FIGURE 7.

Hypothetical model of strand exchange and annealing reactions mediated by RecO(R). 1, RecOR binds SSB-ssDNA and promotes conformational changes of ssDNA favorable for recruitment of RecA to ssDNA at the site of stalled replication or (2A) to the recessed ssDNA end at dsDNA break (DSB). Alternately, (2B) RecO forms intermediate complexes with SSB-ssDNA and facilitates SSA when complementary ssDNA is available during a second-end capture reaction or (3) during annealing of repetitive ends. Reversibility of each intermediate step eliminates the inhibitory effect of RMPs on other functions of SSB-ssDNA complexes and permits selective activation of each pathway only under kinetically favorable conditions.