Abortive termination of bioBFCD RNA synthesized in vitro from the bioABFCD operon of Escherichia coli K-12.

The nature of divergent transcription from the bioABFCD gene cluster of Escherichia coli K-12 has been studied in vitro by using DNA restriction fragments as templates. The in vitro RNA transcript initiated at the promoter pa was found to be similar to the in vivo bioA transcript, whereas the transcription initiated at pB produced a small piece of RNA less than 200 nucleotides long. Substituting ITP for GTP or using an S100 cell-free extract as a source of antiterminator permitted transcription of the bioBFCD gene cluster initiating at the promoter pB to be read through. The possible site for in vitro transcription termination in the bioB region is discussed.