Fig. 2: Single cohesin on DNA resists ~20 pN forces.
a, Forces exerted on cohesin as it moves along the tethered λ-DNA (x direction, left) or perpendicularly to it (y direction, right). Distance shows the relative position of the bead along the corresponding axis. Relates to Supplementary Video 2. b, Typical example of an FD curve (top) and the corresponding single-step photobleaching trace (bottom) showing the rupture of a single cohesin from the tethered λ-DNA at a force of 20 pN. Relates to Supplementary Video 3. c, Normalized distribution of the total rupture forces for the cohesin variant where force was applied via the head domain (n = 89). In c and e, solid lines show theoretical distributions of rupture forces with optimal parameters determined by fitting experimental data. Parameter values are shown in the main text. d, Cohesin’s fluorescent signal colocalizing with the bead before and after two pulling experiments, in which the rupture event was recorded (left), or when the applied force was insufficient (5 pN) for detachment. DNA is not visualized. Bottom graphs show corresponding FD curves for these experiments as a function of both distance and time. e, Normalized distribution of the total rupture forces for the cohesin variant where force was applied via the hinge domain (n = 21). The solid line is the theoretical distribution.
