Transcription of the argF and argI genes of the arginine biosynthetic regulon of Escherichia coli K12, performed in vitro.

The cell-free transcription of the argF and argI genes of the arginine biosynthetic regions is described using an S-30 system capable of coupled in vitro transcription-translation. Template DNA isolated from two independently isolated arginine transducing phages was used in this work. Steady state mRNA synthesis was observed which was attributed to RNAase degradation. Regulation of argF mRNA synthesis, directed by the argF gene carried on the specialized transducing phage phi80dargF is effected to the extent of at least 95% by the arginine holorepressor at the transcriptional stage and at least 80% of the regulation of the expression of the argI gene is mediated at the transcriptional stage. Evidence is presented which indicates that the arginine holorepressor prevents RNA polymerase from binding to the arginine promoter and suggests that the operator and promoter sites may overlap.