title: Autoregulation of repressor synthesis in bacteriophage lambda imm434.
abstract: A 550-bp DNA fragment derived from the immunity region of phage lambda imm434 and carrying the wild-type prm promoter has been inserted upstream of the lacZ gene, in the beta 2 region of an 'in-vitro'-constructed transducing phage. In strains lysogenized with this phage, the rates of transcription from the 434-prm promoter can be assayed as units of beta-galactosidase in the absence or in the presence of increasing levels of 434 repressor. The results obtained indicate the existence of a mechanism of autoregulation for repressor maintenance in strains lysogenic for wild-type phage 434. The rate of transcription from prm in a (434) lysogen is of the same magnitude as that in a (lambda ) lysogen, and, as in the case of lambda , high levels of repressor repress prm whereas low levels stimulate it. An estimation of the strength of the leftward promoters located in the right half of the lambda beta 2 region compared with 434 prm was also obtained.
mesh_terms: D010582:Bacteriophage lambda / Q000235:genetics*; D003090:Coliphages / Q000235:genetics; D004262:DNA Restriction Enzymes; D004274:DNA, Recombinant / Q000378:metabolism; D005786:Gene Expression Regulation; D007763:Lac Operon; D009876:Operon; D012097:Repressor Proteins / Q000378:metabolism*; D014157:Transcription Factors / Q000378:metabolism*; D001616:beta-Galactosidase / Q000378:metabolism
chemical_list: D004274:DNA, Recombinant; D012097:Repressor Proteins; D014157:Transcription Factors; D004262:DNA Restriction Enzymes; D001616:beta-Galactosidase