Sex Factor Activity of Drug-Resistance Factors. In: Wolstenholme GEW, O'connor M, editors. Ciba Foundation Symposium - Bacterial Episomes and Plasmids. Chichester: John Wiley & Sons, Ltd.; 1969. pp. 120-35. [DOI: 10.1002/9780470715345.ch8]

Asymmetry and extent of in vivo transcripition of R-plasmid deoxyribonucleic acid in Escherichia coli

Deoxyribonucleic acid-ribonucleic acid (DNA-RNA) hybridization studies have been performed with R-plasmid DNA (R538-1drd) and in vivo-synthesized RNA. R-plasmid DNA was isolated from Escherichia coli K-12, and the complementary strands were separated in cesium chloride-polyuridylic acid-polyguanylic acid gradients. DNA-RNA hybridization was performed with the separated DNA strands and RNA purified from R-plasmid-carrying cells. The results demonstrated that an asymmetric transcription of the R-plasmid DNA occurs in vivo. Hybridization was only detected with the H strand (denser strand in cesium chloride-polyuridylic acid-polyguanylic acid). By determining the density of the RNA-DNA hybrid in CsCl gradients, it was estimated that greater than 60% of the nucleotide sequences in the R-plasmid DNA are transcribed in logarithmically growing E. coli cells. No R-plasmid-specific RNA was detected in E. coli cells that did not carry the plasmid.

Polynucleotide sequence relationships among some bacterial plasmids

The deoxyribonucleic acid of F-like plasmids appear to share a high degree of nucleotide similarity with each other but are not highly related to I-like plasmids.