title: [Transcription initiation: influence of ionic strength and actinomycin D on the kinetics of the open promoter complex formation between Escherichia coli RNA-polymerase and T7 DNA].
abstract: A membrane filter assay has been devised to study the influence of ionic strength (0--150 mM NaCl) and actinomycin D on the kinetics of the open promoter complex formation between E. coli RNA-polymerase and [3H]DNA of T7 phage. The dependence of the complex formation rate upon the ionic strength is non-monotoneus with a maximum at 75--100 mM. The addition of one actinomycin molecule per 200 base pairs decreases the open promoter complex formation rate at ionic strength less than 100 mM. A promoter site selection model including liner diffusional selection is proposed which is in a good agreement with the experimental results obtained.
mesh_terms: D004279:DNA, Viral / Q000378:metabolism*; D012321:DNA-Directed RNA Polymerases / Q000378:metabolism*; D003609:Dactinomycin / Q000494:pharmacology*; D004926:Escherichia coli / Q000201:enzymology*; D007700:Kinetics; D008433:Mathematics; D009994:Osmolar Concentration; D013604:T-Phages; D014158:Transcription, Genetic / Q000187:drug effects
chemical_list: D004279:DNA, Viral; D003609:Dactinomycin; D012321:DNA-Directed RNA Polymerases
vernacular_title: Initsiatsiia transkriptsii: vliianie ionnoĭ sily i aktinomitsina D na kinetiku formirovaniia otkrytykh promotornykh kompleksov RNK-polimerazy Escherichia coli s DNK faga T7.