MUTATION DISTAL TO THE MESSENGER-RNA ENDPOINT REDUCES TRANSCRIPTION TERMINATION IN THE TRYPTOPHAN OPERON IN ESCHERICHIA-COLI

Mutations abolishing transcription termination were isolated in the region in which transcription of the trytophan (trp) operon normally terminates. This region of the wild type and mutant strains was incorporated into the genome of bacteriophage λ, and phage DNA was analyzed by digestion with restriction endonucleases. The 15 independently isolated mutations were shown to be deletions ranging in extent from 200 to 1000 base-pairs, which lie past the end of the trp operon. One of the mutations causing readthrough into distal lactose (lac) genes deletes 185 base-pairs, beginning 60 nucleotides beyond the point where messenger RNA synthesis ceases in vivo. We infer that the nature of sequences some distance beyond the point of transcription termination can influence the extent of termination at that site. © 1979.