title: Genetic recombination of bacterial plasmid DNA. Physical and genetic analysis of the products of plasmid recombination in Escherichia coli.
abstract: Derivatives of plasmid pBR322 DNA containing tet mutations were constructed by inserting XhoI linkers at various sites in the tetracycline resistance gene. Monomer plasmids containing either the tet-10 allele located at nucleotide position 23 or the tet-14 allele located at nucleotide position 1267 were used to construct a circular dimer containing one copy of each allele and a circular trimer containing one copy of the tet-10 allele and two copies of the tet-14 allele. Genetic recombination of these plasmid DNAs to produce a functional tetracycline resistance gene could be detected as the production of tetracycline-resistant progeny during the growth of transformants or using a restriction mapping assay which detected the rearrangement of the mutant alleles. The structure of individual tetracycline-resistant recombination products was determined by restriction mapping. This analysis suggested that as many as 70% of the plasmid recombination events in Escherichia coli AB1157 could have involved gene conversion events. The formation of these recombination products was most easily predicted by a model involving figure 8 recombination intermediates and the formation of symmetric regions of heteroduplex. Recombination in JC10287 delta(srlR-recA)304 occurred at 5% of the wild-type frequency and appeared to occur by a similar mechanism. Recombination in JC9604 recA56 recB21 recC22 sbcA23 occurred at 20 times the wild-type frequency and appeared to involve multiple independent recombination events.
mesh_terms: D004262:DNA Restriction Enzymes; D004269:DNA, Bacterial / Q000235:genetics*; D004352:Drug Resistance, Microbial; D004587:Electrophoresis, Agar Gel; D004926:Escherichia coli / Q000235:genetics*; D005785:Gene Conversion; D005798:Genes, Bacterial; D009154:Mutation; D009692:Nucleic Acid Heteroduplexes / Q000235:genetics; D010957:Plasmids; D011995:Recombination, Genetic; D013752:Tetracycline
chemical_list: D004269:DNA, Bacterial; D009692:Nucleic Acid Heteroduplexes; D004262:DNA Restriction Enzymes; D013752:Tetracycline