Figure 6.

Effect of the pre-incubation of the partners on the (52–96)Vpr stimulation of the long DNA strand transfer. Reactions were performed with 2 pmol IN, 10 ng of U3U5 substrate and 40 ng of pSP70 target in the presence (lanes 2, 4, 6 and 7) or absence (lanes 1, 3 and 5) of (52–96)Vpr. Either all the partners are pre-incubated for 10 min on ice before 1 h of incubation at 37°C (lanes 1 and 2), U3U5 DNA donor is omitted from the pre-incubation (lanes 3 and 4) or the pSP70 target is omitted from the pre-incubation (lanes 5 and 6). Finally, IN and U3U5 on one side and (52–96)Vpr with pSP70 on the other side were pre-incubated for 10 min on ice before being mixed together (lane 7). The nature of the integration product is reported on the right: ³²P-labeled U3U5 substrate (a), homologous integration products (b) and heterologous integration products (c).