title: Non-chromosomal antibiotic resistance in bacteria. 3. Isolation of the discrete transfer unit of the R-factor R1.
abstract: A covalently-closed circular DNA species, banding at a buoyant density of rho = 1.709 g/cm(3) in CsCl, has been identified in antibiotic-sensitive colonies of E. coli strain AB2463 (rec A(-)) after mating with a Proteus mirabilis strain that carries the R-factor, R1. This plasmid, which represents a stable segregant of R1 that has lost all of the drug resistance determinants present on the parent R-factor but which has retained its ability to be transferred by conjugation, fulfills the functional definition of the R-factor transfer unit (RTF).
mesh_terms: D000900:Anti-Bacterial Agents; D001431:Bacteriological Techniques; D002499:Centrifugation, Density Gradient; D002586:Cesium; D002712:Chlorides; D003227:Conjugation, Genetic; D003433:Crosses, Genetic; D004247:DNA / Q000378:metabolism; D004269:DNA, Bacterial / Q000032:analysis*; D004352:Drug Resistance, Microbial; D004926:Escherichia coli / Q000032:analysis*; D011511:Proteus / Q000032:analysis*; D011513:Proteus mirabilis / Q000378:metabolism; D013395:Sucrose; D014316:Tritium
chemical_list: D000900:Anti-Bacterial Agents; D002712:Chlorides; D004269:DNA, Bacterial; D014316:Tritium; D002586:Cesium; D013395:Sucrose; D004247:DNA