Initiation of genetic recombination and recombination-dependent replication

Recombination initiates at double-stranded DNA breaks and at single-strande d DNA gaps. These DNA strand discontinuities can arise from DNA-damaging ag ents and from normal DNA replication when the DNA polymerase encounters an imperfection in the DNA template or another protein. The machinery of homol ogous recombination acts at these breaks and gaps to promote the events tha t result in gene recombination, as well as the reattachment of detached rep lication arms and the resumption of DNA replication. In Escherichia coli, t hese events require collaboration (RecA, RecBCD, RecFOR, RecQ, RuvABC and S SB proteins) and DNA replication (PriABC proteins and the DNA polymerases). The initial steps common to these recombination and recombination-dependen t replication processes are reviewed.