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- Title
The plasmid system of Escherichia coli strain UR12644: Identification and molecular characteristics of transposons involved in the generation of endogenous R-plasmids.
- Authors
Schöffl, F.; Pühler, A.
- Abstract
Two spontaneously formed R-plasmids (pFS401 and pFS402) originating from the multiple drug-resistant Escherichia coli strain UR12644 were found to carry transposable drug-resistance elements. Incompatibility between these two plasmids was used to select for transposition. An ampicillin transposon (Tn1781) residing on pFS401 and a tetracycline transposon (Tn1771) present on pFS402 were independently translocated to the endogenous RTF-plasmid pFS2. Molecular weight determinations of pFS2::Tn1781(Ap) and pFS2::Tn1771(Tc) revealed a value of 2·9 Mdal for Tn1781 and 7·1 Mdal for Tn1771. The arrangement of 3 PstI and 1 BamHI restriction endonuclease sites was found to be characteristic for the ampicillin transposon whereas the restriction map of Tn1771 features a nearly symmetrical location of 3 EcoRI cleavage sites, two of them close to the termini and one in the middle of the transposon. A model is presented suggesting the existence of repetitive DNA-segments at these positions which represent the structural preconditions for the genetic properties of Tn1771. The role of a cryptic plasmid involved in the generation of the endogenous R-plasmids pFS401 and pFS402 is discussed.
- Publication
Genetics Research, 1979, Vol 34, Issue 3, p287
- ISSN
0016-6723
- Publication type
Article
- DOI
10.1017/S0016672300019522