The relationship between function and DNA sequence in an intercistronic regulatory region in phage lambda.

rho factor-mediated transcription termination at the tr1 terminator site of bacteriophage lambda is examined. Mutations affecting the termination event are characterised. These mutations define features of the site which seem to be important to terminator function. In addition, other related transcriptional and translational regulatory elements are defined within the region surrounding the termination site. The potential molecular interactions and structural overlaps of these control signals apparently couple the regulation of the decision between lytic and lysogenic growth patterns by phage lambda.