README for SupplementaryFigure2A_HTkB_Ktrip

*** This file contains the raw data obtained from tethered particle motion experiments shown in Supplementary Figure 2 of:
Article: Modulation of archaean hypernucleosome structure and stability by Mg2+
Authors: Ilias Zarguit, Marc K. M. Cajili, Bert van Erp, Samuel Schwab, Nico van der Vis, Marianne Bakker, John van Noort, and Remus T. Dame
Corresponding author: rtdame@chem.leidenuniv.nl

Legend Supplementary Figure 2: Tethered particle motion experiments reveal that hypernucleosomes with lysine-alanine substitutions that cancel stacking interactions of HTkB still form hypernucleosomes and that compaction is enhanced by Mg2+.  (A) Tethered particle motion experiments demonstrate that the HTkBK27A,K62A,K66A stacking mutant can still form hypernucleosome structures on DNA substrates. Upon mutating the lysines involved in stacking into alanines, the midpoint concentration shifts from 2.46 ± 1.1 to 271.78 ± 1.1 nM, demonstrating that the affinity and the cooperativity are highly affected by the mutation. In the presence of 5 mM of Mg2+ ions, the midpoint concentration shifts to 40.73 ± 1.2 nM, demonstrating that Mg2+ ions promote the formation of hypernucleosome complexes also in absence of stacking interactions. B) Mg2+ titration experiments show a decrease in RMS upon increased concentration of Mg2+ ions.  

*** The data was obtained using tethered particle motion as described in the associated article.

*** Each individual sheet contains data obtained for each concentration of HTkBK27A,K62A,K66A (as indicated in the sheet name). The sheet "Averaged Values" contains the average plotted in Figure 1.  
Each sheet contains data from individual tethered DNA molecules or protein-DNA complexes, with each row corresponding to one bead/tether.

Column A: Root mean square = RMS in nm
Column B: Anisotropy = Anisotropic ratio (movement in x-direction/movement in y-direction)
Column C: Stdev = Standard deviation
Column G: Fit parameters = The mean and standard deviation values obtained from fitting a normal distribution to the root mean square values (column A)

The values given in column B and C are tether quality criteria and used for data filtering as described in the associated article.
Histograms showing the distribution of the root mean square values are shown together with the fit and a kernel density estimator.
