Prevalence of recombinational versus mutational events in damaged plasmid DNA containing regions of homology with the chromosome.
Plasmid DNA modified by in vitro treatments was transformed in E. coli bacterial cells. A streptomycin-resistant strain, carrying the peculiar rpsL421 mutation, was used as a recipient for the cloning vector pNO1523, which carries the wild-type (streptomycin-sensitive) rpsL allele. Transformants were streptomycin-sensitive unless a change in plasmid sequence had occurred. The analysis of the MaeI restriction pattern of plasmids isolated from streptomycin-resistant transformants, together with the detection of the phenotype that they conferred to a streptomycin-dependent strain, allowed us to identify plasmids that had undergone recombination with the host chromosome. The number of these plasmids exceeded by far that of plasmids resulting from mutational events.
Institute of Microbiology, University of Trieste, Italy.
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Dolzani
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Lagatolla
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Monti-Bragadin
D002876:Chromosomes, Bacterial; D002945:Cisplatin / Q000494:pharmacology; D004249:DNA Damage; D004269:DNA, Bacterial / Q000187:drug effects / Q000235:genetics* / Q000528:radiation effects; D015252:Deoxyribonucleases, Type II Site-Specific; D004352:Drug Resistance, Microbial / Q000235:genetics; D004926:Escherichia coli / Q000235:genetics; D029968:Escherichia coli Proteins; D005020:Ethyl Methanesulfonate / Q000494:pharmacology; D016296:Mutagenesis; D010641:Phenotype; D010957:Plasmids; D012150:Polymorphism, Restriction Fragment Length; D011995:Recombination, Genetic; D000091243:Ribosomal Protein S9; D013014:SOS Response, Genetics; D012689:Sequence Homology, Nucleic Acid; D014169:Transformation, Bacterial; D014466:Ultraviolet Rays
D004269:DNA, Bacterial; D029968:Escherichia coli Proteins; D000091243:Ribosomal Protein S9; C000717190:RpsI protein, E coli; D005020:Ethyl Methanesulfonate; C040836:CTAG-specific type II deoxyribonucleases; D015252:Deoxyribonucleases, Type II Site-Specific; D002945:Cisplatin