Can catalyze the hydrolysis of ATP in the presence of single-stranded DNA, the ATP-dependent uptake of single-stranded DNA by duplex DNA, and the ATP-dependent hybridization of homologous single-stranded DNAs. It interacts with LexA causing its activation and leading to its autocatalytic cleavage. Plays a central role in DNA metabolism, participating in general homologous recombination, recombinational (postreplication) DNA repair, and prophage induction. Belongs to the RecA family.