Movies 1-4.  Cartoon Animation showing the rotation of dsDNA around six subunits of the ATP hexamer without twisting and coiling.  Binding of gp16 to the same phosphate backbone chain in each transition at a location 60° different from last subunit urges dsDNA to move forward 1.8 base pairs.  Since the dsDNA chain is transferred from one point on the phosphate backbone to another point, rotation of the hexameric ring or the dsDNA itself is not required.  One ATP is hydrolyzed in each transitional step, and six ATPs are consumed for one cycle to translocate dsDNA one helical turn of 360° (10.5 base pairs) thus, 10.5 bp per helical pitch ÷ 6 subunit using 6 ATP = 1.8 bp/ATP agrees with the previously reported numberof base pairs per ATP determined empirically.

Motion 1.  Direct observation of ATPase complex queued and moving along dsDNA.Cy3 conjugated gp16 was incubated with phi29 genomic dsDNA and tethered between two polylysine beads and visualized using single molecule TIRF.  Upon addition of ATP, motion of the gp16 along the DNA was directly observed and recorded.


Note: If you can not see the movies in the website, please download the movies from the following link and open them with you own media player:

Movie 1: 1.wmv (WMV format)

Movie 2: 2.wmv (WMV format)

Movie 3: 3.wmv (WMV format)

Movie 4: 4.wmv (WMV format)

Motion Movie: (AVI format)