FIGURE 6.

The RecA-RFP promotes DNA strand exchange in the presence of ATP or dATP at pH 6.2. DNA strand exchange was carried out with 5′-end labeled linear dsDNA, circular ssDNA, and either wild-type or the fluorescent RecA protein at either pH 7.5 or 6.2. A, DNA strand exchange in the presence of ATP. B, DNA strand exchange in the presence of dATP. The bands are labeled as follows: joint molecule, homologously paired joint molecule intermediate; ncDNA, nicked circular dsDNA product; dsDNA, linear dsDNA substrate; ssDNA, the displaced ssDNA product of complete DNA strand exchange.