding to methylated DNA in the absence or presence of MeCP2. Error bars represent SD. g, A representative kymograph of an AF488-nucleosome-containing unmethylated DNA tether incubated with Cy3-MeCP2 and LD655-TBLR1. Arrows denote nucleosome positions. h, Fraction of nucleosomes on unmethylated DNA tethers that were colocalized with TBLR1 in the absence or presence of MeCP2. Error bars represent SD.