README for Figure 2_HTkB_5mM_Mg

*** This file contains the raw data obtained from tethered particle motion experiments shown in 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 Figure 2: Mg2+ promotes formation and enhances HTkA/B and HMfA/B hypernucleosome compaction. A) In 5 mM MgCl2, the HTkA/B protein titration curves shift to lower concentrations, evidenced by the reduction in midpoint concentrations (see Table 1). The reduction in midpoint concentration indicates an effective increase in affinity. The increase in steepness suggests enhanced cooperativity. The lower RMS at saturating conditions implies a more tightly packed hypernucleosome complex. (B) In 5 mM MgCl2, the HMfA/B protein titration curves show a similar trend in affinity, cooperativity, and compaction as HTkA/B. Each measurement (N ≥ 100) was done in duplicate, with the error bars representing the standard deviation. Dashed lines are added to guide the eye.

*** The data was obtained using tethered particle motion as described in the associated article.  RMS values in absence of Mg2+ is derived from Figure 2. 

*** Each individual sheet contains data obtained for each concentration of HTkB in the presence of 5 mM Mg2+ (as indicated in the sheet name). The sheet "Averaged Values" contains the average plotted in Figure 2.  
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.
