Fig 3.

Reporter system for the screening of randomized kasOp₃ mutants not repressed by ScbR. (A) Schematic representation of the reporter system, which bears two plasmids: a ScbR expression plasmid and a reporter plasmid. The promoter library was constructed by inserting the mutant promoters into the reporter plasmid. The bioluminescence of the reporter indicates whether the mutant promoters were regulated by ScbR. (B) Bioluminescence levels of the strains in which ScbR repression was abolished screened by the two-plasmid reporter system at the time of the stationary phase. (C) Sequences of the site OA region of native kasOp and four mutants not repressed by ScbR. Promoter kasOp₃₆₁ is renamed kasOp*. RBR is the abbreviation of Random mutational Binding Region. The gray letters represent the sequence of the partial −35 and −10 region. The dashed arrows represent the palindromic sequence of the OA site.