README for FigureS2A_data.csv

*** This file contains the raw data obtained on DNA and DNA-HMfB complexes using magnetic tweezers as represented in Figure S2A of

Article: Mechanical and structural properties of archaeal hypernucleosomes
Authors: Henneman, Brouwer, Erkelens, Kuijntjes, van Emmerik, van der Valk, Timmer, Kirolos, van Ingen, van Noort, Dame
Journal: Nucleic Acids Research
DOI: 10.1093/nar/gkaa1196
Corresponding authors: rtdame@chem.leidenuniv.nl and noort@physics.leidenuniv.nl

Legend Figure S2) Force spectroscopy on a torsionally constrained and a torsionally free HMfB-DNA complex. At low force (<2 pN) both complexes were identical in length, and the curve overlapped with the freely-jointed chain model (FJC). At high force (>20 pN) the curves overlapped with the worm-like chain model (WLC) of bare DNA. In between, the hypernucleosome unstacked and subsequently unwrapped. Due to the chiral structure of the hypernucleosome, unstacking induces torque, which stabilized the structure. The torsionally constrained hypernucleosome unstacked at 10 pN, compared to 1.5 pN for the torsionally unconstrained hypernucleosome. The unwrapping transition appeared unaffected. Fitting the torsionally constrained hypernucleosome yielded a higher stacking energy (4.2 ± 0.1 kBT vs 1.6 ± 0.1 kBT per dimer), reflecting an increased energy cost for unstacking the hypernucleosome. The wrapping energy was largely unaffected (9.9 ± 0.1 kBT vs 10.0 ± 0.1 kBT per dimer). The fit, however deviated somewhat from the data in the transition region. Both molecules appeared to contain 103 HMfB dimers, from which 95 were stacked in a hypernucleosome. The force extension curves of both molecules converged to a WLC with a contour length of 3646 base pairs at forces over 30 pN.

*** The data were obtained using Magnetic Tweezers as described in the associated article.

*** Columns show F (Force in pN) and z (Distance in micrometer) of DNA-HMfB complexes. Each column label additionally indicates whether the data was obtained on a torsionally constrained or torsionally free DNA-HMfB complex, as well as whether the data represents a  pulling or release curve.
