title: Promoters largely determine the efficiency of repressor action.
abstract: Operator sequence and repressor protein regulate the activity of the lac promoter over a greater than 1000-fold range. Combinations of the lac operator with other promoter sequences, however, differ vastly in the level of repression. The data presented show that the extent of repression is determined largely by the rates of complex formation of the competing systems operator-repressor and promoter-RNA polymerase and by the rate at which RNA polymerase clears the promoter. Moreover, up to 70-fold differences in the level of repression were found when the operator was placed in different positions within the promoter sequence. A kinetic model is proposed that explains the observed effects and that allows predictions on promoters controlled by negatively acting elements.
authors.affiliation: Zentrum für Molekulare Biologie, Universität Heidelberg, Federal Republic of Germany.
authors.forename: M
authors.initials: M
authors.lastname: Lanzer
authors.forename: H
authors.initials: H
authors.lastname: Bujard
mesh_terms: D001483:Base Sequence; D004926:Escherichia coli / Q000235:genetics*; D007700:Kinetics; D007763:Lac Operon; D008969:Molecular Sequence Data; D010957:Plasmids; D011401:Promoter Regions, Genetic; D012097:Repressor Proteins / Q000378:metabolism*; D014157:Transcription Factors / Q000378:metabolism*; D014158:Transcription, Genetic
chemical_list: D012097:Repressor Proteins; D014157:Transcription Factors