Strand exchange using substrates with interrupted homology. A–D, A representation of the DNA substrates used for the strand exchange assay. The rectangle represents the 1.5 kb region derived from HSV-1 DNA. The wavy line and filled rectangle represent the strand complementary to the ssDNA substrates. B–D, Schematic representations of the pairing of ssM13mp18 DNA with dsM13wins DNA linearized by BamHI, EcoRI, and PacI, respectively. E, Strand exchange was performed by UL12 and ICP8 as described in Materials and Methods with 100 ng of ssM13mp18 DNA (2 nM) and 100 ng dsM13wins DNA (0.8 nM) linearized by the following restriction endonucleases: lanes 1–5, BamHI; lanes 6–10, EcoRI; lanes 11–14, PacI. Reactions were incubated for 15–60 minutes, as indicated. C, No protein control.