title: Cloning of small DNA fragments containing the Escherichia coli tryptophan operon promoter and operator.
abstract: A41-bp AluI restriction fragment from the trp promoter-operator region has been cloned into the PvuII site of pBR322, regenerating PvuII sites. Transformants were selected on media that allowed the selection of trp-operator-bearing plasmids. The cloned 41-bp fragment can be released from the vector by PvuII digestion, and it possesses a functional promoter and operator as demonstrated by in vivo tests. The 41-bp fragment contains several restriction sites: HincII, TaqI, RsaI, and a HpaI site that is located at the center of the operator sequence. Two new operator derivatives, symmetrical about the HpaI site, were prepared from the 41-bp fragment by joining two right-side, or two left-side PvuII-HpaI pieces together at the HpaI site. These derivatives showed in vivo operator activity. Plasmids containing up to five copies of the 41-bp trp-promoter-operator fragment have been constructed. These plasmids should be useful in preparing large amounts of the 41-bp fragment.
mesh_terms: D003001:Cloning, Molecular; D004262:DNA Restriction Enzymes / Q000378:metabolism; D004269:DNA, Bacterial / Q000235:genetics*; D004926:Escherichia coli / Q000235:genetics*; D009876:Operon; D010957:Plasmids; D014158:Transcription, Genetic; D014364:Tryptophan / Q000235:genetics*
chemical_list: D004269:DNA, Bacterial; D014364:Tryptophan; D004262:DNA Restriction Enzymes