A dual-circular plasmid structure dependent on DNA replication generated in monkey COS7 cells and cell extracts.
When monkey COS7 cells are transfected with plasmids pSVod or pSV2-neo, a DNA structure can be detected consisting of two circular forms linked by a duplex bridge. Generation of this structure is enhanced by camptothecin, an inhibitor of DNA topoisomerase I. Generation of dual-circles in vitro, using a DNA replication system with added T-antigen, requires template DNA with an SV40 origin. Heterogeneous dual-circles can be visualized involving two initially independent molecules of different size. Implications for in vitro studies of certain types of recombination are discussed.
Jenab
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Brookdale Center for Molecular Biology, Mount Sinai School of Medicine, New York, NY 10029.
Johnson
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EM
D000818:Animals; D002166:Camptothecin / Q000494:pharmacology; D002460:Cell Line; D004261:DNA Replication; D004270:DNA, Circular; D004279:DNA, Viral; D000882:Haplorhini; D008854:Microscopy, Electron; D009690:Nucleic Acid Conformation; D010957:Plasmids; D011995:Recombination, Genetic; D013539:Simian virus 40 / Q000235:genetics*; D059004:Topoisomerase I Inhibitors; D014162:Transfection
D004270:DNA, Circular; D004279:DNA, Viral; D059004:Topoisomerase I Inhibitors; D002166:Camptothecin