Figure 4.

 RadA protein promotes DNA pairing and strand exchange. (A) The DNA substrates as well as the expected intermediates and products of the DNA strand exchange reaction. (B) An agarose gel displaying a time course for formation of these products. Viral φX174 ssDNA (ss) and linear φX174 dsDNA (ds) were incubated with RadA protein, either with or without a ssDNA binding protein in lanes 1–12. Lanes 13–16 show the same reaction without RadA protein; lanes 17 and 18 show the same reaction with heterologous DNA. (jm) Joint molecules; (nc) nicked circular dsDNA; (sspBS) pBluescript ssDNA used as a heterologous control.