Transcription analysis of the lexA gene of Escherichia coli: attenuation and cotranscription with the neighboring region.

The lexA gene of Escherichia coli encodes a repressor of the genes whose expression is induced by the agents that result in DNA damage. In vivo transcripts of the lexA gene consisted of two species; mRNA-1 of 673 bases and mRNA-2 of approximately 3,000 bases. The transcription in vivo started at a site which was two-base pairs downstream from the in vitro initiation site reported previously. The majority of the transcription stopped at a series of T residues preceeded by a dyad symmetry located immediately after the lexA gene. A small fraction of the transcription passed through the termination site to form the mRNA of downstream gene(s) which would be related to the "SOS functions".