title: Further characterization of the R plasmid Rts1 and its mutant pTW2: replication and incompatibility of the plasmid.
abstract: Incompatibility of the R plasmid Rts1 and its replication mutant pTW2 was studied in recA host cells of Escherichia coli. When the R plasmid R401, belonging to the same incompatibility group as Rts1, was used as a test plasmid, R401 was eliminated preferentially from (Rts-R401)+ cells irrespective of the direction of transfer. In contrast, pTW2 and R401 were mutually excluded. The decreased incompatibility of pTW2 was confirmed by a direct incompatibility test in which a derivative of Rts1 expelled pTW2 exclusively. Alkaline sucrose gradients of pTW2 and Rts1 DNA indicated that approximately one-fourth of the Rts1 genome was deleted in pTW2. In addition, both the various temperature-dependent properties of Rts1 and the inhibitory effect on phage T4 development were also lost in pTW2. A possible mechanism that regulates the stringent replication of Rts1 is discussed.
mesh_terms: D003090:Coliphages / Q000254:growth & development; D004261:DNA Replication; D004269:DNA, Bacterial / Q000096:biosynthesis* / Q000235:genetics; D004270:DNA, Circular / Q000096:biosynthesis* / Q000235:genetics; D004926:Escherichia coli / Q000235:genetics*; D010957:Plasmids; D013696:Temperature
chemical_list: D004269:DNA, Bacterial; D004270:DNA, Circular