video: The movie shows initially the enzyme in a state where no DNA is bound (the DNA is only faintly seen). The enzyme now binds the DNA and one can see how the enzyme closes to grap the double helix. Most polymerases bind so tightly (snugly) that the DNA is fully surrounded by the enzyme. Polymerase-eta in contrast does not close completely but keeps the duplex in a wide open rim structure. This loose fit allows the DNA to move through the enzyme even though highly helix disturbing lesions are present. The loose fit is the secret of why the enzyme can copy DNA even in the presence of cisplatin lesion, which will block all kinds of other polymerases. view more
Credit: Video copyright <i>Science</i>