Demonstration of no DNA rotation by real-time direct observation of single motor DNA packaging. Procapsid was immobilized in glass and the distal end of dsDNA was tethered to a bead. DNA is packaged vertically (A) or horizontally (B) towards the slide surface (graphic is not drawn to scale). (C) The motion of the bead is tracked during DNA packaging without (a and b) and with (c and d) the addition of ATP to the sample. The motion of the bead ceased at later times only when ATP was added (c) and (d) due to the physical restriction of DNA being completely packaged. (a) and (c) show the trajectories of the bead. Different colors represent different time ranges during the translocation. (b) and (d) show the changes in beads travel distance versus time.