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. 2016 Nov 7;11(11):e0165078. doi: 10.1371/journal.pone.0165078

Fig 3. Life time measurements of individual nucleosomes under a constant tension.

Fig 3

(a-b) Representative (a) H3 and (b) CENP-A nucleosome disassembly time trace from random DNA sequence under constant force. Red line is a most likely trace deduced by a step-finding algorithm. The determined step sizes (in nm) indicted next to each step. Top panel: the time trace of the force exerted on the DNA. At time 0, the force was increased abruptly from 1 pN to 30 pN. (c-d) Step-size distribution of (c) H3 and (d) CENP-A disassembly from random DNA (grey bars) and centromeric DNA (red bars). Blue lines indicates the 15–30 nm range expected from a single-nucleosome DNA-unwrapping event. Solid lines are multi-Gaussian fits and the fit parameters are summarized in S4 Table (e-f) Life time distributions of the selected 15–30 nm steps for (e) H3 and (f) CENP-A nucleosome disassembly. Color scheme is the same as (c). Solid lines are single-exponential fits to the data and the fit parameters are summarized in S5 Table. (g-h) Average life times of (g) H3 and (h) CENP-A nucleosomes obtained from single-exponential fits to the life-time distributions measured at different forces. Error bars are standard errors of the mean.