In vitro mutagenesis creates kni binding sites 50bp 5' and 3' of the dl1 and dl4 sites respectively.
Construct: w gene expression is governed by the same regulatory region, though in the opposite relative orientation, as Ecol\lacZrho.50:50.kni, i.e. 700bp rho promoter fragment, maps between -2.2 and -1.5kb upstream of the rho transcription start site, that lacks all four sna-binding sites and has one synthetic sna-binding site 50bp downstream of d4, with kni binding sites created by in vitro mutagenesis 50bp 5' and 3' of the dl1 and dl4 sites respectively.