Is involved in the RecE pathway of recombination. Catalyzes the degradation of double-stranded DNA. Acts progressively in a 5' to 3' direction, releasing 5'-phosphomononucleotides. Has a strong preference for linear duplex substrate DNA and appears to be unable to initiate degradation from single-stranded breaks in DNA. Homotetramer. Transcription is increased specifically in response to 2,4,6-trinitrotoluene (TNT) and its indicator compounds 1,3-DNB, 2,4-DNT, and 2,6-DNT. Has been used to construct a 2,4,6-trinitrotoluene (TNT) biosensor strain. Encoded in the Rac prophage. The protein sequences in X55956 are all from mutants in which fusions to an internal fragment of recE have occurred.