Site-specific recA-independent recombination (fusion) of pMB8-related replicons in Escherichia coli in the region of the replication origins |
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Authors: | N V Tomilin J Hofemeister |
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Affiliation: | 1. Institute of Cytology of the Academy of Sciences of the USSR, LeningradU.S.S.R.;1. Zentralinstitut für Genetik und Kulturpflanzenforschung of the Academy of Sciences of the GDR, GaterslebenG.D.R. |
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Abstract: | Escherichia coli recA+ and recA- cells were co-transformed with a mixture of pMB9 (Tcr) and pST8-26 (Apr, pBR325 derivative) plasmid DNAs followed by selection on plates containing both tetracycline and ampicillin. A set of stable Tcr Apr derivatives was isolated from these transformants. Many of the stable Tcr Apr segregants contained fused pMB9::pST8-26 plasmids with lengths that were about 0.8 kb longer than the sum of the lengths of the parental plasmids; one plasmid (pTF8) was about 1.5 kb shorter. The fusion was not stimulated by UV irradiation of co-transformants and occurred both in recA+ and recA- genetic backgrounds. Restriction analysis of the fused plasmids showed the two replicons were in the same relative orientation, and also indicated unique points of fusion in most cases (in 9 out of 10) which are localised within the 1.6-kb regions around the replication origins (RO). Because the fusion of plasmids of the type used in this study was not described before we have tentatively named it RO-fusion (Replication-Origin-fusion). |
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Keywords: | Plasmid fusion restriction mapping Ap, ampicillin bp, base pairs cccDNA, circular covalently closed DNA kb kilobase pairs RO replication origin tetracycline resistance tk thymidine kinase |
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