Deletion analysis of the Escherichia coli rho-dependent transcription terminator trp t'

We have analyzed with deletion mutations the Escherichia coli rho-dependent transcription terminator trp t'. This site, 211 nucleotides in length, contains multiple sequence elements that are recognized by rho. Among these multiple elements are two that together appear to be important for full transcription termination efficiency in vitro and are similar to the rutA and rutB sequence elements in the lambda tR1 rho-dependent terminator previously described by Chen and Richardson (1987). The results suggest for the first time that common functionally important elements are shared among rho-dependent terminators. Other regions of trp t' also appear to contribute to its functional efficiency, consistent with the idea that rho-dependent terminators contain dispersed and redundant recognition segments.