title: Class of small multicopy plasmids originating from the mutant antibiotic resistance factor R1 drd-19B2.
abstract: The large mutant R-factor R1drd-19B2 gives rise to several classes of small, covalently closed circular deoxyribonucleic acids (DNAs), designated as Rsc DNAs, when harbored by the K-12 strain CRT46 which carries a dnaA mutation. The molecular weights of these DNA molecules range from 3 X 106 to 8.4 X 106. Cells arising from single colonies of CRT46-R1drd-19B2 harbor only one to two copies of the large mutant R-factor and in addition 10 to 20 copies of Rsc plasmid of a discrete size class per chromosome. The larger Rsc DNAs carry the ampicillin resistance gene. After transformation the small circular DNAs are present in Escherichia coli C in a large number of copies, up to 100 copies per chromosome. Hybridization studies between Rsc plasmids indicate that they possess common DNA sequences.
mesh_terms: D000667:Ampicillin / Q000494:pharmacology; D002701:Chloramphenicol / Q000494:pharmacology; D002876:Chromosomes, Bacterial / Q000032:analysis; D004269:DNA, Bacterial / Q000096:biosynthesis*; D004270:DNA, Circular / Q000096:biosynthesis*; D004926:Escherichia coli / Q000187:drug effects / Q000502:physiology*; D005111:Extrachromosomal Inheritance; D005796:Genes; D007612:Kanamycin / Q000494:pharmacology; D008970:Molecular Weight; D009154:Mutation; D009693:Nucleic Acid Hybridization; D010403:Penicillin Resistance; D010957:Plasmids; D011815:R Factors; D013307:Streptomycin / Q000494:pharmacology; D013449:Sulfonamides / Q000494:pharmacology; D014170:Transformation, Genetic
chemical_list: D004269:DNA, Bacterial; D004270:DNA, Circular; D013449:Sulfonamides; D007612:Kanamycin; D002701:Chloramphenicol; D000667:Ampicillin; D013307:Streptomycin