Probably represses a number of genes involved in the response to DNA damage (SOS response), including itself, recA, uvrA, ruvAB and ssb (PubMed:15528664). The probable consensus LexA box is 5'-TGCAC-N4-GTGCA-3' (PubMed:15528664). In the presence of single-stranded DNA, RecA interacts with LexA causing an autocatalytic cleavage which disrupts the DNA-binding part of LexA, leading to derepression of the SOS regulon and eventually DNA repair (Probable). Hydrolysis of Ala-|-Gly bond in repressor LexA. Homodimer. Belongs to the peptidase S24 family.