Figure 3.

Helicase-mediated unwinding of displacement loop (D-loop) intermediates. Strand invasion of a broken DNA molecule into a homologous duplex creates a D-loop. Template-based repair of sequence at the break site can proceed at the paired 3′ end, using the homologous DNA as a template. This process is inhibited by the action of a number of helicases, such as Srs2 and RTEL1, which exhibit ‘anti-recombinase’ activity by unwinding the D-loop. Other helicases, such as HFM1 and MCM8-9, stabilize the D-loop by supporting DNA polymerase activity, increasing the amount of paired heteroduplex DNA.