Represses dinA, dinB, dinC, recA genes and itself by binding to the 14 bp palindromic sequence 5'-CGAACNNNNGTTCG-3'; some genes have a tandem consensus sequence and their binding is cooperative (PubMed:1657879, PubMed:8969214, PubMed:9555905). 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; autocleavage is maximal at pH 11 in the absence of RecA and ssDNA (PubMed:8969214). Hydrolysis of Ala-|-Gly bond in repressor LexA. Homodimer. Expressed during the entire cell cycle with at least a threefold increase when cells develop competence. By mitomycin, requires an intact dinR gene (PubMed:1657879). An SOS-independent induction of dinR occurs during competence, does not require an intact dinR gene (PubMed:1657879). Following treatment with mitomycin C protein levels begin to decrease after a 5-min lag and do not return to their original levels for at least 90 min. 100-fold decrease in homologous recombination efficiency. Belongs to the peptidase S24 family.