title: In vitro transcription initiation from three different Escherichia coli promoters. Effect of supercoiling.
abstract: Transcription initiation from beta-lactamase, tetracycline resistance and RNA 1 promoters, present in plasmid pAT153, were studied employing the abortive initiation technique. Assays appear to be promoter-specific with supercoiled and linear templates. Supercoiling enhances the isomerization rate constant of the open RNA-polymerase--promoter complex formation. Results agree with the in vivo behaviour of the corresponding promoters, and allow us to propose a hypothesis about the effect of supercoiling on transcription initiation.
mesh_terms: D004278:DNA, Superhelical / Q000235:genetics*; D012321:DNA-Directed RNA Polymerases / Q000378:metabolism; D004352:Drug Resistance, Microbial; D004926:Escherichia coli / Q000201:enzymology / Q000235:genetics*; D005786:Gene Expression Regulation; D009876:Operon; D013379:Substrate Specificity; D013752:Tetracycline / Q000494:pharmacology; D014158:Transcription, Genetic; D001618:beta-Lactamases / Q000235:genetics
chemical_list: D004278:DNA, Superhelical; D012321:DNA-Directed RNA Polymerases; D001618:beta-Lactamases; D013752:Tetracycline