Schematic model of the transcription autoregulation of the operon

Copyright information: Taken from "Interactions of Kid–Kis toxin–antitoxin complexes with the operator-promoter region of plasmid R1 are piloted by the Kis antitoxin and tuned by the stoichiometry of Kid–Kis oligomers"Nucleic Acids Research 2007;35(5):1737-1749.Published online 21 Feb 2007PMCID:PMC1865072.© 2007 The Author(s) The gene and the Kid protein are shown in blue and the gene and the Kis protein in orange. Each protein complex is represented by an appropriate combination of blue rectangles (Kid) and orange ellipses (Kis). Free Kid inhibits cell growth. In conditions in which the concentration of Kid is higher than that of Kis Kid–Kis and Kid–Kis–Kid complexes are formed. These complexes repress ribonuclease activity of Kid, but allow efficient transcription. When the concentration of Kid is equal or lower than that of Kis, mostly 1:1 complexes are formed. These complexes do not only repress the ribonuclease activity of Kid, but also the transcription process.