title: Origin of Escherichia coli K-12 Hfr B7.
abstract: Several F' plasmids encoding resistance to tetracycline have been derived from a trg::Tn10 Hfr B7 strain of Escherichia coli K-12. One of these plasmids, JGF312, was analyzed by restriction endonuclease digestion and Southern blot hybridization to cloned chromosomal fragments. This analysis revealed that JGF312 was formed by Tn10-promoted deletion from the Tn10 insertion (31.4 min) to within the prophage rac at 30.1 min. Hfr B7 was shown to result from recombination between IS2 of F delta (33-43) and a chromosomal IS2 located within the rac-man region at 30.9 min on the genetic map.
mesh_terms: D002876:Chromosomes, Bacterial; D004262:DNA Restriction Enzymes; D004251:DNA Transposable Elements; D015246:Deoxyribonuclease EcoRI; D015247:Deoxyribonuclease HindIII; D015252:Deoxyribonucleases, Type II Site-Specific; D004926:Escherichia coli / Q000235:genetics*; D005144:F Factor; D009693:Nucleic Acid Hybridization; D011995:Recombination, Genetic
chemical_list: D004251:DNA Transposable Elements; D004262:DNA Restriction Enzymes; D015246:Deoxyribonuclease EcoRI; D015247:Deoxyribonuclease HindIII; C024388:CTGCAG-specific type II deoxyribonucleases; D015252:Deoxyribonucleases, Type II Site-Specific