FIGURE 8.

A role for ATP hydrolysis during the homology search. A, initial interactions between the RecA presynaptic complex and the dsDNA involve multiple ≥8-bp footholds while minimizing interactions with shorter tracts of microhomology. These ≥8-bp footholds are released more rapidly in the presence of ATP compared with reactions with ATPγS allowing for a more efficient search process. B, iterative binding and release events allow the presynaptic complex to search the dsDNA by intersegmental transfer (IS), as previously demonstrated. C, full alignment can take place quickly once the first correct pairing event has been established. Additional details are presented in the text. D, models for the role of ATP hydrolysis in the release of a single dsDNA foothold. Details are presented under “Discussion.”