Strand Tracking

Using a combination of single molecule and bulk solution measurements, we have examined the DNA translocation activity of EcoR124I. We find that EcoR124I can translocate past single-strand gaps and covalent interstrand crosslinks, inconsistent with an obligatory unwinding mechanism (Figure 8). Instead, translocation of the intact dsDNA occurs principally via contacts to the sugar-phosphate backbone and bases of the 3’–5’ strand; contacts to the 5’–3’ strand (Figure 9) are not essential for motion but do play a key role in stabilising the motor on the DNA (Seidel et al. 2005).