Fig. 4: Tau leads to subtle perturbations at DNA contact points on the nucleosome core.

a Schematic of the sequence and secondary structure of histone H4. The residues highlighted in green display resolved correlations that were used in the analysis described below. Rigid regions that appear in the DARR spectrum are shown as green rectangles and lines, while the mobile regions of the INEPT spectrum are shown in purple. b 2D ¹³C-¹³C DARR spectrum recorded with 20 ms mixing time on labelled histone H4 within 12mer arrays (black) and with 20 mg of added tau (green), in 10 mM Tris, 0.1 mM EDTA, 10 mM KCl, pH 7.5. Conditions were chosen to match those for published chemical shift assignments⁶³. c Zoomed in regions of the 2D DARR spectrum, showing the largest quantified perturbations. d Summed chemical shift perturbations (CSPs) of Cα and Cβ chemical shifts per residue, obtained from single-bond correlations. The bars are split into the contribution from the Cα (white) and Cβ (green) CSP. The dotted line is the average value along the sequence, and the orange line is one standard deviation above the mean. Orange shaded bars are residues that are one standard deviation above the mean. e CSP of side-chain carbons obtained from single bond correlations. The dotted line is the average value along the sequence and the orange line is one standard deviation above the mean. Orange shaded bars are residues that are one standard deviation above the mean. f Perturbations plotted onto the nucleosome structure. Histone H4 is shown in green and residues containing at least one atom with a CSP above one standard deviation above the mean are shaded in orange and labeled.