Identification of a promoter motif regulating the major DNA damage response mechanism of Mycobacterium tuberculosis.

The principal response of many bacteria to DNA damage is mediated by a mechanism dependent on the LexA and RecA proteins. However, Mycobacterium tuberculosis was recently reported to regulate a majority of DNA repair genes independently of RecA and LexA, suggesting that an unknown RecA/LexA-independent mechanism controls the major DNA damage response pathway in this organism. Here we have identified a motif tTGTCRgtg-8nt-TAnnnT that defines a novel RecA/LexA-independent promoter (RecA-NDp) of M. tuberculosis. Furthermore, we show that the RecA-NDp type of promoter precedes DNA repair genes in other Actinomycetales.