Movie S1.

FS-AFM imaging reveals wild-type M/R binding of the DNA substrate via the Rad50 coiled-coil apices. The Rad50 coiled-coils extend from the globular protein core where the apices appear to alternately bind and disengage from the double-helix, creating an intermittently binding movement along the dsDNA template, while the dsDNA seems to be pushed rightwards at the same time (00:00-24:00). A second, larger, M/R aggregate arrives close to the DNA and the coiled-coil apices of this complex bind DNA at two locations. At the times between 24:30 and 25:00 min the DNA strand is pulled to towards the second M/R aggregate via the first connecting Rad50 coiled coil hook, before being released, while the contact between the second Rad50 coiled-coil and the DNA-end remains throughout. Reactions were performed at room temperature in buffer over the course of 29:00 mins. This video is also represented as series of individual frames in Fig 4A. Movie speed = 2 frames per second. The time scale is min : sec and the z scale is 2 nm (dark to light).