We thank the reviewers for pointing this out. We did not intend to draw the unwinding point as far down as we did, and this was an artistic flaw of the original figure. We have now redrawn the figure to show a much smaller amount of dsDNA entering the CMG. We did not redraw the cartoon to have 3 tiers because describing the A, B, C domains of the N-tier is beyond the scope of the Introduction. We have dealt with these aspects in the structural study and in a few other reviews that are submitted and underway.