title: Transcription of bacteriophage deoxyribonucleic acid. Comparison of Escherichia coli and Azotobacter vinelandii sigma subunits.
abstract: The effect of the sigma subunit of RNA polymerase on the rate and asymmetry of the in vitro transcription of Escherichia coli and Azotobacter vinelandii phage DNAs has been studied with purified E. coli and A. vinelandii RNA polymerases and hybrid enzymes containing the core subunits of one enzyme and sigma from the other. The effect of sigma on the rate of transcription is characteristic of the template and not of the enzyme and depends on ionic strength. The rate of transcription of A. vinelandii phage A21 DNA is decreased by sigma at high ionic strength, but shows the more characteristic stimulation at KCl concentrations below 0.05 M. In contrast, the stimulation by sigma of T4 DNA transcription increased with an increase in the KCl concentrations. All combinations of core and sigma subunits behaved similarly with respect to stimulation or inhibition by sigma and with respect to asymmetric transcription of S13 replicative form (RF)DNA. However, the heterologous, but not the homologous combinations of core and sigma transcribed A21 symmetrically. S13 RF DNA in the superhelical, but not in the relaxed configuration, is transcribed asymmetrically by the A. vinelandii core enzyme. A role for the core subunits in specific site recognition is indicated by this observation.
mesh_terms: D000818:Animals; D001395:Azotobacter / Q000201:enzymology*; D001435:Bacteriophages / Q000201:enzymology*; D002417:Cattle; D002499:Centrifugation, Density Gradient; D003090:Coliphages / Q000201:enzymology*; D004247:DNA; D004267:DNA Viruses / Q000378:metabolism; D004279:DNA, Viral / Q000378:metabolism*; D012321:DNA-Directed RNA Polymerases / Q000302:isolation & purification / Q000378:metabolism*; D004926:Escherichia coli / Q000201:enzymology*; D046911:Macromolecular Substances; D009693:Nucleic Acid Hybridization; D009994:Osmolar Concentration; D011189:Potassium Chloride; D013698:Templates, Genetic; D013950:Thymus Gland; D014158:Transcription, Genetic / Q000187:drug effects
chemical_list: D004279:DNA, Viral; D046911:Macromolecular Substances; D011189:Potassium Chloride; D004247:DNA; D012321:DNA-Directed RNA Polymerases