Increased production of a knotted form of plasmid pBR322 DNA in Escherichia coli DNA topoisomerase mutants
1987; Elsevier BV; Volume: 195; Issue: 1 Linguagem: Inglês
10.1016/0022-2836(87)90338-x
ISSN1089-8638
AutoresKazuo Shishido, Naoki Komiyama, S Ikawa,
Tópico(s)Lung Cancer Research Studies
ResumoPlasmid pBR322 prepared from Escherichia coli strains carrying deletion of the DNA topoisomerase I gene (delta topA) with a compensatory mutation of the DNA gyrase gene (gyrA or gyrB) and from their TopA+ transductants was analyzed by agarose gel electrophoresis followed by electron microscopy, and compared with that from isogenic wild-type strains. It was found that about 1% of the plasmid DNA molecules was a knotted species in the topA+ gyr+ strains W3110 and DM4100, while strains DM750 (delta topA gyrA224), DM800 (delta topA gyrB225), SD275 (topA+ gyrA224) and SD108 (topA+ gyrB225) produced six to ten times as much knotted DNA as the topA+ gyr+ controls. The results suggest that the increased production of knotted pBR322 DNA is closely related to mutations of the gyrase genes.
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