Transcription pausing signal detected by sense/antisense transcription

We studied elongation pausing during transcription in vitro on both the sense and the antisense strands of a given gene fragment(5' end of the bla gene of Tn3). The average transcription rate on the sense strand was much lower than that of the antisense strand, and several pauses observed on the former have no detectable antisense partner. A pausing signal was identified, associated with an (AT)6 sequence, in the vicinity of a strong pause on the sense strand and the sole detected pause on the antisense strand. Mutation of this sequence strongly reduced, by a common factor, pausing times at both sites.